--- jsr166/src/jsr166x/ConcurrentSkipListMap.java 2005/03/01 12:48:27 1.6
+++ jsr166/src/jsr166x/ConcurrentSkipListMap.java 2013/01/16 00:51:11 1.23
@@ -1,10 +1,10 @@
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/licenses/publicdomain
+ * http://creativecommons.org/publicdomain/zero/1.0/
*/
-package jsr166x;
+package jsr166x;
import java.util.*;
import java.util.concurrent.*;
@@ -20,8 +20,8 @@ import java.util.concurrent.atomic.*;
* This class implements a concurrent variant of SkipLists providing
* expected average log(n) time cost for the
- * containsKey, get, put and
- * remove operations and their variants. Insertion, removal,
+ * {@code containsKey}, {@code get}, {@code put} and
+ * {@code remove} operations and their variants. Insertion, removal,
* update, and access operations safely execute concurrently by
* multiple threads. Iterators are weakly consistent, returning
* elements reflecting the state of the map at some point at or since
@@ -30,37 +30,37 @@ import java.util.concurrent.atomic.*;
* other operations. Ascending key ordered views and their iterators
* are faster than descending ones.
*
- *
All Map.Entry pairs returned by methods in this class
+ *
All {@code Map.Entry} pairs returned by methods in this class
* and its views represent snapshots of mappings at the time they were
- * produced. They do not support the Entry.setValue
+ * produced. They do not support the {@code Entry.setValue}
* method. (Note however that it is possible to change mappings in the
- * associated map using put, putIfAbsent, or
- * replace, depending on exactly which effect you need.)
+ * associated map using {@code put}, {@code putIfAbsent}, or
+ * {@code replace}, depending on exactly which effect you need.)
*
- *
Beware that, unlike in most collections, the size
+ *
Beware that, unlike in most collections, the {@code size}
* method is not a constant-time operation. Because of the
* asynchronous nature of these maps, determining the current number
* of elements requires a traversal of the elements. Additionally,
- * the bulk operations putAll, equals, and
- * clear are not guaranteed to be performed
+ * the bulk operations {@code putAll}, {@code equals}, and
+ * {@code clear} are not guaranteed to be performed
* atomically. For example, an iterator operating concurrently with a
- * putAll operation might view only some of the added
+ * {@code putAll} operation might view only some of the added
* elements.
*
*
This class and its views and iterators implement all of the
* optional methods of the {@link Map} and {@link Iterator}
* interfaces. Like most other concurrent collections, this class does
- * not permit the use of null keys or values because some
+ * not permit the use of {@code null} keys or values because some
* null return values cannot be reliably distinguished from the
* absence of elements.
*
* @author Doug Lea
* @param the type of keys maintained by this map
- * @param the type of mapped values
+ * @param the type of mapped values
*/
-public class ConcurrentSkipListMap extends AbstractMap
+public class ConcurrentSkipListMap extends AbstractMap
implements ConcurrentNavigableMap,
- Cloneable,
+ Cloneable,
java.io.Serializable {
/*
* This class implements a tree-like two-dimensionally linked skip
@@ -74,19 +74,19 @@ public class ConcurrentSkipListMap
* possible list with 2 levels of index:
*
* Head nodes Index nodes
- * +-+ right +-+ +-+
+ * +-+ right +-+ +-+
* |2|---------------->| |--------------------->| |->null
- * +-+ +-+ +-+
+ * +-+ +-+ +-+
* | down | |
* v v v
- * +-+ +-+ +-+ +-+ +-+ +-+
+ * +-+ +-+ +-+ +-+ +-+ +-+
* |1|----------->| |->| |------>| |----------->| |------>| |->null
- * +-+ +-+ +-+ +-+ +-+ +-+
+ * +-+ +-+ +-+ +-+ +-+ +-+
* v | | | | |
* Nodes next v v v v v
- * +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
+ * +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
* | |->|A|->|B|->|C|->|D|->|E|->|F|->|G|->|H|->|I|->|J|->|K|->null
- * +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
+ * +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
*
* The base lists use a variant of the HM linked ordered set
* algorithm. See Tim Harris, "A pragmatic implementation of
@@ -145,9 +145,9 @@ public class ConcurrentSkipListMap
* Here's the sequence of events for a deletion of node n with
* predecessor b and successor f, initially:
*
- * +------+ +------+ +------+
+ * +------+ +------+ +------+
* ... | b |------>| n |----->| f | ...
- * +------+ +------+ +------+
+ * +------+ +------+ +------+
*
* 1. CAS n's value field from non-null to null.
* From this point on, no public operations encountering
@@ -161,15 +161,15 @@ public class ConcurrentSkipListMap
*
* +------+ +------+ +------+ +------+
* ... | b |------>| n |----->|marker|------>| f | ...
- * +------+ +------+ +------+ +------+
+ * +------+ +------+ +------+ +------+
*
* 3. CAS b's next pointer over both n and its marker.
* From this point on, no new traversals will encounter n,
* and it can eventually be GCed.
* +------+ +------+
* ... | b |----------------------------------->| f | ...
- * +------+ +------+
- *
+ * +------+ +------+
+ *
* A failure at step 1 leads to simple retry due to a lost race
* with another operation. Steps 2-3 can fail because some other
* thread noticed during a traversal a node with null value and
@@ -188,7 +188,7 @@ public class ConcurrentSkipListMap
* nodes. This doesn't change the basic algorithm except for the
* need to make sure base traversals start at predecessors (here,
* b) that are not (structurally) deleted, otherwise retrying
- * after processing the deletion.
+ * after processing the deletion.
*
* Index levels are maintained as lists with volatile next fields,
* using CAS to link and unlink. Races are allowed in index-list
@@ -292,11 +292,11 @@ public class ConcurrentSkipListMap
/**
* Special value used to identify base-level header
- */
+ */
private static final Object BASE_HEADER = new Object();
/**
- * The topmost head index of the skiplist.
+ * The topmost head index of the skiplist.
*/
private transient volatile HeadIndex head;
@@ -325,13 +325,13 @@ public class ConcurrentSkipListMap
private transient DescendingEntrySet descendingEntrySet;
/**
- * Initialize or reset state. Needed by constructors, clone,
+ * Initializes or resets state. Needed by constructors, clone,
* clear, readObject. and ConcurrentSkipListSet.clone.
* (Note that comparator must be separately initialized.)
*/
final void initialize() {
keySet = null;
- entrySet = null;
+ entrySet = null;
values = null;
descendingEntrySet = null;
descendingKeySet = null;
@@ -341,8 +341,8 @@ public class ConcurrentSkipListMap
}
/** Updater for casHead */
- private static final
- AtomicReferenceFieldUpdater
+ private static final
+ AtomicReferenceFieldUpdater
headUpdater = AtomicReferenceFieldUpdater.newUpdater
(ConcurrentSkipListMap.class, HeadIndex.class, "head");
@@ -390,12 +390,12 @@ public class ConcurrentSkipListMap
}
/** Updater for casNext */
- static final AtomicReferenceFieldUpdater
+ static final AtomicReferenceFieldUpdater
nextUpdater = AtomicReferenceFieldUpdater.newUpdater
(Node.class, Node.class, "next");
/** Updater for casValue */
- static final AtomicReferenceFieldUpdater
+ static final AtomicReferenceFieldUpdater
valueUpdater = AtomicReferenceFieldUpdater.newUpdater
(Node.class, Object.class, "value");
@@ -414,7 +414,7 @@ public class ConcurrentSkipListMap
}
/**
- * Return true if this node is a marker. This method isn't
+ * Returns true if this node is a marker. This method isn't
* actually called in an any current code checking for markers
* because callers will have already read value field and need
* to use that read (not another done here) and so directly
@@ -427,7 +427,7 @@ public class ConcurrentSkipListMap
}
/**
- * Return true if this node is the header of base-level list.
+ * Returns true if this node is the header of base-level list.
* @return true if this node is header node
*/
boolean isBaseHeader() {
@@ -465,8 +465,8 @@ public class ConcurrentSkipListMap
}
/**
- * Return value if this node contains a valid key-value pair,
- * else null.
+ * Returns value if this node contains a valid key-value pair,
+ * else null.
* @return this node's value if it isn't a marker or header or
* is deleted, else null.
*/
@@ -478,8 +478,8 @@ public class ConcurrentSkipListMap
}
/**
- * Create and return a new SnapshotEntry holding current
- * mapping if this node holds a valid value, else null
+ * Creates and returns a new SnapshotEntry holding current
+ * mapping if this node holds a valid value, else null.
* @return new entry or null
*/
SnapshotEntry createSnapshot() {
@@ -508,7 +508,7 @@ public class ConcurrentSkipListMap
/**
* Creates index node with given values
- */
+ */
Index(Node node, Index down, Index right) {
this.node = node;
this.key = node.key;
@@ -517,7 +517,7 @@ public class ConcurrentSkipListMap
}
/** Updater for casRight */
- static final AtomicReferenceFieldUpdater
+ static final AtomicReferenceFieldUpdater
rightUpdater = AtomicReferenceFieldUpdater.newUpdater
(Index.class, Index.class, "right");
@@ -546,7 +546,7 @@ public class ConcurrentSkipListMap
*/
final boolean link(Index succ, Index newSucc) {
Node n = node;
- newSucc.right = succ;
+ newSucc.right = succ;
return n.value != null && casRight(succ, newSucc);
}
@@ -573,18 +573,18 @@ public class ConcurrentSkipListMap
super(node, down, right);
this.level = level;
}
- }
+ }
/* ---------------- Map.Entry support -------------- */
/**
* An immutable representation of a key-value mapping as it
* existed at some point in time. This class does not
- * support the Map.Entry.setValue method.
- */
+ * support the {@code Map.Entry.setValue} method.
+ */
static class SnapshotEntry implements Map.Entry {
- private final K key;
- private final V value;
+ private final K key;
+ private final V value;
/**
* Creates a new entry representing the given key and value.
@@ -592,31 +592,31 @@ public class ConcurrentSkipListMap
* @param value the value
*/
SnapshotEntry(K key, V value) {
- this.key = key;
- this.value = value;
- }
-
- /**
- * Returns the key corresponding to this entry.
- *
- * @return the key corresponding to this entry.
- */
+ this.key = key;
+ this.value = value;
+ }
+
+ /**
+ * Returns the key corresponding to this entry.
+ *
+ * @return the key corresponding to this entry
+ */
public K getKey() {
return key;
}
- /**
- * Returns the value corresponding to this entry.
- *
- * @return the value corresponding to this entry.
- */
+ /**
+ * Returns the value corresponding to this entry.
+ *
+ * @return the value corresponding to this entry
+ */
public V getValue() {
- return value;
+ return value;
}
- /**
- * Always fails, throwing UnsupportedOperationException.
- * @throws UnsupportedOperationException always.
+ /**
+ * Always fails, throwing {@code UnsupportedOperationException}.
+ * @throws UnsupportedOperationException always
*/
public V setValue(V value) {
throw new UnsupportedOperationException();
@@ -644,12 +644,12 @@ public class ConcurrentSkipListMap
/**
* Returns a String consisting of the key followed by an
- * equals sign ("=") followed by the associated
+ * equals sign ({@code "="}) followed by the associated
* value.
- * @return a String representation of this entry.
+ * @return a String representation of this entry
*/
public String toString() {
- return getKey() + "=" + getValue();
+ return getKey() + "=" + getValue();
}
}
@@ -688,15 +688,15 @@ public class ConcurrentSkipListMap
* which is propagated back to caller.
*/
private Comparable comparable(Object key) throws ClassCastException {
- if (key == null)
+ if (key == null)
throw new NullPointerException();
- return (comparator != null)
- ? new ComparableUsingComparator(key, comparator)
+ return (comparator != null)
+ ? new ComparableUsingComparator(key, comparator)
: (Comparable)key;
}
/**
- * Compare using comparator or natural ordering. Used when the
+ * Compares using comparator or natural ordering. Used when the
* ComparableUsingComparator approach doesn't apply.
*/
int compare(K k1, K k2) throws ClassCastException {
@@ -708,23 +708,23 @@ public class ConcurrentSkipListMap
}
/**
- * Return true if given key greater than or equal to least and
+ * Returns true if given key greater than or equal to least and
* strictly less than fence, bypassing either test if least or
- * fence oare null. Needed mainly in submap operations.
+ * fence are null. Needed mainly in submap operations.
*/
boolean inHalfOpenRange(K key, K least, K fence) {
- if (key == null)
+ if (key == null)
throw new NullPointerException();
return ((least == null || compare(key, least) >= 0) &&
(fence == null || compare(key, fence) < 0));
}
/**
- * Return true if given key greater than or equal to least and less
+ * Returns true if given key greater than or equal to least and less
* or equal to fence. Needed mainly in submap operations.
*/
boolean inOpenRange(K key, K least, K fence) {
- if (key == null)
+ if (key == null)
throw new NullPointerException();
return ((least == null || compare(key, least) >= 0) &&
(fence == null || compare(key, fence) <= 0));
@@ -733,12 +733,12 @@ public class ConcurrentSkipListMap
/* ---------------- Traversal -------------- */
/**
- * Return a base-level node with key strictly less than given key,
+ * Returns a base-level node with key strictly less than given key,
* or the base-level header if there is no such node. Also
* unlinks indexes to deleted nodes found along the way. Callers
* rely on this side-effect of clearing indices to deleted nodes.
* @param key the key
- * @return a predecessor of key
+ * @return a predecessor of key
*/
private Node findPredecessor(Comparable key) {
for (;;) {
@@ -757,7 +757,7 @@ public class ConcurrentSkipListMap
continue;
}
}
- if ((d = q.down) != null)
+ if ((d = q.down) != null)
q = d;
else
return q.node;
@@ -766,7 +766,7 @@ public class ConcurrentSkipListMap
}
/**
- * Return node holding key or null if no such, clearing out any
+ * Returns node holding key or null if no such, clearing out any
* deleted nodes seen along the way. Repeatedly traverses at
* base-level looking for key starting at predecessor returned
* from findPredecessor, processing base-level deletions as
@@ -787,7 +787,7 @@ public class ConcurrentSkipListMap
* here because doing so would not usually outweigh cost of
* restarting.
*
- * (3) n is a marker or n's predecessor's value field is null,
+ * (3) n is a marker or n's predecessor's value field is null,
* indicating (among other possibilities) that
* findPredecessor returned a deleted node. We can't unlink
* the node because we don't know its predecessor, so rely
@@ -805,16 +805,16 @@ public class ConcurrentSkipListMap
* findLast. They can't easily share code because each uses the
* reads of fields held in locals occurring in the orders they
* were performed.
- *
+ *
* @param key the key
- * @return node holding key, or null if no such.
+ * @return node holding key, or null if no such
*/
private Node findNode(Comparable key) {
for (;;) {
Node b = findPredecessor(key);
Node n = b.next;
for (;;) {
- if (n == null)
+ if (n == null)
return null;
Node f = n.next;
if (n != b.next) // inconsistent read
@@ -829,7 +829,7 @@ public class ConcurrentSkipListMap
int c = key.compareTo(n.key);
if (c < 0)
return null;
- if (c == 0)
+ if (c == 0)
return n;
b = n;
n = f;
@@ -837,7 +837,7 @@ public class ConcurrentSkipListMap
}
}
- /**
+ /**
* Specialized variant of findNode to perform Map.get. Does a weak
* traversal, not bothering to fix any deleted index nodes,
* returning early if it happens to see key in index, and passing
@@ -856,7 +856,7 @@ public class ConcurrentSkipListMap
for (;;) {
K rk;
Index d, r;
- if ((r = q.right) != null &&
+ if ((r = q.right) != null &&
(rk = r.key) != null && rk != bound) {
int c = key.compareTo(rk);
if (c > 0) {
@@ -865,11 +865,11 @@ public class ConcurrentSkipListMap
}
if (c == 0) {
Object v = r.node.value;
- return (v != null)? (V)v : getUsingFindNode(key);
+ return (v != null) ? (V)v : getUsingFindNode(key);
}
bound = rk;
}
- if ((d = q.down) != null)
+ if ((d = q.down) != null)
q = d;
else {
for (Node n = q.node.next; n != null; n = n.next) {
@@ -878,7 +878,7 @@ public class ConcurrentSkipListMap
int c = key.compareTo(nk);
if (c == 0) {
Object v = n.value;
- return (v != null)? (V)v : getUsingFindNode(key);
+ return (v != null) ? (V)v : getUsingFindNode(key);
}
if (c < 0)
return null;
@@ -890,7 +890,7 @@ public class ConcurrentSkipListMap
}
/**
- * Perform map.get via findNode. Used as a backup if doGet
+ * Performs map.get via findNode. Used as a backup if doGet
* encounters an in-progress deletion.
* @param key the key
* @return the value, or null if absent
@@ -916,7 +916,7 @@ public class ConcurrentSkipListMap
/**
* Main insertion method. Adds element if not present, or
* replaces value if present and onlyIfAbsent is false.
- * @param kkey the key
+ * @param kkey the key
* @param value the value that must be associated with key
* @param onlyIfAbsent if should not insert if already present
* @return the old value, or null if newly inserted
@@ -930,7 +930,7 @@ public class ConcurrentSkipListMap
if (n != null) {
Node f = n.next;
if (n != b.next) // inconsistent read
- break;;
+ break;
Object v = n.value;
if (v == null) { // n is deleted
n.helpDelete(b, f);
@@ -952,12 +952,12 @@ public class ConcurrentSkipListMap
}
// else c < 0; fall through
}
-
+
Node z = new Node(kkey, value, n);
- if (!b.casNext(n, z))
+ if (!b.casNext(n, z))
break; // restart if lost race to append to b
- int level = randomLevel();
- if (level > 0)
+ int level = randomLevel();
+ if (level > 0)
insertIndex(z, level);
return null;
}
@@ -965,7 +965,7 @@ public class ConcurrentSkipListMap
}
/**
- * Return a random level for inserting a new node.
+ * Returns a random level for inserting a new node.
* Hardwired to k=1, p=0.5, max 31.
*
* This uses a cheap pseudo-random function that according to
@@ -979,15 +979,15 @@ public class ConcurrentSkipListMap
int level = 0;
int r = randomSeed;
randomSeed = r * 134775813 + 1;
- if (r < 0) {
- while ((r <<= 1) > 0)
+ if (r < 0) {
+ while ((r <<= 1) > 0)
++level;
}
return level;
}
/**
- * Create and add index nodes for given node.
+ * Creates and adds index nodes for given node.
* @param z the node
* @param level the level of the index
*/
@@ -1013,7 +1013,7 @@ public class ConcurrentSkipListMap
level = max + 1;
Index[] idxs = (Index[])new Index[level+1];
Index idx = null;
- for (int i = 1; i <= level; ++i)
+ for (int i = 1; i <= level; ++i)
idxs[i] = idx = new Index(z, idx, null);
HeadIndex oldh;
@@ -1027,7 +1027,7 @@ public class ConcurrentSkipListMap
}
HeadIndex newh = oldh;
Node oldbase = oldh.node;
- for (int j = oldLevel+1; j <= level; ++j)
+ for (int j = oldLevel+1; j <= level; ++j)
newh = new HeadIndex(oldbase, newh, idxs[j], j);
if (casHead(oldh, newh)) {
k = oldLevel;
@@ -1039,7 +1039,7 @@ public class ConcurrentSkipListMap
}
/**
- * Add given index nodes from given level down to 1.
+ * Adds given index nodes from given level down to 1.
* @param idx the topmost index node being inserted
* @param h the value of head to use to insert. This must be
* snapshotted by callers to provide correct insertion level
@@ -1065,7 +1065,7 @@ public class ConcurrentSkipListMap
if (q.unlink(r))
continue;
else
- break;
+ break;
}
if (c > 0) {
q = r;
@@ -1079,17 +1079,17 @@ public class ConcurrentSkipListMap
findNode(key); // cleans up
return;
}
- if (!q.link(r, t))
+ if (!q.link(r, t))
break; // restart
if (--insertionLevel == 0) {
// need final deletion check before return
- if (t.indexesDeletedNode())
- findNode(key);
+ if (t.indexesDeletedNode())
+ findNode(key);
return;
}
}
- if (j > insertionLevel && j <= indexLevel)
+ if (j > insertionLevel && j <= indexLevel)
t = t.down;
q = q.down;
--j;
@@ -1111,7 +1111,7 @@ public class ConcurrentSkipListMap
* index nodes because it might be the case that some or all
* indexes hadn't been inserted yet for this node during initial
* search for it, and we'd like to ensure lack of garbage
- * retention, so must call to be sure.
+ * retention, so must call to be sure.
*
* @param okey the key
* @param value if non-null, the value that must be
@@ -1120,11 +1120,11 @@ public class ConcurrentSkipListMap
*/
private V doRemove(Object okey, Object value) {
Comparable key = comparable(okey);
- for (;;) {
+ for (;;) {
Node b = findPredecessor(key);
Node n = b.next;
for (;;) {
- if (n == null)
+ if (n == null)
return null;
Node f = n.next;
if (n != b.next) // inconsistent read
@@ -1144,15 +1144,15 @@ public class ConcurrentSkipListMap
n = f;
continue;
}
- if (value != null && !value.equals(v))
- return null;
- if (!n.casValue(v, null))
+ if (value != null && !value.equals(v))
+ return null;
+ if (!n.casValue(v, null))
break;
- if (!n.appendMarker(f) || !b.casNext(n, f))
+ if (!n.appendMarker(f) || !b.casNext(n, f))
findNode(key); // Retry via findNode
else {
findPredecessor(key); // Clean index
- if (head.right == null)
+ if (head.right == null)
tryReduceLevel();
}
return (V)v;
@@ -1185,10 +1185,10 @@ public class ConcurrentSkipListMap
HeadIndex d;
HeadIndex e;
if (h.level > 3 &&
- (d = (HeadIndex)h.down) != null &&
- (e = (HeadIndex)d.down) != null &&
- e.right == null &&
- d.right == null &&
+ (d = (HeadIndex)h.down) != null &&
+ (e = (HeadIndex)d.down) != null &&
+ e.right == null &&
+ d.right == null &&
h.right == null &&
casHead(h, d) && // try to set
h.right != null) // recheck
@@ -1196,7 +1196,7 @@ public class ConcurrentSkipListMap
}
/**
- * Version of remove with boolean return. Needed by view classes
+ * Version of remove with boolean return. Needed by view classes.
*/
boolean removep(Object key) {
return doRemove(key, null) != null;
@@ -1214,23 +1214,23 @@ public class ConcurrentSkipListMap
Node n = b.next;
if (n == null)
return null;
- if (n.value != null)
+ if (n.value != null)
return n;
n.helpDelete(b, n.next);
}
}
/**
- * Remove first entry; return either its key or a snapshot.
+ * Removes first entry; return either its key or a snapshot.
* @param keyOnly if true return key, else return SnapshotEntry
* (This is a little ugly, but avoids code duplication.)
* @return null if empty, first key if keyOnly true, else key,value entry
*/
Object doRemoveFirst(boolean keyOnly) {
- for (;;) {
+ for (;;) {
Node b = head.node;
Node n = b.next;
- if (n == null)
+ if (n == null)
return null;
Node f = n.next;
if (n != b.next)
@@ -1246,13 +1246,13 @@ public class ConcurrentSkipListMap
findFirst(); // retry
clearIndexToFirst();
K key = n.key;
- return (keyOnly)? key : new SnapshotEntry(key, (V)v);
+ return keyOnly ? key : new SnapshotEntry(key, (V)v);
}
}
/**
- * Clear out index nodes associated with deleted first entry.
- * Needed by doRemoveFirst
+ * Clears out index nodes associated with deleted first entry.
+ * Needed by doRemoveFirst.
*/
private void clearIndexToFirst() {
for (;;) {
@@ -1260,9 +1260,9 @@ public class ConcurrentSkipListMap
for (;;) {
Index r = q.right;
if (r != null && r.indexesDeletedNode() && !q.unlink(r))
- break;
+ break;
if ((q = q.down) == null) {
- if (head.right == null)
+ if (head.right == null)
tryReduceLevel();
return;
}
@@ -1271,7 +1271,7 @@ public class ConcurrentSkipListMap
}
/**
- * Remove first entry; return key or null if empty.
+ * Removes first entry; return key or null if empty.
*/
K pollFirstKey() {
return (K)doRemoveFirst(true);
@@ -1296,7 +1296,7 @@ public class ConcurrentSkipListMap
if (r.indexesDeletedNode()) {
q.unlink(r);
q = head; // restart
- }
+ }
else
q = r;
} else if ((d = q.down) != null) {
@@ -1305,8 +1305,8 @@ public class ConcurrentSkipListMap
Node b = q.node;
Node n = b.next;
for (;;) {
- if (n == null)
- return (b.isBaseHeader())? null : b;
+ if (n == null)
+ return b.isBaseHeader() ? null : b;
Node f = n.next; // inconsistent read
if (n != b.next)
break;
@@ -1332,13 +1332,13 @@ public class ConcurrentSkipListMap
* @return null if empty, last key if keyOnly true, else key,value entry
*/
Object doRemoveLast(boolean keyOnly) {
- for (;;) {
+ for (;;) {
Node b = findPredecessorOfLast();
Node n = b.next;
if (n == null) {
if (b.isBaseHeader()) // empty
return null;
- else
+ else
continue; // all b's successors are deleted; retry
}
for (;;) {
@@ -1357,18 +1357,18 @@ public class ConcurrentSkipListMap
n = f;
continue;
}
- if (!n.casValue(v, null))
+ if (!n.casValue(v, null))
break;
K key = n.key;
Comparable ck = comparable(key);
- if (!n.appendMarker(f) || !b.casNext(n, f))
+ if (!n.appendMarker(f) || !b.casNext(n, f))
findNode(ck); // Retry via findNode
else {
findPredecessor(ck); // Clean index
- if (head.right == null)
+ if (head.right == null)
tryReduceLevel();
}
- return (keyOnly)? key : new SnapshotEntry(key, (V)v);
+ return keyOnly ? key : new SnapshotEntry(key, (V)v);
}
}
}
@@ -1378,7 +1378,7 @@ public class ConcurrentSkipListMap
* last valid node. Needed by doRemoveLast. It is possible that
* all successors of returned node will have been deleted upon
* return, in which case this method can be retried.
- * @return likely predecessor of last node.
+ * @return likely predecessor of last node
*/
private Node findPredecessorOfLast() {
for (;;) {
@@ -1396,16 +1396,16 @@ public class ConcurrentSkipListMap
continue;
}
}
- if ((d = q.down) != null)
+ if ((d = q.down) != null)
q = d;
- else
+ else
return q.node;
}
}
}
/**
- * Remove last entry; return key or null if empty.
+ * Removes last entry; return key or null if empty.
*/
K pollLastKey() {
return (K)doRemoveLast(true);
@@ -1431,8 +1431,8 @@ public class ConcurrentSkipListMap
Node b = findPredecessor(key);
Node n = b.next;
for (;;) {
- if (n == null)
- return ((rel & LT) == 0 || b.isBaseHeader())? null : b;
+ if (n == null)
+ return ((rel & LT) == 0 || b.isBaseHeader()) ? null : b;
Node f = n.next;
if (n != b.next) // inconsistent read
break;
@@ -1448,7 +1448,7 @@ public class ConcurrentSkipListMap
(c < 0 && (rel & LT) == 0))
return n;
if ( c <= 0 && (rel & LT) != 0)
- return (b.isBaseHeader())? null : b;
+ return b.isBaseHeader() ? null : b;
b = n;
n = f;
}
@@ -1456,7 +1456,7 @@ public class ConcurrentSkipListMap
}
/**
- * Return SnapshotEntry for results of findNear.
+ * Returns SnapshotEntry for results of findNear.
* @param kkey the key
* @param rel the relation -- OR'ed combination of EQ, LT, GT
* @return Entry fitting relation, or null if no such
@@ -1473,28 +1473,28 @@ public class ConcurrentSkipListMap
}
/**
- * Return ceiling, or first node if key is null
+ * Returns ceiling, or first node if key is {@code null}.
*/
Node findCeiling(K key) {
- return (key == null)? findFirst() : findNear(key, GT|EQ);
+ return (key == null) ? findFirst() : findNear(key, GT|EQ);
}
/**
- * Return lower node, or last node if key is null
+ * Returns lower node, or last node if key is {@code null}.
*/
Node findLower(K key) {
- return (key == null)? findLast() : findNear(key, LT);
+ return (key == null) ? findLast() : findNear(key, LT);
}
/**
- * Return SnapshotEntry or key for results of findNear ofter screening
+ * Returns SnapshotEntry or key for results of findNear ofter screening
* to ensure result is in given range. Needed by submaps.
* @param kkey the key
* @param rel the relation -- OR'ed combination of EQ, LT, GT
* @param least minimum allowed key value
* @param fence key greater than maximum allowed key value
* @param keyOnly if true return key, else return SnapshotEntry
- * @return Key or Entry fitting relation, or null if no such
+ * @return Key or Entry fitting relation, or {@code null} if no such
*/
Object getNear(K kkey, int rel, K least, K fence, boolean keyOnly) {
K key = kkey;
@@ -1512,17 +1512,17 @@ public class ConcurrentSkipListMap
return null;
K k = n.key;
V v = n.getValidValue();
- if (v != null)
- return keyOnly? k : new SnapshotEntry(k, v);
+ if (v != null)
+ return keyOnly ? k : new SnapshotEntry(k, v);
}
}
/**
- * Find and remove least element of subrange.
+ * Finds and removes least element of subrange.
* @param least minimum allowed key value
* @param fence key greater than maximum allowed key value
* @param keyOnly if true return key, else return SnapshotEntry
- * @return least Key or Entry, or null if no such
+ * @return least Key or Entry, or {@code null} if no such
*/
Object removeFirstEntryOfSubrange(K least, K fence, boolean keyOnly) {
for (;;) {
@@ -1534,16 +1534,16 @@ public class ConcurrentSkipListMap
return null;
V v = doRemove(k, null);
if (v != null)
- return (keyOnly)? k : new SnapshotEntry(k, v);
+ return keyOnly ? k : new SnapshotEntry(k, v);
}
}
/**
- * Find and remove greatest element of subrange.
+ * Finds and removes greatest element of subrange.
* @param least minimum allowed key value
* @param fence key greater than maximum allowed key value
* @param keyOnly if true return key, else return SnapshotEntry
- * @return least Key or Entry, or null if no such
+ * @return least Key or Entry, or {@code null} if no such
*/
Object removeLastEntryOfSubrange(K least, K fence, boolean keyOnly) {
for (;;) {
@@ -1555,7 +1555,7 @@ public class ConcurrentSkipListMap
return null;
V v = doRemove(k, null);
if (v != null)
- return (keyOnly)? k : new SnapshotEntry(k, v);
+ return keyOnly ? k : new SnapshotEntry(k, v);
}
}
@@ -1563,7 +1563,7 @@ public class ConcurrentSkipListMap
/**
* Constructs a new empty map, sorted according to the keys' natural
- * order.
+ * order.
*/
public ConcurrentSkipListMap() {
this.comparator = null;
@@ -1574,7 +1574,7 @@ public class ConcurrentSkipListMap
* Constructs a new empty map, sorted according to the given comparator.
*
* @param c the comparator that will be used to sort this map. A
- * null value indicates that the keys' natural
+ * {@code null} value indicates that the keys' natural
* ordering should be used.
*/
public ConcurrentSkipListMap(Comparator c) {
@@ -1584,12 +1584,12 @@ public class ConcurrentSkipListMap
/**
* Constructs a new map containing the same mappings as the given map,
- * sorted according to the keys' natural order.
+ * sorted according to the keys' natural order.
*
- * @param m the map whose mappings are to be placed in this map.
+ * @param m the map whose mappings are to be placed in this map
* @throws ClassCastException if the keys in m are not Comparable, or
- * are not mutually comparable.
- * @throws NullPointerException if the specified map is null.
+ * are not mutually comparable
+ * @throws NullPointerException if the specified map is {@code null}
*/
public ConcurrentSkipListMap(Map m) {
this.comparator = null;
@@ -1599,11 +1599,11 @@ public class ConcurrentSkipListMap
/**
* Constructs a new map containing the same mappings as the given
- * SortedMap, sorted according to the same ordering.
+ * {@code SortedMap}, sorted according to the same ordering.
* @param m the sorted map whose mappings are to be placed in this
* map, and whose comparator is to be used to sort this map.
* @throws NullPointerException if the specified sorted map is
- * null.
+ * {@code null}.
*/
public ConcurrentSkipListMap(SortedMap m) {
this.comparator = m.comparator();
@@ -1612,10 +1612,10 @@ public class ConcurrentSkipListMap
}
/**
- * Returns a shallow copy of this Map instance. (The keys and
+ * Returns a shallow copy of this {@code Map} instance. (The keys and
* values themselves are not cloned.)
*
- * @return a shallow copy of this Map.
+ * @return a shallow copy of this Map
*/
public Object clone() {
ConcurrentSkipListMap clone = null;
@@ -1647,7 +1647,7 @@ public class ConcurrentSkipListMap
ArrayList> preds = new ArrayList>();
// initialize
- for (int i = 0; i <= h.level; ++i)
+ for (int i = 0; i <= h.level; ++i)
preds.add(null);
Index q = h;
for (int i = h.level; i > 0; --i) {
@@ -1655,7 +1655,7 @@ public class ConcurrentSkipListMap
q = q.down;
}
- Iterator> it =
+ Iterator> it =
map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry e = it.next();
@@ -1672,7 +1672,7 @@ public class ConcurrentSkipListMap
Index idx = null;
for (int i = 1; i <= j; ++i) {
idx = new Index(z, idx, null);
- if (i > h.level)
+ if (i > h.level)
h = new HeadIndex(h.node, h, idx, i);
if (i < preds.size()) {
@@ -1689,11 +1689,11 @@ public class ConcurrentSkipListMap
/* ---------------- Serialization -------------- */
/**
- * Save the state of the Map instance to a stream.
+ * Saves the state of the {@code Map} instance to a stream.
*
* @serialData The key (Object) and value (Object) for each
- * key-value mapping represented by the Map, followed by
- * null. The key-value mappings are emitted in key-order
+ * key-value mapping represented by the Map, followed by
+ * {@code null}. The key-value mappings are emitted in key-order
* (as determined by the Comparator, or by the keys' natural
* ordering if no Comparator).
*/
@@ -1714,7 +1714,7 @@ public class ConcurrentSkipListMap
}
/**
- * Reconstitute the Map instance from a stream.
+ * Reconstitutes the {@code Map} instance from a stream.
*/
private void readObject(final java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
@@ -1723,7 +1723,7 @@ public class ConcurrentSkipListMap
// Reset transients
initialize();
- /*
+ /*
* This is nearly identical to buildFromSorted, but is
* distinct because readObject calls can't be nicely adapted
* as the kind of iterator needed by buildFromSorted. (They
@@ -1734,7 +1734,7 @@ public class ConcurrentSkipListMap
HeadIndex h = head;
Node basepred = h.node;
ArrayList> preds = new ArrayList>();
- for (int i = 0; i <= h.level; ++i)
+ for (int i = 0; i <= h.level; ++i)
preds.add(null);
Index q = h;
for (int i = h.level; i > 0; --i) {
@@ -1747,7 +1747,7 @@ public class ConcurrentSkipListMap
if (k == null)
break;
Object v = s.readObject();
- if (v == null)
+ if (v == null)
throw new NullPointerException();
K key = (K) k;
V val = (V) v;
@@ -1760,7 +1760,7 @@ public class ConcurrentSkipListMap
Index idx = null;
for (int i = 1; i <= j; ++i) {
idx = new Index(z, idx, null);
- if (i > h.level)
+ if (i > h.level)
h = new HeadIndex(h.node, h, idx, i);
if (i < preds.size()) {
@@ -1777,14 +1777,14 @@ public class ConcurrentSkipListMap
/* ------ Map API methods ------ */
/**
- * Returns true if this map contains a mapping for the specified
+ * Returns {@code true} if this map contains a mapping for the specified
* key.
- * @param key key whose presence in this map is to be tested.
- * @return true if this map contains a mapping for the
- * specified key.
+ * @param key key whose presence in this map is to be tested
+ * @return {@code true} if this map contains a mapping for the
+ * specified key
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if the key is null.
+ * currently in the map
+ * @throws NullPointerException if the key is {@code null}
*/
public boolean containsKey(Object key) {
return doGet(key) != null;
@@ -1792,14 +1792,14 @@ public class ConcurrentSkipListMap
/**
* Returns the value to which this map maps the specified key. Returns
- * null if the map contains no mapping for this key.
+ * {@code null} if the map contains no mapping for this key.
*
- * @param key key whose associated value is to be returned.
+ * @param key key whose associated value is to be returned
* @return the value to which this map maps the specified key, or
- * null if the map contains no mapping for the key.
+ * {@code null} if the map contains no mapping for the key
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if the key is null.
+ * currently in the map
+ * @throws NullPointerException if the key is {@code null}
*/
public V get(Object key) {
return doGet(key);
@@ -1810,17 +1810,17 @@ public class ConcurrentSkipListMap
* If the map previously contained a mapping for this key, the old
* value is replaced.
*
- * @param key key with which the specified value is to be associated.
- * @param value value to be associated with the specified key.
+ * @param key key with which the specified value is to be associated
+ * @param value value to be associated with the specified key
*
- * @return previous value associated with specified key, or null
- * if there was no mapping for key.
+ * @return previous value associated with specified key, or {@code null}
+ * if there was no mapping for key
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if the key or value are null.
+ * currently in the map
+ * @throws NullPointerException if the key or value are {@code null}
*/
public V put(K key, V value) {
- if (value == null)
+ if (value == null)
throw new NullPointerException();
return doPut(key, value, false);
}
@@ -1829,29 +1829,29 @@ public class ConcurrentSkipListMap
* Removes the mapping for this key from this Map if present.
*
* @param key key for which mapping should be removed
- * @return previous value associated with specified key, or null
- * if there was no mapping for key.
+ * @return previous value associated with specified key, or {@code null}
+ * if there was no mapping for key
*
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if the key is null.
+ * currently in the map
+ * @throws NullPointerException if the key is {@code null}
*/
public V remove(Object key) {
return doRemove(key, null);
}
/**
- * Returns true if this map maps one or more keys to the
+ * Returns {@code true} if this map maps one or more keys to the
* specified value. This operation requires time linear in the
* Map size.
*
- * @param value value whose presence in this Map is to be tested.
- * @return true if a mapping to value exists;
- * false otherwise.
- * @throws NullPointerException if the value is null.
- */
+ * @param value value whose presence in this Map is to be tested
+ * @return {@code true} if a mapping to {@code value} exists;
+ * {@code false} otherwise
+ * @throws NullPointerException if the value is {@code null}
+ */
public boolean containsValue(Object value) {
- if (value == null)
+ if (value == null)
throw new NullPointerException();
for (Node n = findFirst(); n != null; n = n.next) {
V v = n.getValidValue();
@@ -1863,8 +1863,8 @@ public class ConcurrentSkipListMap
/**
* Returns the number of elements in this map. If this map
- * contains more than Integer.MAX_VALUE elements, it
- * returns Integer.MAX_VALUE.
+ * contains more than {@code Integer.MAX_VALUE} elements, it
+ * returns {@code Integer.MAX_VALUE}.
*
* Beware that, unlike in most collections, this method is
* NOT a constant-time operation. Because of the
@@ -1875,7 +1875,7 @@ public class ConcurrentSkipListMap
* will be inaccurate. Thus, this method is typically not very
* useful in concurrent applications.
*
- * @return the number of elements in this map.
+ * @return the number of elements in this map
*/
public int size() {
long count = 0;
@@ -1883,12 +1883,12 @@ public class ConcurrentSkipListMap
if (n.getValidValue() != null)
++count;
}
- return (count >= Integer.MAX_VALUE)? Integer.MAX_VALUE : (int)count;
+ return (count >= Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int)count;
}
/**
- * Returns true if this map contains no key-value mappings.
- * @return true if this map contains no key-value mappings.
+ * Returns {@code true} if this map contains no key-value mappings.
+ * @return {@code true} if this map contains no key-value mappings
*/
public boolean isEmpty() {
return findFirst() == null;
@@ -1905,17 +1905,17 @@ public class ConcurrentSkipListMap
* Returns a set view of the keys contained in this map. The set is
* backed by the map, so changes to the map are reflected in the set, and
* vice-versa. The set supports element removal, which removes the
- * corresponding mapping from this map, via the Iterator.remove,
- * Set.remove, removeAll, retainAll, and
- * clear operations. It does not support the add or
- * addAll operations.
- * The view's iterator is a "weakly consistent" iterator that
+ * corresponding mapping from this map, via the {@code Iterator.remove},
+ * {@code Set.remove}, {@code removeAll}, {@code retainAll}, and
+ * {@code clear} operations. It does not support the {@code add} or
+ * {@code addAll} operations.
+ * The view's {@code iterator} is a "weakly consistent" iterator that
* will never throw {@link java.util.ConcurrentModificationException},
* and guarantees to traverse elements as they existed upon
* construction of the iterator, and may (but is not guaranteed to)
* reflect any modifications subsequent to construction.
*
- * @return a set view of the keys contained in this map.
+ * @return a set view of the keys contained in this map
*/
public Set keySet() {
/*
@@ -1936,17 +1936,17 @@ public class ConcurrentSkipListMap
* descending order. The set is backed by the map, so changes to
* the map are reflected in the set, and vice-versa. The set
* supports element removal, which removes the corresponding
- * mapping from this map, via the Iterator.remove,
- * Set.remove, removeAll, retainAll,
- * and clear operations. It does not support the
- * add or addAll operations. The view's
- * iterator is a "weakly consistent" iterator that will
+ * mapping from this map, via the {@code Iterator.remove},
+ * {@code Set.remove}, {@code removeAll}, {@code retainAll},
+ * and {@code clear} operations. It does not support the
+ * {@code add} or {@code addAll} operations. The view's
+ * {@code iterator} is a "weakly consistent" iterator that will
* never throw {@link java.util.ConcurrentModificationException},
* and guarantees to traverse elements as they existed upon
* construction of the iterator, and may (but is not guaranteed
* to) reflect any modifications subsequent to construction.
*
- * @return a set view of the keys contained in this map.
+ * @return a set view of the keys contained in this map
*/
public Set descendingKeySet() {
/*
@@ -1967,18 +1967,18 @@ public class ConcurrentSkipListMap
* The collection is backed by the map, so changes to the map are
* reflected in the collection, and vice-versa. The collection
* supports element removal, which removes the corresponding
- * mapping from this map, via the Iterator.remove,
- * Collection.remove, removeAll,
- * retainAll, and clear operations. It does not
- * support the add or addAll operations. The
- * view's iterator is a "weakly consistent" iterator that
+ * mapping from this map, via the {@code Iterator.remove},
+ * {@code Collection.remove}, {@code removeAll},
+ * {@code retainAll}, and {@code clear} operations. It does not
+ * support the {@code add} or {@code addAll} operations. The
+ * view's {@code iterator} is a "weakly consistent" iterator that
* will never throw {@link
* java.util.ConcurrentModificationException}, and guarantees to
* traverse elements as they existed upon construction of the
* iterator, and may (but is not guaranteed to) reflect any
* modifications subsequent to construction.
*
- * @return a collection view of the values contained in this map.
+ * @return a collection view of the values contained in this map
*/
public Collection values() {
Values vs = values;
@@ -1988,24 +1988,24 @@ public class ConcurrentSkipListMap
/**
* Returns a collection view of the mappings contained in this
* map. Each element in the returned collection is a
- * Map.Entry. The collection is backed by the map, so
+ * {@code Map.Entry}. The collection is backed by the map, so
* changes to the map are reflected in the collection, and
* vice-versa. The collection supports element removal, which
* removes the corresponding mapping from the map, via the
- * Iterator.remove, Collection.remove,
- * removeAll, retainAll, and clear
- * operations. It does not support the add or
- * addAll operations. The view's iterator is a
+ * {@code Iterator.remove}, {@code Collection.remove},
+ * {@code removeAll}, {@code retainAll}, and {@code clear}
+ * operations. It does not support the {@code add} or
+ * {@code addAll} operations. The view's {@code iterator} is a
* "weakly consistent" iterator that will never throw {@link
* java.util.ConcurrentModificationException}, and guarantees to
* traverse elements as they existed upon construction of the
* iterator, and may (but is not guaranteed to) reflect any
* modifications subsequent to construction. The
- * Map.Entry elements returned by
- * iterator.next() do not support the
- * setValue operation.
+ * {@code Map.Entry} elements returned by
+ * {@code iterator.next()} do not support the
+ * {@code setValue} operation.
*
- * @return a collection view of the mappings contained in this map.
+ * @return a collection view of the mappings contained in this map
*/
public Set> entrySet() {
EntrySet es = entrySet;
@@ -2015,24 +2015,24 @@ public class ConcurrentSkipListMap
/**
* Returns a collection view of the mappings contained in this
* map, in descending order. Each element in the returned
- * collection is a Map.Entry. The collection is backed
+ * collection is a {@code Map.Entry}. The collection is backed
* by the map, so changes to the map are reflected in the
* collection, and vice-versa. The collection supports element
* removal, which removes the corresponding mapping from the map,
- * via the Iterator.remove, Collection.remove,
- * removeAll, retainAll, and clear
- * operations. It does not support the add or
- * addAll operations. The view's iterator is a
+ * via the {@code Iterator.remove}, {@code Collection.remove},
+ * {@code removeAll}, {@code retainAll}, and {@code clear}
+ * operations. It does not support the {@code add} or
+ * {@code addAll} operations. The view's {@code iterator} is a
* "weakly consistent" iterator that will never throw {@link
* java.util.ConcurrentModificationException}, and guarantees to
* traverse elements as they existed upon construction of the
* iterator, and may (but is not guaranteed to) reflect any
* modifications subsequent to construction. The
- * Map.Entry elements returned by
- * iterator.next() do not support the
- * setValue operation.
+ * {@code Map.Entry} elements returned by
+ * {@code iterator.next()} do not support the
+ * {@code setValue} operation.
*
- * @return a collection view of the mappings contained in this map.
+ * @return a collection view of the mappings contained in this map
*/
public Set> descendingEntrySet() {
DescendingEntrySet es = descendingEntrySet;
@@ -2043,30 +2043,30 @@ public class ConcurrentSkipListMap
/**
* Compares the specified object with this map for equality.
- * Returns true if the given object is also a map and the
+ * Returns {@code true} if the given object is also a map and the
* two maps represent the same mappings. More formally, two maps
- * t1 and t2 represent the same mappings if
- * t1.keySet().equals(t2.keySet()) and for every key
- * k in t1.keySet(), (t1.get(k)==null ?
- * t2.get(k)==null : t1.get(k).equals(t2.get(k))) . This
+ * {@code t1} and {@code t2} represent the same mappings if
+ * {@code t1.keySet().equals(t2.keySet())} and for every key
+ * {@code k} in {@code t1.keySet()}, {@code (t1.get(k)==null ?
+ * t2.get(k)==null : t1.get(k).equals(t2.get(k))) }. This
* operation may return misleading results if either map is
* concurrently modified during execution of this method.
*
- * @param o object to be compared for equality with this map.
- * @return true if the specified object is equal to this map.
+ * @param o object to be compared for equality with this map
+ * @return {@code true} if the specified object is equal to this map
*/
public boolean equals(Object o) {
- if (o == this)
- return true;
- if (!(o instanceof Map))
- return false;
- Map t = (Map) o;
+ if (o == this)
+ return true;
+ if (!(o instanceof Map))
+ return false;
+ Map t = (Map) o;
try {
- return (containsAllMappings(this, t) &&
+ return (containsAllMappings(this, t) &&
containsAllMappings(t, this));
- } catch(ClassCastException unused) {
+ } catch (ClassCastException unused) {
return false;
- } catch(NullPointerException unused) {
+ } catch (NullPointerException unused) {
return false;
}
}
@@ -2080,7 +2080,7 @@ public class ConcurrentSkipListMap
Entry e = it.next();
Object k = e.getKey();
Object v = e.getValue();
- if (k == null || v == null || !v.equals(a.get(k)))
+ if (k == null || v == null || !v.equals(a.get(k)))
return false;
}
return true;
@@ -2093,71 +2093,71 @@ public class ConcurrentSkipListMap
* with a value, associate it with the given value.
* This is equivalent to
*
- * if (!map.containsKey(key))
- * return map.put(key, value);
+ * if (!map.containsKey(key))
+ * return map.put(key, value);
* else
- * return map.get(key);
+ * return map.get(key);
*
* except that the action is performed atomically.
- * @param key key with which the specified value is to be associated.
- * @param value value to be associated with the specified key.
- * @return previous value associated with specified key, or null
- * if there was no mapping for key.
+ * @param key key with which the specified value is to be associated
+ * @param value value to be associated with the specified key
+ * @return previous value associated with specified key, or {@code null}
+ * if there was no mapping for key
*
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if the key or value are null.
+ * currently in the map
+ * @throws NullPointerException if the key or value are {@code null}
*/
public V putIfAbsent(K key, V value) {
- if (value == null)
+ if (value == null)
throw new NullPointerException();
return doPut(key, value, true);
}
/**
- * Remove entry for key only if currently mapped to given value.
+ * Removes entry for key only if currently mapped to given value.
* Acts as
- *
+ *
* if ((map.containsKey(key) && map.get(key).equals(value)) {
* map.remove(key);
* return true;
* } else return false;
*
* except that the action is performed atomically.
- * @param key key with which the specified value is associated.
- * @param value value associated with the specified key.
+ * @param key key with which the specified value is associated
+ * @param value value associated with the specified key
* @return true if the value was removed, false otherwise
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if the key or value are null.
+ * currently in the map
+ * @throws NullPointerException if the key or value are {@code null}
*/
public boolean remove(Object key, Object value) {
- if (value == null)
+ if (value == null)
throw new NullPointerException();
return doRemove(key, value) != null;
}
/**
- * Replace entry for key only if currently mapped to given value.
+ * Replaces entry for key only if currently mapped to given value.
* Acts as
- *
+ *
* if ((map.containsKey(key) && map.get(key).equals(oldValue)) {
* map.put(key, newValue);
* return true;
* } else return false;
*
* except that the action is performed atomically.
- * @param key key with which the specified value is associated.
- * @param oldValue value expected to be associated with the specified key.
- * @param newValue value to be associated with the specified key.
+ * @param key key with which the specified value is associated
+ * @param oldValue value expected to be associated with the specified key
+ * @param newValue value to be associated with the specified key
* @return true if the value was replaced
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
+ * currently in the map
* @throws NullPointerException if key, oldValue or newValue are
- * null.
+ * {@code null}
*/
public boolean replace(K key, V oldValue, V newValue) {
- if (oldValue == null || newValue == null)
+ if (oldValue == null || newValue == null)
throw new NullPointerException();
Comparable k = comparable(key);
for (;;) {
@@ -2175,24 +2175,24 @@ public class ConcurrentSkipListMap
}
/**
- * Replace entry for key only if currently mapped to some value.
+ * Replaces entry for key only if currently mapped to some value.
* Acts as
- *
+ *
* if ((map.containsKey(key)) {
* return map.put(key, value);
* } else return null;
*
* except that the action is performed atomically.
- * @param key key with which the specified value is associated.
- * @param value value to be associated with the specified key.
- * @return previous value associated with specified key, or null
- * if there was no mapping for key.
+ * @param key key with which the specified value is associated
+ * @param value value to be associated with the specified key
+ * @return previous value associated with specified key, or {@code null}
+ * if there was no mapping for key
* @throws ClassCastException if the key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if the key or value are null.
+ * currently in the map
+ * @throws NullPointerException if the key or value are {@code null}
*/
public V replace(K key, V value) {
- if (value == null)
+ if (value == null)
throw new NullPointerException();
Comparable k = comparable(key);
for (;;) {
@@ -2208,11 +2208,11 @@ public class ConcurrentSkipListMap
/* ------ SortedMap API methods ------ */
/**
- * Returns the comparator used to order this map, or null
+ * Returns the comparator used to order this map, or {@code null}
* if this map uses its keys' natural order.
*
* @return the comparator associated with this map, or
- * null if it uses its keys' natural sort method.
+ * {@code null} if it uses its keys' natural sort method.
*/
public Comparator comparator() {
return comparator;
@@ -2221,10 +2221,10 @@ public class ConcurrentSkipListMap
/**
* Returns the first (lowest) key currently in this map.
*
- * @return the first (lowest) key currently in this map.
- * @throws NoSuchElementException Map is empty.
+ * @return the first (lowest) key currently in this map
+ * @throws NoSuchElementException Map is empty
*/
- public K firstKey() {
+ public K firstKey() {
Node n = findFirst();
if (n == null)
throw new NoSuchElementException();
@@ -2234,8 +2234,8 @@ public class ConcurrentSkipListMap
/**
* Returns the last (highest) key currently in this map.
*
- * @return the last (highest) key currently in this map.
- * @throws NoSuchElementException Map is empty.
+ * @return the last (highest) key currently in this map
+ * @throws NoSuchElementException Map is empty
*/
public K lastKey() {
Node n = findLast();
@@ -2246,24 +2246,24 @@ public class ConcurrentSkipListMap
/**
* Returns a view of the portion of this map whose keys range from
- * fromKey, inclusive, to toKey, exclusive. (If
- * fromKey and toKey are equal, the returned sorted map
+ * {@code fromKey}, inclusive, to {@code toKey}, exclusive. (If
+ * {@code fromKey} and {@code toKey} are equal, the returned sorted map
* is empty.) The returned sorted map is backed by this map, so changes
* in the returned sorted map are reflected in this map, and vice-versa.
-
- * @param fromKey low endpoint (inclusive) of the subMap.
- * @param toKey high endpoint (exclusive) of the subMap.
+ *
+ * @param fromKey low endpoint (inclusive) of the subMap
+ * @param toKey high endpoint (exclusive) of the subMap
*
* @return a view of the portion of this map whose keys range from
- * fromKey, inclusive, to toKey, exclusive.
+ * {@code fromKey}, inclusive, to {@code toKey}, exclusive
*
- * @throws ClassCastException if fromKey and toKey
+ * @throws ClassCastException if {@code fromKey} and {@code toKey}
* cannot be compared to one another using this map's comparator
- * (or, if the map has no comparator, using natural ordering).
- * @throws IllegalArgumentException if fromKey is greater than
- * toKey.
- * @throws NullPointerException if fromKey or toKey is
- * null.
+ * (or, if the map has no comparator, using natural ordering)
+ * @throws IllegalArgumentException if {@code fromKey} is greater than
+ * {@code toKey}
+ * @throws NullPointerException if {@code fromKey} or {@code toKey} is
+ * {@code null}
*/
public ConcurrentNavigableMap subMap(K fromKey, K toKey) {
if (fromKey == null || toKey == null)
@@ -2273,17 +2273,17 @@ public class ConcurrentSkipListMap
/**
* Returns a view of the portion of this map whose keys are
- * strictly less than toKey. The returned sorted map is
+ * strictly less than {@code toKey}. The returned sorted map is
* backed by this map, so changes in the returned sorted map are
* reflected in this map, and vice-versa.
- * @param toKey high endpoint (exclusive) of the headMap.
+ * @param toKey high endpoint (exclusive) of the headMap
* @return a view of the portion of this map whose keys are
- * strictly less than toKey.
+ * strictly less than {@code toKey}
*
- * @throws ClassCastException if toKey is not compatible
+ * @throws ClassCastException if {@code toKey} is not compatible
* with this map's comparator (or, if the map has no comparator,
- * if toKey does not implement Comparable).
- * @throws NullPointerException if toKey is null.
+ * if {@code toKey} does not implement {@code Comparable})
+ * @throws NullPointerException if {@code toKey} is {@code null}
*/
public ConcurrentNavigableMap headMap(K toKey) {
if (toKey == null)
@@ -2293,19 +2293,19 @@ public class ConcurrentSkipListMap
/**
* Returns a view of the portion of this map whose keys are
- * greater than or equal to fromKey. The returned sorted
+ * greater than or equal to {@code fromKey}. The returned sorted
* map is backed by this map, so changes in the returned sorted
* map are reflected in this map, and vice-versa.
- * @param fromKey low endpoint (inclusive) of the tailMap.
+ * @param fromKey low endpoint (inclusive) of the tailMap
* @return a view of the portion of this map whose keys are
- * greater than or equal to fromKey.
- * @throws ClassCastException if fromKey is not
+ * greater than or equal to {@code fromKey}
+ * @throws ClassCastException if {@code fromKey} is not
* compatible with this map's comparator (or, if the map has no
- * comparator, if fromKey does not implement
- * Comparable).
- * @throws NullPointerException if fromKey is null.
+ * comparator, if {@code fromKey} does not implement
+ * {@code Comparable})
+ * @throws NullPointerException if {@code fromKey} is {@code null}
*/
- public ConcurrentNavigableMap tailMap(K fromKey) {
+ public ConcurrentNavigableMap tailMap(K fromKey) {
if (fromKey == null)
throw new NullPointerException();
return new ConcurrentSkipListSubMap(this, fromKey, null);
@@ -2315,16 +2315,16 @@ public class ConcurrentSkipListMap
/**
* Returns a key-value mapping associated with the least key
- * greater than or equal to the given key, or null if
+ * greater than or equal to the given key, or {@code null} if
* there is no such entry. The returned entry does not
- * support the Entry.setValue method.
- *
- * @param key the key.
+ * support the {@code Entry.setValue} method.
+ *
+ * @param key the key
* @return an Entry associated with ceiling of given key, or
- * null if there is no such Entry.
+ * {@code null} if there is no such Entry
* @throws ClassCastException if key cannot be compared with the
- * keys currently in the map.
- * @throws NullPointerException if key is null.
+ * keys currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public Map.Entry ceilingEntry(K key) {
return getNear(key, GT|EQ);
@@ -2332,32 +2332,32 @@ public class ConcurrentSkipListMap
/**
* Returns least key greater than or equal to the given key, or
- * null if there is no such key.
- *
- * @param key the key.
- * @return the ceiling key, or null
- * if there is no such key.
+ * {@code null} if there is no such key.
+ *
+ * @param key the key
+ * @return the ceiling key, or {@code null}
+ * if there is no such key
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if key is null.
+ * currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public K ceilingKey(K key) {
Node n = findNear(key, GT|EQ);
- return (n == null)? null : n.key;
+ return (n == null) ? null : n.key;
}
/**
* Returns a key-value mapping associated with the greatest
- * key strictly less than the given key, or null if there is no
+ * key strictly less than the given key, or {@code null} if there is no
* such entry. The returned entry does not support
- * the Entry.setValue method.
- *
- * @param key the key.
+ * the {@code Entry.setValue} method.
+ *
+ * @param key the key
* @return an Entry with greatest key less than the given
- * key, or null if there is no such Entry.
+ * key, or {@code null} if there is no such Entry
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if key is null.
+ * currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public Map.Entry lowerEntry(K key) {
return getNear(key, LT);
@@ -2365,32 +2365,32 @@ public class ConcurrentSkipListMap
/**
* Returns the greatest key strictly less than the given key, or
- * null if there is no such key.
- *
- * @param key the key.
+ * {@code null} if there is no such key.
+ *
+ * @param key the key
* @return the greatest key less than the given
- * key, or null if there is no such key.
+ * key, or {@code null} if there is no such key
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if key is null.
+ * currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public K lowerKey(K key) {
Node n = findNear(key, LT);
- return (n == null)? null : n.key;
+ return (n == null) ? null : n.key;
}
/**
* Returns a key-value mapping associated with the greatest key
- * less than or equal to the given key, or null if there
+ * less than or equal to the given key, or {@code null} if there
* is no such entry. The returned entry does not support
- * the Entry.setValue method.
- *
- * @param key the key.
- * @return an Entry associated with floor of given key, or null
- * if there is no such Entry.
+ * the {@code Entry.setValue} method.
+ *
+ * @param key the key
+ * @return an Entry associated with floor of given key, or {@code null}
+ * if there is no such Entry
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if key is null.
+ * currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public Map.Entry floorEntry(K key) {
return getNear(key, LT|EQ);
@@ -2398,33 +2398,33 @@ public class ConcurrentSkipListMap
/**
* Returns the greatest key
- * less than or equal to the given key, or null if there
+ * less than or equal to the given key, or {@code null} if there
* is no such key.
- *
- * @param key the key.
- * @return the floor of given key, or null if there is no
- * such key.
+ *
+ * @param key the key
+ * @return the floor of given key, or {@code null} if there is no
+ * such key
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if key is null.
+ * currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public K floorKey(K key) {
Node n = findNear(key, LT|EQ);
- return (n == null)? null : n.key;
+ return (n == null) ? null : n.key;
}
/**
* Returns a key-value mapping associated with the least key
- * strictly greater than the given key, or null if there
+ * strictly greater than the given key, or {@code null} if there
* is no such entry. The returned entry does not support
- * the Entry.setValue method.
- *
- * @param key the key.
+ * the {@code Entry.setValue} method.
+ *
+ * @param key the key
* @return an Entry with least key greater than the given key, or
- * null if there is no such Entry.
+ * {@code null} if there is no such Entry
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if key is null.
+ * currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public Map.Entry higherEntry(K key) {
return getNear(key, GT);
@@ -2432,33 +2432,33 @@ public class ConcurrentSkipListMap
/**
* Returns the least key strictly greater than the given key, or
- * null if there is no such key.
- *
- * @param key the key.
+ * {@code null} if there is no such key.
+ *
+ * @param key the key
* @return the least key greater than the given key, or
- * null if there is no such key.
+ * {@code null} if there is no such key
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
- * @throws NullPointerException if key is null.
+ * currently in the map
+ * @throws NullPointerException if key is {@code null}
*/
public K higherKey(K key) {
Node n = findNear(key, GT);
- return (n == null)? null : n.key;
+ return (n == null) ? null : n.key;
}
/**
* Returns a key-value mapping associated with the least
- * key in this map, or null if the map is empty.
+ * key in this map, or {@code null} if the map is empty.
* The returned entry does not support
- * the Entry.setValue method.
- *
- * @return an Entry with least key, or null
- * if the map is empty.
+ * the {@code Entry.setValue} method.
+ *
+ * @return an Entry with least key, or {@code null}
+ * if the map is empty
*/
public Map.Entry firstEntry() {
for (;;) {
Node n = findFirst();
- if (n == null)
+ if (n == null)
return null;
SnapshotEntry e = n.createSnapshot();
if (e != null)
@@ -2468,17 +2468,17 @@ public class ConcurrentSkipListMap
/**
* Returns a key-value mapping associated with the greatest
- * key in this map, or null if the map is empty.
+ * key in this map, or {@code null} if the map is empty.
* The returned entry does not support
- * the Entry.setValue method.
- *
- * @return an Entry with greatest key, or null
- * if the map is empty.
+ * the {@code Entry.setValue} method.
+ *
+ * @return an Entry with greatest key, or {@code null}
+ * if the map is empty
*/
public Map.Entry lastEntry() {
for (;;) {
Node n = findLast();
- if (n == null)
+ if (n == null)
return null;
SnapshotEntry e = n.createSnapshot();
if (e != null)
@@ -2488,12 +2488,12 @@ public class ConcurrentSkipListMap
/**
* Removes and returns a key-value mapping associated with
- * the least key in this map, or null if the map is empty.
+ * the least key in this map, or {@code null} if the map is empty.
* The returned entry does not support
- * the Entry.setValue method.
- *
- * @return the removed first entry of this map, or null
- * if the map is empty.
+ * the {@code Entry.setValue} method.
+ *
+ * @return the removed first entry of this map, or {@code null}
+ * if the map is empty
*/
public Map.Entry pollFirstEntry() {
return (SnapshotEntry)doRemoveFirst(false);
@@ -2501,12 +2501,12 @@ public class ConcurrentSkipListMap
/**
* Removes and returns a key-value mapping associated with
- * the greatest key in this map, or null if the map is empty.
+ * the greatest key in this map, or {@code null} if the map is empty.
* The returned entry does not support
- * the Entry.setValue method.
- *
- * @return the removed last entry of this map, or null
- * if the map is empty.
+ * the {@code Entry.setValue} method.
+ *
+ * @return the removed last entry of this map, or {@code null}
+ * if the map is empty
*/
public Map.Entry pollLastEntry() {
return (SnapshotEntry)doRemoveLast(false);
@@ -2517,27 +2517,27 @@ public class ConcurrentSkipListMap
/**
* Base of ten kinds of iterator classes:
- * ascending: {map, submap} X {key, value, entry}
- * descending: {map, submap} X {key, entry}
+ * ascending: {map, submap} X {key, value, entry}
+ * descending: {map, submap} X {key, entry}
*/
abstract class Iter {
/** the last node returned by next() */
Node