--- jsr166/src/jsr166e/ConcurrentHashMapV8.java 2011/09/21 11:42:08 1.26
+++ jsr166/src/jsr166e/ConcurrentHashMapV8.java 2012/10/21 04:07:13 1.67
@@ -6,6 +6,10 @@
package jsr166e;
import jsr166e.LongAdder;
+import jsr166e.ForkJoinPool;
+import jsr166e.ForkJoinTask;
+
+import java.util.Comparator;
import java.util.Arrays;
import java.util.Map;
import java.util.Set;
@@ -20,7 +24,11 @@ import java.util.Enumeration;
import java.util.ConcurrentModificationException;
import java.util.NoSuchElementException;
import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.locks.LockSupport;
+import java.util.concurrent.locks.AbstractQueuedSynchronizer;
+import java.util.concurrent.atomic.AtomicReference;
+
import java.io.Serializable;
/**
@@ -39,19 +47,22 @@ import java.io.Serializable;
* block, so may overlap with update operations (including {@code put}
* and {@code remove}). Retrievals reflect the results of the most
* recently completed update operations holding upon their
- * onset. For aggregate operations such as {@code putAll} and {@code
- * clear}, concurrent retrievals may reflect insertion or removal of
- * only some entries. Similarly, Iterators and Enumerations return
- * elements reflecting the state of the hash table at some point at or
- * since the creation of the iterator/enumeration. They do
- * not throw {@link ConcurrentModificationException}.
- * However, iterators are designed to be used by only one thread at a
- * time. Bear in mind that the results of aggregate status methods
- * including {@code size}, {@code isEmpty}, and {@code containsValue}
- * are typically useful only when a map is not undergoing concurrent
- * updates in other threads. Otherwise the results of these methods
- * reflect transient states that may be adequate for monitoring
- * or estimation purposes, but not for program control.
+ * onset. (More formally, an update operation for a given key bears a
+ * happens-before relation with any (non-null) retrieval for
+ * that key reporting the updated value.) For aggregate operations
+ * such as {@code putAll} and {@code clear}, concurrent retrievals may
+ * reflect insertion or removal of only some entries. Similarly,
+ * Iterators and Enumerations return elements reflecting the state of
+ * the hash table at some point at or since the creation of the
+ * iterator/enumeration. They do not throw {@link
+ * ConcurrentModificationException}. However, iterators are designed
+ * to be used by only one thread at a time. Bear in mind that the
+ * results of aggregate status methods including {@code size}, {@code
+ * isEmpty}, and {@code containsValue} are typically useful only when
+ * a map is not undergoing concurrent updates in other threads.
+ * Otherwise the results of these methods reflect transient states
+ * that may be adequate for monitoring or estimation purposes, but not
+ * for program control.
*
* The table is dynamically expanded when there are too many
* collisions (i.e., keys that have distinct hash codes but fall into
@@ -71,7 +82,7 @@ import java.io.Serializable;
* versions of this class, constructors may optionally specify an
* expected {@code concurrencyLevel} as an additional hint for
* internal sizing. Note that using many keys with exactly the same
- * {@code hashCode{}} is a sure way to slow down performance of any
+ * {@code hashCode()} is a sure way to slow down performance of any
* hash table.
*
*
This class and its views and iterators implement all of the
@@ -86,7 +97,9 @@ import java.io.Serializable;
* Java Collections Framework.
*
*
jsr166e note: This class is a candidate replacement for
- * java.util.concurrent.ConcurrentHashMap.
+ * java.util.concurrent.ConcurrentHashMap. During transition, this
+ * class declares and uses nested functional interfaces with different
+ * names but the same forms as those expected for JDK8.
*
* @since 1.5
* @author Doug Lea
@@ -94,28 +107,76 @@ import java.io.Serializable;
* @param the type of mapped values
*/
public class ConcurrentHashMapV8
- implements ConcurrentMap, Serializable {
+ implements ConcurrentMap, Serializable {
private static final long serialVersionUID = 7249069246763182397L;
/**
- * A function computing a mapping from the given key to a value,
- * or {@code null} if there is no mapping. This is a place-holder
- * for an upcoming JDK8 interface.
- */
- public static interface MappingFunction {
- /**
- * Returns a value for the given key, or null if there is no
- * mapping. If this function throws an (unchecked) exception,
- * the exception is rethrown to its caller, and no mapping is
- * recorded. Because this function is invoked within
- * atomicity control, the computation should be short and
- * simple. The most common usage is to construct a new object
- * serving as an initial mapped value.
+ * A partitionable iterator. A Spliterator can be traversed
+ * directly, but can also be partitioned (before traversal) by
+ * creating another Spliterator that covers a non-overlapping
+ * portion of the elements, and so may be amenable to parallel
+ * execution.
+ *
+ * This interface exports a subset of expected JDK8
+ * functionality.
+ *
+ *
Sample usage: Here is one (of the several) ways to compute
+ * the sum of the values held in a map using the ForkJoin
+ * framework. As illustrated here, Spliterators are well suited to
+ * designs in which a task repeatedly splits off half its work
+ * into forked subtasks until small enough to process directly,
+ * and then joins these subtasks. Variants of this style can also
+ * be used in completion-based designs.
+ *
+ *
+ * {@code ConcurrentHashMapV8 m = ...
+ * // split as if have 8 * parallelism, for load balance
+ * int n = m.size();
+ * int p = aForkJoinPool.getParallelism() * 8;
+ * int split = (n < p)? n : p;
+ * long sum = aForkJoinPool.invoke(new SumValues(m.valueSpliterator(), split, null));
+ * // ...
+ * static class SumValues extends RecursiveTask {
+ * final Spliterator s;
+ * final int split; // split while > 1
+ * final SumValues nextJoin; // records forked subtasks to join
+ * SumValues(Spliterator s, int depth, SumValues nextJoin) {
+ * this.s = s; this.depth = depth; this.nextJoin = nextJoin;
+ * }
+ * public Long compute() {
+ * long sum = 0;
+ * SumValues subtasks = null; // fork subtasks
+ * for (int s = split >>> 1; s > 0; s >>>= 1)
+ * (subtasks = new SumValues(s.split(), s, subtasks)).fork();
+ * while (s.hasNext()) // directly process remaining elements
+ * sum += s.next();
+ * for (SumValues t = subtasks; t != null; t = t.nextJoin)
+ * sum += t.join(); // collect subtask results
+ * return sum;
+ * }
+ * }
+ * }
+ */
+ public static interface Spliterator extends Iterator {
+ /**
+ * Returns a Spliterator covering approximately half of the
+ * elements, guaranteed not to overlap with those subsequently
+ * returned by this Spliterator. After invoking this method,
+ * the current Spliterator will not produce any of
+ * the elements of the returned Spliterator, but the two
+ * Spliterators together will produce all of the elements that
+ * would have been produced by this Spliterator had this
+ * method not been called. The exact number of elements
+ * produced by the returned Spliterator is not guaranteed, and
+ * may be zero (i.e., with {@code hasNext()} reporting {@code
+ * false}) if this Spliterator cannot be further split.
*
- * @param key the (non-null) key
- * @return a value, or null if none
+ * @return a Spliterator covering approximately half of the
+ * elements
+ * @throws IllegalStateException if this Spliterator has
+ * already commenced traversing elements
*/
- V map(K key);
+ Spliterator split();
}
/*
@@ -134,83 +195,112 @@ public class ConcurrentHashMapV8
* work off Object types. And similarly, so do the internal
* methods of auxiliary iterator and view classes. All public
* generic typed methods relay in/out of these internal methods,
- * supplying null-checks and casts as needed.
+ * supplying null-checks and casts as needed. This also allows
+ * many of the public methods to be factored into a smaller number
+ * of internal methods (although sadly not so for the five
+ * variants of put-related operations). The validation-based
+ * approach explained below leads to a lot of code sprawl because
+ * retry-control precludes factoring into smaller methods.
*
* The table is lazily initialized to a power-of-two size upon the
- * first insertion. Each bin in the table contains a list of
- * Nodes (most often, zero or one Node). Table accesses require
- * volatile/atomic reads, writes, and CASes. Because there is no
- * other way to arrange this without adding further indirections,
- * we use intrinsics (sun.misc.Unsafe) operations. The lists of
- * nodes within bins are always accurately traversable under
- * volatile reads, so long as lookups check hash code and
- * non-nullness of value before checking key equality.
+ * first insertion. Each bin in the table normally contains a
+ * list of Nodes (most often, the list has only zero or one Node).
+ * Table accesses require volatile/atomic reads, writes, and
+ * CASes. Because there is no other way to arrange this without
+ * adding further indirections, we use intrinsics
+ * (sun.misc.Unsafe) operations. The lists of nodes within bins
+ * are always accurately traversable under volatile reads, so long
+ * as lookups check hash code and non-nullness of value before
+ * checking key equality.
*
* We use the top two bits of Node hash fields for control
* purposes -- they are available anyway because of addressing
* constraints. As explained further below, these top bits are
- * usd as follows:
+ * used as follows:
* 00 - Normal
* 01 - Locked
* 11 - Locked and may have a thread waiting for lock
* 10 - Node is a forwarding node
*
* The lower 30 bits of each Node's hash field contain a
- * transformation (for better randomization -- method "spread") of
- * the key's hash code, except for forwarding nodes, for which the
- * lower bits are zero (and so always have hash field == "MOVED").
+ * transformation of the key's hash code, except for forwarding
+ * nodes, for which the lower bits are zero (and so always have
+ * hash field == MOVED).
*
- * Insertion (via put or putIfAbsent) of the first node in an
+ * Insertion (via put or its variants) of the first node in an
* empty bin is performed by just CASing it to the bin. This is
- * by far the most common case for put operations. Other update
- * operations (insert, delete, and replace) require locks. We do
- * not want to waste the space required to associate a distinct
- * lock object with each bin, so instead use the first node of a
- * bin list itself as a lock. Blocking support for these locks
- * relies on the builtin "synchronized" monitors. However, we
- * also need a tryLock construction, so we overlay these by using
- * bits of the Node hash field for lock control (see above), and
- * so normally use builtin monitors only for blocking and
- * signalling using wait/notifyAll constructions. See
- * Node.tryAwaitLock.
+ * by far the most common case for put operations under most
+ * key/hash distributions. Other update operations (insert,
+ * delete, and replace) require locks. We do not want to waste
+ * the space required to associate a distinct lock object with
+ * each bin, so instead use the first node of a bin list itself as
+ * a lock. Blocking support for these locks relies on the builtin
+ * "synchronized" monitors. However, we also need a tryLock
+ * construction, so we overlay these by using bits of the Node
+ * hash field for lock control (see above), and so normally use
+ * builtin monitors only for blocking and signalling using
+ * wait/notifyAll constructions. See Node.tryAwaitLock.
*
* Using the first node of a list as a lock does not by itself
* suffice though: When a node is locked, any update must first
* validate that it is still the first node after locking it, and
* retry if not. Because new nodes are always appended to lists,
* once a node is first in a bin, it remains first until deleted
- * or the bin becomes invalidated. However, operations that only
- * conditionally update may inspect nodes until the point of
- * update. This is a converse of sorts to the lazy locking
- * technique described by Herlihy & Shavit.
+ * or the bin becomes invalidated (upon resizing). However,
+ * operations that only conditionally update may inspect nodes
+ * until the point of update. This is a converse of sorts to the
+ * lazy locking technique described by Herlihy & Shavit.
*
* The main disadvantage of per-bin locks is that other update
* operations on other nodes in a bin list protected by the same
* lock can stall, for example when user equals() or mapping
- * functions take a long time. However, statistically, this is
- * not a common enough problem to outweigh the time/space overhead
- * of alternatives: Under random hash codes, the frequency of
- * nodes in bins follows a Poisson distribution
+ * functions take a long time. However, statistically, under
+ * random hash codes, this is not a common problem. Ideally, the
+ * frequency of nodes in bins follows a Poisson distribution
* (http://en.wikipedia.org/wiki/Poisson_distribution) with a
* parameter of about 0.5 on average, given the resizing threshold
* of 0.75, although with a large variance because of resizing
* granularity. Ignoring variance, the expected occurrences of
* list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
- * first few values are:
+ * first values are:
*
- * 0: 0.607
- * 1: 0.303
- * 2: 0.076
- * 3: 0.012
- * more: 0.002
+ * 0: 0.60653066
+ * 1: 0.30326533
+ * 2: 0.07581633
+ * 3: 0.01263606
+ * 4: 0.00157952
+ * 5: 0.00015795
+ * 6: 0.00001316
+ * 7: 0.00000094
+ * 8: 0.00000006
+ * more: less than 1 in ten million
*
* Lock contention probability for two threads accessing distinct
- * elements is roughly 1 / (8 * #elements). Function "spread"
- * performs hashCode randomization that improves the likelihood
- * that these assumptions hold unless users define exactly the
- * same value for too many hashCodes.
+ * elements is roughly 1 / (8 * #elements) under random hashes.
+ *
+ * Actual hash code distributions encountered in practice
+ * sometimes deviate significantly from uniform randomness. This
+ * includes the case when N > (1<<30), so some keys MUST collide.
+ * Similarly for dumb or hostile usages in which multiple keys are
+ * designed to have identical hash codes. Also, although we guard
+ * against the worst effects of this (see method spread), sets of
+ * hashes may differ only in bits that do not impact their bin
+ * index for a given power-of-two mask. So we use a secondary
+ * strategy that applies when the number of nodes in a bin exceeds
+ * a threshold, and at least one of the keys implements
+ * Comparable. These TreeBins use a balanced tree to hold nodes
+ * (a specialized form of red-black trees), bounding search time
+ * to O(log N). Each search step in a TreeBin is around twice as
+ * slow as in a regular list, but given that N cannot exceed
+ * (1<<64) (before running out of addresses) this bounds search
+ * steps, lock hold times, etc, to reasonable constants (roughly
+ * 100 nodes inspected per operation worst case) so long as keys
+ * are Comparable (which is very common -- String, Long, etc).
+ * TreeBin nodes (TreeNodes) also maintain the same "next"
+ * traversal pointers as regular nodes, so can be traversed in
+ * iterators in the same way.
*
- * The table is resized when occupancy exceeds an occupancy
+ * The table is resized when occupancy exceeds a percentage
* threshold (nominally, 0.75, but see below). Only a single
* thread performs the resize (using field "sizeCtl", to arrange
* exclusion), but the table otherwise remains usable for reads
@@ -231,31 +321,30 @@ public class ConcurrentHashMapV8
*
* Each bin transfer requires its bin lock. However, unlike other
* cases, a transfer can skip a bin if it fails to acquire its
- * lock, and revisit it later. Method rebuild maintains a buffer
- * of TRANSFER_BUFFER_SIZE bins that have been skipped because of
- * failure to acquire a lock, and blocks only if none are
- * available (i.e., only very rarely). The transfer operation
- * must also ensure that all accessible bins in both the old and
- * new table are usable by any traversal. When there are no lock
- * acquisition failures, this is arranged simply by proceeding
- * from the last bin (table.length - 1) up towards the first.
- * Upon seeing a forwarding node, traversals (see class
- * InternalIterator) arrange to move to the new table without
- * revisiting nodes. However, when any node is skipped during a
- * transfer, all earlier table bins may have become visible, so
- * are initialized with a reverse-forwarding node back to the old
- * table until the new ones are established. (This sometimes
- * requires transiently locking a forwarding node, which is
- * possible under the above encoding.) These more expensive
+ * lock, and revisit it later (unless it is a TreeBin). Method
+ * rebuild maintains a buffer of TRANSFER_BUFFER_SIZE bins that
+ * have been skipped because of failure to acquire a lock, and
+ * blocks only if none are available (i.e., only very rarely).
+ * The transfer operation must also ensure that all accessible
+ * bins in both the old and new table are usable by any traversal.
+ * When there are no lock acquisition failures, this is arranged
+ * simply by proceeding from the last bin (table.length - 1) up
+ * towards the first. Upon seeing a forwarding node, traversals
+ * (see class Iter) arrange to move to the new table
+ * without revisiting nodes. However, when any node is skipped
+ * during a transfer, all earlier table bins may have become
+ * visible, so are initialized with a reverse-forwarding node back
+ * to the old table until the new ones are established. (This
+ * sometimes requires transiently locking a forwarding node, which
+ * is possible under the above encoding.) These more expensive
* mechanics trigger only when necessary.
*
* The traversal scheme also applies to partial traversals of
- * ranges of bins (via an alternate InternalIterator constructor)
- * to support partitioned aggregate operations (that are not
- * otherwise implemented yet). Also, read-only operations give up
- * if ever forwarded to a null table, which provides support for
- * shutdown-style clearing, which is also not currently
- * implemented.
+ * ranges of bins (via an alternate Traverser constructor)
+ * to support partitioned aggregate operations. Also, read-only
+ * operations give up if ever forwarded to a null table, which
+ * provides support for shutdown-style clearing, which is also not
+ * currently implemented.
*
* Lazy table initialization minimizes footprint until first use,
* and also avoids resizings when the first operation is from a
@@ -266,13 +355,17 @@ public class ConcurrentHashMapV8
* The element count is maintained using a LongAdder, which avoids
* contention on updates but can encounter cache thrashing if read
* too frequently during concurrent access. To avoid reading so
- * often, resizing is normally attempted only upon adding to a bin
- * already holding two or more nodes. Under uniform hash
- * distributions, the probability of this occurring at threshold
- * is around 13%, meaning that only about 1 in 8 puts check
- * threshold (and after resizing, many fewer do so). But this
- * approximation has high variance for small table sizes, so we
- * check on any collision for sizes <= 64.
+ * often, resizing is attempted either when a bin lock is
+ * contended, or upon adding to a bin already holding two or more
+ * nodes (checked before adding in the xIfAbsent methods, after
+ * adding in others). Under uniform hash distributions, the
+ * probability of this occurring at threshold is around 13%,
+ * meaning that only about 1 in 8 puts check threshold (and after
+ * resizing, many fewer do so). But this approximation has high
+ * variance for small table sizes, so we check on any collision
+ * for sizes <= 64. The bulk putAll operation further reduces
+ * contention by only committing count updates upon these size
+ * checks.
*
* Maintaining API and serialization compatibility with previous
* versions of this class introduces several oddities. Mainly: We
@@ -329,11 +422,18 @@ public class ConcurrentHashMapV8
*/
private static final int TRANSFER_BUFFER_SIZE = 32;
+ /**
+ * The bin count threshold for using a tree rather than list for a
+ * bin. The value reflects the approximate break-even point for
+ * using tree-based operations.
+ */
+ private static final int TREE_THRESHOLD = 8;
+
/*
* Encodings for special uses of Node hash fields. See above for
* explanation.
*/
- static final int MOVED = 0x80000000; // hash field for fowarding nodes
+ static final int MOVED = 0x80000000; // hash field for forwarding nodes
static final int LOCKED = 0x40000000; // set/tested only as a bit
static final int WAITING = 0xc0000000; // both bits set/tested together
static final int HASH_BITS = 0x3fffffff; // usable bits of normal node hash
@@ -368,19 +468,45 @@ public class ConcurrentHashMapV8
/** For serialization compatibility. Null unless serialized; see below */
private Segment[] segments;
+ /* ---------------- Table element access -------------- */
+
+ /*
+ * Volatile access methods are used for table elements as well as
+ * elements of in-progress next table while resizing. Uses are
+ * null checked by callers, and implicitly bounds-checked, relying
+ * on the invariants that tab arrays have non-zero size, and all
+ * indices are masked with (tab.length - 1) which is never
+ * negative and always less than length. Note that, to be correct
+ * wrt arbitrary concurrency errors by users, bounds checks must
+ * operate on local variables, which accounts for some odd-looking
+ * inline assignments below.
+ */
+
+ static final Node tabAt(Node[] tab, int i) { // used by Iter
+ return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<
* unlocking lock (via a failed CAS from non-waiting LOCKED
* state), unlockers acquire the sync lock and perform a
* notifyAll.
+ *
+ * The initial sanity check on tab and bounds is not currently
+ * necessary in the only usages of this method, but enables
+ * use in other future contexts.
*/
final void tryAwaitLock(Node[] tab, int i) {
- if (tab != null && i >= 0 && i < tab.length) { // bounds check
+ if (tab != null && i >= 0 && i < tab.length) { // sanity check
+ int r = ThreadLocalRandom.current().nextInt(); // randomize spins
int spins = MAX_SPINS, h;
while (tabAt(tab, i) == this && ((h = hash) & LOCKED) != 0) {
if (spins >= 0) {
- if (--spins == MAX_SPINS >>> 1)
- Thread.yield(); // heuristically yield mid-way
+ r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
+ if (r >= 0 && --spins == 0)
+ Thread.yield(); // yield before block
}
else if (casHash(h, h | WAITING)) {
synchronized (this) {
@@ -458,63 +590,522 @@ public class ConcurrentHashMapV8
}
}
- /* ---------------- Table element access -------------- */
+ /* ---------------- TreeBins -------------- */
- /*
- * Volatile access methods are used for table elements as well as
- * elements of in-progress next table while resizing. Uses are
- * null checked by callers, and implicitly bounds-checked, relying
- * on the invariants that tab arrays have non-zero size, and all
- * indices are masked with (tab.length - 1) which is never
- * negative and always less than length. Note that, to be correct
- * wrt arbitrary concurrency errors by users, bounds checks must
- * operate on local variables, which accounts for some odd-looking
- * inline assignments below.
+ /**
+ * Nodes for use in TreeBins
*/
-
- static final Node tabAt(Node[] tab, int i) { // used by InternalIterator
- return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<
+ * for the same T, so we cannot invoke compareTo among them. To
+ * handle this, the tree is ordered primarily by hash value, then
+ * by getClass().getName() order, and then by Comparator order
+ * among elements of the same class. On lookup at a node, if
+ * elements are not comparable or compare as 0, both left and
+ * right children may need to be searched in the case of tied hash
+ * values. (This corresponds to the full list search that would be
+ * necessary if all elements were non-Comparable and had tied
+ * hashes.) The red-black balancing code is updated from
+ * pre-jdk-collections
+ * (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
+ * based in turn on Cormen, Leiserson, and Rivest "Introduction to
+ * Algorithms" (CLR).
+ *
+ * TreeBins also maintain a separate locking discipline than
+ * regular bins. Because they are forwarded via special MOVED
+ * nodes at bin heads (which can never change once established),
+ * we cannot use those nodes as locks. Instead, TreeBin
+ * extends AbstractQueuedSynchronizer to support a simple form of
+ * read-write lock. For update operations and table validation,
+ * the exclusive form of lock behaves in the same way as bin-head
+ * locks. However, lookups use shared read-lock mechanics to allow
+ * multiple readers in the absence of writers. Additionally,
+ * these lookups do not ever block: While the lock is not
+ * available, they proceed along the slow traversal path (via
+ * next-pointers) until the lock becomes available or the list is
+ * exhausted, whichever comes first. (These cases are not fast,
+ * but maximize aggregate expected throughput.) The AQS mechanics
+ * for doing this are straightforward. The lock state is held as
+ * AQS getState(). Read counts are negative; the write count (1)
+ * is positive. There are no signalling preferences among readers
+ * and writers. Since we don't need to export full Lock API, we
+ * just override the minimal AQS methods and use them directly.
+ */
+ static final class TreeBin extends AbstractQueuedSynchronizer {
+ private static final long serialVersionUID = 2249069246763182397L;
+ transient TreeNode root; // root of tree
+ transient TreeNode first; // head of next-pointer list
- private static final void setTabAt(Node[] tab, int i, Node v) {
- UNSAFE.putObjectVolatile(tab, ((long)i< 0; }
+ public final boolean tryAcquire(int ignore) {
+ if (compareAndSetState(0, 1)) {
+ setExclusiveOwnerThread(Thread.currentThread());
+ return true;
+ }
+ return false;
+ }
+ public final boolean tryRelease(int ignore) {
+ setExclusiveOwnerThread(null);
+ setState(0);
+ return true;
+ }
+ public final int tryAcquireShared(int ignore) {
+ for (int c;;) {
+ if ((c = getState()) > 0)
+ return -1;
+ if (compareAndSetState(c, c -1))
+ return 1;
+ }
+ }
+ public final boolean tryReleaseShared(int ignore) {
+ int c;
+ do {} while (!compareAndSetState(c = getState(), c + 1));
+ return c == -1;
+ }
+
+ /** From CLR */
+ private void rotateLeft(TreeNode p) {
+ if (p != null) {
+ TreeNode r = p.right, pp, rl;
+ if ((rl = p.right = r.left) != null)
+ rl.parent = p;
+ if ((pp = r.parent = p.parent) == null)
+ root = r;
+ else if (pp.left == p)
+ pp.left = r;
+ else
+ pp.right = r;
+ r.left = p;
+ p.parent = r;
+ }
+ }
+
+ /** From CLR */
+ private void rotateRight(TreeNode p) {
+ if (p != null) {
+ TreeNode l = p.left, pp, lr;
+ if ((lr = p.left = l.right) != null)
+ lr.parent = p;
+ if ((pp = l.parent = p.parent) == null)
+ root = l;
+ else if (pp.right == p)
+ pp.right = l;
+ else
+ pp.left = l;
+ l.right = p;
+ p.parent = l;
+ }
+ }
+
+ /**
+ * Returns the TreeNode (or null if not found) for the given key
+ * starting at given root.
+ */
+ @SuppressWarnings("unchecked") final TreeNode getTreeNode
+ (int h, Object k, TreeNode p) {
+ Class c = k.getClass();
+ while (p != null) {
+ int dir, ph; Object pk; Class pc;
+ if ((ph = p.hash) == h) {
+ if ((pk = p.key) == k || k.equals(pk))
+ return p;
+ if (c != (pc = pk.getClass()) ||
+ !(k instanceof Comparable) ||
+ (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
+ dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName());
+ TreeNode r = null, s = null, pl, pr;
+ if (dir >= 0) {
+ if ((pl = p.left) != null && h <= pl.hash)
+ s = pl;
+ }
+ else if ((pr = p.right) != null && h >= pr.hash)
+ s = pr;
+ if (s != null && (r = getTreeNode(h, k, s)) != null)
+ return r;
+ }
+ }
+ else
+ dir = (h < ph) ? -1 : 1;
+ p = (dir > 0) ? p.right : p.left;
+ }
+ return null;
+ }
+
+ /**
+ * Wrapper for getTreeNode used by CHM.get. Tries to obtain
+ * read-lock to call getTreeNode, but during failure to get
+ * lock, searches along next links.
+ */
+ final Object getValue(int h, Object k) {
+ Node r = null;
+ int c = getState(); // Must read lock state first
+ for (Node e = first; e != null; e = e.next) {
+ if (c <= 0 && compareAndSetState(c, c - 1)) {
+ try {
+ r = getTreeNode(h, k, root);
+ } finally {
+ releaseShared(0);
+ }
+ break;
+ }
+ else if ((e.hash & HASH_BITS) == h && k.equals(e.key)) {
+ r = e;
+ break;
+ }
+ else
+ c = getState();
+ }
+ return r == null ? null : r.val;
+ }
+
+ /**
+ * Finds or adds a node.
+ * @return null if added
+ */
+ @SuppressWarnings("unchecked") final TreeNode putTreeNode
+ (int h, Object k, Object v) {
+ Class c = k.getClass();
+ TreeNode pp = root, p = null;
+ int dir = 0;
+ while (pp != null) { // find existing node or leaf to insert at
+ int ph; Object pk; Class pc;
+ p = pp;
+ if ((ph = p.hash) == h) {
+ if ((pk = p.key) == k || k.equals(pk))
+ return p;
+ if (c != (pc = pk.getClass()) ||
+ !(k instanceof Comparable) ||
+ (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
+ dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName());
+ TreeNode r = null, s = null, pl, pr;
+ if (dir >= 0) {
+ if ((pl = p.left) != null && h <= pl.hash)
+ s = pl;
+ }
+ else if ((pr = p.right) != null && h >= pr.hash)
+ s = pr;
+ if (s != null && (r = getTreeNode(h, k, s)) != null)
+ return r;
+ }
+ }
+ else
+ dir = (h < ph) ? -1 : 1;
+ pp = (dir > 0) ? p.right : p.left;
+ }
+
+ TreeNode f = first;
+ TreeNode x = first = new TreeNode(h, k, v, f, p);
+ if (p == null)
+ root = x;
+ else { // attach and rebalance; adapted from CLR
+ TreeNode xp, xpp;
+ if (f != null)
+ f.prev = x;
+ if (dir <= 0)
+ p.left = x;
+ else
+ p.right = x;
+ x.red = true;
+ while (x != null && (xp = x.parent) != null && xp.red &&
+ (xpp = xp.parent) != null) {
+ TreeNode xppl = xpp.left;
+ if (xp == xppl) {
+ TreeNode y = xpp.right;
+ if (y != null && y.red) {
+ y.red = false;
+ xp.red = false;
+ xpp.red = true;
+ x = xpp;
+ }
+ else {
+ if (x == xp.right) {
+ rotateLeft(x = xp);
+ xpp = (xp = x.parent) == null ? null : xp.parent;
+ }
+ if (xp != null) {
+ xp.red = false;
+ if (xpp != null) {
+ xpp.red = true;
+ rotateRight(xpp);
+ }
+ }
+ }
+ }
+ else {
+ TreeNode y = xppl;
+ if (y != null && y.red) {
+ y.red = false;
+ xp.red = false;
+ xpp.red = true;
+ x = xpp;
+ }
+ else {
+ if (x == xp.left) {
+ rotateRight(x = xp);
+ xpp = (xp = x.parent) == null ? null : xp.parent;
+ }
+ if (xp != null) {
+ xp.red = false;
+ if (xpp != null) {
+ xpp.red = true;
+ rotateLeft(xpp);
+ }
+ }
+ }
+ }
+ }
+ TreeNode r = root;
+ if (r != null && r.red)
+ r.red = false;
+ }
+ return null;
+ }
+
+ /**
+ * Removes the given node, that must be present before this
+ * call. This is messier than typical red-black deletion code
+ * because we cannot swap the contents of an interior node
+ * with a leaf successor that is pinned by "next" pointers
+ * that are accessible independently of lock. So instead we
+ * swap the tree linkages.
+ */
+ final void deleteTreeNode(TreeNode p) {
+ TreeNode next = (TreeNode)p.next; // unlink traversal pointers
+ TreeNode pred = p.prev;
+ if (pred == null)
+ first = next;
+ else
+ pred.next = next;
+ if (next != null)
+ next.prev = pred;
+ TreeNode replacement;
+ TreeNode pl = p.left;
+ TreeNode pr = p.right;
+ if (pl != null && pr != null) {
+ TreeNode s = pr, sl;
+ while ((sl = s.left) != null) // find successor
+ s = sl;
+ boolean c = s.red; s.red = p.red; p.red = c; // swap colors
+ TreeNode sr = s.right;
+ TreeNode pp = p.parent;
+ if (s == pr) { // p was s's direct parent
+ p.parent = s;
+ s.right = p;
+ }
+ else {
+ TreeNode sp = s.parent;
+ if ((p.parent = sp) != null) {
+ if (s == sp.left)
+ sp.left = p;
+ else
+ sp.right = p;
+ }
+ if ((s.right = pr) != null)
+ pr.parent = s;
+ }
+ p.left = null;
+ if ((p.right = sr) != null)
+ sr.parent = p;
+ if ((s.left = pl) != null)
+ pl.parent = s;
+ if ((s.parent = pp) == null)
+ root = s;
+ else if (p == pp.left)
+ pp.left = s;
+ else
+ pp.right = s;
+ replacement = sr;
+ }
+ else
+ replacement = (pl != null) ? pl : pr;
+ TreeNode pp = p.parent;
+ if (replacement == null) {
+ if (pp == null) {
+ root = null;
+ return;
+ }
+ replacement = p;
+ }
+ else {
+ replacement.parent = pp;
+ if (pp == null)
+ root = replacement;
+ else if (p == pp.left)
+ pp.left = replacement;
+ else
+ pp.right = replacement;
+ p.left = p.right = p.parent = null;
+ }
+ if (!p.red) { // rebalance, from CLR
+ TreeNode x = replacement;
+ while (x != null) {
+ TreeNode xp, xpl;
+ if (x.red || (xp = x.parent) == null) {
+ x.red = false;
+ break;
+ }
+ if (x == (xpl = xp.left)) {
+ TreeNode sib = xp.right;
+ if (sib != null && sib.red) {
+ sib.red = false;
+ xp.red = true;
+ rotateLeft(xp);
+ sib = (xp = x.parent) == null ? null : xp.right;
+ }
+ if (sib == null)
+ x = xp;
+ else {
+ TreeNode sl = sib.left, sr = sib.right;
+ if ((sr == null || !sr.red) &&
+ (sl == null || !sl.red)) {
+ sib.red = true;
+ x = xp;
+ }
+ else {
+ if (sr == null || !sr.red) {
+ if (sl != null)
+ sl.red = false;
+ sib.red = true;
+ rotateRight(sib);
+ sib = (xp = x.parent) == null ? null : xp.right;
+ }
+ if (sib != null) {
+ sib.red = (xp == null) ? false : xp.red;
+ if ((sr = sib.right) != null)
+ sr.red = false;
+ }
+ if (xp != null) {
+ xp.red = false;
+ rotateLeft(xp);
+ }
+ x = root;
+ }
+ }
+ }
+ else { // symmetric
+ TreeNode sib = xpl;
+ if (sib != null && sib.red) {
+ sib.red = false;
+ xp.red = true;
+ rotateRight(xp);
+ sib = (xp = x.parent) == null ? null : xp.left;
+ }
+ if (sib == null)
+ x = xp;
+ else {
+ TreeNode sl = sib.left, sr = sib.right;
+ if ((sl == null || !sl.red) &&
+ (sr == null || !sr.red)) {
+ sib.red = true;
+ x = xp;
+ }
+ else {
+ if (sl == null || !sl.red) {
+ if (sr != null)
+ sr.red = false;
+ sib.red = true;
+ rotateLeft(sib);
+ sib = (xp = x.parent) == null ? null : xp.left;
+ }
+ if (sib != null) {
+ sib.red = (xp == null) ? false : xp.red;
+ if ((sl = sib.left) != null)
+ sl.red = false;
+ }
+ if (xp != null) {
+ xp.red = false;
+ rotateRight(xp);
+ }
+ x = root;
+ }
+ }
+ }
+ }
+ }
+ if (p == replacement && (pp = p.parent) != null) {
+ if (p == pp.left) // detach pointers
+ pp.left = null;
+ else if (p == pp.right)
+ pp.right = null;
+ p.parent = null;
+ }
+ }
}
- /* ---------------- Internal access and update methods -------------- */
+ /* ---------------- Collision reduction methods -------------- */
/**
- * Applies a supplemental hash function to a given hashCode, which
- * defends against poor quality hash functions. The result must
- * be have the top 2 bits clear. For reasonable performance, this
- * function must have good avalanche properties; i.e., that each
- * bit of the argument affects each bit of the result. (Although
- * we don't care about the unused top 2 bits.)
+ * Spreads higher bits to lower, and also forces top 2 bits to 0.
+ * Because the table uses power-of-two masking, sets of hashes
+ * that vary only in bits above the current mask will always
+ * collide. (Among known examples are sets of Float keys holding
+ * consecutive whole numbers in small tables.) To counter this,
+ * we apply a transform that spreads the impact of higher bits
+ * downward. There is a tradeoff between speed, utility, and
+ * quality of bit-spreading. Because many common sets of hashes
+ * are already reasonably distributed across bits (so don't benefit
+ * from spreading), and because we use trees to handle large sets
+ * of collisions in bins, we don't need excessively high quality.
*/
private static final int spread(int h) {
- // Apply base step of MurmurHash; see http://code.google.com/p/smhasher/
- h ^= h >>> 16;
- h *= 0x85ebca6b;
- h ^= h >>> 13;
- h *= 0xc2b2ae35;
- return ((h >>> 16) ^ h) & HASH_BITS; // mask out top bits
+ h ^= (h >>> 18) ^ (h >>> 12);
+ return (h ^ (h >>> 10)) & HASH_BITS;
}
+ /**
+ * Replaces a list bin with a tree bin. Call only when locked.
+ * Fails to replace if the given key is non-comparable or table
+ * is, or needs, resizing.
+ */
+ private final void replaceWithTreeBin(Node[] tab, int index, Object key) {
+ if ((key instanceof Comparable) &&
+ (tab.length >= MAXIMUM_CAPACITY || counter.sum() < (long)sizeCtl)) {
+ TreeBin t = new TreeBin();
+ for (Node e = tabAt(tab, index); e != null; e = e.next)
+ t.putTreeNode(e.hash & HASH_BITS, e.key, e.val);
+ setTabAt(tab, index, new Node(MOVED, t, null, null));
+ }
+ }
+
+ /* ---------------- Internal access and update methods -------------- */
+
/** Implementation for get and containsKey */
private final Object internalGet(Object k) {
int h = spread(k.hashCode());
retry: for (Node[] tab = table; tab != null;) {
- Node e; Object ek, ev; int eh; // locals to read fields once
+ Node e, p; Object ek, ev; int eh; // locals to read fields once
for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) {
if ((eh = e.hash) == MOVED) {
- tab = (Node[])e.key; // restart with new table
- continue retry;
+ if ((ek = e.key) instanceof TreeBin) // search TreeBin
+ return ((TreeBin)ek).getValue(h, k);
+ else { // restart with new table
+ tab = (Node[])ek;
+ continue retry;
+ }
}
- if ((eh & HASH_BITS) == h && (ev = e.val) != null &&
- ((ek = e.key) == k || k.equals(ek)))
+ else if ((eh & HASH_BITS) == h && (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek)))
return ev;
}
break;
@@ -522,72 +1113,6 @@ public class ConcurrentHashMapV8
return null;
}
- /** Implementation for put and putIfAbsent */
- private final Object internalPut(Object k, Object v, boolean replace) {
- int h = spread(k.hashCode());
- Object oldVal = null; // previous value or null if none
- for (Node[] tab = table;;) {
- int i; Node f; int fh; Object fk, fv;
- if (tab == null)
- tab = initTable();
- else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
- if (casTabAt(tab, i, null, new Node(h, k, v, null)))
- break; // no lock when adding to empty bin
- }
- else if ((fh = f.hash) == MOVED)
- tab = (Node[])f.key;
- else if (!replace && (fh & HASH_BITS) == h && (fv = f.val) != null &&
- ((fk = f.key) == k || k.equals(fk))) {
- oldVal = fv; // precheck 1st node for putIfAbsent
- break;
- }
- else if ((fh & LOCKED) != 0)
- f.tryAwaitLock(tab, i);
- else if (f.casHash(fh, fh | LOCKED)) {
- boolean validated = false;
- boolean checkSize = false;
- try {
- if (tabAt(tab, i) == f) {
- validated = true; // retry if 1st already deleted
- for (Node e = f;;) {
- Object ek, ev;
- if ((e.hash & HASH_BITS) == h &&
- (ev = e.val) != null &&
- ((ek = e.key) == k || k.equals(ek))) {
- oldVal = ev;
- if (replace)
- e.val = v;
- break;
- }
- Node last = e;
- if ((e = e.next) == null) {
- last.next = new Node(h, k, v, null);
- if (last != f || tab.length <= 64)
- checkSize = true;
- break;
- }
- }
- }
- } finally { // unlock and signal if needed
- if (!f.casHash(fh | LOCKED, fh)) {
- f.hash = fh;
- synchronized (f) { f.notifyAll(); };
- }
- }
- if (validated) {
- int sc;
- if (checkSize && tab.length < MAXIMUM_CAPACITY &&
- (sc = sizeCtl) >= 0 && counter.sum() >= (long)sc)
- growTable();
- break;
- }
- }
- }
- if (oldVal == null)
- counter.increment(); // update counter outside of locks
- return oldVal;
- }
-
/**
* Implementation for the four public remove/replace methods:
* Replaces node value with v, conditional upon match of cv if
@@ -597,16 +1122,49 @@ public class ConcurrentHashMapV8
int h = spread(k.hashCode());
Object oldVal = null;
for (Node[] tab = table;;) {
- Node f; int i, fh;
+ Node f; int i, fh; Object fk;
if (tab == null ||
(f = tabAt(tab, i = (tab.length - 1) & h)) == null)
break;
- else if ((fh = f.hash) == MOVED)
- tab = (Node[])f.key;
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ boolean validated = false;
+ boolean deleted = false;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ validated = true;
+ TreeNode p = t.getTreeNode(h, k, t.root);
+ if (p != null) {
+ Object pv = p.val;
+ if (cv == null || cv == pv || cv.equals(pv)) {
+ oldVal = pv;
+ if ((p.val = v) == null) {
+ deleted = true;
+ t.deleteTreeNode(p);
+ }
+ }
+ }
+ }
+ } finally {
+ t.release(0);
+ }
+ if (validated) {
+ if (deleted)
+ counter.add(-1L);
+ break;
+ }
+ }
+ else
+ tab = (Node[])fk;
+ }
else if ((fh & HASH_BITS) != h && f.next == null) // precheck
break; // rules out possible existence
- else if ((fh & LOCKED) != 0)
+ else if ((fh & LOCKED) != 0) {
+ checkForResize(); // try resizing if can't get lock
f.tryAwaitLock(tab, i);
+ }
else if (f.casHash(fh, fh | LOCKED)) {
boolean validated = false;
boolean deleted = false;
@@ -644,7 +1202,7 @@ public class ConcurrentHashMapV8
}
if (validated) {
if (deleted)
- counter.decrement();
+ counter.add(-1L);
break;
}
}
@@ -652,33 +1210,373 @@ public class ConcurrentHashMapV8
return oldVal;
}
- /** Implementation for computeIfAbsent and compute. Like put, but messier. */
- // Todo: Somehow reinstate non-termination check
- @SuppressWarnings("unchecked")
- private final V internalCompute(K k,
- MappingFunction fn,
- boolean replace) {
+ /*
+ * Internal versions of the six insertion methods, each a
+ * little more complicated than the last. All have
+ * the same basic structure as the first (internalPut):
+ * 1. If table uninitialized, create
+ * 2. If bin empty, try to CAS new node
+ * 3. If bin stale, use new table
+ * 4. if bin converted to TreeBin, validate and relay to TreeBin methods
+ * 5. Lock and validate; if valid, scan and add or update
+ *
+ * The others interweave other checks and/or alternative actions:
+ * * Plain put checks for and performs resize after insertion.
+ * * putIfAbsent prescans for mapping without lock (and fails to add
+ * if present), which also makes pre-emptive resize checks worthwhile.
+ * * computeIfAbsent extends form used in putIfAbsent with additional
+ * mechanics to deal with, calls, potential exceptions and null
+ * returns from function call.
+ * * compute uses the same function-call mechanics, but without
+ * the prescans
+ * * merge acts as putIfAbsent in the absent case, but invokes the
+ * update function if present
+ * * putAll attempts to pre-allocate enough table space
+ * and more lazily performs count updates and checks.
+ *
+ * Someday when details settle down a bit more, it might be worth
+ * some factoring to reduce sprawl.
+ */
+
+ /** Implementation for put */
+ private final Object internalPut(Object k, Object v) {
int h = spread(k.hashCode());
- V val = null;
- boolean added = false;
- Node[] tab = table;
- outer:for (;;) {
+ int count = 0;
+ for (Node[] tab = table;;) {
+ int i; Node f; int fh; Object fk;
+ if (tab == null)
+ tab = initTable();
+ else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
+ if (casTabAt(tab, i, null, new Node(h, k, v, null)))
+ break; // no lock when adding to empty bin
+ }
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ Object oldVal = null;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 2;
+ TreeNode p = t.putTreeNode(h, k, v);
+ if (p != null) {
+ oldVal = p.val;
+ p.val = v;
+ }
+ }
+ } finally {
+ t.release(0);
+ }
+ if (count != 0) {
+ if (oldVal != null)
+ return oldVal;
+ break;
+ }
+ }
+ else
+ tab = (Node[])fk;
+ }
+ else if ((fh & LOCKED) != 0) {
+ checkForResize();
+ f.tryAwaitLock(tab, i);
+ }
+ else if (f.casHash(fh, fh | LOCKED)) {
+ Object oldVal = null;
+ try { // needed in case equals() throws
+ if (tabAt(tab, i) == f) {
+ count = 1;
+ for (Node e = f;; ++count) {
+ Object ek, ev;
+ if ((e.hash & HASH_BITS) == h &&
+ (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek))) {
+ oldVal = ev;
+ e.val = v;
+ break;
+ }
+ Node last = e;
+ if ((e = e.next) == null) {
+ last.next = new Node(h, k, v, null);
+ if (count >= TREE_THRESHOLD)
+ replaceWithTreeBin(tab, i, k);
+ break;
+ }
+ }
+ }
+ } finally { // unlock and signal if needed
+ if (!f.casHash(fh | LOCKED, fh)) {
+ f.hash = fh;
+ synchronized (f) { f.notifyAll(); };
+ }
+ }
+ if (count != 0) {
+ if (oldVal != null)
+ return oldVal;
+ if (tab.length <= 64)
+ count = 2;
+ break;
+ }
+ }
+ }
+ counter.add(1L);
+ if (count > 1)
+ checkForResize();
+ return null;
+ }
+
+ /** Implementation for putIfAbsent */
+ private final Object internalPutIfAbsent(Object k, Object v) {
+ int h = spread(k.hashCode());
+ int count = 0;
+ for (Node[] tab = table;;) {
+ int i; Node f; int fh; Object fk, fv;
+ if (tab == null)
+ tab = initTable();
+ else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
+ if (casTabAt(tab, i, null, new Node(h, k, v, null)))
+ break;
+ }
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ Object oldVal = null;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 2;
+ TreeNode p = t.putTreeNode(h, k, v);
+ if (p != null)
+ oldVal = p.val;
+ }
+ } finally {
+ t.release(0);
+ }
+ if (count != 0) {
+ if (oldVal != null)
+ return oldVal;
+ break;
+ }
+ }
+ else
+ tab = (Node[])fk;
+ }
+ else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
+ ((fk = f.key) == k || k.equals(fk)))
+ return fv;
+ else {
+ Node g = f.next;
+ if (g != null) { // at least 2 nodes -- search and maybe resize
+ for (Node e = g;;) {
+ Object ek, ev;
+ if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek)))
+ return ev;
+ if ((e = e.next) == null) {
+ checkForResize();
+ break;
+ }
+ }
+ }
+ if (((fh = f.hash) & LOCKED) != 0) {
+ checkForResize();
+ f.tryAwaitLock(tab, i);
+ }
+ else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
+ Object oldVal = null;
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 1;
+ for (Node e = f;; ++count) {
+ Object ek, ev;
+ if ((e.hash & HASH_BITS) == h &&
+ (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek))) {
+ oldVal = ev;
+ break;
+ }
+ Node last = e;
+ if ((e = e.next) == null) {
+ last.next = new Node(h, k, v, null);
+ if (count >= TREE_THRESHOLD)
+ replaceWithTreeBin(tab, i, k);
+ break;
+ }
+ }
+ }
+ } finally {
+ if (!f.casHash(fh | LOCKED, fh)) {
+ f.hash = fh;
+ synchronized (f) { f.notifyAll(); };
+ }
+ }
+ if (count != 0) {
+ if (oldVal != null)
+ return oldVal;
+ if (tab.length <= 64)
+ count = 2;
+ break;
+ }
+ }
+ }
+ }
+ counter.add(1L);
+ if (count > 1)
+ checkForResize();
+ return null;
+ }
+
+ /** Implementation for computeIfAbsent */
+ private final Object internalComputeIfAbsent(K k,
+ Fun mf) {
+ int h = spread(k.hashCode());
+ Object val = null;
+ int count = 0;
+ for (Node[] tab = table;;) {
Node f; int i, fh; Object fk, fv;
if (tab == null)
tab = initTable();
else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
Node node = new Node(fh = h | LOCKED, k, null, null);
- boolean validated = false;
if (casTabAt(tab, i, null, node)) {
- validated = true;
+ count = 1;
try {
- val = fn.map(k);
- if (val != null) {
+ if ((val = mf.apply(k)) != null)
node.val = val;
- added = true;
+ } finally {
+ if (val == null)
+ setTabAt(tab, i, null);
+ if (!node.casHash(fh, h)) {
+ node.hash = h;
+ synchronized (node) { node.notifyAll(); };
+ }
+ }
+ }
+ if (count != 0)
+ break;
+ }
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ boolean added = false;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 1;
+ TreeNode p = t.getTreeNode(h, k, t.root);
+ if (p != null)
+ val = p.val;
+ else if ((val = mf.apply(k)) != null) {
+ added = true;
+ count = 2;
+ t.putTreeNode(h, k, val);
+ }
+ }
+ } finally {
+ t.release(0);
+ }
+ if (count != 0) {
+ if (!added)
+ return val;
+ break;
+ }
+ }
+ else
+ tab = (Node[])fk;
+ }
+ else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
+ ((fk = f.key) == k || k.equals(fk)))
+ return fv;
+ else {
+ Node g = f.next;
+ if (g != null) {
+ for (Node e = g;;) {
+ Object ek, ev;
+ if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek)))
+ return ev;
+ if ((e = e.next) == null) {
+ checkForResize();
+ break;
+ }
+ }
+ }
+ if (((fh = f.hash) & LOCKED) != 0) {
+ checkForResize();
+ f.tryAwaitLock(tab, i);
+ }
+ else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
+ boolean added = false;
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 1;
+ for (Node e = f;; ++count) {
+ Object ek, ev;
+ if ((e.hash & HASH_BITS) == h &&
+ (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek))) {
+ val = ev;
+ break;
+ }
+ Node last = e;
+ if ((e = e.next) == null) {
+ if ((val = mf.apply(k)) != null) {
+ added = true;
+ last.next = new Node(h, k, val, null);
+ if (count >= TREE_THRESHOLD)
+ replaceWithTreeBin(tab, i, k);
+ }
+ break;
+ }
+ }
}
} finally {
+ if (!f.casHash(fh | LOCKED, fh)) {
+ f.hash = fh;
+ synchronized (f) { f.notifyAll(); };
+ }
+ }
+ if (count != 0) {
if (!added)
+ return val;
+ if (tab.length <= 64)
+ count = 2;
+ break;
+ }
+ }
+ }
+ }
+ if (val != null) {
+ counter.add(1L);
+ if (count > 1)
+ checkForResize();
+ }
+ return val;
+ }
+
+ /** Implementation for compute */
+ @SuppressWarnings("unchecked") private final Object internalCompute
+ (K k, boolean onlyIfPresent, BiFun mf) {
+ int h = spread(k.hashCode());
+ Object val = null;
+ int delta = 0;
+ int count = 0;
+ for (Node[] tab = table;;) {
+ Node f; int i, fh; Object fk;
+ if (tab == null)
+ tab = initTable();
+ else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
+ if (onlyIfPresent)
+ break;
+ Node node = new Node(fh = h | LOCKED, k, null, null);
+ if (casTabAt(tab, i, null, node)) {
+ try {
+ count = 1;
+ if ((val = mf.apply(k, null)) != null) {
+ node.val = val;
+ delta = 1;
+ }
+ } finally {
+ if (delta == 0)
setTabAt(tab, i, null);
if (!node.casHash(fh, h)) {
node.hash = h;
@@ -686,43 +1584,74 @@ public class ConcurrentHashMapV8
}
}
}
- if (validated)
+ if (count != 0)
break;
}
- else if ((fh = f.hash) == MOVED)
- tab = (Node[])f.key;
- else if (!replace && (fh & HASH_BITS) == h && (fv = f.val) != null &&
- ((fk = f.key) == k || k.equals(fk))) {
- if (tabAt(tab, i) == f) {
- val = (V)fv;
- break;
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 1;
+ TreeNode p = t.getTreeNode(h, k, t.root);
+ Object pv = (p == null) ? null : p.val;
+ if ((val = mf.apply(k, (V)pv)) != null) {
+ if (p != null)
+ p.val = val;
+ else {
+ count = 2;
+ delta = 1;
+ t.putTreeNode(h, k, val);
+ }
+ }
+ else if (p != null) {
+ delta = -1;
+ t.deleteTreeNode(p);
+ }
+ }
+ } finally {
+ t.release(0);
+ }
+ if (count != 0)
+ break;
}
+ else
+ tab = (Node[])fk;
}
- else if ((fh & LOCKED) != 0)
+ else if ((fh & LOCKED) != 0) {
+ checkForResize();
f.tryAwaitLock(tab, i);
+ }
else if (f.casHash(fh, fh | LOCKED)) {
- boolean validated = false;
- boolean checkSize = false;
try {
if (tabAt(tab, i) == f) {
- validated = true;
- for (Node e = f;;) {
- Object ek, ev, v;
+ count = 1;
+ for (Node e = f, pred = null;; ++count) {
+ Object ek, ev;
if ((e.hash & HASH_BITS) == h &&
(ev = e.val) != null &&
((ek = e.key) == k || k.equals(ek))) {
- if (replace && (v = fn.map(k)) != null)
- ev = e.val = v;
- val = (V)ev;
+ val = mf.apply(k, (V)ev);
+ if (val != null)
+ e.val = val;
+ else {
+ delta = -1;
+ Node en = e.next;
+ if (pred != null)
+ pred.next = en;
+ else
+ setTabAt(tab, i, en);
+ }
break;
}
- Node last = e;
+ pred = e;
if ((e = e.next) == null) {
- if ((val = fn.map(k)) != null) {
- last.next = new Node(h, k, val, null);
- added = true;
- if (last != f || tab.length <= 64)
- checkSize = true;
+ if (!onlyIfPresent && (val = mf.apply(k, null)) != null) {
+ pred.next = new Node(h, k, val, null);
+ delta = 1;
+ if (count >= TREE_THRESHOLD)
+ replaceWithTreeBin(tab, i, k);
}
break;
}
@@ -734,48 +1663,107 @@ public class ConcurrentHashMapV8
synchronized (f) { f.notifyAll(); };
}
}
- if (validated) {
- int sc;
- if (checkSize && tab.length < MAXIMUM_CAPACITY &&
- (sc = sizeCtl) >= 0 && counter.sum() >= (long)sc)
- growTable();
+ if (count != 0) {
+ if (tab.length <= 64)
+ count = 2;
break;
}
}
}
- if (added)
- counter.increment();
+ if (delta != 0) {
+ counter.add((long)delta);
+ if (count > 1)
+ checkForResize();
+ }
return val;
}
- /**
- * Implementation for clear. Steps through each bin, removing all nodes.
- */
- private final void internalClear() {
- long delta = 0L; // negative number of deletions
- int i = 0;
- Node[] tab = table;
- while (tab != null && i < tab.length) {
- int fh;
- Node f = tabAt(tab, i);
- if (f == null)
- ++i;
- else if ((fh = f.hash) == MOVED)
- tab = (Node[])f.key;
- else if ((fh & LOCKED) != 0)
+ /** Implementation for merge */
+ @SuppressWarnings("unchecked") private final Object internalMerge
+ (K k, V v, BiFun mf) {
+ int h = spread(k.hashCode());
+ Object val = null;
+ int delta = 0;
+ int count = 0;
+ for (Node[] tab = table;;) {
+ int i; Node f; int fh; Object fk, fv;
+ if (tab == null)
+ tab = initTable();
+ else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
+ if (casTabAt(tab, i, null, new Node(h, k, v, null))) {
+ delta = 1;
+ val = v;
+ break;
+ }
+ }
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 1;
+ TreeNode p = t.getTreeNode(h, k, t.root);
+ val = (p == null) ? v : mf.apply((V)p.val, v);
+ if (val != null) {
+ if (p != null)
+ p.val = val;
+ else {
+ count = 2;
+ delta = 1;
+ t.putTreeNode(h, k, val);
+ }
+ }
+ else if (p != null) {
+ delta = -1;
+ t.deleteTreeNode(p);
+ }
+ }
+ } finally {
+ t.release(0);
+ }
+ if (count != 0)
+ break;
+ }
+ else
+ tab = (Node[])fk;
+ }
+ else if ((fh & LOCKED) != 0) {
+ checkForResize();
f.tryAwaitLock(tab, i);
+ }
else if (f.casHash(fh, fh | LOCKED)) {
- boolean validated = false;
try {
if (tabAt(tab, i) == f) {
- validated = true;
- for (Node e = f; e != null; e = e.next) {
- if (e.val != null) { // currently always true
- e.val = null;
- --delta;
+ count = 1;
+ for (Node e = f, pred = null;; ++count) {
+ Object ek, ev;
+ if ((e.hash & HASH_BITS) == h &&
+ (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek))) {
+ val = mf.apply(v, (V)ev);
+ if (val != null)
+ e.val = val;
+ else {
+ delta = -1;
+ Node en = e.next;
+ if (pred != null)
+ pred.next = en;
+ else
+ setTabAt(tab, i, en);
+ }
+ break;
+ }
+ pred = e;
+ if ((e = e.next) == null) {
+ val = v;
+ pred.next = new Node(h, k, val, null);
+ delta = 1;
+ if (count >= TREE_THRESHOLD)
+ replaceWithTreeBin(tab, i, k);
+ break;
}
}
- setTabAt(tab, i, null);
}
} finally {
if (!f.casHash(fh | LOCKED, fh)) {
@@ -783,14 +1771,125 @@ public class ConcurrentHashMapV8
synchronized (f) { f.notifyAll(); };
}
}
- if (validated)
- ++i;
+ if (count != 0) {
+ if (tab.length <= 64)
+ count = 2;
+ break;
+ }
}
}
- counter.add(delta);
+ if (delta != 0) {
+ counter.add((long)delta);
+ if (count > 1)
+ checkForResize();
+ }
+ return val;
}
- /* ----------------Table Initialization and Resizing -------------- */
+ /** Implementation for putAll */
+ private final void internalPutAll(Map m) {
+ tryPresize(m.size());
+ long delta = 0L; // number of uncommitted additions
+ boolean npe = false; // to throw exception on exit for nulls
+ try { // to clean up counts on other exceptions
+ for (Map.Entry entry : m.entrySet()) {
+ Object k, v;
+ if (entry == null || (k = entry.getKey()) == null ||
+ (v = entry.getValue()) == null) {
+ npe = true;
+ break;
+ }
+ int h = spread(k.hashCode());
+ for (Node[] tab = table;;) {
+ int i; Node f; int fh; Object fk;
+ if (tab == null)
+ tab = initTable();
+ else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){
+ if (casTabAt(tab, i, null, new Node(h, k, v, null))) {
+ ++delta;
+ break;
+ }
+ }
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ boolean validated = false;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ validated = true;
+ TreeNode p = t.getTreeNode(h, k, t.root);
+ if (p != null)
+ p.val = v;
+ else {
+ t.putTreeNode(h, k, v);
+ ++delta;
+ }
+ }
+ } finally {
+ t.release(0);
+ }
+ if (validated)
+ break;
+ }
+ else
+ tab = (Node[])fk;
+ }
+ else if ((fh & LOCKED) != 0) {
+ counter.add(delta);
+ delta = 0L;
+ checkForResize();
+ f.tryAwaitLock(tab, i);
+ }
+ else if (f.casHash(fh, fh | LOCKED)) {
+ int count = 0;
+ try {
+ if (tabAt(tab, i) == f) {
+ count = 1;
+ for (Node e = f;; ++count) {
+ Object ek, ev;
+ if ((e.hash & HASH_BITS) == h &&
+ (ev = e.val) != null &&
+ ((ek = e.key) == k || k.equals(ek))) {
+ e.val = v;
+ break;
+ }
+ Node last = e;
+ if ((e = e.next) == null) {
+ ++delta;
+ last.next = new Node(h, k, v, null);
+ if (count >= TREE_THRESHOLD)
+ replaceWithTreeBin(tab, i, k);
+ break;
+ }
+ }
+ }
+ } finally {
+ if (!f.casHash(fh | LOCKED, fh)) {
+ f.hash = fh;
+ synchronized (f) { f.notifyAll(); };
+ }
+ }
+ if (count != 0) {
+ if (count > 1) {
+ counter.add(delta);
+ delta = 0L;
+ checkForResize();
+ }
+ break;
+ }
+ }
+ }
+ }
+ } finally {
+ if (delta != 0)
+ counter.add(delta);
+ }
+ if (npe)
+ throw new NullPointerException();
+ }
+
+ /* ---------------- Table Initialization and Resizing -------------- */
/**
* Returns a power of two table size for the given desired capacity.
@@ -819,7 +1918,7 @@ public class ConcurrentHashMapV8
if ((tab = table) == null) {
int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
tab = table = new Node[n];
- sc = n - (n >>> 2) - 1;
+ sc = n - (n >>> 2);
}
} finally {
sizeCtl = sc;
@@ -831,20 +1930,21 @@ public class ConcurrentHashMapV8
}
/**
- * If not already resizing, creates next table and transfers bins.
- * Rechecks occupancy after a transfer to see if another resize is
- * already needed because resizings are lagging additions.
- */
- private final void growTable() {
- int sc = sizeCtl;
- if (sc >= 0 && UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
- try {
- Node[] tab; int n;
- while ((tab = table) != null &&
- (n = tab.length) > 0 && n < MAXIMUM_CAPACITY &&
- counter.sum() >= (long)sc) {
+ * If table is too small and not already resizing, creates next
+ * table and transfers bins. Rechecks occupancy after a transfer
+ * to see if another resize is already needed because resizings
+ * are lagging additions.
+ */
+ private final void checkForResize() {
+ Node[] tab; int n, sc;
+ while ((tab = table) != null &&
+ (n = tab.length) < MAXIMUM_CAPACITY &&
+ (sc = sizeCtl) >= 0 && counter.sum() >= (long)sc &&
+ UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
+ try {
+ if (tab == table) {
table = rebuild(tab);
- sc = (n << 1) - (n >>> 1) - 1;
+ sc = (n << 1) - (n >>> 1);
}
} finally {
sizeCtl = sc;
@@ -852,6 +1952,45 @@ public class ConcurrentHashMapV8
}
}
+ /**
+ * Tries to presize table to accommodate the given number of elements.
+ *
+ * @param size number of elements (doesn't need to be perfectly accurate)
+ */
+ private final void tryPresize(int size) {
+ int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
+ tableSizeFor(size + (size >>> 1) + 1);
+ int sc;
+ while ((sc = sizeCtl) >= 0) {
+ Node[] tab = table; int n;
+ if (tab == null || (n = tab.length) == 0) {
+ n = (sc > c) ? sc : c;
+ if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
+ try {
+ if (table == tab) {
+ table = new Node[n];
+ sc = n - (n >>> 2);
+ }
+ } finally {
+ sizeCtl = sc;
+ }
+ }
+ }
+ else if (c <= sc || n >= MAXIMUM_CAPACITY)
+ break;
+ else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
+ try {
+ if (table == tab) {
+ table = rebuild(tab);
+ sc = (n << 1) - (n >>> 1);
+ }
+ } finally {
+ sizeCtl = sc;
+ }
+ }
+ }
+ }
+
/*
* Moves and/or copies the nodes in each bin to new table. See
* above for explanation.
@@ -871,12 +2010,12 @@ public class ConcurrentHashMapV8
for (int i = bin;;) { // start upwards sweep
int fh; Node f;
if ((f = tabAt(tab, i)) == null) {
- if (bin >= 0) { // no lock needed (or available)
+ if (bin >= 0) { // Unbuffered; no lock needed (or available)
if (!casTabAt(tab, i, f, fwd))
continue;
}
else { // transiently use a locked forwarding node
- Node g = new Node(MOVED|LOCKED, nextTab, null, null);
+ Node g = new Node(MOVED|LOCKED, nextTab, null, null);
if (!casTabAt(tab, i, f, g))
continue;
setTabAt(nextTab, i, null);
@@ -888,35 +2027,31 @@ public class ConcurrentHashMapV8
}
}
}
- else if (((fh = f.hash) & LOCKED) == 0 && f.casHash(fh, fh|LOCKED)) {
+ else if ((fh = f.hash) == MOVED) {
+ Object fk = f.key;
+ if (fk instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ boolean validated = false;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ validated = true;
+ splitTreeBin(nextTab, i, t);
+ setTabAt(tab, i, fwd);
+ }
+ } finally {
+ t.release(0);
+ }
+ if (!validated)
+ continue;
+ }
+ }
+ else if ((fh & LOCKED) == 0 && f.casHash(fh, fh|LOCKED)) {
boolean validated = false;
try { // split to lo and hi lists; copying as needed
if (tabAt(tab, i) == f) {
validated = true;
- Node e = f, lastRun = f;
- Node lo = null, hi = null;
- int runBit = e.hash & n;
- for (Node p = e.next; p != null; p = p.next) {
- int b = p.hash & n;
- if (b != runBit) {
- runBit = b;
- lastRun = p;
- }
- }
- if (runBit == 0)
- lo = lastRun;
- else
- hi = lastRun;
- for (Node p = e; p != lastRun; p = p.next) {
- int ph = p.hash & HASH_BITS;
- Object pk = p.key, pv = p.val;
- if ((ph & n) == 0)
- lo = new Node(ph, pk, pv, lo);
- else
- hi = new Node(ph, pk, pv, hi);
- }
- setTabAt(nextTab, i, lo);
- setTabAt(nextTab, i + n, hi);
+ splitBin(nextTab, i, f);
setTabAt(tab, i, fwd);
}
} finally {
@@ -961,34 +2096,171 @@ public class ConcurrentHashMapV8
}
}
+ /**
+ * Splits a normal bin with list headed by e into lo and hi parts;
+ * installs in given table.
+ */
+ private static void splitBin(Node[] nextTab, int i, Node e) {
+ int bit = nextTab.length >>> 1; // bit to split on
+ int runBit = e.hash & bit;
+ Node lastRun = e, lo = null, hi = null;
+ for (Node p = e.next; p != null; p = p.next) {
+ int b = p.hash & bit;
+ if (b != runBit) {
+ runBit = b;
+ lastRun = p;
+ }
+ }
+ if (runBit == 0)
+ lo = lastRun;
+ else
+ hi = lastRun;
+ for (Node p = e; p != lastRun; p = p.next) {
+ int ph = p.hash & HASH_BITS;
+ Object pk = p.key, pv = p.val;
+ if ((ph & bit) == 0)
+ lo = new Node(ph, pk, pv, lo);
+ else
+ hi = new Node(ph, pk, pv, hi);
+ }
+ setTabAt(nextTab, i, lo);
+ setTabAt(nextTab, i + bit, hi);
+ }
+
+ /**
+ * Splits a tree bin into lo and hi parts; installs in given table.
+ */
+ private static void splitTreeBin(Node[] nextTab, int i, TreeBin t) {
+ int bit = nextTab.length >>> 1;
+ TreeBin lt = new TreeBin();
+ TreeBin ht = new TreeBin();
+ int lc = 0, hc = 0;
+ for (Node e = t.first; e != null; e = e.next) {
+ int h = e.hash & HASH_BITS;
+ Object k = e.key, v = e.val;
+ if ((h & bit) == 0) {
+ ++lc;
+ lt.putTreeNode(h, k, v);
+ }
+ else {
+ ++hc;
+ ht.putTreeNode(h, k, v);
+ }
+ }
+ Node ln, hn; // throw away trees if too small
+ if (lc <= (TREE_THRESHOLD >>> 1)) {
+ ln = null;
+ for (Node p = lt.first; p != null; p = p.next)
+ ln = new Node(p.hash, p.key, p.val, ln);
+ }
+ else
+ ln = new Node(MOVED, lt, null, null);
+ setTabAt(nextTab, i, ln);
+ if (hc <= (TREE_THRESHOLD >>> 1)) {
+ hn = null;
+ for (Node p = ht.first; p != null; p = p.next)
+ hn = new Node(p.hash, p.key, p.val, hn);
+ }
+ else
+ hn = new Node(MOVED, ht, null, null);
+ setTabAt(nextTab, i + bit, hn);
+ }
+
+ /**
+ * Implementation for clear. Steps through each bin, removing all
+ * nodes.
+ */
+ private final void internalClear() {
+ long delta = 0L; // negative number of deletions
+ int i = 0;
+ Node[] tab = table;
+ while (tab != null && i < tab.length) {
+ int fh; Object fk;
+ Node f = tabAt(tab, i);
+ if (f == null)
+ ++i;
+ else if ((fh = f.hash) == MOVED) {
+ if ((fk = f.key) instanceof TreeBin) {
+ TreeBin t = (TreeBin)fk;
+ t.acquire(0);
+ try {
+ if (tabAt(tab, i) == f) {
+ for (Node p = t.first; p != null; p = p.next) {
+ if (p.val != null) { // (currently always true)
+ p.val = null;
+ --delta;
+ }
+ }
+ t.first = null;
+ t.root = null;
+ ++i;
+ }
+ } finally {
+ t.release(0);
+ }
+ }
+ else
+ tab = (Node[])fk;
+ }
+ else if ((fh & LOCKED) != 0) {
+ counter.add(delta); // opportunistically update count
+ delta = 0L;
+ f.tryAwaitLock(tab, i);
+ }
+ else if (f.casHash(fh, fh | LOCKED)) {
+ try {
+ if (tabAt(tab, i) == f) {
+ for (Node e = f; e != null; e = e.next) {
+ if (e.val != null) { // (currently always true)
+ e.val = null;
+ --delta;
+ }
+ }
+ setTabAt(tab, i, null);
+ ++i;
+ }
+ } finally {
+ if (!f.casHash(fh | LOCKED, fh)) {
+ f.hash = fh;
+ synchronized (f) { f.notifyAll(); };
+ }
+ }
+ }
+ }
+ if (delta != 0)
+ counter.add(delta);
+ }
+
/* ----------------Table Traversal -------------- */
/**
* Encapsulates traversal for methods such as containsValue; also
- * serves as a base class for other iterators.
+ * serves as a base class for other iterators and bulk tasks.
*
* At each step, the iterator snapshots the key ("nextKey") and
* value ("nextVal") of a valid node (i.e., one that, at point of
- * snapshot, has a nonnull user value). Because val fields can
+ * snapshot, has a non-null user value). Because val fields can
* change (including to null, indicating deletion), field nextVal
* might not be accurate at point of use, but still maintains the
* weak consistency property of holding a value that was once
* valid.
*
* Internal traversals directly access these fields, as in:
- * {@code while (it.next != null) { process(it.nextKey); it.advance(); }}
+ * {@code while (it.advance() != null) { process(it.nextKey); }}
*
- * Exported iterators (subclasses of ViewIterator) extract key,
- * value, or key-value pairs as return values of Iterator.next(),
- * and encapsulate the it.next check as hasNext();
- *
- * The iterator visits each valid node that was reachable upon
- * iterator construction once. It might miss some that were added
- * to a bin after the bin was visited, which is OK wrt consistency
- * guarantees. Maintaining this property in the face of possible
- * ongoing resizes requires a fair amount of bookkeeping state
- * that is difficult to optimize away amidst volatile accesses.
- * Even so, traversal maintains reasonable throughput.
+ * Exported iterators must track whether the iterator has advanced
+ * (in hasNext vs next) (by setting/checking/nulling field
+ * nextVal), and then extract key, value, or key-value pairs as
+ * return values of next().
+ *
+ * The iterator visits once each still-valid node that was
+ * reachable upon iterator construction. It might miss some that
+ * were added to a bin after the bin was visited, which is OK wrt
+ * consistency guarantees. Maintaining this property in the face
+ * of possible ongoing resizes requires a fair amount of
+ * bookkeeping state that is difficult to optimize away amidst
+ * volatile accesses. Even so, traversal maintains reasonable
+ * throughput.
*
* Normally, iteration proceeds bin-by-bin traversing lists.
* However, if the table has been resized, then all future steps
@@ -998,10 +2270,15 @@ public class ConcurrentHashMapV8
* across threads, iteration terminates if a bounds checks fails
* for a table read.
*
- * The range-based constructor enables creation of parallel
- * range-splitting traversals. (Not yet implemented.)
+ * This class extends ForkJoinTask to streamline parallel
+ * iteration in bulk operations (see BulkTask). This adds only an
+ * int of space overhead, which is close enough to negligible in
+ * cases where it is not needed to not worry about it. Because
+ * ForkJoinTask is Serializable, but iterators need not be, we
+ * need to add warning suppressions.
*/
- static class InternalIterator {
+ @SuppressWarnings("serial") static class Traverser extends ForkJoinTask {
+ final ConcurrentHashMapV8 map;
Node next; // the next entry to use
Node last; // the last entry used
Object nextKey; // cached key field of next
@@ -1009,54 +2286,90 @@ public class ConcurrentHashMapV8
Node[] tab; // current table; updated if resized
int index; // index of bin to use next
int baseIndex; // current index of initial table
- final int baseLimit; // index bound for initial table
- final int baseSize; // initial table size
+ int baseLimit; // index bound for initial table
+ int baseSize; // initial table size
/** Creates iterator for all entries in the table. */
- InternalIterator(Node[] tab) {
- this.tab = tab;
- baseLimit = baseSize = (tab == null) ? 0 : tab.length;
- index = baseIndex = 0;
- next = null;
- advance();
- }
-
- /** Creates iterator for the given range of the table */
- InternalIterator(Node[] tab, int lo, int hi) {
- this.tab = tab;
- baseSize = (tab == null) ? 0 : tab.length;
- baseLimit = (hi <= baseSize) ? hi : baseSize;
- index = baseIndex = lo;
- next = null;
- advance();
+ Traverser(ConcurrentHashMapV8 map) {
+ this.map = map;
}
- /** Advances next. See above for explanation. */
- final void advance() {
+ /** Creates iterator for split() methods */
+ Traverser(Traverser it) {
+ ConcurrentHashMapV8 m; Node[] t;
+ if ((m = this.map = it.map) == null)
+ t = null;
+ else if ((t = it.tab) == null && // force parent tab initialization
+ (t = it.tab = m.table) != null)
+ it.baseLimit = it.baseSize = t.length;
+ this.tab = t;
+ this.baseSize = it.baseSize;
+ it.baseLimit = this.index = this.baseIndex =
+ ((this.baseLimit = it.baseLimit) + it.baseIndex + 1) >>> 1;
+ }
+
+ /**
+ * Advances next; returns nextVal or null if terminated.
+ * See above for explanation.
+ */
+ final Object advance() {
Node e = last = next;
+ Object ev = null;
outer: do {
if (e != null) // advance past used/skipped node
e = e.next;
while (e == null) { // get to next non-null bin
- Node[] t; int b, i, n; // checks must use locals
- if ((b = baseIndex) >= baseLimit || (i = index) < 0 ||
- (t = tab) == null || i >= (n = t.length))
+ ConcurrentHashMapV8 m;
+ Node[] t; int b, i, n; Object ek; // checks must use locals
+ if ((t = tab) != null)
+ n = t.length;
+ else if ((m = map) != null && (t = tab = m.table) != null)
+ n = baseLimit = baseSize = t.length;
+ else
+ break outer;
+ if ((b = baseIndex) >= baseLimit ||
+ (i = index) < 0 || i >= n)
break outer;
- else if ((e = tabAt(t, i)) != null && e.hash == MOVED)
- tab = (Node[])e.key; // restarts due to null val
- else // visit upper slots if present
- index = (i += baseSize) < n ? i : (baseIndex = b + 1);
+ if ((e = tabAt(t, i)) != null && e.hash == MOVED) {
+ if ((ek = e.key) instanceof TreeBin)
+ e = ((TreeBin)ek).first;
+ else {
+ tab = (Node[])ek;
+ continue; // restarts due to null val
+ }
+ } // visit upper slots if present
+ index = (i += baseSize) < n ? i : (baseIndex = b + 1);
}
nextKey = e.key;
- } while ((nextVal = e.val) == null);// skip deleted or special nodes
+ } while ((ev = e.val) == null); // skip deleted or special nodes
next = e;
+ return nextVal = ev;
+ }
+
+ public final void remove() {
+ if (nextVal == null && last == null)
+ advance();
+ Node e = last;
+ if (e == null)
+ throw new IllegalStateException();
+ last = null;
+ map.remove(e.key);
}
+
+ public final boolean hasNext() {
+ return nextVal != null || advance() != null;
+ }
+
+ public final boolean hasMoreElements() { return hasNext(); }
+ public final void setRawResult(Object x) { }
+ public R getRawResult() { return null; }
+ public boolean exec() { return true; }
}
/* ---------------- Public operations -------------- */
/**
- * Creates a new, empty map with the default initial table size (16),
+ * Creates a new, empty map with the default initial table size (16).
*/
public ConcurrentHashMapV8() {
this.counter = new LongAdder();
@@ -1090,7 +2403,7 @@ public class ConcurrentHashMapV8
public ConcurrentHashMapV8(Map m) {
this.counter = new LongAdder();
this.sizeCtl = DEFAULT_CAPACITY;
- putAll(m);
+ internalPutAll(m);
}
/**
@@ -1137,8 +2450,8 @@ public class ConcurrentHashMapV8
if (initialCapacity < concurrencyLevel) // Use at least as many bins
initialCapacity = concurrencyLevel; // as estimated threads
long size = (long)(1.0 + (long)initialCapacity / loadFactor);
- int cap = ((size >= (long)MAXIMUM_CAPACITY) ?
- MAXIMUM_CAPACITY: tableSizeFor((int)size));
+ int cap = (size >= (long)MAXIMUM_CAPACITY) ?
+ MAXIMUM_CAPACITY : tableSizeFor((int)size);
this.counter = new LongAdder();
this.sizeCtl = cap;
}
@@ -1160,9 +2473,18 @@ public class ConcurrentHashMapV8
(int)n);
}
- final long longSize() { // accurate version of size needed for views
+ /**
+ * Returns the number of mappings. This method should be used
+ * instead of {@link #size} because a ConcurrentHashMap may
+ * contain more mappings than can be represented as an int. The
+ * value returned is a snapshot; the actual count may differ if
+ * there are ongoing concurrent insertions or removals.
+ *
+ * @return the number of mappings
+ */
+ public long mappingCount() {
long n = counter.sum();
- return (n < 0L) ? 0L : n;
+ return (n < 0L) ? 0L : n; // ignore transient negative values
}
/**
@@ -1176,14 +2498,30 @@ public class ConcurrentHashMapV8
*
* @throws NullPointerException if the specified key is null
*/
- @SuppressWarnings("unchecked")
- public V get(Object key) {
+ @SuppressWarnings("unchecked") public V get(Object key) {
if (key == null)
throw new NullPointerException();
return (V)internalGet(key);
}
/**
+ * Returns the value to which the specified key is mapped,
+ * or the given defaultValue if this map contains no mapping for the key.
+ *
+ * @param key the key
+ * @param defaultValue the value to return if this map contains
+ * no mapping for the given key
+ * @return the mapping for the key, if present; else the defaultValue
+ * @throws NullPointerException if the specified key is null
+ */
+ @SuppressWarnings("unchecked") public V getValueOrDefault(Object key, V defaultValue) {
+ if (key == null)
+ throw new NullPointerException();
+ V v = (V) internalGet(key);
+ return v == null ? defaultValue : v;
+ }
+
+ /**
* Tests if the specified object is a key in this table.
*
* @param key possible key
@@ -1212,11 +2550,10 @@ public class ConcurrentHashMapV8
if (value == null)
throw new NullPointerException();
Object v;
- InternalIterator it = new InternalIterator(table);
- while (it.next != null) {
- if ((v = it.nextVal) == value || value.equals(v))
+ Traverser it = new Traverser(this);
+ while ((v = it.advance()) != null) {
+ if (v == value || value.equals(v))
return true;
- it.advance();
}
return false;
}
@@ -1253,11 +2590,10 @@ public class ConcurrentHashMapV8
* {@code null} if there was no mapping for {@code key}
* @throws NullPointerException if the specified key or value is null
*/
- @SuppressWarnings("unchecked")
- public V put(K key, V value) {
+ @SuppressWarnings("unchecked") public V put(K key, V value) {
if (key == null || value == null)
throw new NullPointerException();
- return (V)internalPut(key, value, true);
+ return (V)internalPut(key, value);
}
/**
@@ -1267,11 +2603,10 @@ public class ConcurrentHashMapV8
* or {@code null} if there was no mapping for the key
* @throws NullPointerException if the specified key or value is null
*/
- @SuppressWarnings("unchecked")
- public V putIfAbsent(K key, V value) {
+ @SuppressWarnings("unchecked") public V putIfAbsent(K key, V value) {
if (key == null || value == null)
throw new NullPointerException();
- return (V)internalPut(key, value, false);
+ return (V)internalPutIfAbsent(key, value);
}
/**
@@ -1282,66 +2617,40 @@ public class ConcurrentHashMapV8
* @param m mappings to be stored in this map
*/
public void putAll(Map m) {
- if (m == null)
- throw new NullPointerException();
- /*
- * If uninitialized, try to preallocate big enough table
- */
- if (table == null) {
- int size = m.size();
- int n = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
- tableSizeFor(size + (size >>> 1) + 1);
- int sc = sizeCtl;
- if (n < sc)
- n = sc;
- if (sc >= 0 &&
- UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
- try {
- if (table == null) {
- table = new Node[n];
- sc = n - (n >>> 2) - 1;
- }
- } finally {
- sizeCtl = sc;
- }
- }
- }
- for (Map.Entry e : m.entrySet()) {
- Object ek = e.getKey(), ev = e.getValue();
- if (ek == null || ev == null)
- throw new NullPointerException();
- internalPut(ek, ev, true);
- }
+ internalPutAll(m);
}
/**
* If the specified key is not already associated with a value,
- * computes its value using the given mappingFunction, and if
- * non-null, enters it into the map. This is equivalent to
- * {@code
+ * computes its value using the given mappingFunction and enters
+ * it into the map unless null. This is equivalent to
+ * {@code
* if (map.containsKey(key))
* return map.get(key);
- * value = mappingFunction.map(key);
+ * value = mappingFunction.apply(key);
* if (value != null)
* map.put(key, value);
* return value;}
*
- * except that the action is performed atomically. Some attempted
- * update operations on this map by other threads may be blocked
- * while computation is in progress, so the computation should be
- * short and simple, and must not attempt to update any other
- * mappings of this Map. The most appropriate usage is to
+ * except that the action is performed atomically. If the
+ * function returns {@code null} no mapping is recorded. If the
+ * function itself throws an (unchecked) exception, the exception
+ * is rethrown to its caller, and no mapping is recorded. Some
+ * attempted update operations on this map by other threads may be
+ * blocked while computation is in progress, so the computation
+ * should be short and simple, and must not attempt to update any
+ * other mappings of this Map. The most appropriate usage is to
* construct a new object serving as an initial mapped value, or
* memoized result, as in:
+ *
* {@code
- * map.computeIfAbsent(key, new MappingFunction() {
+ * map.computeIfAbsent(key, new Fun() {
* public V map(K k) { return new Value(f(k)); }});}
*
* @param key key with which the specified value is to be associated
* @param mappingFunction the function to compute a value
* @return the current (existing or computed) value associated with
- * the specified key, or {@code null} if the computation
- * returned {@code null}
+ * the specified key, or null if the computed value is null
* @throws NullPointerException if the specified key or mappingFunction
* is null
* @throws IllegalStateException if the computation detectably
@@ -1350,47 +2659,131 @@ public class ConcurrentHashMapV8
* @throws RuntimeException or Error if the mappingFunction does so,
* in which case the mapping is left unestablished
*/
- public V computeIfAbsent(K key, MappingFunction mappingFunction) {
+ @SuppressWarnings("unchecked") public V computeIfAbsent
+ (K key, Fun mappingFunction) {
if (key == null || mappingFunction == null)
throw new NullPointerException();
- return internalCompute(key, mappingFunction, false);
+ return (V)internalComputeIfAbsent(key, mappingFunction);
}
/**
- * Computes the value associated with the given key using the given
- * mappingFunction, and if non-null, enters it into the map. This
- * is equivalent to
+ * If the given key is present, computes a new mapping value given a key and
+ * its current mapped value. This is equivalent to
* {@code
- * value = mappingFunction.map(key);
- * if (value != null)
- * map.put(key, value);
- * else
- * value = map.get(key);
- * return value;}
+ * if (map.containsKey(key)) {
+ * value = remappingFunction.apply(key, map.get(key));
+ * if (value != null)
+ * map.put(key, value);
+ * else
+ * map.remove(key);
+ * }
+ * }
+ *
+ * except that the action is performed atomically. If the
+ * function returns {@code null}, the mapping is removed. If the
+ * function itself throws an (unchecked) exception, the exception
+ * is rethrown to its caller, and the current mapping is left
+ * unchanged. Some attempted update operations on this map by
+ * other threads may be blocked while computation is in progress,
+ * so the computation should be short and simple, and must not
+ * attempt to update any other mappings of this Map. For example,
+ * to either create or append new messages to a value mapping:
*
- * except that the action is performed atomically. Some attempted
- * update operations on this map by other threads may be blocked
- * while computation is in progress, so the computation should be
- * short and simple, and must not attempt to update any other
- * mappings of this Map.
+ * @param key key with which the specified value is to be associated
+ * @param remappingFunction the function to compute a value
+ * @return the new value associated with the specified key, or null if none
+ * @throws NullPointerException if the specified key or remappingFunction
+ * is null
+ * @throws IllegalStateException if the computation detectably
+ * attempts a recursive update to this map that would
+ * otherwise never complete
+ * @throws RuntimeException or Error if the remappingFunction does so,
+ * in which case the mapping is unchanged
+ */
+ @SuppressWarnings("unchecked") public V computeIfPresent
+ (K key, BiFun remappingFunction) {
+ if (key == null || remappingFunction == null)
+ throw new NullPointerException();
+ return (V)internalCompute(key, true, remappingFunction);
+ }
+
+ /**
+ * Computes a new mapping value given a key and
+ * its current mapped value (or {@code null} if there is no current
+ * mapping). This is equivalent to
+ * {@code
+ * value = remappingFunction.apply(key, map.get(key));
+ * if (value != null)
+ * map.put(key, value);
+ * else
+ * map.remove(key);
+ * }
+ *
+ * except that the action is performed atomically. If the
+ * function returns {@code null}, the mapping is removed. If the
+ * function itself throws an (unchecked) exception, the exception
+ * is rethrown to its caller, and the current mapping is left
+ * unchanged. Some attempted update operations on this map by
+ * other threads may be blocked while computation is in progress,
+ * so the computation should be short and simple, and must not
+ * attempt to update any other mappings of this Map. For example,
+ * to either create or append new messages to a value mapping:
+ *
+ * {@code
+ * Map map = ...;
+ * final String msg = ...;
+ * map.compute(key, new BiFun() {
+ * public String apply(Key k, String v) {
+ * return (v == null) ? msg : v + msg;});}}
*
* @param key key with which the specified value is to be associated
- * @param mappingFunction the function to compute a value
- * @return the current value associated with
- * the specified key, or {@code null} if the computation
- * returned {@code null} and the value was not otherwise present
- * @throws NullPointerException if the specified key or mappingFunction
+ * @param remappingFunction the function to compute a value
+ * @return the new value associated with the specified key, or null if none
+ * @throws NullPointerException if the specified key or remappingFunction
* is null
* @throws IllegalStateException if the computation detectably
* attempts a recursive update to this map that would
* otherwise never complete
- * @throws RuntimeException or Error if the mappingFunction does so,
+ * @throws RuntimeException or Error if the remappingFunction does so,
* in which case the mapping is unchanged
*/
- public V compute(K key, MappingFunction mappingFunction) {
- if (key == null || mappingFunction == null)
+ @SuppressWarnings("unchecked") public V compute
+ (K key, BiFun remappingFunction) {
+ if (key == null || remappingFunction == null)
throw new NullPointerException();
- return internalCompute(key, mappingFunction, true);
+ return (V)internalCompute(key, false, remappingFunction);
+ }
+
+ /**
+ * If the specified key is not already associated
+ * with a value, associate it with the given value.
+ * Otherwise, replace the value with the results of
+ * the given remapping function. This is equivalent to:
+ * {@code
+ * if (!map.containsKey(key))
+ * map.put(value);
+ * else {
+ * newValue = remappingFunction.apply(map.get(key), value);
+ * if (value != null)
+ * map.put(key, value);
+ * else
+ * map.remove(key);
+ * }
+ * }
+ * except that the action is performed atomically. If the
+ * function returns {@code null}, the mapping is removed. If the
+ * function itself throws an (unchecked) exception, the exception
+ * is rethrown to its caller, and the current mapping is left
+ * unchanged. Some attempted update operations on this map by
+ * other threads may be blocked while computation is in progress,
+ * so the computation should be short and simple, and must not
+ * attempt to update any other mappings of this Map.
+ */
+ @SuppressWarnings("unchecked") public V merge
+ (K key, V value, BiFun remappingFunction) {
+ if (key == null || value == null || remappingFunction == null)
+ throw new NullPointerException();
+ return (V)internalMerge(key, value, remappingFunction);
}
/**
@@ -1402,8 +2795,7 @@ public class ConcurrentHashMapV8
* {@code null} if there was no mapping for {@code key}
* @throws NullPointerException if the specified key is null
*/
- @SuppressWarnings("unchecked")
- public V remove(Object key) {
+ @SuppressWarnings("unchecked") public V remove(Object key) {
if (key == null)
throw new NullPointerException();
return (V)internalReplace(key, null, null);
@@ -1440,8 +2832,7 @@ public class ConcurrentHashMapV8
* or {@code null} if there was no mapping for the key
* @throws NullPointerException if the specified key or value is null
*/
- @SuppressWarnings("unchecked")
- public V replace(K key, V value) {
+ @SuppressWarnings("unchecked") public V replace(K key, V value) {
if (key == null || value == null)
throw new NullPointerException();
return (V)internalReplace(key, value, null);
@@ -1538,6 +2929,33 @@ public class ConcurrentHashMapV8
}
/**
+ * Returns a partitionable iterator of the keys in this map.
+ *
+ * @return a partitionable iterator of the keys in this map
+ */
+ public Spliterator keySpliterator() {
+ return new KeyIterator(this);
+ }
+
+ /**
+ * Returns a partitionable iterator of the values in this map.
+ *
+ * @return a partitionable iterator of the values in this map
+ */
+ public Spliterator valueSpliterator() {
+ return new ValueIterator(this);
+ }
+
+ /**
+ * Returns a partitionable iterator of the entries in this map.
+ *
+ * @return a partitionable iterator of the entries in this map
+ */
+ public Spliterator> entrySpliterator() {
+ return new EntryIterator(this);
+ }
+
+ /**
* Returns the hash code value for this {@link Map}, i.e.,
* the sum of, for each key-value pair in the map,
* {@code key.hashCode() ^ value.hashCode()}.
@@ -1546,10 +2964,10 @@ public class ConcurrentHashMapV8
*/
public int hashCode() {
int h = 0;
- InternalIterator it = new InternalIterator(table);
- while (it.next != null) {
- h += it.nextKey.hashCode() ^ it.nextVal.hashCode();
- it.advance();
+ Traverser it = new Traverser(this);
+ Object v;
+ while ((v = it.advance()) != null) {
+ h += it.nextKey.hashCode() ^ v.hashCode();
}
return h;
}
@@ -1566,17 +2984,17 @@ public class ConcurrentHashMapV8
* @return a string representation of this map
*/
public String toString() {
- InternalIterator it = new InternalIterator(table);
+ Traverser it = new Traverser(this);
StringBuilder sb = new StringBuilder();
sb.append('{');
- if (it.next != null) {
+ Object v;
+ if ((v = it.advance()) != null) {
for (;;) {
- Object k = it.nextKey, v = it.nextVal;
+ Object k = it.nextKey;
sb.append(k == this ? "(this Map)" : k);
sb.append('=');
sb.append(v == this ? "(this Map)" : v);
- it.advance();
- if (it.next == null)
+ if ((v = it.advance()) == null)
break;
sb.append(',').append(' ');
}
@@ -1599,13 +3017,12 @@ public class ConcurrentHashMapV8
if (!(o instanceof Map))
return false;
Map m = (Map) o;
- InternalIterator it = new InternalIterator(table);
- while (it.next != null) {
- Object val = it.nextVal;
+ Traverser it = new Traverser(this);
+ Object val;
+ while ((val = it.advance()) != null) {
Object v = m.get(it.nextKey);
if (v == null || (v != val && !v.equals(val)))
return false;
- it.advance();
}
for (Map.Entry e : m.entrySet()) {
Object mk, mv, v;
@@ -1621,97 +3038,85 @@ public class ConcurrentHashMapV8
/* ----------------Iterators -------------- */
- /**
- * Base class for key, value, and entry iterators. Adds a map
- * reference to InternalIterator to support Iterator.remove.
- */
- static abstract class ViewIterator extends InternalIterator {
- final ConcurrentHashMapV8 map;
- ViewIterator(ConcurrentHashMapV8 map) {
- super(map.table);
- this.map = map;
+ @SuppressWarnings("serial") static final class KeyIterator extends Traverser
+ implements Spliterator, Enumeration {
+ KeyIterator(ConcurrentHashMapV8 map) { super(map); }
+ KeyIterator(Traverser it) {
+ super(it);
}
-
- public final void remove() {
- if (last == null)
+ public KeyIterator split() {
+ if (last != null || (next != null && nextVal == null))
throw new IllegalStateException();
- map.remove(last.key);
- last = null;
+ return new KeyIterator(this);
}
-
- public final boolean hasNext() { return next != null; }
- public final boolean hasMoreElements() { return next != null; }
- }
-
- static final class KeyIterator extends ViewIterator
- implements Iterator, Enumeration {
- KeyIterator(ConcurrentHashMapV8 map) { super(map); }
-
- @SuppressWarnings("unchecked")
- public final K next() {
- if (next == null)
+ @SuppressWarnings("unchecked") public final K next() {
+ if (nextVal == null && advance() == null)
throw new NoSuchElementException();
Object k = nextKey;
- advance();
- return (K)k;
+ nextVal = null;
+ return (K) k;
}
public final K nextElement() { return next(); }
}
- static final class ValueIterator extends ViewIterator
- implements Iterator, Enumeration {
+ @SuppressWarnings("serial") static final class ValueIterator extends Traverser
+ implements Spliterator, Enumeration {
ValueIterator(ConcurrentHashMapV8 map) { super(map); }
+ ValueIterator(Traverser it) {
+ super(it);
+ }
+ public ValueIterator split() {
+ if (last != null || (next != null && nextVal == null))
+ throw new IllegalStateException();
+ return new ValueIterator(this);
+ }
- @SuppressWarnings("unchecked")
- public final V next() {
- if (next == null)
+ @SuppressWarnings("unchecked") public final V next() {
+ Object v;
+ if ((v = nextVal) == null && (v = advance()) == null)
throw new NoSuchElementException();
- Object v = nextVal;
- advance();
- return (V)v;
+ nextVal = null;
+ return (V) v;
}
public final V nextElement() { return next(); }
}
- static final class EntryIterator extends ViewIterator
- implements Iterator> {
+ @SuppressWarnings("serial") static final class EntryIterator extends Traverser
+ implements Spliterator> {
EntryIterator(ConcurrentHashMapV8 map) { super(map); }
-
- @SuppressWarnings("unchecked")
- public final Map.Entry next() {
- if (next == null)
- throw new NoSuchElementException();
- Object k = nextKey;
- Object v = nextVal;
- advance();
- return new WriteThroughEntry((K)k, (V)v, map);
+ EntryIterator(Traverser it) {
+ super(it);
+ }
+ public EntryIterator split() {
+ if (last != null || (next != null && nextVal == null))
+ throw new IllegalStateException();
+ return new EntryIterator(this);
}
- }
-
- static final class SnapshotEntryIterator extends ViewIterator
- implements Iterator> {
- SnapshotEntryIterator(ConcurrentHashMapV8 map) { super(map); }
- @SuppressWarnings("unchecked")
- public final Map.Entry next() {
- if (next == null)
+ @SuppressWarnings("unchecked") public final Map.Entry next() {
+ Object v;
+ if ((v = nextVal) == null && (v = advance()) == null)
throw new NoSuchElementException();
Object k = nextKey;
- Object v = nextVal;
- advance();
- return new SnapshotEntry((K)k, (V)v);
+ nextVal = null;
+ return new MapEntry((K)k, (V)v, map);
}
}
/**
- * Base of writeThrough and Snapshot entry classes
+ * Exported Entry for iterators
*/
- static abstract class MapEntry implements Map.Entry {
+ static final class MapEntry implements Map.Entry {
final K key; // non-null
V val; // non-null
- MapEntry(K key, V val) { this.key = key; this.val = val; }
+ final ConcurrentHashMapV8 map;
+ MapEntry(K key, V val, ConcurrentHashMapV8 map) {
+ this.key = key;
+ this.val = val;
+ this.map = map;
+ }
public final K getKey() { return key; }
public final V getValue() { return val; }
public final int hashCode() { return key.hashCode() ^ val.hashCode(); }
@@ -1726,29 +3131,13 @@ public class ConcurrentHashMapV8
(v == val || v.equals(val)));
}
- public abstract V setValue(V value);
- }
-
- /**
- * Entry used by EntryIterator.next(), that relays setValue
- * changes to the underlying map.
- */
- static final class WriteThroughEntry extends MapEntry
- implements Map.Entry {
- final ConcurrentHashMapV8 map;
- WriteThroughEntry(K key, V val, ConcurrentHashMapV8 map) {
- super(key, val);
- this.map = map;
- }
-
/**
* Sets our entry's value and writes through to the map. The
- * value to return is somewhat arbitrary here. Since a
- * WriteThroughEntry does not necessarily track asynchronous
- * changes, the most recent "previous" value could be
- * different from what we return (or could even have been
- * removed in which case the put will re-establish). We do not
- * and cannot guarantee more.
+ * value to return is somewhat arbitrary here. Since we do not
+ * necessarily track asynchronous changes, the most recent
+ * "previous" value could be different from what we return (or
+ * could even have been removed in which case the put will
+ * re-establish). We do not and cannot guarantee more.
*/
public final V setValue(V value) {
if (value == null) throw new NullPointerException();
@@ -1759,48 +3148,33 @@ public class ConcurrentHashMapV8
}
}
- /**
- * Internal version of entry, that doesn't write though changes
- */
- static final class SnapshotEntry extends MapEntry
- implements Map.Entry {
- SnapshotEntry(K key, V val) { super(key, val); }
- public final V setValue(V value) { // only locally update
- if (value == null) throw new NullPointerException();
- V v = val;
- val = value;
- return v;
- }
- }
-
/* ----------------Views -------------- */
/**
- * Base class for views. This is done mainly to allow adding
- * customized parallel traversals (not yet implemented.)
+ * Base class for views.
*/
- static abstract class MapView {
+ static abstract class CHMView {
final ConcurrentHashMapV8 map;
- MapView(ConcurrentHashMapV8 map) { this.map = map; }
+ CHMView(ConcurrentHashMapV8 map) { this.map = map; }
public final int size() { return map.size(); }
public final boolean isEmpty() { return map.isEmpty(); }
public final void clear() { map.clear(); }
// implementations below rely on concrete classes supplying these
- abstract Iterator iter();
+ abstract public Iterator iterator();
abstract public boolean contains(Object o);
abstract public boolean remove(Object o);
private static final String oomeMsg = "Required array size too large";
public final Object[] toArray() {
- long sz = map.longSize();
+ long sz = map.mappingCount();
if (sz > (long)(MAX_ARRAY_SIZE))
throw new OutOfMemoryError(oomeMsg);
int n = (int)sz;
Object[] r = new Object[n];
int i = 0;
- Iterator it = iter();
+ Iterator it = iterator();
while (it.hasNext()) {
if (i == n) {
if (n >= MAX_ARRAY_SIZE)
@@ -1816,9 +3190,8 @@ public class ConcurrentHashMapV8
return (i == n) ? r : Arrays.copyOf(r, i);
}
- @SuppressWarnings("unchecked")
- public final T[] toArray(T[] a) {
- long sz = map.longSize();
+ @SuppressWarnings("unchecked") public final T[] toArray(T[] a) {
+ long sz = map.mappingCount();
if (sz > (long)(MAX_ARRAY_SIZE))
throw new OutOfMemoryError(oomeMsg);
int m = (int)sz;
@@ -1827,7 +3200,7 @@ public class ConcurrentHashMapV8
.newInstance(a.getClass().getComponentType(), m);
int n = r.length;
int i = 0;
- Iterator it = iter();
+ Iterator it = iterator();
while (it.hasNext()) {
if (i == n) {
if (n >= MAX_ARRAY_SIZE)
@@ -1849,7 +3222,7 @@ public class ConcurrentHashMapV8
public final int hashCode() {
int h = 0;
- for (Iterator it = iter(); it.hasNext();)
+ for (Iterator it = iterator(); it.hasNext();)
h += it.next().hashCode();
return h;
}
@@ -1857,7 +3230,7 @@ public class ConcurrentHashMapV8
public final String toString() {
StringBuilder sb = new StringBuilder();
sb.append('[');
- Iterator it = iter();
+ Iterator it = iterator();
if (it.hasNext()) {
for (;;) {
Object e = it.next();
@@ -1881,9 +3254,9 @@ public class ConcurrentHashMapV8
return true;
}
- public final boolean removeAll(Collection c) {
+ public final boolean removeAll(Collection c) {
boolean modified = false;
- for (Iterator it = iter(); it.hasNext();) {
+ for (Iterator it = iterator(); it.hasNext();) {
if (c.contains(it.next())) {
it.remove();
modified = true;
@@ -1894,7 +3267,7 @@ public class ConcurrentHashMapV8
public final boolean retainAll(Collection c) {
boolean modified = false;
- for (Iterator it = iter(); it.hasNext();) {
+ for (Iterator it = iterator(); it.hasNext();) {
if (!c.contains(it.next())) {
it.remove();
modified = true;
@@ -1905,17 +3278,15 @@ public class ConcurrentHashMapV8
}
- static final class KeySet extends MapView implements Set {
- KeySet(ConcurrentHashMapV8 map) { super(map); }
+ static final class KeySet extends CHMView implements Set {
+ KeySet(ConcurrentHashMapV8 map) {
+ super(map);
+ }
public final boolean contains(Object o) { return map.containsKey(o); }
public final boolean remove(Object o) { return map.remove(o) != null; }
-
public final Iterator iterator() {
return new KeyIterator(map);
}
- final Iterator iter() {
- return new KeyIterator(map);
- }
public final boolean add(K e) {
throw new UnsupportedOperationException();
}
@@ -1930,11 +3301,11 @@ public class ConcurrentHashMapV8
}
}
- static final class Values extends MapView
- implements Collection {
+
+ static final class Values extends CHMView
+ implements Collection {
Values(ConcurrentHashMapV8 map) { super(map); }
public final boolean contains(Object o) { return map.containsValue(o); }
-
public final boolean remove(Object o) {
if (o != null) {
Iterator it = new ValueIterator(map);
@@ -1950,21 +3321,18 @@ public class ConcurrentHashMapV8
public final Iterator iterator() {
return new ValueIterator(map);
}
- final Iterator iter() {
- return new ValueIterator(map);
- }
public final boolean add(V e) {
throw new UnsupportedOperationException();
}
public final boolean addAll(Collection c) {
throw new UnsupportedOperationException();
}
+
}
- static final class EntrySet extends MapView
+ static final class EntrySet extends CHMView
implements Set> {
EntrySet(ConcurrentHashMapV8 map) { super(map); }
-
public final boolean contains(Object o) {
Object k, v, r; Map.Entry e;
return ((o instanceof Map.Entry) &&
@@ -1973,7 +3341,6 @@ public class ConcurrentHashMapV8
(v = e.getValue()) != null &&
(v == r || v.equals(r)));
}
-
public final boolean remove(Object o) {
Object k, v; Map.Entry e;
return ((o instanceof Map.Entry) &&
@@ -1981,13 +3348,9 @@ public class ConcurrentHashMapV8
(v = e.getValue()) != null &&
map.remove(k, v));
}
-
public final Iterator> iterator() {
return new EntryIterator(map);
}
- final Iterator iter() {
- return new SnapshotEntryIterator(map);
- }
public final boolean add(Entry e) {
throw new UnsupportedOperationException();
}
@@ -2023,9 +3386,8 @@ public class ConcurrentHashMapV8
* for each key-value mapping, followed by a null pair.
* The key-value mappings are emitted in no particular order.
*/
- @SuppressWarnings("unchecked")
- private void writeObject(java.io.ObjectOutputStream s)
- throws java.io.IOException {
+ @SuppressWarnings("unchecked") private void writeObject(java.io.ObjectOutputStream s)
+ throws java.io.IOException {
if (segments == null) { // for serialization compatibility
segments = (Segment[])
new Segment[DEFAULT_CONCURRENCY_LEVEL];
@@ -2033,11 +3395,11 @@ public class ConcurrentHashMapV8
segments[i] = new Segment(LOAD_FACTOR);
}
s.defaultWriteObject();
- InternalIterator it = new InternalIterator(table);
- while (it.next != null) {
+ Traverser it = new Traverser(this);
+ Object v;
+ while ((v = it.advance()) != null) {
s.writeObject(it.nextKey);
- s.writeObject(it.nextVal);
- it.advance();
+ s.writeObject(v);
}
s.writeObject(null);
s.writeObject(null);
@@ -2048,9 +3410,8 @@ public class ConcurrentHashMapV8
* Reconstitutes the instance from a stream (that is, deserializes it).
* @param s the stream
*/
- @SuppressWarnings("unchecked")
- private void readObject(java.io.ObjectInputStream s)
- throws java.io.IOException, ClassNotFoundException {
+ @SuppressWarnings("unchecked") private void readObject(java.io.ObjectInputStream s)
+ throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
this.segments = null; // unneeded
// initialize transient final field
@@ -2063,7 +3424,8 @@ public class ConcurrentHashMapV8
K k = (K) s.readObject();
V v = (V) s.readObject();
if (k != null && v != null) {
- p = new Node(spread(k.hashCode()), k, v, p);
+ int h = spread(k.hashCode());
+ p = new Node(h, k, v, p);
++size;
}
else
@@ -2079,6 +3441,7 @@ public class ConcurrentHashMapV8
n = tableSizeFor(sz + (sz >>> 1) + 1);
}
int sc = sizeCtl;
+ boolean collide = false;
if (n > sc &&
UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
try {
@@ -2089,27 +3452,3068 @@ public class ConcurrentHashMapV8
while (p != null) {
int j = p.hash & mask;
Node next = p.next;
- p.next = tabAt(tab, j);
+ Node q = p.next = tabAt(tab, j);
setTabAt(tab, j, p);
+ if (!collide && q != null && q.hash == p.hash)
+ collide = true;
p = next;
}
table = tab;
counter.add(size);
- sc = n - (n >>> 2) - 1;
+ sc = n - (n >>> 2);
}
} finally {
sizeCtl = sc;
}
+ if (collide) { // rescan and convert to TreeBins
+ Node[] tab = table;
+ for (int i = 0; i < tab.length; ++i) {
+ int c = 0;
+ for (Node e = tabAt(tab, i); e != null; e = e.next) {
+ if (++c > TREE_THRESHOLD &&
+ (e.key instanceof Comparable)) {
+ replaceWithTreeBin(tab, i, e.key);
+ break;
+ }
+ }
+ }
+ }
}
if (!init) { // Can only happen if unsafely published.
while (p != null) {
- internalPut(p.key, p.val, true);
+ internalPut(p.key, p.val);
p = p.next;
}
}
}
}
+
+ // -------------------------------------------------------
+
+ // Sams
+ /** Interface describing a void action of one argument */
+ public interface Action { void apply(A a); }
+ /** Interface describing a void action of two arguments */
+ public interface BiAction { void apply(A a, B b); }
+ /** Interface describing a function of one argument */
+ public interface Fun { T apply(A a); }
+ /** Interface describing a function of two arguments */
+ public interface BiFun { T apply(A a, B b); }
+ /** Interface describing a function of no arguments */
+ public interface Generator { T apply(); }
+ /** Interface describing a function mapping its argument to a double */
+ public interface ObjectToDouble { double apply(A a); }
+ /** Interface describing a function mapping its argument to a long */
+ public interface ObjectToLong { long apply(A a); }
+ /** Interface describing a function mapping its argument to an int */
+ public interface ObjectToInt {int apply(A a); }
+ /** Interface describing a function mapping two arguments to a double */
+ public interface ObjectByObjectToDouble { double apply(A a, B b); }
+ /** Interface describing a function mapping two arguments to a long */
+ public interface ObjectByObjectToLong { long apply(A a, B b); }
+ /** Interface describing a function mapping two arguments to an int */
+ public interface ObjectByObjectToInt {int apply(A a, B b); }
+ /** Interface describing a function mapping a double to a double */
+ public interface DoubleToDouble { double apply(double a); }
+ /** Interface describing a function mapping a long to a long */
+ public interface LongToLong { long apply(long a); }
+ /** Interface describing a function mapping an int to an int */
+ public interface IntToInt { int apply(int a); }
+ /** Interface describing a function mapping two doubles to a double */
+ public interface DoubleByDoubleToDouble { double apply(double a, double b); }
+ /** Interface describing a function mapping two longs to a long */
+ public interface LongByLongToLong { long apply(long a, long b); }
+ /** Interface describing a function mapping two ints to an int */
+ public interface IntByIntToInt { int apply(int a, int b); }
+
+
+ // -------------------------------------------------------
+
+ /**
+ * Returns an extended {@link Parallel} view of this map using the
+ * given executor for bulk parallel operations.
+ *
+ * @param executor the executor
+ * @return a parallel view
+ */
+ public Parallel parallel(ForkJoinPool executor) {
+ return new Parallel(executor);
+ }
+
+ /**
+ * An extended view of a ConcurrentHashMap supporting bulk
+ * parallel operations. These operations are designed to be
+ * safely, and often sensibly, applied even with maps that are
+ * being concurrently updated by other threads; for example, when
+ * computing a snapshot summary of the values in a shared
+ * registry. There are three kinds of operation, each with four
+ * forms, accepting functions with Keys, Values, Entries, and
+ * (Key, Value) arguments and/or return values. Because the
+ * elements of a ConcurrentHashMap are not ordered in any
+ * particular way, and may be processed in different orders in
+ * different parallel executions, the correctness of supplied
+ * functions should not depend on any ordering, or on any other
+ * objects or values that may transiently change while computation
+ * is in progress; and except for forEach actions, should ideally
+ * be side-effect-free.
+ *
+ *
+ * - forEach: Perform a given action on each element.
+ * A variant form applies a given transformation on each element
+ * before performing the action.
+ *
+ * - search: Return the first available non-null result of
+ * applying a given function on each element; skipping further
+ * search when a result is found.
+ *
+ * - reduce: Accumulate each element. The supplied reduction
+ * function cannot rely on ordering (more formally, it should be
+ * both associative and commutative). There are five variants:
+ *
+ *
+ *
+ * - Plain reductions. (There is not a form of this method for
+ * (key, value) function arguments since there is no corresponding
+ * return type.)
+ *
+ * - Mapped reductions that accumulate the results of a given
+ * function applied to each element.
+ *
+ * - Reductions to scalar doubles, longs, and ints, using a
+ * given basis value.
+ *
+ *
+ *
+ *
+ *
+ * The concurrency properties of the bulk operations follow
+ * from those of ConcurrentHashMap: Any non-null result returned
+ * from {@code get(key)} and related access methods bears a
+ * happens-before relation with the associated insertion or
+ * update. The result of any bulk operation reflects the
+ * composition of these per-element relations (but is not
+ * necessarily atomic with respect to the map as a whole unless it
+ * is somehow known to be quiescent). Conversely, because keys
+ * and values in the map are never null, null serves as a reliable
+ * atomic indicator of the current lack of any result. To
+ * maintain this property, null serves as an implicit basis for
+ * all non-scalar reduction operations. For the double, long, and
+ * int versions, the basis should be one that, when combined with
+ * any other value, returns that other value (more formally, it
+ * should be the identity element for the reduction). Most common
+ * reductions have these properties; for example, computing a sum
+ * with basis 0 or a minimum with basis MAX_VALUE.
+ *
+ *
Search and transformation functions provided as arguments
+ * should similarly return null to indicate the lack of any result
+ * (in which case it is not used). In the case of mapped
+ * reductions, this also enables transformations to serve as
+ * filters, returning null (or, in the case of primitive
+ * specializations, the identity basis) if the element should not
+ * be combined. You can create compound transformations and
+ * filterings by composing them yourself under this "null means
+ * there is nothing there now" rule before using them in search or
+ * reduce operations.
+ *
+ *
Methods accepting and/or returning Entry arguments maintain
+ * key-value associations. They may be useful for example when
+ * finding the key for the greatest value. Note that "plain" Entry
+ * arguments can be supplied using {@code new
+ * AbstractMap.SimpleEntry(k,v)}.
+ *
+ *
Bulk operations may complete abruptly, throwing an
+ * exception encountered in the application of a supplied
+ * function. Bear in mind when handling such exceptions that other
+ * concurrently executing functions could also have thrown
+ * exceptions, or would have done so if the first exception had
+ * not occurred.
+ *
+ *
Parallel speedups compared to sequential processing are
+ * common but not guaranteed. Operations involving brief
+ * functions on small maps may execute more slowly than sequential
+ * loops if the underlying work to parallelize the computation is
+ * more expensive than the computation itself. Similarly,
+ * parallelization may not lead to much actual parallelism if all
+ * processors are busy performing unrelated tasks.
+ *
+ *
All arguments to all task methods must be non-null.
+ *
+ *
jsr166e note: During transition, this class
+ * uses nested functional interfaces with different names but the
+ * same forms as those expected for JDK8.
+ */
+ public class Parallel {
+ final ForkJoinPool fjp;
+
+ /**
+ * Returns an extended view of this map using the given
+ * executor for bulk parallel operations.
+ *
+ * @param executor the executor
+ */
+ public Parallel(ForkJoinPool executor) {
+ this.fjp = executor;
+ }
+
+ /**
+ * Performs the given action for each (key, value).
+ *
+ * @param action the action
+ */
+ public void forEach(BiAction action) {
+ fjp.invoke(ForkJoinTasks.forEach
+ (ConcurrentHashMapV8.this, action));
+ }
+
+ /**
+ * Performs the given action for each non-null transformation
+ * of each (key, value).
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case the action is not applied)
+ * @param action the action
+ */
+ public void forEach(BiFun transformer,
+ Action action) {
+ fjp.invoke(ForkJoinTasks.forEach
+ (ConcurrentHashMapV8.this, transformer, action));
+ }
+
+ /**
+ * Returns a non-null result from applying the given search
+ * function on each (key, value), or null if none. Upon
+ * success, further element processing is suppressed and the
+ * results of any other parallel invocations of the search
+ * function are ignored.
+ *
+ * @param searchFunction a function returning a non-null
+ * result on success, else null
+ * @return a non-null result from applying the given search
+ * function on each (key, value), or null if none
+ */
+ public U search(BiFun searchFunction) {
+ return fjp.invoke(ForkJoinTasks.search
+ (ConcurrentHashMapV8.this, searchFunction));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all (key, value) pairs using the given reducer to
+ * combine values, or null if none.
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case it is not combined)
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all (key, value) pairs
+ */
+ public U reduce(BiFun transformer,
+ BiFun reducer) {
+ return fjp.invoke(ForkJoinTasks.reduce
+ (ConcurrentHashMapV8.this, transformer, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all (key, value) pairs using the given reducer to
+ * combine values, and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all (key, value) pairs
+ */
+ public double reduceToDouble(ObjectByObjectToDouble transformer,
+ double basis,
+ DoubleByDoubleToDouble reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceToDouble
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all (key, value) pairs using the given reducer to
+ * combine values, and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all (key, value) pairs
+ */
+ public long reduceToLong(ObjectByObjectToLong transformer,
+ long basis,
+ LongByLongToLong reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceToLong
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all (key, value) pairs using the given reducer to
+ * combine values, and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all (key, value) pairs
+ */
+ public int reduceToInt(ObjectByObjectToInt transformer,
+ int basis,
+ IntByIntToInt reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceToInt
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Performs the given action for each key.
+ *
+ * @param action the action
+ */
+ public void forEachKey(Action action) {
+ fjp.invoke(ForkJoinTasks.forEachKey
+ (ConcurrentHashMapV8.this, action));
+ }
+
+ /**
+ * Performs the given action for each non-null transformation
+ * of each key.
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case the action is not applied)
+ * @param action the action
+ */
+ public void forEachKey(Fun transformer,
+ Action action) {
+ fjp.invoke(ForkJoinTasks.forEachKey
+ (ConcurrentHashMapV8.this, transformer, action));
+ }
+
+ /**
+ * Returns a non-null result from applying the given search
+ * function on each key, or null if none. Upon success,
+ * further element processing is suppressed and the results of
+ * any other parallel invocations of the search function are
+ * ignored.
+ *
+ * @param searchFunction a function returning a non-null
+ * result on success, else null
+ * @return a non-null result from applying the given search
+ * function on each key, or null if none
+ */
+ public U searchKeys(Fun searchFunction) {
+ return fjp.invoke(ForkJoinTasks.searchKeys
+ (ConcurrentHashMapV8.this, searchFunction));
+ }
+
+ /**
+ * Returns the result of accumulating all keys using the given
+ * reducer to combine values, or null if none.
+ *
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating all keys using the given
+ * reducer to combine values, or null if none
+ */
+ public K reduceKeys(BiFun reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceKeys
+ (ConcurrentHashMapV8.this, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all keys using the given reducer to combine values, or
+ * null if none.
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case it is not combined)
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all keys
+ */
+ public U reduceKeys(Fun transformer,
+ BiFun reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceKeys
+ (ConcurrentHashMapV8.this, transformer, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all keys using the given reducer to combine values, and
+ * the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all keys
+ */
+ public double reduceKeysToDouble(ObjectToDouble transformer,
+ double basis,
+ DoubleByDoubleToDouble reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceKeysToDouble
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all keys using the given reducer to combine values, and
+ * the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all keys
+ */
+ public long reduceKeysToLong(ObjectToLong transformer,
+ long basis,
+ LongByLongToLong reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceKeysToLong
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all keys using the given reducer to combine values, and
+ * the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all keys
+ */
+ public int reduceKeysToInt(ObjectToInt transformer,
+ int basis,
+ IntByIntToInt reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceKeysToInt
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Performs the given action for each value.
+ *
+ * @param action the action
+ */
+ public void forEachValue(Action action) {
+ fjp.invoke(ForkJoinTasks.forEachValue
+ (ConcurrentHashMapV8.this, action));
+ }
+
+ /**
+ * Performs the given action for each non-null transformation
+ * of each value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case the action is not applied)
+ */
+ public void forEachValue(Fun transformer,
+ Action action) {
+ fjp.invoke(ForkJoinTasks.forEachValue
+ (ConcurrentHashMapV8.this, transformer, action));
+ }
+
+ /**
+ * Returns a non-null result from applying the given search
+ * function on each value, or null if none. Upon success,
+ * further element processing is suppressed and the results of
+ * any other parallel invocations of the search function are
+ * ignored.
+ *
+ * @param searchFunction a function returning a non-null
+ * result on success, else null
+ * @return a non-null result from applying the given search
+ * function on each value, or null if none
+ *
+ */
+ public U searchValues(Fun searchFunction) {
+ return fjp.invoke(ForkJoinTasks.searchValues
+ (ConcurrentHashMapV8.this, searchFunction));
+ }
+
+ /**
+ * Returns the result of accumulating all values using the
+ * given reducer to combine values, or null if none.
+ *
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating all values
+ */
+ public V reduceValues(BiFun reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceValues
+ (ConcurrentHashMapV8.this, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all values using the given reducer to combine values, or
+ * null if none.
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case it is not combined)
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all values
+ */
+ public U reduceValues(Fun transformer,
+ BiFun reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceValues
+ (ConcurrentHashMapV8.this, transformer, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all values using the given reducer to combine values,
+ * and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all values
+ */
+ public double reduceValuesToDouble(ObjectToDouble transformer,
+ double basis,
+ DoubleByDoubleToDouble reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceValuesToDouble
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all values using the given reducer to combine values,
+ * and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all values
+ */
+ public long reduceValuesToLong(ObjectToLong transformer,
+ long basis,
+ LongByLongToLong reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceValuesToLong
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all values using the given reducer to combine values,
+ * and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all values
+ */
+ public int reduceValuesToInt(ObjectToInt transformer,
+ int basis,
+ IntByIntToInt reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceValuesToInt
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Performs the given action for each entry.
+ *
+ * @param action the action
+ */
+ public void forEachEntry(Action> action) {
+ fjp.invoke(ForkJoinTasks.forEachEntry
+ (ConcurrentHashMapV8.this, action));
+ }
+
+ /**
+ * Performs the given action for each non-null transformation
+ * of each entry.
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case the action is not applied)
+ * @param action the action
+ */
+ public void forEachEntry(Fun, ? extends U> transformer,
+ Action action) {
+ fjp.invoke(ForkJoinTasks.forEachEntry
+ (ConcurrentHashMapV8.this, transformer, action));
+ }
+
+ /**
+ * Returns a non-null result from applying the given search
+ * function on each entry, or null if none. Upon success,
+ * further element processing is suppressed and the results of
+ * any other parallel invocations of the search function are
+ * ignored.
+ *
+ * @param searchFunction a function returning a non-null
+ * result on success, else null
+ * @return a non-null result from applying the given search
+ * function on each entry, or null if none
+ */
+ public U searchEntries(Fun, ? extends U> searchFunction) {
+ return fjp.invoke(ForkJoinTasks.searchEntries
+ (ConcurrentHashMapV8.this, searchFunction));
+ }
+
+ /**
+ * Returns the result of accumulating all entries using the
+ * given reducer to combine values, or null if none.
+ *
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating all entries
+ */
+ public Map.Entry reduceEntries(BiFun, Map.Entry, ? extends Map.Entry> reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceEntries
+ (ConcurrentHashMapV8.this, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all entries using the given reducer to combine values,
+ * or null if none.
+ *
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case it is not combined).
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all entries
+ */
+ public U reduceEntries(Fun, ? extends U> transformer,
+ BiFun reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceEntries
+ (ConcurrentHashMapV8.this, transformer, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all entries using the given reducer to combine values,
+ * and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all entries
+ */
+ public double reduceEntriesToDouble(ObjectToDouble> transformer,
+ double basis,
+ DoubleByDoubleToDouble reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceEntriesToDouble
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all entries using the given reducer to combine values,
+ * and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all entries
+ */
+ public long reduceEntriesToLong(ObjectToLong> transformer,
+ long basis,
+ LongByLongToLong reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceEntriesToLong
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+
+ /**
+ * Returns the result of accumulating the given transformation
+ * of all entries using the given reducer to combine values,
+ * and the given basis as an identity value.
+ *
+ * @param transformer a function returning the transformation
+ * for an element
+ * @param basis the identity (initial default value) for the reduction
+ * @param reducer a commutative associative combining function
+ * @return the result of accumulating the given transformation
+ * of all entries
+ */
+ public int reduceEntriesToInt(ObjectToInt> transformer,
+ int basis,
+ IntByIntToInt reducer) {
+ return fjp.invoke(ForkJoinTasks.reduceEntriesToInt
+ (ConcurrentHashMapV8.this, transformer, basis, reducer));
+ }
+ }
+
+ // ---------------------------------------------------------------------
+
+ /**
+ * Predefined tasks for performing bulk parallel operations on
+ * ConcurrentHashMaps. These tasks follow the forms and rules used
+ * in class {@link Parallel}. Each method has the same name, but
+ * returns a task rather than invoking it. These methods may be
+ * useful in custom applications such as submitting a task without
+ * waiting for completion, or combining with other tasks.
+ */
+ public static class ForkJoinTasks {
+ private ForkJoinTasks() {}
+
+ /**
+ * Returns a task that when invoked, performs the given
+ * action for each (key, value)
+ *
+ * @param map the map
+ * @param action the action
+ * @return the task
+ */
+ public static ForkJoinTask forEach
+ (ConcurrentHashMapV8 map,
+ BiAction action) {
+ if (action == null) throw new NullPointerException();
+ return new ForEachMappingTask(map, null, -1, action);
+ }
+
+ /**
+ * Returns a task that when invoked, performs the given
+ * action for each non-null transformation of each (key, value)
+ *
+ * @param map the map
+ * @param transformer a function returning the transformation
+ * for an element, or null of there is no transformation (in
+ * which case the action is not applied)
+ * @param action the action
+ * @return the task
+ */
+ public static ForkJoinTask forEach
+ (ConcurrentHashMapV8 map,
+ BiFun transformer,
+ Action action) {
+ if (transformer == null || action == null)
+ throw new NullPointerException();
+ return new ForEachTransformedMappingTask
+ (map, null, -1, transformer, action);
+ }
+
+ /**
+ * Returns a task that when invoked, returns a non-null result
+ * from applying the given search function on each (key,
+ * value), or null if none. Upon success, further element
+ * processing is suppressed and the results of any other
+ * parallel invocations of the search function are ignored.
+ *
+ * @param map the map
+ * @param searchFunction a function returning a non-null
+ * result on success, else null
+ * @return the task
+ */
+ public static ForkJoinTask search
+ (ConcurrentHashMapV8