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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package jsr166e; |
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import jsr166e.LongAdder; |
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import java.util.Map; |
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import java.util.Set; |
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import java.util.Collection; |
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import java.util.AbstractMap; |
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import java.util.AbstractSet; |
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import java.util.AbstractCollection; |
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import java.util.Hashtable; |
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import java.util.HashMap; |
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import java.util.Iterator; |
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import java.util.Enumeration; |
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import java.util.ConcurrentModificationException; |
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import java.util.NoSuchElementException; |
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import java.util.concurrent.ConcurrentMap; |
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import java.io.Serializable; |
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/** |
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* A hash table supporting full concurrency of retrievals and |
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* high expected concurrency for updates. This class obeys the |
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* same functional specification as {@link java.util.Hashtable}, and |
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* includes versions of methods corresponding to each method of |
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* {@code Hashtable}. However, even though all operations are |
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* thread-safe, retrieval operations do <em>not</em> entail locking, |
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* and there is <em>not</em> any support for locking the entire table |
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* in a way that prevents all access. This class is fully |
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* interoperable with {@code Hashtable} in programs that rely on its |
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* thread safety but not on its synchronization details. |
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* |
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* <p> Retrieval operations (including {@code get}) generally do not |
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* block, so may overlap with update operations (including {@code put} |
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* and {@code remove}). Retrievals reflect the results of the most |
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* recently <em>completed</em> update operations holding upon their |
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* onset. For aggregate operations such as {@code putAll} and {@code |
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* clear}, concurrent retrievals may reflect insertion or removal of |
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* only some entries. Similarly, Iterators and Enumerations return |
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* elements reflecting the state of the hash table at some point at or |
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* since the creation of the iterator/enumeration. They do |
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* <em>not</em> throw {@link ConcurrentModificationException}. |
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* However, iterators are designed to be used by only one thread at a |
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* time. Bear in mind that the results of aggregate status methods |
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* including {@code size}, {@code isEmpty}, and {@code containsValue} |
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* are typically useful only when a map is not undergoing concurrent |
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* updates in other threads. Otherwise the results of these methods |
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* reflect transient states that may be adequate for monitoring |
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1.16 |
* or estimation purposes, but not for program control. |
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1.1 |
* |
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1.16 |
* <p> The table is dynamically expanded when there are too many |
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* collisions (i.e., keys that have distinct hash codes but fall into |
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* the same slot modulo the table size), with the expected average |
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* effect of maintaining roughly two bins per mapping. There may be |
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* much variance around this average as mappings are added and |
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* removed, but overall, this maintains a commonly accepted time/space |
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* tradeoff for hash tables. However, resizing this or any other kind |
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* of hash table may be a relatively slow operation. When possible, it |
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* is a good idea to provide a size estimate as an optional {@code |
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* initialCapacity} constructor argument. An additional optional |
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* {@code loadFactor} constructor argument provides a further means of |
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* customizing initial table capacity by specifying the table density |
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* to be used in calculating the amount of space to allocate for the |
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* given number of elements. Also, for compatibility with previous |
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* versions of this class, constructors may optionally specify an |
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* expected {@code concurrencyLevel} as an additional hint for |
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* internal sizing. Note that using many keys with exactly the same |
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* {@code hashCode{}} is a sure way to slow down performance of any |
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* hash table. |
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1.1 |
* |
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* <p>This class and its views and iterators implement all of the |
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* <em>optional</em> methods of the {@link Map} and {@link Iterator} |
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* interfaces. |
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* |
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* <p> Like {@link Hashtable} but unlike {@link HashMap}, this class |
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* does <em>not</em> allow {@code null} to be used as a key or value. |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* <p><em>jsr166e note: This class is a candidate replacement for |
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* java.util.concurrent.ConcurrentHashMap.<em> |
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* |
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jsr166 |
1.19 |
* @since 1.8 |
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1.1 |
* @author Doug Lea |
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* @param <K> the type of keys maintained by this map |
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* @param <V> the type of mapped values |
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*/ |
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public class ConcurrentHashMapV8<K, V> |
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implements ConcurrentMap<K, V>, Serializable { |
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private static final long serialVersionUID = 7249069246763182397L; |
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/** |
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* A function computing a mapping from the given key to a value, |
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jsr166 |
1.8 |
* or {@code null} if there is no mapping. This is a place-holder |
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* for an upcoming JDK8 interface. |
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1.1 |
*/ |
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public static interface MappingFunction<K, V> { |
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/** |
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* Returns a value for the given key, or null if there is no |
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* mapping. If this function throws an (unchecked) exception, |
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* the exception is rethrown to its caller, and no mapping is |
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* recorded. Because this function is invoked within |
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* atomicity control, the computation should be short and |
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* simple. The most common usage is to construct a new object |
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* serving as an initial mapped value. |
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* |
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* @param key the (non-null) key |
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* @return a value, or null if none |
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*/ |
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V map(K key); |
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} |
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/* |
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* Overview: |
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* |
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* The primary design goal of this hash table is to maintain |
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* concurrent readability (typically method get(), but also |
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* iterators and related methods) while minimizing update |
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* contention. |
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* |
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* Each key-value mapping is held in a Node. Because Node fields |
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* can contain special values, they are defined using plain Object |
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* types. Similarly in turn, all internal methods that use them |
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1.14 |
* work off Object types. And similarly, so do the internal |
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* methods of auxiliary iterator and view classes. All public |
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* generic typed methods relay in/out of these internal methods, |
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* supplying null-checks and casts as needed. |
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1.1 |
* |
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* The table is lazily initialized to a power-of-two size upon the |
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1.14 |
* first insertion. Each bin in the table contains a list of |
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* Nodes (most often, zero or one Node). Table accesses require |
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* volatile/atomic reads, writes, and CASes. Because there is no |
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* other way to arrange this without adding further indirections, |
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* we use intrinsics (sun.misc.Unsafe) operations. The lists of |
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* nodes within bins are always accurately traversable under |
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* volatile reads, so long as lookups check hash code and |
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* non-nullness of value before checking key equality. (All valid |
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* hash codes are nonnegative. Negative values are reserved for |
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* special forwarding nodes; see below.) |
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* |
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* Insertion (via put or putIfAbsent) of the first node in an |
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* empty bin is performed by just CASing it to the bin. This is |
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* on average by far the most common case for put operations. |
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* Other update operations (insert, delete, and replace) require |
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* locks. We do not want to waste the space required to associate |
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* a distinct lock object with each bin, so instead use the first |
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* node of a bin list itself as a lock, using plain "synchronized" |
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* locks. These save space and we can live with block-structured |
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* lock/unlock operations. Using the first node of a list as a |
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* lock does not by itself suffice though: When a node is locked, |
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* any update must first validate that it is still the first node, |
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* and retry if not. Because new nodes are always appended to |
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* lists, once a node is first in a bin, it remains first until |
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* deleted or the bin becomes invalidated. However, operations |
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* that only conditionally update can and sometimes do inspect |
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* nodes until the point of update. This is a converse of sorts to |
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* the lazy locking technique described by Herlihy & Shavit. |
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* |
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* The main disadvantage of this approach is that most update |
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* operations on other nodes in a bin list protected by the same |
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* lock can stall, for example when user equals() or mapping |
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* functions take a long time. However, statistically, this is |
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* not a common enough problem to outweigh the time/space overhead |
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* of alternatives: Under random hash codes, the frequency of |
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* nodes in bins follows a Poisson distribution |
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* (http://en.wikipedia.org/wiki/Poisson_distribution) with a |
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1.16 |
* parameter of about 0.5 on average, given the resizing threshold |
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* of 0.75, although with a large variance because of resizing |
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* granularity. Ignoring variance, the expected occurrences of |
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* list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The |
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* first few values are: |
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* |
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* 0: 0.607 |
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* 1: 0.303 |
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* 2: 0.076 |
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* 3: 0.012 |
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* more: 0.002 |
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* |
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* Lock contention probability for two threads accessing distinct |
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* elements is roughly 1 / (8 * #elements). Function "spread" |
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* performs hashCode randomization that improves the likelihood |
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* that these assumptions hold unless users define exactly the |
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* same value for too many hashCodes. |
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dl |
1.1 |
* |
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* The table is resized when occupancy exceeds a threshold. Only |
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* a single thread performs the resize (using field "resizing", to |
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* arrange exclusion), but the table otherwise remains usable for |
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dl |
1.14 |
* reads and updates. Resizing proceeds by transferring bins, one |
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* by one, from the table to the next table. Upon transfer, the |
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* old table bin contains only a special forwarding node (with |
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* negative hash field) that contains the next table as its |
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* key. On encountering a forwarding node, access and update |
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dl |
1.1 |
* operations restart, using the new table. To ensure concurrent |
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* readability of traversals, transfers must proceed from the last |
200 |
dl |
1.14 |
* bin (table.length - 1) up towards the first. Upon seeing a |
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* forwarding node, traversals (see class InternalIterator) |
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* arrange to move to the new table for the rest of the traversal |
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* without revisiting nodes. This constrains bin transfers to a |
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* particular order, and so can block indefinitely waiting for the |
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* next lock, and other threads cannot help with the transfer. |
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* However, expected stalls are infrequent enough to not warrant |
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* the additional overhead of access and iteration schemes that |
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* could admit out-of-order or concurrent bin transfers. |
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* |
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* This traversal scheme also applies to partial traversals of |
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* ranges of bins (via an alternate InternalIterator constructor) |
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* to support partitioned aggregate operations (that are not |
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* otherwise implemented yet). Also, read-only operations give up |
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* if ever forwarded to a null table, which provides support for |
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* shutdown-style clearing, which is also not currently |
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* implemented. |
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* |
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* Lazy table initialization minimizes footprint until first use, |
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* and also avoids resizings when the first operation is from a |
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* putAll, constructor with map argument, or deserialization. |
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* These cases attempt to override the targetCapacity used in |
222 |
dl |
1.16 |
* growTable. These harmlessly fail to take effect in cases of |
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* races with other ongoing resizings. Uses of the threshold and |
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* targetCapacity during attempted initializations or resizings |
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* are racy but fall back on checks to preserve correctness. |
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dl |
1.1 |
* |
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* The element count is maintained using a LongAdder, which avoids |
228 |
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* contention on updates but can encounter cache thrashing if read |
229 |
dl |
1.14 |
* too frequently during concurrent access. To avoid reading so |
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dl |
1.2 |
* often, resizing is normally attempted only upon adding to a bin |
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dl |
1.16 |
* already holding two or more nodes. Under uniform hash |
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* distributions, the probability of this occurring at threshold |
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* is around 13%, meaning that only about 1 in 8 puts check |
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* threshold (and after resizing, many fewer do so). But this |
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* approximation has high variance for small table sizes, so we |
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* check on any collision for sizes <= 64. Further, to increase |
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* the probability that a resize occurs soon enough, we offset the |
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* threshold (see THRESHOLD_OFFSET) by the expected number of puts |
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* between checks. |
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dl |
1.14 |
* |
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* Maintaining API and serialization compatibility with previous |
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* versions of this class introduces several oddities. Mainly: We |
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* leave untouched but unused constructor arguments refering to |
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* concurrencyLevel. We also declare an unused "Segment" class |
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* that is instantiated in minimal form only when serializing. |
246 |
dl |
1.1 |
*/ |
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/* ---------------- Constants -------------- */ |
249 |
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250 |
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/** |
251 |
dl |
1.16 |
* The largest possible table capacity. This value must be |
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* exactly 1<<30 to stay within Java array allocation and indexing |
253 |
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* bounds for power of two table sizes. |
254 |
dl |
1.1 |
*/ |
255 |
dl |
1.14 |
private static final int MAXIMUM_CAPACITY = 1 << 30; |
256 |
dl |
1.1 |
|
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/** |
258 |
dl |
1.14 |
* The default initial table capacity. Must be a power of 2 |
259 |
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* (i.e., at least 1) and at most MAXIMUM_CAPACITY. |
260 |
dl |
1.1 |
*/ |
261 |
dl |
1.14 |
private static final int DEFAULT_CAPACITY = 16; |
262 |
dl |
1.1 |
|
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/** |
264 |
dl |
1.16 |
* The load factor for this table. Overrides of this value in |
265 |
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* constructors affect only the initial table capacity. The |
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* actual floating point value isn't normally used, because it is |
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* simpler to rely on the expression {@code n - (n >>> 2)} for the |
268 |
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* associated resizing threshold. |
269 |
dl |
1.1 |
*/ |
270 |
dl |
1.16 |
private static final float LOAD_FACTOR = 0.75f; |
271 |
dl |
1.1 |
|
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/** |
273 |
jsr166 |
1.7 |
* The count value to offset thresholds to compensate for checking |
274 |
dl |
1.14 |
* for the need to resize only when inserting into bins with two |
275 |
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* or more elements. See above for explanation. |
276 |
dl |
1.1 |
*/ |
277 |
dl |
1.14 |
private static final int THRESHOLD_OFFSET = 8; |
278 |
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|
279 |
dl |
1.16 |
/** |
280 |
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* The default concurrency level for this table. Unused except as |
281 |
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* a sizing hint, but defined for compatibility with previous |
282 |
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* versions of this class. |
283 |
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*/ |
284 |
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private static final int DEFAULT_CONCURRENCY_LEVEL = 16; |
285 |
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|
286 |
dl |
1.14 |
/* ---------------- Nodes -------------- */ |
287 |
dl |
1.1 |
|
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/** |
289 |
dl |
1.14 |
* Key-value entry. Note that this is never exported out as a |
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* user-visible Map.Entry. Nodes with a negative hash field are |
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* special, and do not contain user keys or values. Otherwise, |
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* keys are never null, and null val fields indicate that a node |
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* is in the process of being deleted or created. For purposes of |
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* read-only, access, a key may be read before a val, but can only |
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* be used after checking val. (For an update operation, when a |
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* lock is held on a node, order doesn't matter.) |
297 |
dl |
1.1 |
*/ |
298 |
dl |
1.14 |
static final class Node { |
299 |
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final int hash; |
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final Object key; |
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volatile Object val; |
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volatile Node next; |
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304 |
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Node(int hash, Object key, Object val, Node next) { |
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this.hash = hash; |
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this.key = key; |
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this.val = val; |
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this.next = next; |
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} |
310 |
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} |
311 |
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312 |
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/** |
313 |
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* Sign bit of node hash value indicating to use table in node.key. |
314 |
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*/ |
315 |
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private static final int SIGN_BIT = 0x80000000; |
316 |
dl |
1.1 |
|
317 |
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/* ---------------- Fields -------------- */ |
318 |
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|
319 |
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/** |
320 |
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* The array of bins. Lazily initialized upon first insertion. |
321 |
dl |
1.14 |
* Size is always a power of two. Accessed directly by iterators. |
322 |
dl |
1.1 |
*/ |
323 |
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transient volatile Node[] table; |
324 |
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|
325 |
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/** The counter maintaining number of elements. */ |
326 |
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private transient final LongAdder counter; |
327 |
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/** Nonzero when table is being initialized or resized. Updated via CAS. */ |
328 |
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private transient volatile int resizing; |
329 |
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/** The next element count value upon which to resize the table. */ |
330 |
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private transient int threshold; |
331 |
dl |
1.14 |
/** The target capacity; volatile to cover initialization races. */ |
332 |
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private transient volatile int targetCapacity; |
333 |
dl |
1.1 |
|
334 |
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// views |
335 |
dl |
1.14 |
private transient KeySet<K,V> keySet; |
336 |
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private transient Values<K,V> values; |
337 |
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private transient EntrySet<K,V> entrySet; |
338 |
dl |
1.1 |
|
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jsr166 |
1.7 |
/** For serialization compatibility. Null unless serialized; see below */ |
340 |
dl |
1.14 |
private Segment<K,V>[] segments; |
341 |
dl |
1.1 |
|
342 |
dl |
1.14 |
/* ---------------- Table element access -------------- */ |
343 |
dl |
1.1 |
|
344 |
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/* |
345 |
jsr166 |
1.7 |
* Volatile access methods are used for table elements as well as |
346 |
dl |
1.14 |
* elements of in-progress next table while resizing. Uses are |
347 |
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* null checked by callers, and implicitly bounds-checked, relying |
348 |
|
|
* on the invariants that tab arrays have non-zero size, and all |
349 |
|
|
* indices are masked with (tab.length - 1) which is never |
350 |
|
|
* negative and always less than length. Note that, to be correct |
351 |
|
|
* wrt arbitrary concurrency errors by users, bounds checks must |
352 |
|
|
* operate on local variables, which accounts for some odd-looking |
353 |
|
|
* inline assignments below. |
354 |
dl |
1.1 |
*/ |
355 |
|
|
|
356 |
dl |
1.14 |
static final Node tabAt(Node[] tab, int i) { // used by InternalIterator |
357 |
dl |
1.1 |
return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE); |
358 |
|
|
} |
359 |
|
|
|
360 |
|
|
private static final boolean casTabAt(Node[] tab, int i, Node c, Node v) { |
361 |
|
|
return UNSAFE.compareAndSwapObject(tab, ((long)i<<ASHIFT)+ABASE, c, v); |
362 |
|
|
} |
363 |
|
|
|
364 |
|
|
private static final void setTabAt(Node[] tab, int i, Node v) { |
365 |
|
|
UNSAFE.putObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE, v); |
366 |
|
|
} |
367 |
|
|
|
368 |
dl |
1.14 |
/* ----------------Table Initialization and Resizing -------------- */ |
369 |
|
|
|
370 |
|
|
/** |
371 |
|
|
* Returns a power of two table size for the given desired capacity. |
372 |
|
|
* See Hackers Delight, sec 3.2 |
373 |
|
|
*/ |
374 |
|
|
private static final int tableSizeFor(int c) { |
375 |
|
|
int n = c - 1; |
376 |
|
|
n |= n >>> 1; |
377 |
|
|
n |= n >>> 2; |
378 |
|
|
n |= n >>> 4; |
379 |
|
|
n |= n >>> 8; |
380 |
|
|
n |= n >>> 16; |
381 |
|
|
return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1; |
382 |
dl |
1.2 |
} |
383 |
|
|
|
384 |
dl |
1.14 |
/** |
385 |
|
|
* If not already resizing, initializes or creates next table and |
386 |
|
|
* transfers bins. Initial table size uses the capacity recorded |
387 |
|
|
* in targetCapacity. Rechecks occupancy after a transfer to see |
388 |
|
|
* if another resize is already needed because resizings are |
389 |
|
|
* lagging additions. |
390 |
|
|
* |
391 |
|
|
* @return current table |
392 |
|
|
*/ |
393 |
|
|
private final Node[] growTable() { |
394 |
|
|
if (resizing == 0 && |
395 |
|
|
UNSAFE.compareAndSwapInt(this, resizingOffset, 0, 1)) { |
396 |
|
|
try { |
397 |
|
|
for (;;) { |
398 |
|
|
Node[] tab = table; |
399 |
dl |
1.16 |
int n, c, m; |
400 |
dl |
1.14 |
if (tab == null) |
401 |
|
|
n = (c = targetCapacity) > 0 ? c : DEFAULT_CAPACITY; |
402 |
dl |
1.16 |
else if ((m = tab.length) < MAXIMUM_CAPACITY && |
403 |
|
|
counter.sum() >= (long)threshold) |
404 |
|
|
n = m << 1; |
405 |
dl |
1.14 |
else |
406 |
|
|
break; |
407 |
dl |
1.16 |
threshold = n - (n >>> 2) - THRESHOLD_OFFSET; |
408 |
dl |
1.14 |
Node[] nextTab = new Node[n]; |
409 |
|
|
if (tab != null) |
410 |
|
|
transfer(tab, nextTab, |
411 |
|
|
new Node(SIGN_BIT, nextTab, null, null)); |
412 |
|
|
table = nextTab; |
413 |
|
|
if (tab == null) |
414 |
|
|
break; |
415 |
|
|
} |
416 |
|
|
} finally { |
417 |
|
|
resizing = 0; |
418 |
|
|
} |
419 |
|
|
} |
420 |
|
|
else if (table == null) |
421 |
|
|
Thread.yield(); // lost initialization race; just spin |
422 |
|
|
return table; |
423 |
|
|
} |
424 |
|
|
|
425 |
jsr166 |
1.20 |
/** |
426 |
dl |
1.14 |
* Reclassifies nodes in each bin to new table. Because we are |
427 |
|
|
* using power-of-two expansion, the elements from each bin must |
428 |
|
|
* either stay at same index, or move with a power of two |
429 |
|
|
* offset. We eliminate unnecessary node creation by catching |
430 |
|
|
* cases where old nodes can be reused because their next fields |
431 |
dl |
1.16 |
* won't change. Statistically, only about one-sixth of them need |
432 |
|
|
* cloning when a table doubles. The nodes they replace will be |
433 |
|
|
* garbage collectable as soon as they are no longer referenced by |
434 |
|
|
* any reader thread that may be in the midst of concurrently |
435 |
|
|
* traversing table. |
436 |
dl |
1.14 |
* |
437 |
|
|
* Transfers are done from the bottom up to preserve iterator |
438 |
|
|
* traversability. On each step, the old bin is locked, |
439 |
|
|
* moved/copied, and then replaced with a forwarding node. |
440 |
|
|
*/ |
441 |
|
|
private static final void transfer(Node[] tab, Node[] nextTab, Node fwd) { |
442 |
|
|
int n = tab.length; |
443 |
|
|
Node ignore = nextTab[n + n - 1]; // force bounds check |
444 |
|
|
for (int i = n - 1; i >= 0; --i) { |
445 |
|
|
for (Node e;;) { |
446 |
|
|
if ((e = tabAt(tab, i)) != null) { |
447 |
|
|
boolean validated = false; |
448 |
|
|
synchronized (e) { |
449 |
|
|
if (tabAt(tab, i) == e) { |
450 |
|
|
validated = true; |
451 |
|
|
Node lo = null, hi = null, lastRun = e; |
452 |
|
|
int runBit = e.hash & n; |
453 |
|
|
for (Node p = e.next; p != null; p = p.next) { |
454 |
|
|
int b = p.hash & n; |
455 |
|
|
if (b != runBit) { |
456 |
|
|
runBit = b; |
457 |
|
|
lastRun = p; |
458 |
|
|
} |
459 |
|
|
} |
460 |
|
|
if (runBit == 0) |
461 |
|
|
lo = lastRun; |
462 |
|
|
else |
463 |
|
|
hi = lastRun; |
464 |
|
|
for (Node p = e; p != lastRun; p = p.next) { |
465 |
|
|
int ph = p.hash; |
466 |
|
|
Object pk = p.key, pv = p.val; |
467 |
|
|
if ((ph & n) == 0) |
468 |
|
|
lo = new Node(ph, pk, pv, lo); |
469 |
|
|
else |
470 |
|
|
hi = new Node(ph, pk, pv, hi); |
471 |
|
|
} |
472 |
|
|
setTabAt(nextTab, i, lo); |
473 |
|
|
setTabAt(nextTab, i + n, hi); |
474 |
|
|
setTabAt(tab, i, fwd); |
475 |
|
|
} |
476 |
|
|
} |
477 |
|
|
if (validated) |
478 |
|
|
break; |
479 |
|
|
} |
480 |
|
|
else if (casTabAt(tab, i, e, fwd)) |
481 |
|
|
break; |
482 |
|
|
} |
483 |
|
|
} |
484 |
dl |
1.2 |
} |
485 |
|
|
|
486 |
dl |
1.14 |
/* ---------------- Internal access and update methods -------------- */ |
487 |
|
|
|
488 |
|
|
/** |
489 |
|
|
* Applies a supplemental hash function to a given hashCode, which |
490 |
|
|
* defends against poor quality hash functions. The result must |
491 |
|
|
* be non-negative, and for reasonable performance must have good |
492 |
|
|
* avalanche properties; i.e., that each bit of the argument |
493 |
|
|
* affects each bit (except sign bit) of the result. |
494 |
|
|
*/ |
495 |
|
|
private static final int spread(int h) { |
496 |
|
|
// Apply base step of MurmurHash; see http://code.google.com/p/smhasher/ |
497 |
|
|
h ^= h >>> 16; |
498 |
|
|
h *= 0x85ebca6b; |
499 |
|
|
h ^= h >>> 13; |
500 |
|
|
h *= 0xc2b2ae35; |
501 |
|
|
return (h >>> 16) ^ (h & 0x7fffffff); // mask out sign bit |
502 |
|
|
} |
503 |
dl |
1.1 |
|
504 |
dl |
1.14 |
/** Implementation for get and containsKey */ |
505 |
jsr166 |
1.4 |
private final Object internalGet(Object k) { |
506 |
dl |
1.1 |
int h = spread(k.hashCode()); |
507 |
dl |
1.14 |
retry: for (Node[] tab = table; tab != null;) { |
508 |
|
|
Node e; Object ek, ev; int eh; // locals to read fields once |
509 |
|
|
for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) { |
510 |
|
|
if ((eh = e.hash) == h) { |
511 |
|
|
if ((ev = e.val) != null && |
512 |
|
|
((ek = e.key) == k || k.equals(ek))) |
513 |
dl |
1.1 |
return ev; |
514 |
|
|
} |
515 |
dl |
1.14 |
else if (eh < 0) { // sign bit set |
516 |
|
|
tab = (Node[])e.key; // bin was moved during resize |
517 |
dl |
1.1 |
continue retry; |
518 |
|
|
} |
519 |
|
|
} |
520 |
|
|
break; |
521 |
|
|
} |
522 |
|
|
return null; |
523 |
|
|
} |
524 |
|
|
|
525 |
dl |
1.10 |
/** Implementation for put and putIfAbsent */ |
526 |
dl |
1.1 |
private final Object internalPut(Object k, Object v, boolean replace) { |
527 |
|
|
int h = spread(k.hashCode()); |
528 |
dl |
1.14 |
Object oldVal = null; // previous value or null if none |
529 |
|
|
for (Node[] tab = table;;) { |
530 |
|
|
Node e; int i; Object ek, ev; |
531 |
dl |
1.1 |
if (tab == null) |
532 |
dl |
1.14 |
tab = growTable(); |
533 |
dl |
1.1 |
else if ((e = tabAt(tab, i = (tab.length - 1) & h)) == null) { |
534 |
dl |
1.2 |
if (casTabAt(tab, i, null, new Node(h, k, v, null))) |
535 |
dl |
1.14 |
break; // no lock when adding to empty bin |
536 |
|
|
} |
537 |
|
|
else if (e.hash < 0) // resized -- restart with new table |
538 |
|
|
tab = (Node[])e.key; |
539 |
|
|
else if (!replace && e.hash == h && (ev = e.val) != null && |
540 |
|
|
((ek = e.key) == k || k.equals(ek))) { |
541 |
|
|
if (tabAt(tab, i) == e) { // inspect and validate 1st node |
542 |
|
|
oldVal = ev; // without lock for putIfAbsent |
543 |
dl |
1.1 |
break; |
544 |
dl |
1.14 |
} |
545 |
dl |
1.1 |
} |
546 |
|
|
else { |
547 |
|
|
boolean validated = false; |
548 |
|
|
boolean checkSize = false; |
549 |
dl |
1.14 |
synchronized (e) { // lock the 1st node of bin list |
550 |
dl |
1.10 |
if (tabAt(tab, i) == e) { |
551 |
dl |
1.14 |
validated = true; // retry if 1st already deleted |
552 |
dl |
1.10 |
for (Node first = e;;) { |
553 |
jsr166 |
1.11 |
if (e.hash == h && |
554 |
dl |
1.14 |
((ek = e.key) == k || k.equals(ek)) && |
555 |
|
|
(ev = e.val) != null) { |
556 |
dl |
1.1 |
oldVal = ev; |
557 |
|
|
if (replace) |
558 |
|
|
e.val = v; |
559 |
dl |
1.10 |
break; |
560 |
dl |
1.1 |
} |
561 |
dl |
1.10 |
Node last = e; |
562 |
|
|
if ((e = e.next) == null) { |
563 |
dl |
1.2 |
last.next = new Node(h, k, v, null); |
564 |
|
|
if (last != first || tab.length <= 64) |
565 |
dl |
1.1 |
checkSize = true; |
566 |
dl |
1.10 |
break; |
567 |
dl |
1.1 |
} |
568 |
|
|
} |
569 |
|
|
} |
570 |
|
|
} |
571 |
|
|
if (validated) { |
572 |
|
|
if (checkSize && tab.length < MAXIMUM_CAPACITY && |
573 |
dl |
1.16 |
resizing == 0 && counter.sum() >= (long)threshold) |
574 |
dl |
1.14 |
growTable(); |
575 |
dl |
1.1 |
break; |
576 |
|
|
} |
577 |
|
|
} |
578 |
|
|
} |
579 |
|
|
if (oldVal == null) |
580 |
dl |
1.14 |
counter.increment(); // update counter outside of locks |
581 |
dl |
1.1 |
return oldVal; |
582 |
|
|
} |
583 |
|
|
|
584 |
|
|
/** |
585 |
dl |
1.10 |
* Implementation for the four public remove/replace methods: |
586 |
|
|
* Replaces node value with v, conditional upon match of cv if |
587 |
|
|
* non-null. If resulting value is null, delete. |
588 |
dl |
1.1 |
*/ |
589 |
|
|
private final Object internalReplace(Object k, Object v, Object cv) { |
590 |
|
|
int h = spread(k.hashCode()); |
591 |
dl |
1.14 |
for (Node[] tab = table;;) { |
592 |
|
|
Node e; int i; |
593 |
|
|
if (tab == null || |
594 |
|
|
(e = tabAt(tab, i = (tab.length - 1) & h)) == null) |
595 |
|
|
return null; |
596 |
|
|
else if (e.hash < 0) |
597 |
dl |
1.1 |
tab = (Node[])e.key; |
598 |
|
|
else { |
599 |
dl |
1.14 |
Object oldVal = null; |
600 |
dl |
1.1 |
boolean validated = false; |
601 |
|
|
boolean deleted = false; |
602 |
jsr166 |
1.4 |
synchronized (e) { |
603 |
dl |
1.10 |
if (tabAt(tab, i) == e) { |
604 |
|
|
validated = true; |
605 |
|
|
Node pred = null; |
606 |
|
|
do { |
607 |
|
|
Object ek, ev; |
608 |
|
|
if (e.hash == h && |
609 |
dl |
1.14 |
((ek = e.key) == k || k.equals(ek)) && |
610 |
|
|
((ev = e.val) != null)) { |
611 |
dl |
1.1 |
if (cv == null || cv == ev || cv.equals(ev)) { |
612 |
|
|
oldVal = ev; |
613 |
|
|
if ((e.val = v) == null) { |
614 |
|
|
deleted = true; |
615 |
|
|
Node en = e.next; |
616 |
|
|
if (pred != null) |
617 |
|
|
pred.next = en; |
618 |
|
|
else |
619 |
|
|
setTabAt(tab, i, en); |
620 |
|
|
} |
621 |
|
|
} |
622 |
dl |
1.10 |
break; |
623 |
dl |
1.1 |
} |
624 |
dl |
1.14 |
} while ((e = (pred = e).next) != null); |
625 |
dl |
1.1 |
} |
626 |
|
|
} |
627 |
|
|
if (validated) { |
628 |
|
|
if (deleted) |
629 |
|
|
counter.decrement(); |
630 |
dl |
1.14 |
return oldVal; |
631 |
dl |
1.1 |
} |
632 |
|
|
} |
633 |
|
|
} |
634 |
|
|
} |
635 |
|
|
|
636 |
dl |
1.14 |
/** Implementation for computeIfAbsent and compute. Like put, but messier. */ |
637 |
dl |
1.1 |
@SuppressWarnings("unchecked") |
638 |
dl |
1.2 |
private final V internalCompute(K k, |
639 |
|
|
MappingFunction<? super K, ? extends V> f, |
640 |
|
|
boolean replace) { |
641 |
dl |
1.1 |
int h = spread(k.hashCode()); |
642 |
|
|
V val = null; |
643 |
|
|
boolean added = false; |
644 |
|
|
Node[] tab = table; |
645 |
dl |
1.14 |
outer:for (;;) { |
646 |
|
|
Node e; int i; Object ek, ev; |
647 |
dl |
1.1 |
if (tab == null) |
648 |
dl |
1.14 |
tab = growTable(); |
649 |
dl |
1.1 |
else if ((e = tabAt(tab, i = (tab.length - 1) & h)) == null) { |
650 |
dl |
1.2 |
Node node = new Node(h, k, null, null); |
651 |
dl |
1.10 |
boolean validated = false; |
652 |
dl |
1.14 |
synchronized (node) { // must lock while computing value |
653 |
dl |
1.1 |
if (casTabAt(tab, i, null, node)) { |
654 |
|
|
validated = true; |
655 |
|
|
try { |
656 |
|
|
val = f.map(k); |
657 |
|
|
if (val != null) { |
658 |
|
|
node.val = val; |
659 |
|
|
added = true; |
660 |
|
|
} |
661 |
|
|
} finally { |
662 |
|
|
if (!added) |
663 |
|
|
setTabAt(tab, i, null); |
664 |
|
|
} |
665 |
|
|
} |
666 |
|
|
} |
667 |
dl |
1.10 |
if (validated) |
668 |
|
|
break; |
669 |
dl |
1.1 |
} |
670 |
|
|
else if (e.hash < 0) |
671 |
|
|
tab = (Node[])e.key; |
672 |
dl |
1.14 |
else if (!replace && e.hash == h && (ev = e.val) != null && |
673 |
|
|
((ek = e.key) == k || k.equals(ek))) { |
674 |
|
|
if (tabAt(tab, i) == e) { |
675 |
|
|
val = (V)ev; |
676 |
|
|
break; |
677 |
|
|
} |
678 |
|
|
} |
679 |
dl |
1.5 |
else if (Thread.holdsLock(e)) |
680 |
|
|
throw new IllegalStateException("Recursive map computation"); |
681 |
dl |
1.1 |
else { |
682 |
dl |
1.10 |
boolean validated = false; |
683 |
dl |
1.1 |
boolean checkSize = false; |
684 |
jsr166 |
1.4 |
synchronized (e) { |
685 |
dl |
1.10 |
if (tabAt(tab, i) == e) { |
686 |
|
|
validated = true; |
687 |
|
|
for (Node first = e;;) { |
688 |
|
|
if (e.hash == h && |
689 |
dl |
1.14 |
((ek = e.key) == k || k.equals(ek)) && |
690 |
|
|
((ev = e.val) != null)) { |
691 |
|
|
Object fv; |
692 |
dl |
1.10 |
if (replace && (fv = f.map(k)) != null) |
693 |
|
|
ev = e.val = fv; |
694 |
dl |
1.1 |
val = (V)ev; |
695 |
dl |
1.10 |
break; |
696 |
dl |
1.1 |
} |
697 |
dl |
1.10 |
Node last = e; |
698 |
|
|
if ((e = e.next) == null) { |
699 |
dl |
1.1 |
if ((val = f.map(k)) != null) { |
700 |
dl |
1.2 |
last.next = new Node(h, k, val, null); |
701 |
|
|
added = true; |
702 |
|
|
if (last != first || tab.length <= 64) |
703 |
dl |
1.1 |
checkSize = true; |
704 |
|
|
} |
705 |
dl |
1.10 |
break; |
706 |
dl |
1.1 |
} |
707 |
|
|
} |
708 |
|
|
} |
709 |
|
|
} |
710 |
dl |
1.10 |
if (validated) { |
711 |
|
|
if (checkSize && tab.length < MAXIMUM_CAPACITY && |
712 |
dl |
1.16 |
resizing == 0 && counter.sum() >= (long)threshold) |
713 |
dl |
1.14 |
growTable(); |
714 |
dl |
1.10 |
break; |
715 |
|
|
} |
716 |
dl |
1.1 |
} |
717 |
dl |
1.10 |
} |
718 |
dl |
1.1 |
if (added) |
719 |
|
|
counter.increment(); |
720 |
|
|
return val; |
721 |
|
|
} |
722 |
|
|
|
723 |
|
|
/** |
724 |
dl |
1.2 |
* Implementation for clear. Steps through each bin, removing all nodes. |
725 |
dl |
1.1 |
*/ |
726 |
|
|
private final void internalClear() { |
727 |
dl |
1.14 |
long delta = 0L; // negative number of deletions |
728 |
dl |
1.1 |
int i = 0; |
729 |
|
|
Node[] tab = table; |
730 |
|
|
while (tab != null && i < tab.length) { |
731 |
|
|
Node e = tabAt(tab, i); |
732 |
|
|
if (e == null) |
733 |
|
|
++i; |
734 |
|
|
else if (e.hash < 0) |
735 |
|
|
tab = (Node[])e.key; |
736 |
|
|
else { |
737 |
|
|
boolean validated = false; |
738 |
jsr166 |
1.4 |
synchronized (e) { |
739 |
dl |
1.1 |
if (tabAt(tab, i) == e) { |
740 |
|
|
validated = true; |
741 |
dl |
1.14 |
Node en; |
742 |
dl |
1.1 |
do { |
743 |
dl |
1.14 |
en = e.next; |
744 |
|
|
if (e.val != null) { // currently always true |
745 |
dl |
1.1 |
e.val = null; |
746 |
dl |
1.14 |
--delta; |
747 |
dl |
1.1 |
} |
748 |
dl |
1.14 |
} while ((e = en) != null); |
749 |
dl |
1.1 |
setTabAt(tab, i, null); |
750 |
|
|
} |
751 |
|
|
} |
752 |
dl |
1.14 |
if (validated) |
753 |
dl |
1.1 |
++i; |
754 |
|
|
} |
755 |
|
|
} |
756 |
dl |
1.14 |
counter.add(delta); |
757 |
dl |
1.1 |
} |
758 |
|
|
|
759 |
dl |
1.14 |
/* ----------------Table Traversal -------------- */ |
760 |
|
|
|
761 |
dl |
1.1 |
/** |
762 |
dl |
1.14 |
* Encapsulates traversal for methods such as containsValue; also |
763 |
|
|
* serves as a base class for other iterators. |
764 |
|
|
* |
765 |
|
|
* At each step, the iterator snapshots the key ("nextKey") and |
766 |
|
|
* value ("nextVal") of a valid node (i.e., one that, at point of |
767 |
|
|
* snapshot, has a nonnull user value). Because val fields can |
768 |
|
|
* change (including to null, indicating deletion), field nextVal |
769 |
|
|
* might not be accurate at point of use, but still maintains the |
770 |
|
|
* weak consistency property of holding a value that was once |
771 |
|
|
* valid. |
772 |
|
|
* |
773 |
|
|
* Internal traversals directly access these fields, as in: |
774 |
|
|
* {@code while (it.next != null) { process(nextKey); it.advance(); }} |
775 |
|
|
* |
776 |
|
|
* Exported iterators (subclasses of ViewIterator) extract key, |
777 |
|
|
* value, or key-value pairs as return values of Iterator.next(), |
778 |
jsr166 |
1.17 |
* and encapsulate the it.next check as hasNext(); |
779 |
dl |
1.14 |
* |
780 |
|
|
* The iterator visits each valid node that was reachable upon |
781 |
|
|
* iterator construction once. It might miss some that were added |
782 |
|
|
* to a bin after the bin was visited, which is OK wrt consistency |
783 |
|
|
* guarantees. Maintaining this property in the face of possible |
784 |
|
|
* ongoing resizes requires a fair amount of bookkeeping state |
785 |
|
|
* that is difficult to optimize away amidst volatile accesses. |
786 |
|
|
* Even so, traversal maintains reasonable throughput. |
787 |
|
|
* |
788 |
|
|
* Normally, iteration proceeds bin-by-bin traversing lists. |
789 |
|
|
* However, if the table has been resized, then all future steps |
790 |
|
|
* must traverse both the bin at the current index as well as at |
791 |
|
|
* (index + baseSize); and so on for further resizings. To |
792 |
|
|
* paranoically cope with potential sharing by users of iterators |
793 |
|
|
* across threads, iteration terminates if a bounds checks fails |
794 |
|
|
* for a table read. |
795 |
|
|
* |
796 |
|
|
* The range-based constructor enables creation of parallel |
797 |
|
|
* range-splitting traversals. (Not yet implemented.) |
798 |
|
|
*/ |
799 |
|
|
static class InternalIterator { |
800 |
|
|
Node next; // the next entry to use |
801 |
|
|
Node last; // the last entry used |
802 |
|
|
Object nextKey; // cached key field of next |
803 |
|
|
Object nextVal; // cached val field of next |
804 |
|
|
Node[] tab; // current table; updated if resized |
805 |
|
|
int index; // index of bin to use next |
806 |
|
|
int baseIndex; // current index of initial table |
807 |
|
|
final int baseLimit; // index bound for initial table |
808 |
|
|
final int baseSize; // initial table size |
809 |
|
|
|
810 |
|
|
/** Creates iterator for all entries in the table. */ |
811 |
|
|
InternalIterator(Node[] tab) { |
812 |
|
|
this.tab = tab; |
813 |
|
|
baseLimit = baseSize = (tab == null) ? 0 : tab.length; |
814 |
|
|
index = baseIndex = 0; |
815 |
|
|
next = null; |
816 |
|
|
advance(); |
817 |
|
|
} |
818 |
|
|
|
819 |
|
|
/** Creates iterator for the given range of the table */ |
820 |
|
|
InternalIterator(Node[] tab, int lo, int hi) { |
821 |
|
|
this.tab = tab; |
822 |
|
|
baseSize = (tab == null) ? 0 : tab.length; |
823 |
jsr166 |
1.15 |
baseLimit = (hi <= baseSize) ? hi : baseSize; |
824 |
dl |
1.14 |
index = baseIndex = lo; |
825 |
|
|
next = null; |
826 |
|
|
advance(); |
827 |
|
|
} |
828 |
|
|
|
829 |
|
|
/** Advances next. See above for explanation. */ |
830 |
|
|
final void advance() { |
831 |
|
|
Node e = last = next; |
832 |
|
|
outer: do { |
833 |
|
|
if (e != null) // pass used or skipped node |
834 |
dl |
1.1 |
e = e.next; |
835 |
dl |
1.14 |
while (e == null) { // get to next non-null bin |
836 |
|
|
Node[] t; int b, i, n; // checks must use locals |
837 |
|
|
if ((b = baseIndex) >= baseLimit || (i = index) < 0 || |
838 |
|
|
(t = tab) == null || i >= (n = t.length)) |
839 |
|
|
break outer; |
840 |
|
|
else if ((e = tabAt(t, i)) != null && e.hash < 0) |
841 |
|
|
tab = (Node[])e.key; // restarts due to null val |
842 |
|
|
else // visit upper slots if present |
843 |
|
|
index = (i += baseSize) < n ? i : (baseIndex = b + 1); |
844 |
dl |
1.1 |
} |
845 |
dl |
1.14 |
nextKey = e.key; |
846 |
|
|
} while ((nextVal = e.val) == null); // skip deleted or special nodes |
847 |
|
|
next = e; |
848 |
dl |
1.1 |
} |
849 |
|
|
} |
850 |
|
|
|
851 |
|
|
/* ---------------- Public operations -------------- */ |
852 |
|
|
|
853 |
|
|
/** |
854 |
dl |
1.16 |
* Creates a new, empty map with the default initial table size (16), |
855 |
dl |
1.1 |
*/ |
856 |
dl |
1.16 |
public ConcurrentHashMapV8() { |
857 |
dl |
1.14 |
this.counter = new LongAdder(); |
858 |
dl |
1.16 |
this.targetCapacity = DEFAULT_CAPACITY; |
859 |
dl |
1.1 |
} |
860 |
|
|
|
861 |
|
|
/** |
862 |
dl |
1.16 |
* Creates a new, empty map with an initial table size |
863 |
|
|
* accommodating the specified number of elements without the need |
864 |
|
|
* to dynamically resize. |
865 |
dl |
1.1 |
* |
866 |
|
|
* @param initialCapacity The implementation performs internal |
867 |
|
|
* sizing to accommodate this many elements. |
868 |
|
|
* @throws IllegalArgumentException if the initial capacity of |
869 |
jsr166 |
1.18 |
* elements is negative |
870 |
dl |
1.1 |
*/ |
871 |
dl |
1.16 |
public ConcurrentHashMapV8(int initialCapacity) { |
872 |
|
|
if (initialCapacity < 0) |
873 |
|
|
throw new IllegalArgumentException(); |
874 |
|
|
int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ? |
875 |
|
|
MAXIMUM_CAPACITY : |
876 |
|
|
tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1)); |
877 |
|
|
this.counter = new LongAdder(); |
878 |
|
|
this.targetCapacity = cap; |
879 |
dl |
1.1 |
} |
880 |
|
|
|
881 |
|
|
/** |
882 |
dl |
1.16 |
* Creates a new map with the same mappings as the given map. |
883 |
dl |
1.1 |
* |
884 |
dl |
1.16 |
* @param m the map |
885 |
dl |
1.1 |
*/ |
886 |
dl |
1.16 |
public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) { |
887 |
|
|
this.counter = new LongAdder(); |
888 |
|
|
this.targetCapacity = DEFAULT_CAPACITY; |
889 |
|
|
putAll(m); |
890 |
dl |
1.1 |
} |
891 |
|
|
|
892 |
|
|
/** |
893 |
dl |
1.16 |
* Creates a new, empty map with an initial table size based on |
894 |
|
|
* the given number of elements ({@code initialCapacity}) and |
895 |
|
|
* initial table density ({@code loadFactor}). |
896 |
|
|
* |
897 |
|
|
* @param initialCapacity the initial capacity. The implementation |
898 |
|
|
* performs internal sizing to accommodate this many elements, |
899 |
|
|
* given the specified load factor. |
900 |
|
|
* @param loadFactor the load factor (table density) for |
901 |
jsr166 |
1.18 |
* establishing the initial table size |
902 |
dl |
1.16 |
* @throws IllegalArgumentException if the initial capacity of |
903 |
|
|
* elements is negative or the load factor is nonpositive |
904 |
dl |
1.1 |
*/ |
905 |
dl |
1.16 |
public ConcurrentHashMapV8(int initialCapacity, float loadFactor) { |
906 |
|
|
this(initialCapacity, loadFactor, 1); |
907 |
dl |
1.1 |
} |
908 |
|
|
|
909 |
|
|
/** |
910 |
dl |
1.16 |
* Creates a new, empty map with an initial table size based on |
911 |
|
|
* the given number of elements ({@code initialCapacity}), table |
912 |
|
|
* density ({@code loadFactor}), and number of concurrently |
913 |
|
|
* updating threads ({@code concurrencyLevel}). |
914 |
dl |
1.1 |
* |
915 |
dl |
1.16 |
* @param initialCapacity the initial capacity. The implementation |
916 |
|
|
* performs internal sizing to accommodate this many elements, |
917 |
|
|
* given the specified load factor. |
918 |
|
|
* @param loadFactor the load factor (table density) for |
919 |
jsr166 |
1.18 |
* establishing the initial table size |
920 |
dl |
1.16 |
* @param concurrencyLevel the estimated number of concurrently |
921 |
|
|
* updating threads. The implementation may use this value as |
922 |
|
|
* a sizing hint. |
923 |
|
|
* @throws IllegalArgumentException if the initial capacity is |
924 |
|
|
* negative or the load factor or concurrencyLevel are |
925 |
jsr166 |
1.18 |
* nonpositive |
926 |
dl |
1.1 |
*/ |
927 |
dl |
1.16 |
public ConcurrentHashMapV8(int initialCapacity, |
928 |
|
|
float loadFactor, int concurrencyLevel) { |
929 |
|
|
if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0) |
930 |
|
|
throw new IllegalArgumentException(); |
931 |
|
|
if (initialCapacity < concurrencyLevel) // Use at least as many bins |
932 |
|
|
initialCapacity = concurrencyLevel; // as estimated threads |
933 |
|
|
long size = (long)(1.0 + (long)initialCapacity / loadFactor); |
934 |
|
|
int cap = ((size >= (long)MAXIMUM_CAPACITY) ? |
935 |
|
|
MAXIMUM_CAPACITY: tableSizeFor((int)size)); |
936 |
|
|
this.counter = new LongAdder(); |
937 |
|
|
this.targetCapacity = cap; |
938 |
dl |
1.1 |
} |
939 |
|
|
|
940 |
|
|
/** |
941 |
dl |
1.14 |
* {@inheritDoc} |
942 |
dl |
1.1 |
*/ |
943 |
|
|
public boolean isEmpty() { |
944 |
dl |
1.2 |
return counter.sum() <= 0L; // ignore transient negative values |
945 |
dl |
1.1 |
} |
946 |
|
|
|
947 |
|
|
/** |
948 |
dl |
1.14 |
* {@inheritDoc} |
949 |
dl |
1.1 |
*/ |
950 |
|
|
public int size() { |
951 |
|
|
long n = counter.sum(); |
952 |
jsr166 |
1.15 |
return ((n < 0L) ? 0 : |
953 |
|
|
(n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE : |
954 |
dl |
1.14 |
(int)n); |
955 |
dl |
1.1 |
} |
956 |
|
|
|
957 |
|
|
/** |
958 |
|
|
* Returns the value to which the specified key is mapped, |
959 |
|
|
* or {@code null} if this map contains no mapping for the key. |
960 |
|
|
* |
961 |
|
|
* <p>More formally, if this map contains a mapping from a key |
962 |
|
|
* {@code k} to a value {@code v} such that {@code key.equals(k)}, |
963 |
|
|
* then this method returns {@code v}; otherwise it returns |
964 |
|
|
* {@code null}. (There can be at most one such mapping.) |
965 |
|
|
* |
966 |
|
|
* @throws NullPointerException if the specified key is null |
967 |
|
|
*/ |
968 |
|
|
@SuppressWarnings("unchecked") |
969 |
|
|
public V get(Object key) { |
970 |
|
|
if (key == null) |
971 |
|
|
throw new NullPointerException(); |
972 |
|
|
return (V)internalGet(key); |
973 |
|
|
} |
974 |
|
|
|
975 |
|
|
/** |
976 |
|
|
* Tests if the specified object is a key in this table. |
977 |
|
|
* |
978 |
|
|
* @param key possible key |
979 |
|
|
* @return {@code true} if and only if the specified object |
980 |
|
|
* is a key in this table, as determined by the |
981 |
jsr166 |
1.18 |
* {@code equals} method; {@code false} otherwise |
982 |
dl |
1.1 |
* @throws NullPointerException if the specified key is null |
983 |
|
|
*/ |
984 |
|
|
public boolean containsKey(Object key) { |
985 |
|
|
if (key == null) |
986 |
|
|
throw new NullPointerException(); |
987 |
|
|
return internalGet(key) != null; |
988 |
|
|
} |
989 |
|
|
|
990 |
|
|
/** |
991 |
|
|
* Returns {@code true} if this map maps one or more keys to the |
992 |
dl |
1.14 |
* specified value. Note: This method may require a full traversal |
993 |
|
|
* of the map, and is much slower than method {@code containsKey}. |
994 |
dl |
1.1 |
* |
995 |
|
|
* @param value value whose presence in this map is to be tested |
996 |
|
|
* @return {@code true} if this map maps one or more keys to the |
997 |
|
|
* specified value |
998 |
|
|
* @throws NullPointerException if the specified value is null |
999 |
|
|
*/ |
1000 |
|
|
public boolean containsValue(Object value) { |
1001 |
|
|
if (value == null) |
1002 |
|
|
throw new NullPointerException(); |
1003 |
dl |
1.14 |
Object v; |
1004 |
|
|
InternalIterator it = new InternalIterator(table); |
1005 |
|
|
while (it.next != null) { |
1006 |
|
|
if ((v = it.nextVal) == value || value.equals(v)) |
1007 |
|
|
return true; |
1008 |
|
|
it.advance(); |
1009 |
|
|
} |
1010 |
|
|
return false; |
1011 |
dl |
1.1 |
} |
1012 |
|
|
|
1013 |
|
|
/** |
1014 |
|
|
* Legacy method testing if some key maps into the specified value |
1015 |
|
|
* in this table. This method is identical in functionality to |
1016 |
|
|
* {@link #containsValue}, and exists solely to ensure |
1017 |
|
|
* full compatibility with class {@link java.util.Hashtable}, |
1018 |
|
|
* which supported this method prior to introduction of the |
1019 |
|
|
* Java Collections framework. |
1020 |
|
|
* |
1021 |
|
|
* @param value a value to search for |
1022 |
|
|
* @return {@code true} if and only if some key maps to the |
1023 |
|
|
* {@code value} argument in this table as |
1024 |
|
|
* determined by the {@code equals} method; |
1025 |
|
|
* {@code false} otherwise |
1026 |
|
|
* @throws NullPointerException if the specified value is null |
1027 |
|
|
*/ |
1028 |
|
|
public boolean contains(Object value) { |
1029 |
|
|
return containsValue(value); |
1030 |
|
|
} |
1031 |
|
|
|
1032 |
|
|
/** |
1033 |
|
|
* Maps the specified key to the specified value in this table. |
1034 |
|
|
* Neither the key nor the value can be null. |
1035 |
|
|
* |
1036 |
|
|
* <p> The value can be retrieved by calling the {@code get} method |
1037 |
|
|
* with a key that is equal to the original key. |
1038 |
|
|
* |
1039 |
|
|
* @param key key with which the specified value is to be associated |
1040 |
|
|
* @param value value to be associated with the specified key |
1041 |
|
|
* @return the previous value associated with {@code key}, or |
1042 |
|
|
* {@code null} if there was no mapping for {@code key} |
1043 |
|
|
* @throws NullPointerException if the specified key or value is null |
1044 |
|
|
*/ |
1045 |
|
|
@SuppressWarnings("unchecked") |
1046 |
|
|
public V put(K key, V value) { |
1047 |
|
|
if (key == null || value == null) |
1048 |
|
|
throw new NullPointerException(); |
1049 |
|
|
return (V)internalPut(key, value, true); |
1050 |
|
|
} |
1051 |
|
|
|
1052 |
|
|
/** |
1053 |
|
|
* {@inheritDoc} |
1054 |
|
|
* |
1055 |
|
|
* @return the previous value associated with the specified key, |
1056 |
|
|
* or {@code null} if there was no mapping for the key |
1057 |
|
|
* @throws NullPointerException if the specified key or value is null |
1058 |
|
|
*/ |
1059 |
|
|
@SuppressWarnings("unchecked") |
1060 |
|
|
public V putIfAbsent(K key, V value) { |
1061 |
|
|
if (key == null || value == null) |
1062 |
|
|
throw new NullPointerException(); |
1063 |
|
|
return (V)internalPut(key, value, false); |
1064 |
|
|
} |
1065 |
|
|
|
1066 |
|
|
/** |
1067 |
|
|
* Copies all of the mappings from the specified map to this one. |
1068 |
|
|
* These mappings replace any mappings that this map had for any of the |
1069 |
|
|
* keys currently in the specified map. |
1070 |
|
|
* |
1071 |
|
|
* @param m mappings to be stored in this map |
1072 |
|
|
*/ |
1073 |
|
|
public void putAll(Map<? extends K, ? extends V> m) { |
1074 |
|
|
if (m == null) |
1075 |
|
|
throw new NullPointerException(); |
1076 |
dl |
1.14 |
/* |
1077 |
|
|
* If uninitialized, try to adjust targetCapacity to |
1078 |
|
|
* accommodate the given number of elements. |
1079 |
|
|
*/ |
1080 |
|
|
if (table == null) { |
1081 |
|
|
int size = m.size(); |
1082 |
|
|
int cap = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY : |
1083 |
dl |
1.16 |
tableSizeFor(size + (size >>> 1) + 1); |
1084 |
dl |
1.14 |
if (cap > targetCapacity) |
1085 |
|
|
targetCapacity = cap; |
1086 |
|
|
} |
1087 |
|
|
for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) |
1088 |
|
|
put(e.getKey(), e.getValue()); |
1089 |
dl |
1.1 |
} |
1090 |
|
|
|
1091 |
|
|
/** |
1092 |
|
|
* If the specified key is not already associated with a value, |
1093 |
|
|
* computes its value using the given mappingFunction, and if |
1094 |
|
|
* non-null, enters it into the map. This is equivalent to |
1095 |
jsr166 |
1.13 |
* <pre> {@code |
1096 |
|
|
* if (map.containsKey(key)) |
1097 |
|
|
* return map.get(key); |
1098 |
|
|
* value = mappingFunction.map(key); |
1099 |
|
|
* if (value != null) |
1100 |
|
|
* map.put(key, value); |
1101 |
|
|
* return value;}</pre> |
1102 |
dl |
1.1 |
* |
1103 |
|
|
* except that the action is performed atomically. Some attempted |
1104 |
dl |
1.5 |
* update operations on this map by other threads may be blocked |
1105 |
|
|
* while computation is in progress, so the computation should be |
1106 |
|
|
* short and simple, and must not attempt to update any other |
1107 |
|
|
* mappings of this Map. The most appropriate usage is to |
1108 |
|
|
* construct a new object serving as an initial mapped value, or |
1109 |
|
|
* memoized result, as in: |
1110 |
jsr166 |
1.13 |
* <pre> {@code |
1111 |
dl |
1.5 |
* map.computeIfAbsent(key, new MappingFunction<K, V>() { |
1112 |
jsr166 |
1.13 |
* public V map(K k) { return new Value(f(k)); }});}</pre> |
1113 |
dl |
1.1 |
* |
1114 |
|
|
* @param key key with which the specified value is to be associated |
1115 |
|
|
* @param mappingFunction the function to compute a value |
1116 |
|
|
* @return the current (existing or computed) value associated with |
1117 |
|
|
* the specified key, or {@code null} if the computation |
1118 |
jsr166 |
1.18 |
* returned {@code null} |
1119 |
dl |
1.1 |
* @throws NullPointerException if the specified key or mappingFunction |
1120 |
jsr166 |
1.18 |
* is null |
1121 |
dl |
1.5 |
* @throws IllegalStateException if the computation detectably |
1122 |
|
|
* attempts a recursive update to this map that would |
1123 |
jsr166 |
1.18 |
* otherwise never complete |
1124 |
dl |
1.1 |
* @throws RuntimeException or Error if the mappingFunction does so, |
1125 |
jsr166 |
1.18 |
* in which case the mapping is left unestablished |
1126 |
dl |
1.1 |
*/ |
1127 |
|
|
public V computeIfAbsent(K key, MappingFunction<? super K, ? extends V> mappingFunction) { |
1128 |
|
|
if (key == null || mappingFunction == null) |
1129 |
|
|
throw new NullPointerException(); |
1130 |
dl |
1.2 |
return internalCompute(key, mappingFunction, false); |
1131 |
|
|
} |
1132 |
|
|
|
1133 |
|
|
/** |
1134 |
dl |
1.5 |
* Computes the value associated with the given key using the given |
1135 |
dl |
1.2 |
* mappingFunction, and if non-null, enters it into the map. This |
1136 |
|
|
* is equivalent to |
1137 |
jsr166 |
1.13 |
* <pre> {@code |
1138 |
|
|
* value = mappingFunction.map(key); |
1139 |
|
|
* if (value != null) |
1140 |
|
|
* map.put(key, value); |
1141 |
|
|
* else |
1142 |
|
|
* value = map.get(key); |
1143 |
|
|
* return value;}</pre> |
1144 |
dl |
1.2 |
* |
1145 |
|
|
* except that the action is performed atomically. Some attempted |
1146 |
dl |
1.5 |
* update operations on this map by other threads may be blocked |
1147 |
|
|
* while computation is in progress, so the computation should be |
1148 |
|
|
* short and simple, and must not attempt to update any other |
1149 |
|
|
* mappings of this Map. |
1150 |
dl |
1.2 |
* |
1151 |
|
|
* @param key key with which the specified value is to be associated |
1152 |
|
|
* @param mappingFunction the function to compute a value |
1153 |
|
|
* @return the current value associated with |
1154 |
|
|
* the specified key, or {@code null} if the computation |
1155 |
jsr166 |
1.18 |
* returned {@code null} and the value was not otherwise present |
1156 |
dl |
1.2 |
* @throws NullPointerException if the specified key or mappingFunction |
1157 |
jsr166 |
1.18 |
* is null |
1158 |
dl |
1.5 |
* @throws IllegalStateException if the computation detectably |
1159 |
|
|
* attempts a recursive update to this map that would |
1160 |
jsr166 |
1.18 |
* otherwise never complete |
1161 |
dl |
1.2 |
* @throws RuntimeException or Error if the mappingFunction does so, |
1162 |
jsr166 |
1.18 |
* in which case the mapping is unchanged |
1163 |
dl |
1.2 |
*/ |
1164 |
|
|
public V compute(K key, MappingFunction<? super K, ? extends V> mappingFunction) { |
1165 |
|
|
if (key == null || mappingFunction == null) |
1166 |
|
|
throw new NullPointerException(); |
1167 |
|
|
return internalCompute(key, mappingFunction, true); |
1168 |
dl |
1.1 |
} |
1169 |
|
|
|
1170 |
|
|
/** |
1171 |
|
|
* Removes the key (and its corresponding value) from this map. |
1172 |
|
|
* This method does nothing if the key is not in the map. |
1173 |
|
|
* |
1174 |
|
|
* @param key the key that needs to be removed |
1175 |
|
|
* @return the previous value associated with {@code key}, or |
1176 |
|
|
* {@code null} if there was no mapping for {@code key} |
1177 |
|
|
* @throws NullPointerException if the specified key is null |
1178 |
|
|
*/ |
1179 |
|
|
@SuppressWarnings("unchecked") |
1180 |
|
|
public V remove(Object key) { |
1181 |
|
|
if (key == null) |
1182 |
|
|
throw new NullPointerException(); |
1183 |
jsr166 |
1.3 |
return (V)internalReplace(key, null, null); |
1184 |
dl |
1.1 |
} |
1185 |
|
|
|
1186 |
|
|
/** |
1187 |
|
|
* {@inheritDoc} |
1188 |
|
|
* |
1189 |
|
|
* @throws NullPointerException if the specified key is null |
1190 |
|
|
*/ |
1191 |
|
|
public boolean remove(Object key, Object value) { |
1192 |
|
|
if (key == null) |
1193 |
|
|
throw new NullPointerException(); |
1194 |
|
|
if (value == null) |
1195 |
|
|
return false; |
1196 |
|
|
return internalReplace(key, null, value) != null; |
1197 |
|
|
} |
1198 |
|
|
|
1199 |
|
|
/** |
1200 |
|
|
* {@inheritDoc} |
1201 |
|
|
* |
1202 |
|
|
* @throws NullPointerException if any of the arguments are null |
1203 |
|
|
*/ |
1204 |
|
|
public boolean replace(K key, V oldValue, V newValue) { |
1205 |
|
|
if (key == null || oldValue == null || newValue == null) |
1206 |
|
|
throw new NullPointerException(); |
1207 |
jsr166 |
1.3 |
return internalReplace(key, newValue, oldValue) != null; |
1208 |
dl |
1.1 |
} |
1209 |
|
|
|
1210 |
|
|
/** |
1211 |
|
|
* {@inheritDoc} |
1212 |
|
|
* |
1213 |
|
|
* @return the previous value associated with the specified key, |
1214 |
|
|
* or {@code null} if there was no mapping for the key |
1215 |
|
|
* @throws NullPointerException if the specified key or value is null |
1216 |
|
|
*/ |
1217 |
|
|
@SuppressWarnings("unchecked") |
1218 |
|
|
public V replace(K key, V value) { |
1219 |
|
|
if (key == null || value == null) |
1220 |
|
|
throw new NullPointerException(); |
1221 |
jsr166 |
1.3 |
return (V)internalReplace(key, value, null); |
1222 |
dl |
1.1 |
} |
1223 |
|
|
|
1224 |
|
|
/** |
1225 |
|
|
* Removes all of the mappings from this map. |
1226 |
|
|
*/ |
1227 |
|
|
public void clear() { |
1228 |
|
|
internalClear(); |
1229 |
|
|
} |
1230 |
|
|
|
1231 |
|
|
/** |
1232 |
|
|
* Returns a {@link Set} view of the keys contained in this map. |
1233 |
|
|
* The set is backed by the map, so changes to the map are |
1234 |
|
|
* reflected in the set, and vice-versa. The set supports element |
1235 |
|
|
* removal, which removes the corresponding mapping from this map, |
1236 |
|
|
* via the {@code Iterator.remove}, {@code Set.remove}, |
1237 |
|
|
* {@code removeAll}, {@code retainAll}, and {@code clear} |
1238 |
|
|
* operations. It does not support the {@code add} or |
1239 |
|
|
* {@code addAll} operations. |
1240 |
|
|
* |
1241 |
|
|
* <p>The view's {@code iterator} is a "weakly consistent" iterator |
1242 |
|
|
* that will never throw {@link ConcurrentModificationException}, |
1243 |
|
|
* and guarantees to traverse elements as they existed upon |
1244 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
1245 |
|
|
* reflect any modifications subsequent to construction. |
1246 |
|
|
*/ |
1247 |
|
|
public Set<K> keySet() { |
1248 |
dl |
1.14 |
KeySet<K,V> ks = keySet; |
1249 |
|
|
return (ks != null) ? ks : (keySet = new KeySet<K,V>(this)); |
1250 |
dl |
1.1 |
} |
1251 |
|
|
|
1252 |
|
|
/** |
1253 |
|
|
* Returns a {@link Collection} view of the values contained in this map. |
1254 |
|
|
* The collection is backed by the map, so changes to the map are |
1255 |
|
|
* reflected in the collection, and vice-versa. The collection |
1256 |
|
|
* supports element removal, which removes the corresponding |
1257 |
|
|
* mapping from this map, via the {@code Iterator.remove}, |
1258 |
|
|
* {@code Collection.remove}, {@code removeAll}, |
1259 |
|
|
* {@code retainAll}, and {@code clear} operations. It does not |
1260 |
|
|
* support the {@code add} or {@code addAll} operations. |
1261 |
|
|
* |
1262 |
|
|
* <p>The view's {@code iterator} is a "weakly consistent" iterator |
1263 |
|
|
* that will never throw {@link ConcurrentModificationException}, |
1264 |
|
|
* and guarantees to traverse elements as they existed upon |
1265 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
1266 |
|
|
* reflect any modifications subsequent to construction. |
1267 |
|
|
*/ |
1268 |
|
|
public Collection<V> values() { |
1269 |
dl |
1.14 |
Values<K,V> vs = values; |
1270 |
|
|
return (vs != null) ? vs : (values = new Values<K,V>(this)); |
1271 |
dl |
1.1 |
} |
1272 |
|
|
|
1273 |
|
|
/** |
1274 |
|
|
* Returns a {@link Set} view of the mappings contained in this map. |
1275 |
|
|
* The set is backed by the map, so changes to the map are |
1276 |
|
|
* reflected in the set, and vice-versa. The set supports element |
1277 |
|
|
* removal, which removes the corresponding mapping from the map, |
1278 |
|
|
* via the {@code Iterator.remove}, {@code Set.remove}, |
1279 |
|
|
* {@code removeAll}, {@code retainAll}, and {@code clear} |
1280 |
|
|
* operations. It does not support the {@code add} or |
1281 |
|
|
* {@code addAll} operations. |
1282 |
|
|
* |
1283 |
|
|
* <p>The view's {@code iterator} is a "weakly consistent" iterator |
1284 |
|
|
* that will never throw {@link ConcurrentModificationException}, |
1285 |
|
|
* and guarantees to traverse elements as they existed upon |
1286 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
1287 |
|
|
* reflect any modifications subsequent to construction. |
1288 |
|
|
*/ |
1289 |
|
|
public Set<Map.Entry<K,V>> entrySet() { |
1290 |
dl |
1.14 |
EntrySet<K,V> es = entrySet; |
1291 |
|
|
return (es != null) ? es : (entrySet = new EntrySet<K,V>(this)); |
1292 |
dl |
1.1 |
} |
1293 |
|
|
|
1294 |
|
|
/** |
1295 |
|
|
* Returns an enumeration of the keys in this table. |
1296 |
|
|
* |
1297 |
|
|
* @return an enumeration of the keys in this table |
1298 |
|
|
* @see #keySet() |
1299 |
|
|
*/ |
1300 |
|
|
public Enumeration<K> keys() { |
1301 |
dl |
1.14 |
return new KeyIterator<K,V>(this); |
1302 |
dl |
1.1 |
} |
1303 |
|
|
|
1304 |
|
|
/** |
1305 |
|
|
* Returns an enumeration of the values in this table. |
1306 |
|
|
* |
1307 |
|
|
* @return an enumeration of the values in this table |
1308 |
|
|
* @see #values() |
1309 |
|
|
*/ |
1310 |
|
|
public Enumeration<V> elements() { |
1311 |
dl |
1.14 |
return new ValueIterator<K,V>(this); |
1312 |
dl |
1.1 |
} |
1313 |
|
|
|
1314 |
|
|
/** |
1315 |
dl |
1.2 |
* Returns the hash code value for this {@link Map}, i.e., |
1316 |
|
|
* the sum of, for each key-value pair in the map, |
1317 |
|
|
* {@code key.hashCode() ^ value.hashCode()}. |
1318 |
|
|
* |
1319 |
|
|
* @return the hash code value for this map |
1320 |
dl |
1.1 |
*/ |
1321 |
|
|
public int hashCode() { |
1322 |
dl |
1.14 |
int h = 0; |
1323 |
|
|
InternalIterator it = new InternalIterator(table); |
1324 |
|
|
while (it.next != null) { |
1325 |
|
|
h += it.nextKey.hashCode() ^ it.nextVal.hashCode(); |
1326 |
|
|
it.advance(); |
1327 |
|
|
} |
1328 |
|
|
return h; |
1329 |
dl |
1.1 |
} |
1330 |
|
|
|
1331 |
|
|
/** |
1332 |
dl |
1.2 |
* Returns a string representation of this map. The string |
1333 |
|
|
* representation consists of a list of key-value mappings (in no |
1334 |
|
|
* particular order) enclosed in braces ("{@code {}}"). Adjacent |
1335 |
|
|
* mappings are separated by the characters {@code ", "} (comma |
1336 |
|
|
* and space). Each key-value mapping is rendered as the key |
1337 |
|
|
* followed by an equals sign ("{@code =}") followed by the |
1338 |
|
|
* associated value. |
1339 |
|
|
* |
1340 |
|
|
* @return a string representation of this map |
1341 |
dl |
1.1 |
*/ |
1342 |
|
|
public String toString() { |
1343 |
dl |
1.14 |
InternalIterator it = new InternalIterator(table); |
1344 |
|
|
StringBuilder sb = new StringBuilder(); |
1345 |
|
|
sb.append('{'); |
1346 |
|
|
if (it.next != null) { |
1347 |
|
|
for (;;) { |
1348 |
|
|
Object k = it.nextKey, v = it.nextVal; |
1349 |
|
|
sb.append(k == this ? "(this Map)" : k); |
1350 |
|
|
sb.append('='); |
1351 |
|
|
sb.append(v == this ? "(this Map)" : v); |
1352 |
|
|
it.advance(); |
1353 |
|
|
if (it.next == null) |
1354 |
|
|
break; |
1355 |
|
|
sb.append(',').append(' '); |
1356 |
|
|
} |
1357 |
|
|
} |
1358 |
|
|
return sb.append('}').toString(); |
1359 |
dl |
1.1 |
} |
1360 |
|
|
|
1361 |
|
|
/** |
1362 |
dl |
1.2 |
* Compares the specified object with this map for equality. |
1363 |
|
|
* Returns {@code true} if the given object is a map with the same |
1364 |
|
|
* mappings as this map. This operation may return misleading |
1365 |
|
|
* results if either map is concurrently modified during execution |
1366 |
|
|
* of this method. |
1367 |
|
|
* |
1368 |
|
|
* @param o object to be compared for equality with this map |
1369 |
|
|
* @return {@code true} if the specified object is equal to this map |
1370 |
dl |
1.1 |
*/ |
1371 |
|
|
public boolean equals(Object o) { |
1372 |
dl |
1.14 |
if (o != this) { |
1373 |
|
|
if (!(o instanceof Map)) |
1374 |
|
|
return false; |
1375 |
|
|
Map<?,?> m = (Map<?,?>) o; |
1376 |
|
|
InternalIterator it = new InternalIterator(table); |
1377 |
|
|
while (it.next != null) { |
1378 |
|
|
Object val = it.nextVal; |
1379 |
|
|
Object v = m.get(it.nextKey); |
1380 |
|
|
if (v == null || (v != val && !v.equals(val))) |
1381 |
dl |
1.1 |
return false; |
1382 |
dl |
1.14 |
it.advance(); |
1383 |
|
|
} |
1384 |
dl |
1.1 |
for (Map.Entry<?,?> e : m.entrySet()) { |
1385 |
dl |
1.14 |
Object mk, mv, v; |
1386 |
|
|
if ((mk = e.getKey()) == null || |
1387 |
|
|
(mv = e.getValue()) == null || |
1388 |
|
|
(v = internalGet(mk)) == null || |
1389 |
|
|
(mv != v && !mv.equals(v))) |
1390 |
dl |
1.1 |
return false; |
1391 |
|
|
} |
1392 |
dl |
1.14 |
} |
1393 |
|
|
return true; |
1394 |
|
|
} |
1395 |
|
|
|
1396 |
|
|
/* ----------------Iterators -------------- */ |
1397 |
|
|
|
1398 |
|
|
/** |
1399 |
|
|
* Base class for key, value, and entry iterators. Adds a map |
1400 |
|
|
* reference to InternalIterator to support Iterator.remove. |
1401 |
|
|
*/ |
1402 |
|
|
static abstract class ViewIterator<K,V> extends InternalIterator { |
1403 |
|
|
final ConcurrentHashMapV8<K, V> map; |
1404 |
|
|
ViewIterator(ConcurrentHashMapV8<K, V> map) { |
1405 |
|
|
super(map.table); |
1406 |
|
|
this.map = map; |
1407 |
|
|
} |
1408 |
|
|
|
1409 |
|
|
public final void remove() { |
1410 |
|
|
if (last == null) |
1411 |
|
|
throw new IllegalStateException(); |
1412 |
|
|
map.remove(last.key); |
1413 |
|
|
last = null; |
1414 |
|
|
} |
1415 |
|
|
|
1416 |
|
|
public final boolean hasNext() { return next != null; } |
1417 |
|
|
public final boolean hasMoreElements() { return next != null; } |
1418 |
|
|
} |
1419 |
|
|
|
1420 |
|
|
static final class KeyIterator<K,V> extends ViewIterator<K,V> |
1421 |
|
|
implements Iterator<K>, Enumeration<K> { |
1422 |
|
|
KeyIterator(ConcurrentHashMapV8<K, V> map) { super(map); } |
1423 |
|
|
|
1424 |
|
|
@SuppressWarnings("unchecked") |
1425 |
|
|
public final K next() { |
1426 |
|
|
if (next == null) |
1427 |
|
|
throw new NoSuchElementException(); |
1428 |
|
|
Object k = nextKey; |
1429 |
|
|
advance(); |
1430 |
|
|
return (K)k; |
1431 |
|
|
} |
1432 |
|
|
|
1433 |
|
|
public final K nextElement() { return next(); } |
1434 |
|
|
} |
1435 |
|
|
|
1436 |
|
|
static final class ValueIterator<K,V> extends ViewIterator<K,V> |
1437 |
|
|
implements Iterator<V>, Enumeration<V> { |
1438 |
|
|
ValueIterator(ConcurrentHashMapV8<K, V> map) { super(map); } |
1439 |
|
|
|
1440 |
|
|
@SuppressWarnings("unchecked") |
1441 |
|
|
public final V next() { |
1442 |
|
|
if (next == null) |
1443 |
|
|
throw new NoSuchElementException(); |
1444 |
|
|
Object v = nextVal; |
1445 |
|
|
advance(); |
1446 |
|
|
return (V)v; |
1447 |
|
|
} |
1448 |
|
|
|
1449 |
|
|
public final V nextElement() { return next(); } |
1450 |
|
|
} |
1451 |
|
|
|
1452 |
|
|
static final class EntryIterator<K,V> extends ViewIterator<K,V> |
1453 |
|
|
implements Iterator<Map.Entry<K,V>> { |
1454 |
|
|
EntryIterator(ConcurrentHashMapV8<K, V> map) { super(map); } |
1455 |
|
|
|
1456 |
|
|
@SuppressWarnings("unchecked") |
1457 |
|
|
public final Map.Entry<K,V> next() { |
1458 |
|
|
if (next == null) |
1459 |
|
|
throw new NoSuchElementException(); |
1460 |
|
|
Object k = nextKey; |
1461 |
|
|
Object v = nextVal; |
1462 |
|
|
advance(); |
1463 |
|
|
return new WriteThroughEntry<K,V>(map, (K)k, (V)v); |
1464 |
dl |
1.1 |
} |
1465 |
|
|
} |
1466 |
|
|
|
1467 |
|
|
/** |
1468 |
|
|
* Custom Entry class used by EntryIterator.next(), that relays |
1469 |
|
|
* setValue changes to the underlying map. |
1470 |
|
|
*/ |
1471 |
dl |
1.14 |
static final class WriteThroughEntry<K,V> implements Map.Entry<K, V> { |
1472 |
|
|
final ConcurrentHashMapV8<K, V> map; |
1473 |
|
|
final K key; // non-null |
1474 |
|
|
V val; // non-null |
1475 |
|
|
WriteThroughEntry(ConcurrentHashMapV8<K, V> map, K key, V val) { |
1476 |
|
|
this.map = map; this.key = key; this.val = val; |
1477 |
|
|
} |
1478 |
|
|
|
1479 |
|
|
public final K getKey() { return key; } |
1480 |
|
|
public final V getValue() { return val; } |
1481 |
|
|
public final int hashCode() { return key.hashCode() ^ val.hashCode(); } |
1482 |
|
|
public final String toString(){ return key + "=" + val; } |
1483 |
|
|
|
1484 |
|
|
public final boolean equals(Object o) { |
1485 |
|
|
Object k, v; Map.Entry<?,?> e; |
1486 |
|
|
return ((o instanceof Map.Entry) && |
1487 |
|
|
(k = (e = (Map.Entry<?,?>)o).getKey()) != null && |
1488 |
|
|
(v = e.getValue()) != null && |
1489 |
|
|
(k == key || k.equals(key)) && |
1490 |
|
|
(v == val || v.equals(val))); |
1491 |
dl |
1.1 |
} |
1492 |
|
|
|
1493 |
|
|
/** |
1494 |
|
|
* Sets our entry's value and writes through to the map. The |
1495 |
|
|
* value to return is somewhat arbitrary here. Since a |
1496 |
|
|
* WriteThroughEntry does not necessarily track asynchronous |
1497 |
|
|
* changes, the most recent "previous" value could be |
1498 |
|
|
* different from what we return (or could even have been |
1499 |
|
|
* removed in which case the put will re-establish). We do not |
1500 |
|
|
* and cannot guarantee more. |
1501 |
|
|
*/ |
1502 |
dl |
1.14 |
public final V setValue(V value) { |
1503 |
dl |
1.1 |
if (value == null) throw new NullPointerException(); |
1504 |
dl |
1.14 |
V v = val; |
1505 |
|
|
val = value; |
1506 |
|
|
map.put(key, value); |
1507 |
dl |
1.1 |
return v; |
1508 |
|
|
} |
1509 |
|
|
} |
1510 |
|
|
|
1511 |
dl |
1.14 |
/* ----------------Views -------------- */ |
1512 |
dl |
1.1 |
|
1513 |
dl |
1.14 |
/* |
1514 |
|
|
* These currently just extend java.util.AbstractX classes, but |
1515 |
|
|
* may need a new custom base to support partitioned traversal. |
1516 |
|
|
*/ |
1517 |
dl |
1.1 |
|
1518 |
dl |
1.14 |
static final class KeySet<K,V> extends AbstractSet<K> { |
1519 |
|
|
final ConcurrentHashMapV8<K, V> map; |
1520 |
|
|
KeySet(ConcurrentHashMapV8<K, V> map) { this.map = map; } |
1521 |
dl |
1.1 |
|
1522 |
dl |
1.14 |
public final int size() { return map.size(); } |
1523 |
|
|
public final boolean isEmpty() { return map.isEmpty(); } |
1524 |
|
|
public final void clear() { map.clear(); } |
1525 |
|
|
public final boolean contains(Object o) { return map.containsKey(o); } |
1526 |
|
|
public final boolean remove(Object o) { return map.remove(o) != null; } |
1527 |
|
|
public final Iterator<K> iterator() { |
1528 |
|
|
return new KeyIterator<K,V>(map); |
1529 |
dl |
1.1 |
} |
1530 |
|
|
} |
1531 |
|
|
|
1532 |
dl |
1.14 |
static final class Values<K,V> extends AbstractCollection<V> { |
1533 |
|
|
final ConcurrentHashMapV8<K, V> map; |
1534 |
|
|
Values(ConcurrentHashMapV8<K, V> map) { this.map = map; } |
1535 |
|
|
|
1536 |
|
|
public final int size() { return map.size(); } |
1537 |
|
|
public final boolean isEmpty() { return map.isEmpty(); } |
1538 |
|
|
public final void clear() { map.clear(); } |
1539 |
|
|
public final boolean contains(Object o) { return map.containsValue(o); } |
1540 |
|
|
public final Iterator<V> iterator() { |
1541 |
|
|
return new ValueIterator<K,V>(map); |
1542 |
dl |
1.1 |
} |
1543 |
|
|
} |
1544 |
|
|
|
1545 |
dl |
1.14 |
static final class EntrySet<K,V> extends AbstractSet<Map.Entry<K,V>> { |
1546 |
|
|
final ConcurrentHashMapV8<K, V> map; |
1547 |
|
|
EntrySet(ConcurrentHashMapV8<K, V> map) { this.map = map; } |
1548 |
|
|
|
1549 |
|
|
public final int size() { return map.size(); } |
1550 |
|
|
public final boolean isEmpty() { return map.isEmpty(); } |
1551 |
|
|
public final void clear() { map.clear(); } |
1552 |
|
|
public final Iterator<Map.Entry<K,V>> iterator() { |
1553 |
|
|
return new EntryIterator<K,V>(map); |
1554 |
dl |
1.1 |
} |
1555 |
dl |
1.14 |
|
1556 |
|
|
public final boolean contains(Object o) { |
1557 |
|
|
Object k, v, r; Map.Entry<?,?> e; |
1558 |
|
|
return ((o instanceof Map.Entry) && |
1559 |
|
|
(k = (e = (Map.Entry<?,?>)o).getKey()) != null && |
1560 |
|
|
(r = map.get(k)) != null && |
1561 |
|
|
(v = e.getValue()) != null && |
1562 |
|
|
(v == r || v.equals(r))); |
1563 |
dl |
1.1 |
} |
1564 |
dl |
1.14 |
|
1565 |
|
|
public final boolean remove(Object o) { |
1566 |
|
|
Object k, v; Map.Entry<?,?> e; |
1567 |
|
|
return ((o instanceof Map.Entry) && |
1568 |
|
|
(k = (e = (Map.Entry<?,?>)o).getKey()) != null && |
1569 |
|
|
(v = e.getValue()) != null && |
1570 |
|
|
map.remove(k, v)); |
1571 |
dl |
1.1 |
} |
1572 |
|
|
} |
1573 |
|
|
|
1574 |
|
|
/* ---------------- Serialization Support -------------- */ |
1575 |
|
|
|
1576 |
|
|
/** |
1577 |
dl |
1.14 |
* Stripped-down version of helper class used in previous version, |
1578 |
|
|
* declared for the sake of serialization compatibility |
1579 |
dl |
1.1 |
*/ |
1580 |
dl |
1.14 |
static class Segment<K,V> implements Serializable { |
1581 |
dl |
1.1 |
private static final long serialVersionUID = 2249069246763182397L; |
1582 |
|
|
final float loadFactor; |
1583 |
|
|
Segment(float lf) { this.loadFactor = lf; } |
1584 |
|
|
} |
1585 |
|
|
|
1586 |
|
|
/** |
1587 |
|
|
* Saves the state of the {@code ConcurrentHashMapV8} instance to a |
1588 |
|
|
* stream (i.e., serializes it). |
1589 |
|
|
* @param s the stream |
1590 |
|
|
* @serialData |
1591 |
|
|
* the key (Object) and value (Object) |
1592 |
|
|
* for each key-value mapping, followed by a null pair. |
1593 |
|
|
* The key-value mappings are emitted in no particular order. |
1594 |
|
|
*/ |
1595 |
|
|
@SuppressWarnings("unchecked") |
1596 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
1597 |
|
|
throws java.io.IOException { |
1598 |
|
|
if (segments == null) { // for serialization compatibility |
1599 |
|
|
segments = (Segment<K,V>[]) |
1600 |
|
|
new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL]; |
1601 |
|
|
for (int i = 0; i < segments.length; ++i) |
1602 |
dl |
1.16 |
segments[i] = new Segment<K,V>(LOAD_FACTOR); |
1603 |
dl |
1.1 |
} |
1604 |
|
|
s.defaultWriteObject(); |
1605 |
dl |
1.14 |
InternalIterator it = new InternalIterator(table); |
1606 |
|
|
while (it.next != null) { |
1607 |
|
|
s.writeObject(it.nextKey); |
1608 |
|
|
s.writeObject(it.nextVal); |
1609 |
|
|
it.advance(); |
1610 |
|
|
} |
1611 |
dl |
1.1 |
s.writeObject(null); |
1612 |
|
|
s.writeObject(null); |
1613 |
|
|
segments = null; // throw away |
1614 |
|
|
} |
1615 |
|
|
|
1616 |
|
|
/** |
1617 |
jsr166 |
1.9 |
* Reconstitutes the instance from a stream (that is, deserializes it). |
1618 |
dl |
1.1 |
* @param s the stream |
1619 |
|
|
*/ |
1620 |
|
|
@SuppressWarnings("unchecked") |
1621 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1622 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1623 |
|
|
s.defaultReadObject(); |
1624 |
|
|
this.segments = null; // unneeded |
1625 |
jsr166 |
1.21 |
// initialize transient final field |
1626 |
dl |
1.14 |
UNSAFE.putObjectVolatile(this, counterOffset, new LongAdder()); |
1627 |
|
|
this.targetCapacity = DEFAULT_CAPACITY; |
1628 |
|
|
|
1629 |
|
|
// Create all nodes, then place in table once size is known |
1630 |
|
|
long size = 0L; |
1631 |
|
|
Node p = null; |
1632 |
dl |
1.1 |
for (;;) { |
1633 |
dl |
1.14 |
K k = (K) s.readObject(); |
1634 |
|
|
V v = (V) s.readObject(); |
1635 |
|
|
if (k != null && v != null) { |
1636 |
|
|
p = new Node(spread(k.hashCode()), k, v, p); |
1637 |
|
|
++size; |
1638 |
|
|
} |
1639 |
|
|
else |
1640 |
dl |
1.1 |
break; |
1641 |
dl |
1.14 |
} |
1642 |
|
|
if (p != null) { |
1643 |
|
|
boolean init = false; |
1644 |
|
|
if (resizing == 0 && |
1645 |
|
|
UNSAFE.compareAndSwapInt(this, resizingOffset, 0, 1)) { |
1646 |
|
|
try { |
1647 |
|
|
if (table == null) { |
1648 |
|
|
init = true; |
1649 |
|
|
int n; |
1650 |
|
|
if (size >= (long)(MAXIMUM_CAPACITY >>> 1)) |
1651 |
|
|
n = MAXIMUM_CAPACITY; |
1652 |
|
|
else { |
1653 |
|
|
int sz = (int)size; |
1654 |
dl |
1.16 |
n = tableSizeFor(sz + (sz >>> 1) + 1); |
1655 |
dl |
1.14 |
} |
1656 |
dl |
1.16 |
threshold = n - (n >>> 2) - THRESHOLD_OFFSET; |
1657 |
dl |
1.14 |
Node[] tab = new Node[n]; |
1658 |
|
|
int mask = n - 1; |
1659 |
|
|
while (p != null) { |
1660 |
|
|
int j = p.hash & mask; |
1661 |
|
|
Node next = p.next; |
1662 |
|
|
p.next = tabAt(tab, j); |
1663 |
|
|
setTabAt(tab, j, p); |
1664 |
|
|
p = next; |
1665 |
|
|
} |
1666 |
|
|
table = tab; |
1667 |
|
|
counter.add(size); |
1668 |
|
|
} |
1669 |
|
|
} finally { |
1670 |
|
|
resizing = 0; |
1671 |
|
|
} |
1672 |
|
|
} |
1673 |
|
|
if (!init) { // Can only happen if unsafely published. |
1674 |
|
|
while (p != null) { |
1675 |
|
|
internalPut(p.key, p.val, true); |
1676 |
|
|
p = p.next; |
1677 |
|
|
} |
1678 |
|
|
} |
1679 |
dl |
1.1 |
} |
1680 |
|
|
} |
1681 |
|
|
|
1682 |
|
|
// Unsafe mechanics |
1683 |
|
|
private static final sun.misc.Unsafe UNSAFE; |
1684 |
|
|
private static final long counterOffset; |
1685 |
|
|
private static final long resizingOffset; |
1686 |
|
|
private static final long ABASE; |
1687 |
|
|
private static final int ASHIFT; |
1688 |
|
|
|
1689 |
|
|
static { |
1690 |
|
|
int ss; |
1691 |
|
|
try { |
1692 |
|
|
UNSAFE = getUnsafe(); |
1693 |
|
|
Class<?> k = ConcurrentHashMapV8.class; |
1694 |
|
|
counterOffset = UNSAFE.objectFieldOffset |
1695 |
|
|
(k.getDeclaredField("counter")); |
1696 |
|
|
resizingOffset = UNSAFE.objectFieldOffset |
1697 |
|
|
(k.getDeclaredField("resizing")); |
1698 |
|
|
Class<?> sc = Node[].class; |
1699 |
|
|
ABASE = UNSAFE.arrayBaseOffset(sc); |
1700 |
|
|
ss = UNSAFE.arrayIndexScale(sc); |
1701 |
|
|
} catch (Exception e) { |
1702 |
|
|
throw new Error(e); |
1703 |
|
|
} |
1704 |
|
|
if ((ss & (ss-1)) != 0) |
1705 |
|
|
throw new Error("data type scale not a power of two"); |
1706 |
|
|
ASHIFT = 31 - Integer.numberOfLeadingZeros(ss); |
1707 |
|
|
} |
1708 |
|
|
|
1709 |
|
|
/** |
1710 |
|
|
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1711 |
|
|
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1712 |
|
|
* into a jdk. |
1713 |
|
|
* |
1714 |
|
|
* @return a sun.misc.Unsafe |
1715 |
|
|
*/ |
1716 |
|
|
private static sun.misc.Unsafe getUnsafe() { |
1717 |
|
|
try { |
1718 |
|
|
return sun.misc.Unsafe.getUnsafe(); |
1719 |
|
|
} catch (SecurityException se) { |
1720 |
|
|
try { |
1721 |
|
|
return java.security.AccessController.doPrivileged |
1722 |
|
|
(new java.security |
1723 |
|
|
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1724 |
|
|
public sun.misc.Unsafe run() throws Exception { |
1725 |
|
|
java.lang.reflect.Field f = sun.misc |
1726 |
|
|
.Unsafe.class.getDeclaredField("theUnsafe"); |
1727 |
|
|
f.setAccessible(true); |
1728 |
|
|
return (sun.misc.Unsafe) f.get(null); |
1729 |
|
|
}}); |
1730 |
|
|
} catch (java.security.PrivilegedActionException e) { |
1731 |
|
|
throw new RuntimeException("Could not initialize intrinsics", |
1732 |
|
|
e.getCause()); |
1733 |
|
|
} |
1734 |
|
|
} |
1735 |
|
|
} |
1736 |
|
|
|
1737 |
|
|
} |