/*
* Copyright 2000-2014 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
package com.intellij.util.containers;
import com.intellij.util.IncorrectOperationException;
import com.intellij.util.concurrency.AtomicFieldUpdater;
import gnu.trove.TObjectHashingStrategy;
import org.jetbrains.annotations.NotNull;
import sun.misc.Unsafe;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.*;
import java.util.HashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.locks.LockSupport;
// IJ specific:
// copied from Doug Lea ConcurrentHashMap (see http://gee.cs.oswego.edu/dl/concurrency-interest/index.html) except:
// added hashing strategy argument
// Null keys are NOT allowed
// Null values are NOT allowed
// NOT serializable
/**
* A hash table supporting full concurrency of retrievals and
* high expected concurrency for updates. This class obeys the
* same functional specification as {@link java.util.Hashtable}, and
* includes versions of methods corresponding to each method of
* {@code Hashtable}. However, even though all operations are
* thread-safe, retrieval operations do <em>not</em> entail locking,
* and there is <em>not</em> any support for locking the entire table
* in a way that prevents all access. This class is fully
* interoperable with {@code Hashtable} in programs that rely on its
* thread safety but not on its synchronization details.
* <p/>
* <p>Retrieval operations (including {@code get}) generally do not
* block, so may overlap with update operations (including {@code put}
* and {@code remove}). Retrievals reflect the results of the most
* recently <em>completed</em> update operations holding upon their
* onset. (More formally, an update operation for a given key bears a
* <em>happens-before</em> relation with any (non-null) retrieval for
* that key reporting the updated value.) For aggregate operations
* such as {@code putAll} and {@code clear}, concurrent retrievals may
* reflect insertion or removal of only some entries. Similarly,
* Iterators, Spliterators and Enumerations return elements reflecting the
* state of the hash table at some point at or since the creation of the
* iterator/enumeration. They do <em>not</em> throw {@link
* java.util.ConcurrentModificationException ConcurrentModificationException}.
* However, iterators are designed to be used by only one thread at a time.
* Bear in mind that the results of aggregate status methods including
* {@code size}, {@code isEmpty}, and {@code containsValue} are typically
* useful only when a map is not undergoing concurrent updates in other threads.
* Otherwise the results of these methods reflect transient states
* that may be adequate for monitoring or estimation purposes, but not
* for program control.
* <p/>
* <p>The table is dynamically expanded when there are too many
* collisions (i.e., keys that have distinct hash codes but fall into
* the same slot modulo the table size), with the expected average
* effect of maintaining roughly two bins per mapping (corresponding
* to a 0.75 load factor threshold for resizing). There may be much
* variance around this average as mappings are added and removed, but
* overall, this maintains a commonly accepted time/space tradeoff for
* hash tables. However, resizing this or any other kind of hash
* table may be a relatively slow operation. When possible, it is a
* good idea to provide a size estimate as an optional {@code
* initialCapacity} constructor argument. An additional optional
* {@code loadFactor} constructor argument provides a further means of
* customizing initial table capacity by specifying the table density
* to be used in calculating the amount of space to allocate for the
* given number of elements. Also, for compatibility with previous
* versions of this class, constructors may optionally specify an
* expected {@code concurrencyLevel} as an additional hint for
* internal sizing. Note that using many keys with exactly the same
* {@code hashCode()} is a sure way to slow down performance of any
* hash table. To ameliorate impact, when keys are {@link Comparable},
* this class may use comparison order among keys to help break ties.
* <p/>
* <p>A ConcurrentHashMap can be used as a scalable frequency map (a
* form of histogram or multiset) by using {@link
* java.util.concurrent.atomic.LongAdder} values and initializing via
* {@link #computeIfAbsent computeIfAbsent}. For example, to add a count
* to a {@code ConcurrentHashMap<String,LongAdder> freqs}, you can use
* {@code freqs.computeIfAbsent(key, k -> new LongAdder()).increment();}
* <p/>
* <p>This class and its views and iterators implement all of the
* <em>optional</em> methods of the {@link Map} and {@link Iterator}
* interfaces.
* <p/>
* <p>Like {@link Hashtable} but unlike {@link HashMap}, this class
* does <em>not</em> allow {@code null} to be used as a key or value.
* <p/>
* <p>ConcurrentHashMaps support a set of sequential and parallel bulk
* operations that, unlike most Stream methods, are designed
* to be safely, and often sensibly, applied even with maps that are
* being concurrently updated by other threads; for example, when
* computing a snapshot summary of the values in a shared registry.
* There are three kinds of operation, each with four forms, accepting
* functions with Keys, Values, Entries, and (Key, Value) arguments
* and/or return values. Because the elements of a ConcurrentHashMap
* are not ordered in any particular way, and may be processed in
* different orders in different parallel executions, the correctness
* of supplied functions should not depend on any ordering, or on any
* other objects or values that may transiently change while
* computation is in progress; and except for forEach actions, should
* ideally be side-effect-free. Bulk operations on {@link java.util.Map.Entry}
* objects do not support method {@code setValue}.
* <p/>
* <ul>
* <li> forEach: Perform a given action on each element.
* A variant form applies a given transformation on each element
* before performing the action.</li>
* <p/>
* <li> search: Return the first available non-null result of
* applying a given function on each element; skipping further
* search when a result is found.</li>
* <p/>
* <li> reduce: Accumulate each element. The supplied reduction
* function cannot rely on ordering (more formally, it should be
* both associative and commutative). There are five variants:
* <p/>
* <ul>
* <p/>
* <li> Plain reductions. (There is not a form of this method for
* (key, value) function arguments since there is no corresponding
* return type.)</li>
* <p/>
* <li> Mapped reductions that accumulate the results of a given
* function applied to each element.</li>
* <p/>
* <li> Reductions to scalar doubles, longs, and ints, using a
* given basis value.</li>
* <p/>
* </ul>
* </li>
* </ul>
* <p/>
* <p>These bulk operations accept a {@code parallelismThreshold}
* argument. Methods proceed sequentially if the current map size is
* estimated to be less than the given threshold. Using a value of
* {@code Long.MAX_VALUE} suppresses all parallelism. Using a value
* of {@code 1} results in maximal parallelism by partitioning into
* enough subtasks to fully utilize the
* ForkJoinPool#commonPool() that is used for all parallel
* computations. Normally, you would initially choose one of these
* extreme values, and then measure performance of using in-between
* values that trade off overhead versus throughput.
* <p/>
* <p>The concurrency properties of bulk operations follow
* from those of ConcurrentHashMap: Any non-null result returned
* from {@code get(key)} and related access methods bears a
* happens-before relation with the associated insertion or
* update. The result of any bulk operation reflects the
* composition of these per-element relations (but is not
* necessarily atomic with respect to the map as a whole unless it
* is somehow known to be quiescent). Conversely, because keys
* and values in the map are never null, null serves as a reliable
* atomic indicator of the current lack of any result. To
* maintain this property, null serves as an implicit basis for
* all non-scalar reduction operations. For the double, long, and
* int versions, the basis should be one that, when combined with
* any other value, returns that other value (more formally, it
* should be the identity element for the reduction). Most common
* reductions have these properties; for example, computing a sum
* with basis 0 or a minimum with basis MAX_VALUE.
* <p/>
* <p>Search and transformation functions provided as arguments
* should similarly return null to indicate the lack of any result
* (in which case it is not used). In the case of mapped
* reductions, this also enables transformations to serve as
* filters, returning null (or, in the case of primitive
* specializations, the identity basis) if the element should not
* be combined. You can create compound transformations and
* filterings by composing them yourself under this "null means
* there is nothing there now" rule before using them in search or
* reduce operations.
* <p/>
* <p>Methods accepting and/or returning Entry arguments maintain
* key-value associations. They may be useful for example when
* finding the key for the greatest value. Note that "plain" Entry
* arguments can be supplied using {@code new
* AbstractMap.SimpleEntry(k,v)}.
* <p/>
* <p>Bulk operations may complete abruptly, throwing an
* exception encountered in the application of a supplied
* function. Bear in mind when handling such exceptions that other
* concurrently executing functions could also have thrown
* exceptions, or would have done so if the first exception had
* not occurred.
* <p/>
* <p>Speedups for parallel compared to sequential forms are common
* but not guaranteed. Parallel operations involving brief functions
* on small maps may execute more slowly than sequential forms if the
* underlying work to parallelize the computation is more expensive
* than the computation itself. Similarly, parallelization may not
* lead to much actual parallelism if all processors are busy
* performing unrelated tasks.
* <p/>
* <p>All arguments to all task methods must be non-null.
* <p/>
* <p>This class is a member of the
* <a href="{@docRoot}/../technotes/guides/collections/index.html">
* Java Collections Framework</a>.
*
* @param <K> the type of keys maintained by this map
* @param <V> the type of mapped values
* @author Doug Lea
* @since 1.5
* @deprecated Use {@link ContainerUtil#newConcurrentMap()} instead
*/
public final class ConcurrentHashMap<K, V> extends AbstractMap<K, V>
implements ConcurrentMap<K, V>, TObjectHashingStrategy<K> {
/*
* Overview:
*
* The primary design goal of this hash table is to maintain
* concurrent readability (typically method get(), but also
* iterators and related methods) while minimizing update
* contention. Secondary goals are to keep space consumption about
* the same or better than java.util.HashMap, and to support high
* initial insertion rates on an empty table by many threads.
*
* This map usually acts as a binned (bucketed) hash table. Each
* key-value mapping is held in a Node. Most nodes are instances
* of the basic Node class with hash, key, value, and next
* fields. However, various subclasses exist: TreeNodes are
* arranged in balanced trees, not lists. TreeBins hold the roots
* of sets of TreeNodes. ForwardingNodes are placed at the heads
* of bins during resizing. ReservationNodes are used as
* placeholders while establishing values in computeIfAbsent and
* related methods. The types TreeBin, ForwardingNode, and
* ReservationNode do not hold normal user keys, values, or
* hashes, and are readily distinguishable during search etc
* because they have negative hash fields and null key and value
* fields. (These special nodes are either uncommon or transient,
* so the impact of carrying around some unused fields is
* insignificant.)
*
* The table is lazily initialized to a power-of-two size upon the
* first insertion. Each bin in the table normally contains a
* list of Nodes (most often, the list has only zero or one Node).
* Table accesses require volatile/atomic reads, writes, and
* CASes. Because there is no other way to arrange this without
* adding further indirections, we use intrinsics
* (sun.misc.Unsafe) operations.
*
* We use the top (sign) bit of Node hash fields for control
* purposes -- it is available anyway because of addressing
* constraints. Nodes with negative hash fields are specially
* handled or ignored in map methods.
*
* Insertion (via put or its variants) of the first node in an
* empty bin is performed by just CASing it to the bin. This is
* by far the most common case for put operations under most
* key/hash distributions. Other update operations (insert,
* delete, and replace) require locks. We do not want to waste
* the space required to associate a distinct lock object with
* each bin, so instead use the first node of a bin list itself as
* a lock. Locking support for these locks relies on builtin
* "synchronized" monitors.
*
* Using the first node of a list as a lock does not by itself
* suffice though: When a node is locked, any update must first
* validate that it is still the first node after locking it, and
* retry if not. Because new nodes are always appended to lists,
* once a node is first in a bin, it remains first until deleted
* or the bin becomes invalidated (upon resizing).
*
* The main disadvantage of per-bin locks is that other update
* operations on other nodes in a bin list protected by the same
* lock can stall, for example when user equals() or mapping
* functions take a long time. However, statistically, under
* random hash codes, this is not a common problem. Ideally, the
* frequency of nodes in bins follows a Poisson distribution
* (http://en.wikipedia.org/wiki/Poisson_distribution) with a
* parameter of about 0.5 on average, given the resizing threshold
* of 0.75, although with a large variance because of resizing
* granularity. Ignoring variance, the expected occurrences of
* list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
* first values are:
*
* 0: 0.60653066
* 1: 0.30326533
* 2: 0.07581633
* 3: 0.01263606
* 4: 0.00157952
* 5: 0.00015795
* 6: 0.00001316
* 7: 0.00000094
* 8: 0.00000006
* more: less than 1 in ten million
*
* Lock contention probability for two threads accessing distinct
* elements is roughly 1 / (8 * #elements) under random hashes.
*
* Actual hash code distributions encountered in practice
* sometimes deviate significantly from uniform randomness. This
* includes the case when N > (1<<30), so some keys MUST collide.
* Similarly for dumb or hostile usages in which multiple keys are
* designed to have identical hash codes or ones that differs only
* in masked-out high bits. So we use a secondary strategy that
* applies when the number of nodes in a bin exceeds a
* threshold. These TreeBins use a balanced tree to hold nodes (a
* specialized form of red-black trees), bounding search time to
* O(log N). Each search step in a TreeBin is at least twice as
* slow as in a regular list, but given that N cannot exceed
* (1<<64) (before running out of addresses) this bounds search
* steps, lock hold times, etc, to reasonable constants (roughly
* 100 nodes inspected per operation worst case) so long as keys
* are Comparable (which is very common -- String, Long, etc).
* TreeBin nodes (TreeNodes) also maintain the same "next"
* traversal pointers as regular nodes, so can be traversed in
* iterators in the same way.
*
* The table is resized when occupancy exceeds a percentage
* threshold (nominally, 0.75, but see below). Any thread
* noticing an overfull bin may assist in resizing after the
* initiating thread allocates and sets up the replacement array.
* However, rather than stalling, these other threads may proceed
* with insertions etc. The use of TreeBins shields us from the
* worst case effects of overfilling while resizes are in
* progress. Resizing proceeds by transferring bins, one by one,
* from the table to the next table. However, threads claim small
* blocks of indices to transfer (via field transferIndex) before
* doing so, reducing contention. A generation stamp in field
* sizeCtl ensures that resizings do not overlap. Because we are
* using power-of-two expansion, the elements from each bin must
* either stay at same index, or move with a power of two
* offset. We eliminate unnecessary node creation by catching
* cases where old nodes can be reused because their next fields
* won't change. On average, only about one-sixth of them need
* cloning when a table doubles. The nodes they replace will be
* garbage collectable as soon as they are no longer referenced by
* any reader thread that may be in the midst of concurrently
* traversing table. Upon transfer, the old table bin contains
* only a special forwarding node (with hash field "MOVED") that
* contains the next table as its key. On encountering a
* forwarding node, access and update operations restart, using
* the new table.
*
* Each bin transfer requires its bin lock, which can stall
* waiting for locks while resizing. However, because other
* threads can join in and help resize rather than contend for
* locks, average aggregate waits become shorter as resizing
* progresses. The transfer operation must also ensure that all
* accessible bins in both the old and new table are usable by any
* traversal. This is arranged in part by proceeding from the
* last bin (table.length - 1) up towards the first. Upon seeing
* a forwarding node, traversals (see class Traverser) arrange to
* move to the new table without revisiting nodes. To ensure that
* no intervening nodes are skipped even when moved out of order,
* a stack (see class TableStack) is created on first encounter of
* a forwarding node during a traversal, to maintain its place if
* later processing the current table. The need for these
* save/restore mechanics is relatively rare, but when one
* forwarding node is encountered, typically many more will be.
* So Traversers use a simple caching scheme to avoid creating so
* many new TableStack nodes. (Thanks to Peter Levart for
* suggesting use of a stack here.)
*
* The traversal scheme also applies to partial traversals of
* ranges of bins (via an alternate Traverser constructor)
* to support partitioned aggregate operations. Also, read-only
* operations give up if ever forwarded to a null table, which
* provides support for shutdown-style clearing, which is also not
* currently implemented.
*
* Lazy table initialization minimizes footprint until first use,
* and also avoids resizings when the first operation is from a
* putAll, constructor with map argument, or deserialization.
* These cases attempt to override the initial capacity settings,
* but harmlessly fail to take effect in cases of races.
*
* The element count is maintained using a specialization of
* LongAdder. We need to incorporate a specialization rather than
* just use a LongAdder in order to access implicit
* contention-sensing that leads to creation of multiple
* CounterCells. The counter mechanics avoid contention on
* updates but can encounter cache thrashing if read too
* frequently during concurrent access. To avoid reading so often,
* resizing under contention is attempted only upon adding to a
* bin already holding two or more nodes. Under uniform hash
* distributions, the probability of this occurring at threshold
* is around 13%, meaning that only about 1 in 8 puts check
* threshold (and after resizing, many fewer do so).
*
* TreeBins use a special form of comparison for search and
* related operations (which is the main reason we cannot use
* existing collections such as TreeMaps). TreeBins contain
* Comparable elements, but may contain others, as well as
* elements that are Comparable but not necessarily Comparable for
* the same T, so we cannot invoke compareTo among them. To handle
* this, the tree is ordered primarily by hash value, then by
* Comparable.compareTo order if applicable. On lookup at a node,
* if elements are not comparable or compare as 0 then both left
* and right children may need to be searched in the case of tied
* hash values. (This corresponds to the full list search that
* would be necessary if all elements were non-Comparable and had
* tied hashes.) On insertion, to keep a total ordering (or as
* close as is required here) across rebalancings, we compare
* classes and identityHashCodes as tie-breakers. The red-black
* balancing code is updated from pre-jdk-collections
* (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
* based in turn on Cormen, Leiserson, and Rivest "Introduction to
* Algorithms" (CLR).
*
* TreeBins also require an additional locking mechanism. While
* list traversal is always possible by readers even during
* updates, tree traversal is not, mainly because of tree-rotations
* that may change the root node and/or its linkages. TreeBins
* include a simple read-write lock mechanism parasitic on the
* main bin-synchronization strategy: Structural adjustments
* associated with an insertion or removal are already bin-locked
* (and so cannot conflict with other writers) but must wait for
* ongoing readers to finish. Since there can be only one such
* waiter, we use a simple scheme using a single "waiter" field to
* block writers. However, readers need never block. If the root
* lock is held, they proceed along the slow traversal path (via
* next-pointers) until the lock becomes available or the list is
* exhausted, whichever comes first. These cases are not fast, but
* maximize aggregate expected throughput.
*
* Maintaining API and serialization compatibility with previous
* versions of this class introduces several oddities. Mainly: We
* leave untouched but unused constructor arguments refering to
* concurrencyLevel. We accept a loadFactor constructor argument,
* but apply it only to initial table capacity (which is the only
* time that we can guarantee to honor it.) We also declare an
* unused "Segment" class that is instantiated in minimal form
* only when serializing.
*
* Also, solely for compatibility with previous versions of this
* class, it extends AbstractMap, even though all of its methods
* are overridden, so it is just useless baggage.
*
* This file is organized to make things a little easier to follow
* while reading than they might otherwise: First the main static
* declarations and utilities, then fields, then main public
* methods (with a few factorings of multiple public methods into
* internal ones), then sizing methods, trees, traversers, and
* bulk operations.
*/
/* ---------------- Constants -------------- */
/**
* The largest possible table capacity. This value must be
* exactly 1<<30 to stay within Java array allocation and indexing
* bounds for power of two table sizes, and is further required
* because the top two bits of 32bit hash fields are used for
* control purposes.
*/
private static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* The default initial table capacity. Must be a power of 2
* (i.e., at least 1) and at most MAXIMUM_CAPACITY.
*/
static final int DEFAULT_CAPACITY = 16;
/**
* The largest possible (non-power of two) array size.
* Needed by toArray and related methods.
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* The load factor for this table. Overrides of this value in
* constructors affect only the initial table capacity. The
* actual floating point value isn't normally used -- it is
* simpler to use expressions such as {@code n - (n >>> 2)} for
* the associated resizing threshold.
*/
static final float LOAD_FACTOR = 0.75f;
/**
* The bin count threshold for using a tree rather than list for a
* bin. Bins are converted to trees when adding an element to a
* bin with at least this many nodes. The value must be greater
* than 2, and should be at least 8 to mesh with assumptions in
* tree removal about conversion back to plain bins upon
* shrinkage.
*/
private static final int TREEIFY_THRESHOLD = 8;
/**
* The bin count threshold for untreeifying a (split) bin during a
* resize operation. Should be less than TREEIFY_THRESHOLD, and at
* most 6 to mesh with shrinkage detection under removal.
*/
private static final int UNTREEIFY_THRESHOLD = 6;
/**
* The smallest table capacity for which bins may be treeified.
* (Otherwise the table is resized if too many nodes in a bin.)
* The value should be at least 4 * TREEIFY_THRESHOLD to avoid
* conflicts between resizing and treeification thresholds.
*/
private static final int MIN_TREEIFY_CAPACITY = 64;
/**
* Minimum number of rebinnings per transfer step. Ranges are
* subdivided to allow multiple resizer threads. This value
* serves as a lower bound to avoid resizers encountering
* excessive memory contention. The value should be at least
* DEFAULT_CAPACITY.
*/
private static final int MIN_TRANSFER_STRIDE = 16;
/**
* The number of bits used for generation stamp in sizeCtl.
* Must be at least 6 for 32bit arrays.
*/
private static final int RESIZE_STAMP_BITS = 16;
/**
* The maximum number of threads that can help resize.
* Must fit in 32 - RESIZE_STAMP_BITS bits.
*/
private static final int MAX_RESIZERS = (1 << (32 - RESIZE_STAMP_BITS)) - 1;
/**
* The bit shift for recording size stamp in sizeCtl.
*/
private static final int RESIZE_STAMP_SHIFT = 32 - RESIZE_STAMP_BITS;
/*
* Encodings for Node hash fields. See above for explanation.
*/
private static final int MOVED = -1; // hash for forwarding nodes
private static final int TREEBIN = -2; // hash for roots of trees
private static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
/**
* Number of CPUS, to place bounds on some sizings
*/
private static final int NCPU = Runtime.getRuntime().availableProcessors();
/* ---------------- Nodes -------------- */
/**
* Key-value entry. This class is never exported out as a
* user-mutable Map.Entry (i.e., one supporting setValue; see
* MapEntry below), but can be used for read-only traversals used
* in bulk tasks. Subclasses of Node with a negative hash field
* are special, and contain null keys and values (but are never
* exported). Otherwise, keys and vals are never null.
*/
private static class Node<K, V> implements Map.Entry<K, V> {
final int hash;
final K key;
volatile V val;
volatile Node<K, V> next;
@NotNull final TObjectHashingStrategy<K> myHashingStrategy;
Node(int hash, K key, V val, Node<K, V> next, @NotNull TObjectHashingStrategy<K> hashingStrategy) {
this.hash = hash;
this.key = key;
this.val = val;
this.next = next;
myHashingStrategy = hashingStrategy;
}
@Override
public final K getKey() {
return key;
}
@Override
public final V getValue() {
return val;
}
@Override
public final int hashCode() {
return key.hashCode() ^ val.hashCode();
}
@Override
public final String toString() {
return key + "=" + val;
}
@Override
public final V setValue(V value) {
throw new UnsupportedOperationException();
}
@Override
public final boolean equals(Object o) {
Object k;
Object v;
Object u;
Map.Entry<?, ?> e;
return o instanceof Entry &&
(k = (e = (Entry<?, ?>)o).getKey()) != null &&
(v = e.getValue()) != null &&
(k == key || myHashingStrategy.equals((K)k, key)) &&
(v == (u = val) || v.equals(u));
}
/**
* Virtualized support for map.get(); overridden in subclasses.
*/
Node<K, V> find(int h, Object k) {
Node<K, V> e = this;
if (k != null) {
do {
K ek;
if (e.hash == h &&
((ek = e.key) == k || ek != null && myHashingStrategy.equals((K)k, ek))) {
return e;
}
}
while ((e = e.next) != null);
}
return null;
}
}
/* ---------------- Static utilities -------------- */
/**
* Spreads (XORs) higher bits of hash to lower and also forces top
* bit to 0. Because the table uses power-of-two masking, sets of
* hashes that vary only in bits above the current mask will
* always collide. (Among known examples are sets of Float keys
* holding consecutive whole numbers in small tables.) So we
* apply a transform that spreads the impact of higher bits
* downward. There is a tradeoff between speed, utility, and
* quality of bit-spreading. Because many common sets of hashes
* are already reasonably distributed (so don't benefit from
* spreading), and because we use trees to handle large sets of
* collisions in bins, we just XOR some shifted bits in the
* cheapest possible way to reduce systematic lossage, as well as
* to incorporate impact of the highest bits that would otherwise
* never be used in index calculations because of table bounds.
*/
private static int spread(int h) {
return (h ^ (h >>> 16)) & HASH_BITS;
}
/**
* Returns a power of two table size for the given desired capacity.
* See Hackers Delight, sec 3.2
*/
private static int tableSizeFor(int c) {
int n = c - 1;
n |= n >>> 1;
n |= n >>> 2;
n |= n >>> 4;
n |= n >>> 8;
n |= n >>> 16;
return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
}
/**
* Returns x's Class if it is of the form "class C implements
* Comparable<C>", else null.
*/
private static Class<?> comparableClassFor(Object x) {
if (x instanceof Comparable) {
Class<?> c;
Type[] ts, as;
Type t;
ParameterizedType p;
if ((c = x.getClass()) == String.class) // bypass checks
{
return c;
}
if ((ts = c.getGenericInterfaces()) != null) {
for (int i = 0; i < ts.length; ++i) {
if (((t = ts[i]) instanceof ParameterizedType) &&
((p = (ParameterizedType)t).getRawType() ==
Comparable.class) &&
(as = p.getActualTypeArguments()) != null &&
as.length == 1 && as[0] == c) // type arg is c
{
return c;
}
}
}
}
return null;
}
/**
* Returns k.compareTo(x) if x matches kc (k's screened comparable
* class), else 0.
*/
@SuppressWarnings({"rawtypes", "unchecked"}) // for cast to Comparable
private static int compareComparables(Class<?> kc, Object k, Object x) {
return (x == null || x.getClass() != kc ? 0 :
((Comparable)k).compareTo(x));
}
/* ---------------- Table element access -------------- */
/*
* Volatile access methods are used for table elements as well as
* elements of in-progress next table while resizing. All uses of
* the tab arguments must be null checked by callers. All callers
* also paranoically precheck that tab's length is not zero (or an
* equivalent check), thus ensuring that any index argument taking
* the form of a hash value anded with (length - 1) is a valid
* index. Note that, to be correct wrt arbitrary concurrency
* errors by users, these checks must operate on local variables,
* which accounts for some odd-looking inline assignments below.
* Note that calls to setTabAt always occur within locked regions,
* and so in principle require only release ordering, not
* full volatile semantics, but are currently coded as volatile
* writes to be conservative.
*/
@SuppressWarnings("unchecked")
private static <K, V> Node<K, V> tabAt(Node<K, V>[] tab, int i) {
return (Node<K, V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
}
private static <K, V> boolean casTabAt(Node<K, V>[] tab, int i,
Node<K, V> c, Node<K, V> v) {
return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
}
private static <K, V> void setTabAt(Node<K, V>[] tab, int i, Node<K, V> v) {
U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
}
/* ---------------- Fields -------------- */
/**
* The array of bins. Lazily initialized upon first insertion.
* Size is always a power of two. Accessed directly by iterators.
*/
private transient volatile Node<K, V>[] table;
/**
* The next table to use; non-null only while resizing.
*/
private transient volatile Node<K, V>[] nextTable;
/**
* Base counter value, used mainly when there is no contention,
* but also as a fallback during table initialization
* races. Updated via CAS.
*/
private transient volatile long baseCount;
/**
* Table initialization and resizing control. When negative, the
* table is being initialized or resized: -1 for initialization,
* else -(1 + the number of active resizing threads). Otherwise,
* when table is null, holds the initial table size to use upon
* creation, or 0 for default. After initialization, holds the
* next element count value upon which to resize the table.
*/
private transient volatile int sizeCtl;
/**
* The next table index (plus one) to split while resizing.
*/
private transient volatile int transferIndex;
/**
* Spinlock (locked via CAS) used when resizing and/or creating CounterCells.
*/
private transient volatile int cellsBusy;
/**
* Table of counter cells. When non-null, size is a power of 2.
*/
private transient volatile CounterCell[] counterCells;
// views
private transient KeySetView<K, V> keySet;
private transient ValuesView<K, V> values;
private transient EntrySetView<K, V> entrySet;
@NotNull private final TObjectHashingStrategy<K> myHashingStrategy;
/* ---------------- Public operations -------------- */
/**
* Creates a new, empty map with the default initial table size (16).
*/
public ConcurrentHashMap() {
this(DEFAULT_CAPACITY);
}
/**
* Creates a new, empty map with an initial table size
* accommodating the specified number of elements without the need
* to dynamically resize.
*
* @param initialCapacity The implementation performs internal
* sizing to accommodate this many elements.
* @throws IllegalArgumentException if the initial capacity of
* elements is negative
*/
public ConcurrentHashMap(int initialCapacity) {
this(initialCapacity, LOAD_FACTOR);
}
/**
* Creates a new map with the same mappings as the given map.
*
* @param m the map
*/
public ConcurrentHashMap(Map<? extends K, ? extends V> m) {
this(DEFAULT_CAPACITY);
putAll(m);
}
/**
* Creates a new, empty map with an initial table size based on
* the given number of elements ({@code initialCapacity}) and
* initial table density ({@code loadFactor}).
*
* @param initialCapacity the initial capacity. The implementation
* performs internal sizing to accommodate this many elements,
* given the specified load factor.
* @param loadFactor the load factor (table density) for
* establishing the initial table size
* @throws IllegalArgumentException if the initial capacity of
* elements is negative or the load factor is nonpositive
* @since 1.6
*/
public ConcurrentHashMap(int initialCapacity, float loadFactor) {
this(initialCapacity, loadFactor, 1);
}
/**
* Creates a new, empty map with an initial table size based on
* the given number of elements ({@code initialCapacity}), table
* density ({@code loadFactor}), and number of concurrently
* updating threads ({@code concurrencyLevel}).
*
* @param initialCapacity the initial capacity. The implementation
* performs internal sizing to accommodate this many elements,
* given the specified load factor.
* @param loadFactor the load factor (table density) for
* establishing the initial table size
* @param concurrencyLevel the estimated number of concurrently
* updating threads. The implementation may use this value as
* a sizing hint.
* @throws IllegalArgumentException if the initial capacity is
* negative or the load factor or concurrencyLevel are
* nonpositive
*/
public ConcurrentHashMap(int initialCapacity,
float loadFactor, int concurrencyLevel) {
this(initialCapacity, loadFactor, concurrencyLevel, THIS);
}
private static final TObjectHashingStrategy THIS = new TObjectHashingStrategy() {
@Override
public int computeHashCode(Object object) {
throw new IncorrectOperationException();
}
@Override
public boolean equals(Object o1, Object o2) {
throw new IncorrectOperationException();
}
};
public ConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel, @NotNull TObjectHashingStrategy<K> hashingStrategy) {
if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0) {
throw new IllegalArgumentException();
}
if (initialCapacity < concurrencyLevel) // Use at least as many bins
{
initialCapacity = concurrencyLevel; // as estimated threads
}
long size = (long)(1.0 + (long)initialCapacity / loadFactor);
int cap = (size >= (long)MAXIMUM_CAPACITY) ?
MAXIMUM_CAPACITY : tableSizeFor((int)size);
this.sizeCtl = cap;
myHashingStrategy = hashingStrategy == THIS ? this : hashingStrategy;
}
public ConcurrentHashMap(@NotNull TObjectHashingStrategy<K> hashingStrategy) {
this(DEFAULT_CAPACITY, LOAD_FACTOR, NCPU, hashingStrategy);
}
// Original (since JDK1.2) Map methods
/**
* {@inheritDoc}
*/
@Override
public int size() {
long n = sumCount();
return ((n < 0L) ? 0 :
(n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
(int)n);
}
/**
* {@inheritDoc}
*/
@Override
public boolean isEmpty() {
return sumCount() <= 0L; // ignore transient negative values
}
/**
* Returns the value to which the specified key is mapped,
* or {@code null} if this map contains no mapping for the key.
* <p/>
* <p>More formally, if this map contains a mapping from a key
* {@code k} to a value {@code v} such that {@code key.equals(k)},
* then this method returns {@code v}; otherwise it returns
* {@code null}. (There can be at most one such mapping.)
*
* @throws NullPointerException if the specified key is null
*/
@Override
public V get(@NotNull Object key) {
Node<K, V>[] tab;
Node<K, V> e, p;
int n, eh;
int h = hash((K)key);
if ((tab = table) != null && (n = tab.length) > 0 &&
(e = tabAt(tab, (n - 1) & h)) != null) {
if ((eh = e.hash) == h) {
if (isEqual((K)key, e.key)) {
return e.val;
}
}
else if (eh < 0) {
return (p = e.find(h, key)) != null ? p.val : null;
}
while ((e = e.next) != null) {
if (e.hash == h &&
(isEqual((K)key, e.key))) {
return e.val;
}
}
}
return null;
}
/**
* Tests if the specified object is a key in this table.
*
* @param key possible key
* @return {@code true} if and only if the specified object
* is a key in this table, as determined by the
* {@code equals} method; {@code false} otherwise
* @throws NullPointerException if the specified key is null
*/
@Override
public boolean containsKey(Object key) {
return get(key) != null;
}
/**
* Returns {@code true} if this map maps one or more keys to the
* specified value. Note: This method may require a full traversal
* of the map, and is much slower than method {@code containsKey}.
*
* @param value value whose presence in this map is to be tested
* @return {@code true} if this map maps one or more keys to the
* specified value
* @throws NullPointerException if the specified value is null
*/
@Override
public boolean containsValue(@NotNull Object value) {
Node<K, V>[] t;
if ((t = table) != null) {
Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
for (Node<K, V> p; (p = it.advance()) != null; ) {
V v;
if ((v = p.val) == value || (v != null && value.equals(v))) {
return true;
}
}
}
return false;
}
/**
* Maps the specified key to the specified value in this table.
* Neither the key nor the value can be null.
* <p/>
* <p>The value can be retrieved by calling the {@code get} method
* with a key that is equal to the original key.
*
* @param key key with which the specified value is to be associated
* @param value value to be associated with the specified key
* @return the previous value associated with {@code key}, or
* {@code null} if there was no mapping for {@code key}
* @throws NullPointerException if the specified key or value is null
*/
@Override
public V put(@NotNull K key, @NotNull V value) {
return putVal(key, value, false);
}
/**
* Implementation for put and putIfAbsent
*/
private V putVal(@NotNull K key, @NotNull V value, boolean onlyIfAbsent) {
int hash = hash((K)key);
int binCount = 0;
for (Node<K, V>[] tab = table; ; ) {
Node<K, V> f;
int n, i, fh;
if (tab == null || (n = tab.length) == 0) {
tab = initTable();
}
else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {
if (casTabAt(tab, i, null,
new Node<K, V>(hash, key, value, null, myHashingStrategy))) {
break; // no lock when adding to empty bin
}
}
else if ((fh = f.hash) == MOVED) {
tab = helpTransfer(tab, f);
}
else {
V oldVal = null;
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node<K, V> e = f; ; ++binCount) {
if (e.hash == hash &&
(isEqual((K)key, e.key))) {
oldVal = e.val;
if (!onlyIfAbsent) {
e.val = value;
}
break;
}
Node<K, V> pred = e;
if ((e = e.next) == null) {
pred.next = new Node<K, V>(hash, key,
value, null, myHashingStrategy);
break;
}
}
}
else if (f instanceof TreeBin) {
Node<K, V> p;
binCount = 2;
if ((p = ((TreeBin<K, V>)f).putTreeVal(hash, key,
value)) != null) {
oldVal = p.val;
if (!onlyIfAbsent) {
p.val = value;
}
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD) {
treeifyBin(tab, i);
}
if (oldVal != null) {
return oldVal;
}
break;
}
}
}
addCount(1L, binCount);
return null;
}
/**
* Copies all of the mappings from the specified map to this one.
* These mappings replace any mappings that this map had for any of the
* keys currently in the specified map.
*
* @param m mappings to be stored in this map
*/
@Override
public void putAll(Map<? extends K, ? extends V> m) {
tryPresize(m.size());
for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
putVal(e.getKey(), e.getValue(), false);
}
}
/**
* Removes the key (and its corresponding value) from this map.
* This method does nothing if the key is not in the map.
*
* @param key the key that needs to be removed
* @return the previous value associated with {@code key}, or
* {@code null} if there was no mapping for {@code key}
* @throws NullPointerException if the specified key is null
*/
@Override
public V remove(Object key) {
return replaceNode(key, null, null);
}
/**
* Implementation for the four public remove/replace methods:
* Replaces node value with v, conditional upon match of cv if
* non-null. If resulting value is null, delete.
*/
private V replaceNode(Object key, V value, Object cv) {
int hash = hash((K)key);
for (Node<K, V>[] tab = table; ; ) {
Node<K, V> f;
int n, i, fh;
if (tab == null || (n = tab.length) == 0 ||
(f = tabAt(tab, i = (n - 1) & hash)) == null) {
break;
}
else if ((fh = f.hash) == MOVED) {
tab = helpTransfer(tab, f);
}
else {
V oldVal = null;
boolean validated = false;
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
validated = true;
for (Node<K, V> e = f, pred = null; ; ) {
if (e.hash == hash &&
isEqual((K)key, e.key)) {
V ev = e.val;
if (cv == null || cv == ev ||
(ev != null && cv.equals(ev))) {
oldVal = ev;
if (value != null) {
e.val = value;
}
else if (pred != null) {
pred.next = e.next;
}
else {
setTabAt(tab, i, e.next);
}
}
break;
}
pred = e;
if ((e = e.next) == null) {
break;
}
}
}
else if (f instanceof TreeBin) {
validated = true;
TreeBin<K, V> t = (TreeBin<K, V>)f;
TreeNode<K, V> r, p;
if ((r = t.root) != null &&
(p = r.findTreeNode(hash, key, null)) != null) {
V pv = p.val;
if (cv == null || cv == pv ||
(pv != null && cv.equals(pv))) {
oldVal = pv;
if (value != null) {
p.val = value;
}
else if (t.removeTreeNode(p)) {
setTabAt(tab, i, untreeify(t.first));
}
}
}
}
}
}
if (validated) {
if (oldVal != null) {
if (value == null) {
addCount(-1L, -1);
}
return oldVal;
}
break;
}
}
}
return null;
}
/**
* Removes all of the mappings from this map.
*/
@Override
public void clear() {
if (isEmpty()) return;
long delta = 0L; // negative number of deletions
int i = 0;
Node<K, V>[] tab = table;
while (tab != null && i < tab.length) {
int fh;
Node<K, V> f = tabAt(tab, i);
if (f == null) {
++i;
}
else if ((fh = f.hash) == MOVED) {
tab = helpTransfer(tab, f);
i = 0; // restart
}
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
Node<K, V> p = (fh >= 0 ? f :
(f instanceof TreeBin) ?
((TreeBin<K, V>)f).first : null);
while (p != null) {
--delta;
p = p.next;
}
setTabAt(tab, i++, null);
}
}
}
}
if (delta != 0L) {
addCount(delta, -1);
}
}
/**
* Returns a {@link Set} view of the keys contained in this map.
* The set is backed by the map, so changes to the map are
* reflected in the set, and vice-versa. The set supports element
* removal, which removes the corresponding mapping from this map,
* via the {@code Iterator.remove}, {@code Set.remove},
* {@code removeAll}, {@code retainAll}, and {@code clear}
* operations. It does not support the {@code add} or
* {@code addAll} operations.
* <p/>
* <p>The view's iterators and spliterators are
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
* <p/>
* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
*
* @return the set view
*/
@Override
public KeySetView<K, V> keySet() {
KeySetView<K, V> ks;
return (ks = keySet) != null ? ks : (keySet = new KeySetView<K, V>(this, null));
}
/**
* Returns a {@link Collection} view of the values contained in this map.
* The collection is backed by the map, so changes to the map are
* reflected in the collection, and vice-versa. The collection
* supports element removal, which removes the corresponding
* mapping from this map, via the {@code Iterator.remove},
* {@code Collection.remove}, {@code removeAll},
* {@code retainAll}, and {@code clear} operations. It does not
* support the {@code add} or {@code addAll} operations.
* <p/>
* <p>The view's iterators and spliterators are
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
* <p/>
* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT}
* and {@link Spliterator#NONNULL}.
*
* @return the collection view
*/
@Override
public Collection<V> values() {
ValuesView<K, V> vs;
return (vs = values) != null ? vs : (values = new ValuesView<K, V>(this));
}
/**
* Returns a {@link Set} view of the mappings contained in this map.
* The set is backed by the map, so changes to the map are
* reflected in the set, and vice-versa. The set supports element
* removal, which removes the corresponding mapping from the map,
* via the {@code Iterator.remove}, {@code Set.remove},
* {@code removeAll}, {@code retainAll}, and {@code clear}
* operations.
* <p/>
* <p>The view's iterators and spliterators are
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
* <p/>
* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
*
* @return the set view
*/
@Override
public Set<Map.Entry<K, V>> entrySet() {
EntrySetView<K, V> es;
return (es = entrySet) != null ? es : (entrySet = new EntrySetView<K, V>(this));
}
/**
* Returns the hash code value for this {@link Map}, i.e.,
* the sum of, for each key-value pair in the map,
* {@code key.hashCode() ^ value.hashCode()}.
*
* @return the hash code value for this map
*/
@Override
public int hashCode() {
int h = 0;
Node<K, V>[] t;
if ((t = table) != null) {
Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
for (Node<K, V> p; (p = it.advance()) != null; ) {
h += hash(p.key) ^ p.val.hashCode();
}
}
return h;
}
/**
* Returns a string representation of this map. The string
* representation consists of a list of key-value mappings (in no
* particular order) enclosed in braces ("{@code {}}"). Adjacent
* mappings are separated by the characters {@code ", "} (comma
* and space). Each key-value mapping is rendered as the key
* followed by an equals sign ("{@code =}") followed by the
* associated value.
*
* @return a string representation of this map
*/
@Override
public String toString() {
Node<K, V>[] t;
int f = (t = table) == null ? 0 : t.length;
Traverser<K, V> it = new Traverser<K, V>(t, f, 0, f);
StringBuilder sb = new StringBuilder();
sb.append('{');
Node<K, V> p;
if ((p = it.advance()) != null) {
for (; ; ) {
K k = p.key;
V v = p.val;
sb.append(k == this ? "(this Map)" : k);
sb.append('=');
sb.append(v == this ? "(this Map)" : v);
if ((p = it.advance()) == null) {
break;
}
sb.append(',').append(' ');
}
}
return sb.append('}').toString();
}
/**
* Compares the specified object with this map for equality.
* Returns {@code true} if the given object is a map with the same
* mappings as this map. This operation may return misleading
* results if either map is concurrently modified during execution
* of this method.
*
* @param o object to be compared for equality with this map
* @return {@code true} if the specified object is equal to this map
*/
@Override
public boolean equals(Object o) {
if (o != this) {
if (!(o instanceof Map)) {
return false;
}
Map<?, ?> m = (Map<?, ?>)o;
Node<K, V>[] t;
int f = (t = table) == null ? 0 : t.length;
Traverser<K, V> it = new Traverser<K, V>(t, f, 0, f);
for (Node<K, V> p; (p = it.advance()) != null; ) {
V val = p.val;
Object v = m.get(p.key);
if (v == null || (v != val && !v.equals(val))) {
return false;
}
}
for (Map.Entry<?, ?> e : m.entrySet()) {
Object mk, mv, v;
if ((mk = e.getKey()) == null ||
(mv = e.getValue()) == null ||
(v = get(mk)) == null ||
(mv != v && !mv.equals(v))) {
return false;
}
}
}
return true;
}
// ConcurrentMap methods
/**
* {@inheritDoc}
*
* @return the previous value associated with the specified key,
* or {@code null} if there was no mapping for the key
* @throws NullPointerException if the specified key or value is null
*/
@Override
public V putIfAbsent(@NotNull K key, @NotNull V value) {
return putVal(key, value, true);
}
/**
* {@inheritDoc}
*
* @throws NullPointerException if the specified key is null
*/
@Override
public boolean remove(@NotNull Object key, Object value) {
return value != null && replaceNode(key, null, value) != null;
}
/**
* {@inheritDoc}
*
* @throws NullPointerException if any of the arguments are null
*/
@Override
public boolean replace(@NotNull K key, @NotNull V oldValue, @NotNull V newValue) {
return replaceNode(key, newValue, oldValue) != null;
}
/**
* {@inheritDoc}
*
* @return the previous value associated with the specified key,
* or {@code null} if there was no mapping for the key
* @throws NullPointerException if the specified key or value is null
*/
@Override
public V replace(@NotNull K key, @NotNull V value) {
return replaceNode(key, value, null);
}
// Overrides of JDK8+ Map extension method defaults
/**
* Returns the value to which the specified key is mapped, or the
* given default value if this map contains no mapping for the
* key.
*
* @param key the key whose associated value is to be returned
* @param defaultValue the value to return if this map contains
* no mapping for the given key
* @return the mapping for the key, if present; else the default value
* @throws NullPointerException if the specified key is null
*/
@SuppressWarnings("override") //no method in JDK6
public V getOrDefault(@NotNull Object key, V defaultValue) {
V v;
return (v = get(key)) == null ? defaultValue : v;
}
// Hashtable legacy methods
/**
* Returns an enumeration of the keys in this table.
*
* @return an enumeration of the keys in this table
* @see #keySet()
*/
public Enumeration<K> keys() {
Node<K, V>[] t;
int f = (t = table) == null ? 0 : t.length;
return new KeyIterator<K, V>(t, f, 0, f, this);
}
/**
* Returns an enumeration of the values in this table.
*
* @return an enumeration of the values in this table
* @see #values()
*/
public Enumeration<V> elements() {
Node<K, V>[] t;
int f = (t = table) == null ? 0 : t.length;
return new ValueIterator<K, V>(t, f, 0, f, this);
}
// ConcurrentHashMap-only methods
/**
* Returns the number of mappings. This method should be used
* instead of {@link #size} because a ConcurrentHashMap may
* contain more mappings than can be represented as an int. The
* value returned is an estimate; the actual count may differ if
* there are concurrent insertions or removals.
*
* @return the number of mappings
* @since 1.8
*/
private long mappingCount() {
long n = sumCount();
return (n < 0L) ? 0L : n; // ignore transient negative values
}
/**
* Creates a new {@link Set} backed by a ConcurrentHashMap
* from the given type to {@code Boolean.TRUE}.
*
* @param <K> the element type of the returned set
* @return the new set
* @since 1.8
*/
private static <K> KeySetView<K, Boolean> newKeySet() {
return new KeySetView<K, Boolean>
(new ConcurrentHashMap<K, Boolean>(), Boolean.TRUE);
}
/* ---------------- Special Nodes -------------- */
/**
* A node inserted at head of bins during transfer operations.
*/
private static final class ForwardingNode<K, V> extends Node<K, V> {
private final Node<K, V>[] nextTable;
private ForwardingNode(Node<K, V>[] tab, @NotNull TObjectHashingStrategy<K> hashingStrategy) {
super(MOVED, null, null, null, hashingStrategy);
this.nextTable = tab;
}
@Override
Node<K, V> find(int h, Object k) {
// loop to avoid arbitrarily deep recursion on forwarding nodes
outer:
for (Node<K, V>[] tab = nextTable; ; ) {
Node<K, V> e;
int n;
if (k == null || tab == null || (n = tab.length) == 0 ||
(e = tabAt(tab, (n - 1) & h)) == null) {
return null;
}
for (; ; ) {
int eh;
if ((eh = e.hash) == h &&
(isEqual((K)k, e.key, myHashingStrategy))) {
return e;
}
if (eh < 0) {
if (e instanceof ForwardingNode) {
tab = ((ForwardingNode<K, V>)e).nextTable;
continue outer;
}
else {
return e.find(h, k);
}
}
if ((e = e.next) == null) {
return null;
}
}
}
}
}
/* ---------------- Table Initialization and Resizing -------------- */
/**
* Returns the stamp bits for resizing a table of size n.
* Must be negative when shifted left by RESIZE_STAMP_SHIFT.
*/
private static int resizeStamp(int n) {
return Integer.numberOfLeadingZeros(n) | (1 << (RESIZE_STAMP_BITS - 1));
}
/**
* Initializes table, using the size recorded in sizeCtl.
*/
private Node<K, V>[] initTable() {
Node<K, V>[] tab;
int sc;
while ((tab = table) == null || tab.length == 0) {
if ((sc = sizeCtl) < 0) {
Thread.yield(); // lost initialization race; just spin
}
else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
try {
if ((tab = table) == null || tab.length == 0) {
int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
@SuppressWarnings("unchecked")
Node<K, V>[] nt = (Node<K, V>[])new Node<?, ?>[n];
table = tab = nt;
sc = n - (n >>> 2);
}
}
finally {
sizeCtl = sc;
}
break;
}
}
return tab;
}
/**
* Adds to count, and if table is too small and not already
* resizing, initiates transfer. If already resizing, helps
* perform transfer if work is available. Rechecks occupancy
* after a transfer to see if another resize is already needed
* because resizings are lagging additions.
*
* @param x the count to add
* @param check if <0, don't check resize, if <= 1 only check if uncontended
*/
private void addCount(long x, int check) {
CounterCell[] as;
long b, s;
if ((as = counterCells) != null ||
!U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
CounterCell a;
long v;
int m;
boolean uncontended = true;
if (as == null || (m = as.length - 1) < 0 ||
(a = as[ThreadLocalRandom.getProbe() & m]) == null ||
!(uncontended =
U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
fullAddCount(x, uncontended);
return;
}
if (check <= 1) {
return;
}
s = sumCount();
}
if (check >= 0) {
Node<K, V>[] tab, nt;
int n, sc;
while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
(n = tab.length) < MAXIMUM_CAPACITY) {
int rs = resizeStamp(n);
if (sc < 0) {
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
sc == rs + MAX_RESIZERS || (nt = nextTable) == null ||
transferIndex <= 0) {
break;
}
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) {
transfer(tab, nt);
}
}
else if (U.compareAndSwapInt(this, SIZECTL, sc,
(rs << RESIZE_STAMP_SHIFT) + 2)) {
transfer(tab, null);
}
s = sumCount();
}
}
}
/**
* Helps transfer if a resize is in progress.
*/
private Node<K, V>[] helpTransfer(Node<K, V>[] tab, Node<K, V> f) {
Node<K, V>[] nextTab;
int sc;
if (tab != null && (f instanceof ForwardingNode) &&
(nextTab = ((ForwardingNode<K, V>)f).nextTable) != null) {
int rs = resizeStamp(tab.length);
while (nextTab == nextTable && table == tab &&
(sc = sizeCtl) < 0) {
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
sc == rs + MAX_RESIZERS || transferIndex <= 0) {
break;
}
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) {
transfer(tab, nextTab);
break;
}
}
return nextTab;
}
return table;
}
/**
* Tries to presize table to accommodate the given number of elements.
*
* @param size number of elements (doesn't need to be perfectly accurate)
*/
private void tryPresize(int size) {
int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
tableSizeFor(size + (size >>> 1) + 1);
int sc;
while ((sc = sizeCtl) >= 0) {
Node<K, V>[] tab = table;
int n;
if (tab == null || (n = tab.length) == 0) {
n = (sc > c) ? sc : c;
if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
try {
if (table == tab) {
@SuppressWarnings("unchecked")
Node<K, V>[] nt = (Node<K, V>[])new Node<?, ?>[n];
table = nt;
sc = n - (n >>> 2);
}
}
finally {
sizeCtl = sc;
}
}
}
else if (c <= sc || n >= MAXIMUM_CAPACITY) {
break;
}
else if (tab == table) {
int rs = resizeStamp(n);
if (sc < 0) {
Node<K,V>[] nt;
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
sc == rs + MAX_RESIZERS || (nt = nextTable) == null ||
transferIndex <= 0)
break;
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1))
transfer(tab, nt);
}
else if (U.compareAndSwapInt(this, SIZECTL, sc,
(rs << RESIZE_STAMP_SHIFT) + 2)) {
transfer(tab, null);
}
}
}
}
/**
* Moves and/or copies the nodes in each bin to new table. See
* above for explanation.
*/
private void transfer(Node<K, V>[] tab, Node<K, V>[] nextTab) {
int n = tab.length, stride;
if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE) {
stride = MIN_TRANSFER_STRIDE; // subdivide range
}
if (nextTab == null) { // initiating
try {
@SuppressWarnings("unchecked")
Node<K, V>[] nt = (Node<K, V>[])new Node<?, ?>[n << 1];
nextTab = nt;
}
catch (Throwable ex) { // try to cope with OOME
sizeCtl = Integer.MAX_VALUE;
return;
}
nextTable = nextTab;
transferIndex = n;
}
int nextn = nextTab.length;
ForwardingNode<K, V> fwd = new ForwardingNode<K, V>(nextTab, myHashingStrategy);
boolean advance = true;
boolean finishing = false; // to ensure sweep before committing nextTab
for (int i = 0, bound = 0; ; ) {
Node<K, V> f;
int fh;
while (advance) {
int nextIndex, nextBound;
if (--i >= bound || finishing) {
advance = false;
}
else if ((nextIndex = transferIndex) <= 0) {
i = -1;
advance = false;
}
else if (U.compareAndSwapInt
(this, TRANSFERINDEX, nextIndex,
nextBound = (nextIndex > stride ?
nextIndex - stride : 0))) {
bound = nextBound;
i = nextIndex - 1;
advance = false;
}
}
if (i < 0 || i >= n || i + n >= nextn) {
int sc;
if (finishing) {
nextTable = null;
table = nextTab;
sizeCtl = (n << 1) - (n >>> 1);
return;
}
if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, sc - 1)) {
if ((sc - 2) != resizeStamp(n) << RESIZE_STAMP_SHIFT) {
return;
}
finishing = advance = true;
i = n; // recheck before commit
}
}
else if ((f = tabAt(tab, i)) == null) {
advance = casTabAt(tab, i, null, fwd);
}
else if ((fh = f.hash) == MOVED) {
advance = true; // already processed
}
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
Node<K, V> ln, hn;
if (fh >= 0) {
int runBit = fh & n;
Node<K, V> lastRun = f;
for (Node<K, V> p = f.next; p != null; p = p.next) {
int b = p.hash & n;
if (b != runBit) {
runBit = b;
lastRun = p;
}
}
if (runBit == 0) {
ln = lastRun;
hn = null;
}
else {
hn = lastRun;
ln = null;
}
for (Node<K, V> p = f; p != lastRun; p = p.next) {
int ph = p.hash;
K pk = p.key;
V pv = p.val;
if ((ph & n) == 0) {
ln = new Node<K, V>(ph, pk, pv, ln, myHashingStrategy);
}
else {
hn = new Node<K, V>(ph, pk, pv, hn, myHashingStrategy);
}
}
setTabAt(nextTab, i, ln);
setTabAt(nextTab, i + n, hn);
setTabAt(tab, i, fwd);
advance = true;
}
else if (f instanceof TreeBin) {
TreeBin<K, V> t = (TreeBin<K, V>)f;
TreeNode<K, V> lo = null, loTail = null;
TreeNode<K, V> hi = null, hiTail = null;
int lc = 0, hc = 0;
for (Node<K, V> e = t.first; e != null; e = e.next) {
int h = e.hash;
TreeNode<K, V> p = new TreeNode<K, V>(h, e.key, e.val, null, null, myHashingStrategy);
if ((h & n) == 0) {
if ((p.prev = loTail) == null) {
lo = p;
}
else {
loTail.next = p;
}
loTail = p;
++lc;
}
else {
if ((p.prev = hiTail) == null) {
hi = p;
}
else {
hiTail.next = p;
}
hiTail = p;
++hc;
}
}
ln = (lc <= UNTREEIFY_THRESHOLD) ? untreeify(lo) :
(hc != 0) ? new TreeBin<K, V>(lo, myHashingStrategy) : t;
hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
(lc != 0) ? new TreeBin<K, V>(hi, myHashingStrategy) : t;
setTabAt(nextTab, i, ln);
setTabAt(nextTab, i + n, hn);
setTabAt(tab, i, fwd);
advance = true;
}
}
}
}
}
}
/* ---------------- Counter support -------------- */
/**
* A padded cell for distributing counts. Adapted from LongAdder
* and Striped64. See their internal docs for explanation.
*/
static final class CounterCell {
volatile long p0;
volatile long p1;
volatile long p2;
volatile long p3;
volatile long p4;
volatile long p5;
volatile long p6;
volatile long value;
volatile long q0;
volatile long q1;
volatile long q2;
volatile long q3;
volatile long q4;
volatile long q5;
volatile long q6;
CounterCell(long x) {
value = x;
}
}
private long sumCount() {
CounterCell[] as = counterCells;
CounterCell a;
long sum = baseCount;
if (as != null) {
for (int i = 0; i < as.length; ++i) {
if ((a = as[i]) != null) {
sum += a.value;
}
}
}
return sum;
}
// See LongAdder version for explanation
private void fullAddCount(long x, boolean wasUncontended) {
int h;
if ((h = ThreadLocalRandom.getProbe()) == 0) {
ThreadLocalRandom.localInit(); // force initialization
h = ThreadLocalRandom.getProbe();
wasUncontended = true;
}
boolean collide = false; // True if last slot nonempty
for (; ; ) {
CounterCell[] as;
CounterCell a;
int n;
long v;
if ((as = counterCells) != null && (n = as.length) > 0) {
if ((a = as[(n - 1) & h]) == null) {
if (cellsBusy == 0) { // Try to attach new Cell
CounterCell r = new CounterCell(x); // Optimistic create
if (cellsBusy == 0 &&
U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
boolean created = false;
try { // Recheck under lock
CounterCell[] rs;
int m, j;
if ((rs = counterCells) != null &&
(m = rs.length) > 0 &&
rs[j = (m - 1) & h] == null) {
rs[j] = r;
created = true;
}
}
finally {
cellsBusy = 0;
}
if (created) {
break;
}
continue; // Slot is now non-empty
}
}
collide = false;
}
else if (!wasUncontended) // CAS already known to fail
{
wasUncontended = true; // Continue after rehash
}
else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x)) {
break;
}
else if (counterCells != as || n >= NCPU) {
collide = false; // At max size or stale
}
else if (!collide) {
collide = true;
}
else if (cellsBusy == 0 &&
U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
try {
if (counterCells == as) {// Expand table unless stale
CounterCell[] rs = new CounterCell[n << 1];
for (int i = 0; i < n; ++i) {
rs[i] = as[i];
}
counterCells = rs;
}
}
finally {
cellsBusy = 0;
}
collide = false;
continue; // Retry with expanded table
}
h = ThreadLocalRandom.advanceProbe(h);
}
else if (cellsBusy == 0 && counterCells == as &&
U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
boolean init = false;
try { // Initialize table
if (counterCells == as) {
CounterCell[] rs = new CounterCell[2];
rs[h & 1] = new CounterCell(x);
counterCells = rs;
init = true;
}
}
finally {
cellsBusy = 0;
}
if (init) {
break;
}
}
else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x)) {
break; // Fall back on using base
}
}
}
/* ---------------- Conversion from/to TreeBins -------------- */
/**
* Replaces all linked nodes in bin at given index unless table is
* too small, in which case resizes instead.
*/
private void treeifyBin(Node<K, V>[] tab, int index) {
Node<K, V> b;
int n;
if (tab != null) {
if ((n = tab.length) < MIN_TREEIFY_CAPACITY) {
tryPresize(n << 1);
}
else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
synchronized (b) {
if (tabAt(tab, index) == b) {
TreeNode<K, V> hd = null, tl = null;
for (Node<K, V> e = b; e != null; e = e.next) {
TreeNode<K, V> p =
new TreeNode<K, V>(e.hash, e.key, e.val,
null, null, myHashingStrategy);
if ((p.prev = tl) == null) {
hd = p;
}
else {
tl.next = p;
}
tl = p;
}
setTabAt(tab, index, new TreeBin<K, V>(hd, myHashingStrategy));
}
}
}
}
}
/**
* Returns a list on non-TreeNodes replacing those in given list.
*/
private static <K, V> Node<K, V> untreeify(Node<K, V> b) {
Node<K, V> hd = null, tl = null;
for (Node<K, V> q = b; q != null; q = q.next) {
Node<K, V> p = new Node<K, V>(q.hash, q.key, q.val, null, q.myHashingStrategy);
if (tl == null) {
hd = p;
}
else {
tl.next = p;
}
tl = p;
}
return hd;
}
/* ---------------- TreeNodes -------------- */
/**
* Nodes for use in TreeBins
*/
private static final class TreeNode<K, V> extends Node<K, V> {
private TreeNode<K, V> parent; // red-black tree links
private TreeNode<K, V> left;
private TreeNode<K, V> right;
private TreeNode<K, V> prev; // needed to unlink next upon deletion
private boolean red;
TreeNode(int hash, K key, V val, Node<K, V> next,
TreeNode<K, V> parent, TObjectHashingStrategy<K> hashingStrategy) {
super(hash, key, val, next, hashingStrategy);
this.parent = parent;
}
@Override
Node<K, V> find(int h, Object k) {
return findTreeNode(h, k, null);
}
/**
* Returns the TreeNode (or null if not found) for the given key
* starting at given root.
*/
private TreeNode<K, V> findTreeNode(int h, Object k, Class<?> kc) {
if (k != null) {
TreeNode<K, V> p = this;
do {
int ph, dir;
K pk = p.key;
TreeNode<K, V> q;
TreeNode<K, V> pl = p.left, pr = p.right;
if ((ph = p.hash) > h) {
p = pl;
}
else if (ph < h) {
p = pr;
}
else if (isEqual((K)k, pk, myHashingStrategy)) {
return p;
}
else if (pl == null) {
p = pr;
}
else if (pr == null) {
p = pl;
}
else if ((kc != null ||
(kc = comparableClassFor(k)) != null) &&
(dir = compareComparables(kc, k, pk)) != 0) {
p = (dir < 0) ? pl : pr;
}
else if ((q = pr.findTreeNode(h, k, kc)) != null) {
return q;
}
else {
p = pl;
}
}
while (p != null);
}
return null;
}
}
/* ---------------- TreeBins -------------- */
/**
* TreeNodes used at the heads of bins. TreeBins do not hold user
* keys or values, but instead point to list of TreeNodes and
* their root. They also maintain a parasitic read-write lock
* forcing writers (who hold bin lock) to wait for readers (who do
* not) to complete before tree restructuring operations.
*/
private static final class TreeBin<K, V> extends Node<K, V> {
private TreeNode<K, V> root;
private volatile TreeNode<K, V> first;
private volatile Thread waiter;
private volatile int lockState;
// values for lockState
private static final int WRITER = 1; // set while holding write lock
private static final int WAITER = 2; // set when waiting for write lock
private static final int READER = 4; // increment value for setting read lock
/**
* Tie-breaking utility for ordering insertions when equal
* hashCodes and non-comparable. We don't require a total
* order, just a consistent insertion rule to maintain
* equivalence across rebalancings. Tie-breaking further than
* necessary simplifies testing a bit.
*/
private static int tieBreakOrder(Object a, Object b) {
int d;
if (a == null || b == null ||
(d = a.getClass().getName().
compareTo(b.getClass().getName())) == 0) {
d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
-1 : 1);
}
return d;
}
/**
* Creates bin with initial set of nodes headed by b.
*/
private TreeBin(TreeNode<K, V> b, TObjectHashingStrategy<K> hashingStrategy) {
super(TREEBIN, null, null, null, hashingStrategy);
this.first = b;
TreeNode<K, V> r = null;
for (TreeNode<K, V> x = b, next; x != null; x = next) {
next = (TreeNode<K, V>)x.next;
x.left = x.right = null;
if (r == null) {
x.parent = null;
x.red = false;
r = x;
}
else {
K k = x.key;
int h = x.hash;
Class<?> kc = null;
for (TreeNode<K, V> p = r; ; ) {
int dir, ph;
K pk = p.key;
if ((ph = p.hash) > h) {
dir = -1;
}
else if (ph < h) {
dir = 1;
}
else if ((kc == null &&
(kc = comparableClassFor(k)) == null) ||
(dir = compareComparables(kc, k, pk)) == 0) {
dir = tieBreakOrder(k, pk);
}
TreeNode<K, V> xp = p;
if ((p = (dir <= 0) ? p.left : p.right) == null) {
x.parent = xp;
if (dir <= 0) {
xp.left = x;
}
else {
xp.right = x;
}
r = balanceInsertion(r, x);
break;
}
}
}
}
this.root = r;
assert checkInvariants(root);
}
/**
* Acquires write lock for tree restructuring.
*/
private void lockRoot() {
if (!U.compareAndSwapInt(this, LOCKSTATE, 0, WRITER)) {
contendedLock(); // offload to separate method
}
}
/**
* Releases write lock for tree restructuring.
*/
private void unlockRoot() {
lockState = 0;
}
/**
* Possibly blocks awaiting root lock.
*/
private void contendedLock() {
boolean waiting = false;
for (int s; ; ) {
if (((s = lockState) & ~WAITER) == 0) {
if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) {
if (waiting) {
waiter = null;
}
return;
}
}
else if ((s & WAITER) == 0) {
if (U.compareAndSwapInt(this, LOCKSTATE, s, s | WAITER)) {
waiting = true;
waiter = Thread.currentThread();
}
}
else if (waiting) {
LockSupport.park(this);
}
}
}
/**
* Returns matching node or null if none. Tries to search
* using tree comparisons from root, but continues linear
* search when lock not available.
*/
@Override
final Node<K, V> find(int h, Object k) {
if (k != null) {
for (Node<K, V> e = first; e != null; ) {
int s;
if (((s = lockState) & (WAITER | WRITER)) != 0) {
if (e.hash == h &&
isEqual((K)k, e.key, myHashingStrategy)) {
return e;
}
e = e.next;
}
else if (U.compareAndSwapInt(this, LOCKSTATE, s,
s + READER)) {
TreeNode<K, V> r, p;
try {
p = ((r = root) == null ? null :
r.findTreeNode(h, k, null));
}
finally {
int ls;
do {
}
while (!U.compareAndSwapInt
(this, LOCKSTATE,
ls = lockState, ls - READER));
Thread w;
if (ls == (READER | WAITER) && (w = waiter) != null) {
LockSupport.unpark(w);
}
}
return p;
}
}
}
return null;
}
/**
* Finds or adds a node.
*
* @return null if added
*/
private TreeNode<K, V> putTreeVal(int h, K k, V v) {
Class<?> kc = null;
boolean searched = false;
for (TreeNode<K, V> p = root; ; ) {
int dir, ph;
if (p == null) {
first = root = new TreeNode<K, V>(h, k, v, null, null, myHashingStrategy);
break;
}
K pk = p.key;
if ((ph = p.hash) > h) {
dir = -1;
}
else if (ph < h) {
dir = 1;
}
else if (isEqual(k, pk, myHashingStrategy)) {
return p;
}
else if ((kc == null &&
(kc = comparableClassFor(k)) == null) ||
(dir = compareComparables(kc, k, pk)) == 0) {
if (!searched) {
TreeNode<K, V> q, ch;
searched = true;
if (((ch = p.left) != null &&
(q = ch.findTreeNode(h, k, kc)) != null) ||
((ch = p.right) != null &&
(q = ch.findTreeNode(h, k, kc)) != null)) {
return q;
}
}
dir = tieBreakOrder(k, pk);
}
TreeNode<K, V> xp = p;
if ((p = (dir <= 0) ? p.left : p.right) == null) {
TreeNode<K, V> x, f = first;
first = x = new TreeNode<K, V>(h, k, v, f, xp, myHashingStrategy);
if (f != null) {
f.prev = x;
}
if (dir <= 0) {
xp.left = x;
}
else {
xp.right = x;
}
if (!xp.red) {
x.red = true;
}
else {
lockRoot();
try {
root = balanceInsertion(root, x);
}
finally {
unlockRoot();
}
}
break;
}
}
assert checkInvariants(root);
return null;
}
/**
* Removes the given node, that must be present before this
* call. This is messier than typical red-black deletion code
* because we cannot swap the contents of an interior node
* with a leaf successor that is pinned by "next" pointers
* that are accessible independently of lock. So instead we
* swap the tree linkages.
*
* @return true if now too small, so should be untreeified
*/
private boolean removeTreeNode(TreeNode<K, V> p) {
TreeNode<K, V> next = (TreeNode<K, V>)p.next;
TreeNode<K, V> pred = p.prev; // unlink traversal pointers
TreeNode<K, V> r, rl;
if (pred == null) {
first = next;
}
else {
pred.next = next;
}
if (next != null) {
next.prev = pred;
}
if (first == null) {
root = null;
return true;
}
if ((r = root) == null || r.right == null || // too small
(rl = r.left) == null || rl.left == null) {
return true;
}
lockRoot();
try {
TreeNode<K, V> replacement;
TreeNode<K, V> pl = p.left;
TreeNode<K, V> pr = p.right;
if (pl != null && pr != null) {
TreeNode<K, V> s = pr, sl;
while ((sl = s.left) != null) // find successor
{
s = sl;
}
boolean c = s.red;
s.red = p.red;
p.red = c; // swap colors
TreeNode<K, V> sr = s.right;
TreeNode<K, V> pp = p.parent;
if (s == pr) { // p was s's direct parent
p.parent = s;
s.right = p;
}
else {
TreeNode<K, V> sp = s.parent;
if ((p.parent = sp) != null) {
if (s == sp.left) {
sp.left = p;
}
else {
sp.right = p;
}
}
if ((s.right = pr) != null) {
pr.parent = s;
}
}
p.left = null;
if ((p.right = sr) != null) {
sr.parent = p;
}
if ((s.left = pl) != null) {
pl.parent = s;
}
if ((s.parent = pp) == null) {
r = s;
}
else if (p == pp.left) {
pp.left = s;
}
else {
pp.right = s;
}
if (sr != null) {
replacement = sr;
}
else {
replacement = p;
}
}
else if (pl != null) {
replacement = pl;
}
else if (pr != null) {
replacement = pr;
}
else {
replacement = p;
}
if (replacement != p) {
TreeNode<K, V> pp = replacement.parent = p.parent;
if (pp == null) {
r = replacement;
}
else if (p == pp.left) {
pp.left = replacement;
}
else {
pp.right = replacement;
}
p.left = p.right = p.parent = null;
}
root = (p.red) ? r : balanceDeletion(r, replacement);
if (p == replacement) { // detach pointers
TreeNode<K, V> pp;
if ((pp = p.parent) != null) {
if (p == pp.left) {
pp.left = null;
}
else if (p == pp.right) {
pp.right = null;
}
p.parent = null;
}
}
}
finally {
unlockRoot();
}
assert checkInvariants(root);
return false;
}
/* ------------------------------------------------------------ */
// Red-black tree methods, all adapted from CLR
private static <K, V> TreeNode<K, V> rotateLeft(TreeNode<K, V> root,
TreeNode<K, V> p) {
TreeNode<K, V> r, pp, rl;
if (p != null && (r = p.right) != null) {
if ((rl = p.right = r.left) != null) {
rl.parent = p;
}
if ((pp = r.parent = p.parent) == null) {
(root = r).red = false;
}
else if (pp.left == p) {
pp.left = r;
}
else {
pp.right = r;
}
r.left = p;
p.parent = r;
}
return root;
}
private static <K, V> TreeNode<K, V> rotateRight(TreeNode<K, V> root,
TreeNode<K, V> p) {
TreeNode<K, V> l, pp, lr;
if (p != null && (l = p.left) != null) {
if ((lr = p.left = l.right) != null) {
lr.parent = p;
}
if ((pp = l.parent = p.parent) == null) {
(root = l).red = false;
}
else if (pp.right == p) {
pp.right = l;
}
else {
pp.left = l;
}
l.right = p;
p.parent = l;
}
return root;
}
private static <K, V> TreeNode<K, V> balanceInsertion(TreeNode<K, V> root,
TreeNode<K, V> x) {
x.red = true;
for (TreeNode<K, V> xp, xpp, xppl, xppr; ; ) {
if ((xp = x.parent) == null) {
x.red = false;
return x;
}
else if (!xp.red || (xpp = xp.parent) == null) {
return root;
}
if (xp == (xppl = xpp.left)) {
if ((xppr = xpp.right) != null && xppr.red) {
xppr.red = false;
xp.red = false;
xpp.red = true;
x = xpp;
}
else {
if (x == xp.right) {
root = rotateLeft(root, x = xp);
xpp = (xp = x.parent) == null ? null : xp.parent;
}
if (xp != null) {
xp.red = false;
if (xpp != null) {
xpp.red = true;
root = rotateRight(root, xpp);
}
}
}
}
else {
if (xppl != null && xppl.red) {
xppl.red = false;
xp.red = false;
xpp.red = true;
x = xpp;
}
else {
if (x == xp.left) {
root = rotateRight(root, x = xp);
xpp = (xp = x.parent) == null ? null : xp.parent;
}
if (xp != null) {
xp.red = false;
if (xpp != null) {
xpp.red = true;
root = rotateLeft(root, xpp);
}
}
}
}
}
}
private static <K, V> TreeNode<K, V> balanceDeletion(TreeNode<K, V> root,
TreeNode<K, V> x) {
for (TreeNode<K, V> xp, xpl, xpr; ; ) {
if (x == null || x == root) {
return root;
}
else if ((xp = x.parent) == null) {
x.red = false;
return x;
}
else if (x.red) {
x.red = false;
return root;
}
else if ((xpl = xp.left) == x) {
if ((xpr = xp.right) != null && xpr.red) {
xpr.red = false;
xp.red = true;
root = rotateLeft(root, xp);
xpr = (xp = x.parent) == null ? null : xp.right;
}
if (xpr == null) {
x = xp;
}
else {
TreeNode<K, V> sl = xpr.left, sr = xpr.right;
if ((sr == null || !sr.red) &&
(sl == null || !sl.red)) {
xpr.red = true;
x = xp;
}
else {
if (sr == null || !sr.red) {
if (sl != null) {
sl.red = false;
}
xpr.red = true;
root = rotateRight(root, xpr);
xpr = (xp = x.parent) == null ?
null : xp.right;
}
if (xpr != null) {
xpr.red = (xp == null) ? false : xp.red;
if ((sr = xpr.right) != null) {
sr.red = false;
}
}
if (xp != null) {
xp.red = false;
root = rotateLeft(root, xp);
}
x = root;
}
}
}
else { // symmetric
if (xpl != null && xpl.red) {
xpl.red = false;
xp.red = true;
root = rotateRight(root, xp);
xpl = (xp = x.parent) == null ? null : xp.left;
}
if (xpl == null) {
x = xp;
}
else {
TreeNode<K, V> sl = xpl.left, sr = xpl.right;
if ((sl == null || !sl.red) &&
(sr == null || !sr.red)) {
xpl.red = true;
x = xp;
}
else {
if (sl == null || !sl.red) {
if (sr != null) {
sr.red = false;
}
xpl.red = true;
root = rotateLeft(root, xpl);
xpl = (xp = x.parent) == null ?
null : xp.left;
}
if (xpl != null) {
xpl.red = (xp == null) ? false : xp.red;
if ((sl = xpl.left) != null) {
sl.red = false;
}
}
if (xp != null) {
xp.red = false;
root = rotateRight(root, xp);
}
x = root;
}
}
}
}
}
/**
* Recursive invariant check
*/
private static <K, V> boolean checkInvariants(TreeNode<K, V> t) {
TreeNode<K, V> tp = t.parent, tl = t.left, tr = t.right,
tb = t.prev, tn = (TreeNode<K, V>)t.next;
if (tb != null && tb.next != t) {
return false;
}
if (tn != null && tn.prev != t) {
return false;
}
if (tp != null && t != tp.left && t != tp.right) {
return false;
}
if (tl != null && (tl.parent != t || tl.hash > t.hash)) {
return false;
}
if (tr != null && (tr.parent != t || tr.hash < t.hash)) {
return false;
}
if (t.red && tl != null && tl.red && tr != null && tr.red) {
return false;
}
if (tl != null && !checkInvariants(tl)) {
return false;
}
if (tr != null && !checkInvariants(tr)) {
return false;
}
return true;
}
private static final Unsafe U;
private static final long LOCKSTATE;
static {
try {
U = AtomicFieldUpdater.getUnsafe();
Class<?> k = TreeBin.class;
LOCKSTATE = U.objectFieldOffset
(k.getDeclaredField("lockState"));
}
catch (Exception e) {
throw new Error(e);
}
}
}
/* ----------------Table Traversal -------------- */
/**
* Records the table, its length, and current traversal index for a
* traverser that must process a region of a forwarded table before
* proceeding with current table.
*/
private static final class TableStack<K, V> {
private int length;
private int index;
private Node<K, V>[] tab;
private TableStack<K, V> next;
}
/**
* Encapsulates traversal for methods such as containsValue; also
* serves as a base class for other iterators and spliterators.
* <p/>
* Method advance visits once each still-valid node that was
* reachable upon iterator construction. It might miss some that
* were added to a bin after the bin was visited, which is OK wrt
* consistency guarantees. Maintaining this property in the face
* of possible ongoing resizes requires a fair amount of
* bookkeeping state that is difficult to optimize away amidst
* volatile accesses. Even so, traversal maintains reasonable
* throughput.
* <p/>
* Normally, iteration proceeds bin-by-bin traversing lists.
* However, if the table has been resized, then all future steps
* must traverse both the bin at the current index as well as at
* (index + baseSize); and so on for further resizings. To
* paranoically cope with potential sharing by users of iterators
* across threads, iteration terminates if a bounds checks fails
* for a table read.
*/
private static class Traverser<K, V> {
private Node<K, V>[] tab; // current table; updated if resized
Node<K, V> next; // the next entry to use
private TableStack<K, V> stack, spare; // to save/restore on ForwardingNodes
private int index; // index of bin to use next
private int baseIndex; // current index of initial table
private final int baseLimit; // index bound for initial table
private final int baseSize; // initial table size
private Traverser(Node<K, V>[] tab, int size, int index, int limit) {
this.tab = tab;
this.baseSize = size;
this.baseIndex = this.index = index;
this.baseLimit = limit;
this.next = null;
}
/**
* Advances if possible, returning next valid node, or null if none.
*/
final Node<K, V> advance() {
Node<K, V> e;
if ((e = next) != null) {
e = e.next;
}
for (; ; ) {
Node<K, V>[] t;
int i, n; // must use locals in checks
if (e != null) {
return next = e;
}
if (baseIndex >= baseLimit || (t = tab) == null ||
(n = t.length) <= (i = index) || i < 0) {
return next = null;
}
if ((e = tabAt(t, i)) != null && e.hash < 0) {
if (e instanceof ForwardingNode) {
tab = ((ForwardingNode<K, V>)e).nextTable;
e = null;
pushState(t, i, n);
continue;
}
else if (e instanceof TreeBin) {
e = ((TreeBin<K, V>)e).first;
}
else {
e = null;
}
}
if (stack != null) {
recoverState(n);
}
else if ((index = i + baseSize) >= n) {
index = ++baseIndex; // visit upper slots if present
}
}
}
/**
* Saves traversal state upon encountering a forwarding node.
*/
private void pushState(Node<K, V>[] t, int i, int n) {
TableStack<K, V> s = spare; // reuse if possible
if (s != null) {
spare = s.next;
}
else {
s = new TableStack<K, V>();
}
s.tab = t;
s.length = n;
s.index = i;
s.next = stack;
stack = s;
}
/**
* Possibly pops traversal state.
*
* @param n length of current table
*/
private void recoverState(int n) {
TableStack<K, V> s;
int len;
while ((s = stack) != null && (index += (len = s.length)) >= n) {
n = len;
index = s.index;
tab = s.tab;
s.tab = null;
TableStack<K, V> next = s.next;
s.next = spare; // save for reuse
stack = next;
spare = s;
}
if (s == null && (index += baseSize) >= n) {
index = ++baseIndex;
}
}
}
/**
* Base of key, value, and entry Iterators. Adds fields to
* Traverser to support iterator.remove.
*/
private static class BaseIterator<K, V> extends Traverser<K, V> {
final ConcurrentHashMap<K, V> map;
Node<K, V> lastReturned;
private BaseIterator(Node<K, V>[] tab, int size, int index, int limit,
ConcurrentHashMap<K, V> map) {
super(tab, size, index, limit);
this.map = map;
advance();
}
public final boolean hasNext() {
return next != null;
}
public final boolean hasMoreElements() {
return next != null;
}
public final void remove() {
Node<K, V> p;
if ((p = lastReturned) == null) {
throw new IllegalStateException();
}
lastReturned = null;
map.replaceNode(p.key, null, null);
}
}
private static final class KeyIterator<K, V> extends BaseIterator<K, V>
implements Iterator<K>, Enumeration<K> {
KeyIterator(Node<K, V>[] tab, int index, int size, int limit,
ConcurrentHashMap<K, V> map) {
super(tab, index, size, limit, map);
}
@Override
public final K next() {
Node<K, V> p;
if ((p = next) == null) {
throw new NoSuchElementException();
}
K k = p.key;
lastReturned = p;
advance();
return k;
}
@Override
public final K nextElement() {
return next();
}
}
private static final class ValueIterator<K, V> extends BaseIterator<K, V>
implements Iterator<V>, Enumeration<V> {
ValueIterator(Node<K, V>[] tab, int index, int size, int limit,
ConcurrentHashMap<K, V> map) {
super(tab, index, size, limit, map);
}
@Override
public final V next() {
Node<K, V> p;
if ((p = next) == null) {
throw new NoSuchElementException();
}
V v = p.val;
lastReturned = p;
advance();
return v;
}
@Override
public final V nextElement() {
return next();
}
}
private static final class EntryIterator<K, V> extends BaseIterator<K, V>
implements Iterator<Map.Entry<K, V>> {
EntryIterator(Node<K, V>[] tab, int index, int size, int limit,
ConcurrentHashMap<K, V> map) {
super(tab, index, size, limit, map);
}
@Override
public final Map.Entry<K, V> next() {
Node<K, V> p;
if ((p = next) == null) {
throw new NoSuchElementException();
}
K k = p.key;
V v = p.val;
lastReturned = p;
advance();
return new MapEntry<K, V>(k, v, map);
}
}
/**
* Exported Entry for EntryIterator
*/
private static final class MapEntry<K, V> implements Map.Entry<K, V> {
private final K key; // non-null
private V val; // non-null
private final ConcurrentHashMap<K, V> map;
MapEntry(K key, V val, ConcurrentHashMap<K, V> map) {
this.key = key;
this.val = val;
this.map = map;
}
@Override
public K getKey() {
return key;
}
@Override
public V getValue() {
return val;
}
@Override
public int hashCode() {
return map.hash((K)key) ^ val.hashCode();
}
@Override
public String toString() {
return key + "=" + val;
}
@Override
public boolean equals(Object o) {
Object k, v;
Map.Entry<?, ?> e;
return ((o instanceof Map.Entry) &&
(k = (e = (Map.Entry<?, ?>)o).getKey()) != null &&
(v = e.getValue()) != null &&
(map.isEqual((K)k, key)) &&
(v == val || v.equals(val)));
}
/**
* Sets our entry's value and writes through to the map. The
* value to return is somewhat arbitrary here. Since we do not
* necessarily track asynchronous changes, the most recent
* "previous" value could be different from what we return (or
* could even have been removed, in which case the put will
* re-establish). We do not and cannot guarantee more.
*/
@Override
public V setValue(@NotNull V value) {
V v = val;
val = value;
map.put(key, value);
return v;
}
}
/* ----------------Views -------------- */
/**
* Base class for views.
*/
private abstract static class CollectionView<K, V, E>
implements Collection<E> {
final ConcurrentHashMap<K, V> map;
CollectionView(@NotNull ConcurrentHashMap<K, V> map) {
this.map = map;
}
/**
* Returns the map backing this view.
*
* @return the map backing this view
*/
public ConcurrentHashMap<K, V> getMap() {
return map;
}
/**
* Removes all of the elements from this view, by removing all
* the mappings from the map backing this view.
*/
@Override
public final void clear() {
map.clear();
}
@Override
public final int size() {
return map.size();
}
@Override
public final boolean isEmpty() {
return map.isEmpty();
}
// implementations below rely on concrete classes supplying these
// abstract methods
/**
* Returns an iterator over the elements in this collection.
* <p/>
* <p>The returned iterator is
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
*
* @return an iterator over the elements in this collection
*/
@Override
public abstract Iterator<E> iterator();
@Override
public abstract boolean contains(Object o);
@Override
public abstract boolean remove(Object o);
private static final String oomeMsg = "Required array size too large";
@NotNull
@Override
public final Object[] toArray() {
long sz = map.mappingCount();
if (sz > MAX_ARRAY_SIZE) {
throw new OutOfMemoryError(oomeMsg);
}
int n = (int)sz;
Object[] r = new Object[n];
int i = 0;
for (E e : this) {
if (i == n) {
if (n >= MAX_ARRAY_SIZE) {
throw new OutOfMemoryError(oomeMsg);
}
if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1) {
n = MAX_ARRAY_SIZE;
}
else {
n += (n >>> 1) + 1;
}
r = Arrays.copyOf(r, n);
}
r[i++] = e;
}
return (i == n) ? r : Arrays.copyOf(r, i);
}
@NotNull
@Override
@SuppressWarnings("unchecked")
public final <T> T[] toArray(@NotNull T[] a) {
long sz = map.mappingCount();
if (sz > MAX_ARRAY_SIZE) {
throw new OutOfMemoryError(oomeMsg);
}
int m = (int)sz;
T[] r = (a.length >= m) ? a :
(T[])java.lang.reflect.Array
.newInstance(a.getClass().getComponentType(), m);
int n = r.length;
int i = 0;
for (E e : this) {
if (i == n) {
if (n >= MAX_ARRAY_SIZE) {
throw new OutOfMemoryError(oomeMsg);
}
if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1) {
n = MAX_ARRAY_SIZE;
}
else {
n += (n >>> 1) + 1;
}
r = Arrays.copyOf(r, n);
}
r[i++] = (T)e;
}
if (a == r && i < n) {
r[i] = null; // null-terminate
return r;
}
return (i == n) ? r : Arrays.copyOf(r, i);
}
/**
* Returns a string representation of this collection.
* The string representation consists of the string representations
* of the collection's elements in the order they are returned by
* its iterator, enclosed in square brackets ({@code "[]"}).
* Adjacent elements are separated by the characters {@code ", "}
* (comma and space). Elements are converted to strings as by
* {@link String#valueOf(Object)}.
*
* @return a string representation of this collection
*/
@Override
public final String toString() {
StringBuilder sb = new StringBuilder();
sb.append('[');
Iterator<E> it = iterator();
if (it.hasNext()) {
for (; ; ) {
Object e = it.next();
sb.append(e == this ? "(this Collection)" : e);
if (!it.hasNext()) {
break;
}
sb.append(',').append(' ');
}
}
return sb.append(']').toString();
}
@Override
public final boolean containsAll(@NotNull Collection<?> c) {
if (c != this) {
for (Object e : c) {
if (e == null || !contains(e)) {
return false;
}
}
}
return true;
}
@Override
public final boolean removeAll(@NotNull Collection<?> c) {
boolean modified = false;
for (Iterator<E> it = iterator(); it.hasNext(); ) {
if (c.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
@Override
public final boolean retainAll(@NotNull Collection<?> c) {
boolean modified = false;
for (Iterator<E> it = iterator(); it.hasNext(); ) {
if (!c.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
}
/**
* A view of a ConcurrentHashMap as a {@link Set} of keys, in
* which additions may optionally be enabled by mapping to a
* common value. This class cannot be directly instantiated.
* See {@link #keySet() keySet()},
* @since 1.8
*/
private static class KeySetView<K, V> extends CollectionView<K, V, K>
implements Set<K> {
private final V value;
KeySetView(ConcurrentHashMap<K, V> map, V value) { // non-public
super(map);
this.value = value;
}
/**
* Returns the default mapped value for additions,
* or {@code null} if additions are not supported.
*
* @return the default mapped value for additions, or {@code null}
* if not supported
*/
public V getMappedValue() {
return value;
}
/**
* {@inheritDoc}
*
* @throws NullPointerException if the specified key is null
*/
@Override
public boolean contains(Object o) {
return map.containsKey(o);
}
/**
* Removes the key from this map view, by removing the key (and its
* corresponding value) from the backing map. This method does
* nothing if the key is not in the map.
*
* @param o the key to be removed from the backing map
* @return {@code true} if the backing map contained the specified key
* @throws NullPointerException if the specified key is null
*/
@Override
public boolean remove(Object o) {
return map.remove(o) != null;
}
/**
* @return an iterator over the keys of the backing map
*/
@NotNull
@Override
public Iterator<K> iterator() {
Node<K, V>[] t;
ConcurrentHashMap<K, V> m = map;
int f = (t = m.table) == null ? 0 : t.length;
return new KeyIterator<K, V>(t, f, 0, f, m);
}
/**
* Adds the specified key to this set view by mapping the key to
* the default mapped value in the backing map, if defined.
*
* @param e key to be added
* @return {@code true} if this set changed as a result of the call
* @throws NullPointerException if the specified key is null
* @throws UnsupportedOperationException if no default mapped value
* for additions was provided
*/
@Override
public boolean add(@NotNull K e) {
V v;
if ((v = value) == null) {
throw new UnsupportedOperationException();
}
return map.putVal(e, v, true) == null;
}
/**
* Adds all of the elements in the specified collection to this set,
* as if by calling {@link #add} on each one.
*
* @param c the elements to be inserted into this set
* @return {@code true} if this set changed as a result of the call
* @throws NullPointerException if the collection or any of its
* elements are {@code null}
* @throws UnsupportedOperationException if no default mapped value
* for additions was provided
*/
@Override
public boolean addAll(@NotNull Collection<? extends K> c) {
boolean added = false;
V v;
if ((v = value) == null) {
throw new UnsupportedOperationException();
}
for (K e : c) {
if (map.putVal(e, v, true) == null) {
added = true;
}
}
return added;
}
@Override
public int hashCode() {
int h = 0;
for (K e : this) {
h += map.hash(e);
}
return h;
}
@Override
public boolean equals(Object o) {
Set<?> c;
return ((o instanceof Set) &&
((c = (Set<?>)o) == this ||
(containsAll(c) && c.containsAll(this))));
}
}
/**
* A view of a ConcurrentHashMap as a {@link Collection} of
* values, in which additions are disabled. This class cannot be
* directly instantiated. See {@link #values()}.
*/
private static final class ValuesView<K, V> extends CollectionView<K, V, V>
implements Collection<V> {
ValuesView(ConcurrentHashMap<K, V> map) {
super(map);
}
@Override
public final boolean contains(Object o) {
return map.containsValue(o);
}
@Override
public final boolean remove(Object o) {
if (o != null) {
for (Iterator<V> it = iterator(); it.hasNext(); ) {
if (o.equals(it.next())) {
it.remove();
return true;
}
}
}
return false;
}
@NotNull
@Override
public final Iterator<V> iterator() {
ConcurrentHashMap<K, V> m = map;
Node<K, V>[] t;
int f = (t = m.table) == null ? 0 : t.length;
return new ValueIterator<K, V>(t, f, 0, f, m);
}
@Override
public final boolean add(V e) {
throw new UnsupportedOperationException();
}
@Override
public final boolean addAll(@NotNull Collection<? extends V> c) {
throw new UnsupportedOperationException();
}
}
/**
* A view of a ConcurrentHashMap as a {@link Set} of (key, value)
* entries. This class cannot be directly instantiated. See
* {@link #entrySet()}.
*/
private static final class EntrySetView<K, V> extends CollectionView<K, V, Map.Entry<K, V>>
implements Set<Map.Entry<K, V>> {
private EntrySetView(ConcurrentHashMap<K, V> map) {
super(map);
}
@Override
public boolean contains(Object o) {
Object k, v, r;
Map.Entry<?, ?> e;
return ((o instanceof Map.Entry) &&
(k = (e = (Map.Entry<?, ?>)o).getKey()) != null &&
(r = map.get(k)) != null &&
(v = e.getValue()) != null &&
(v == r || v.equals(r)));
}
@Override
public boolean remove(Object o) {
Object k, v;
Map.Entry<?, ?> e;
return ((o instanceof Map.Entry) &&
(k = (e = (Map.Entry<?, ?>)o).getKey()) != null &&
(v = e.getValue()) != null &&
map.remove(k, v));
}
/**
* @return an iterator over the entries of the backing map
*/
@NotNull
@Override
public Iterator<Map.Entry<K, V>> iterator() {
ConcurrentHashMap<K, V> m = map;
Node<K, V>[] t;
int f = (t = m.table) == null ? 0 : t.length;
return new EntryIterator<K, V>(t, f, 0, f, m);
}
@Override
public boolean add(Entry<K, V> e) {
return map.putVal(e.getKey(), e.getValue(), false) == null;
}
@Override
public boolean addAll(@NotNull Collection<? extends Entry<K, V>> c) {
boolean added = false;
for (Entry<K, V> e : c) {
if (add(e)) {
added = true;
}
}
return added;
}
@Override
public final int hashCode() {
int h = 0;
Node<K, V>[] t;
if ((t = map.table) != null) {
Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
for (Node<K, V> p; (p = it.advance()) != null; ) {
h += p.hashCode();
}
}
return h;
}
@Override
public final boolean equals(Object o) {
Set<?> c;
return ((o instanceof Set) &&
((c = (Set<?>)o) == this ||
(containsAll(c) && c.containsAll(this))));
}
}
// -------------------------------------------------------
// Unsafe mechanics
private static final Unsafe U;
private static final long SIZECTL;
private static final long TRANSFERINDEX;
private static final long BASECOUNT;
private static final long CELLSBUSY;
private static final long CELLVALUE;
private static final long ABASE;
private static final int ASHIFT;
static {
try {
U = AtomicFieldUpdater.getUnsafe();
Class<?> k = ConcurrentHashMap.class;
SIZECTL = U.objectFieldOffset
(k.getDeclaredField("sizeCtl"));
TRANSFERINDEX = U.objectFieldOffset
(k.getDeclaredField("transferIndex"));
BASECOUNT = U.objectFieldOffset
(k.getDeclaredField("baseCount"));
CELLSBUSY = U.objectFieldOffset
(k.getDeclaredField("cellsBusy"));
Class<?> ck = CounterCell.class;
CELLVALUE = U.objectFieldOffset
(ck.getDeclaredField("value"));
Class<?> ak = Node[].class;
ABASE = U.arrayBaseOffset(ak);
int scale = U.arrayIndexScale(ak);
if ((scale & (scale - 1)) != 0) {
throw new Error("data type scale not a power of two");
}
ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
}
catch (Exception e) {
throw new Error(e);
}
}
//////////////// IJ specific
@Override
public int computeHashCode(final K object) {
return object == null ? 0 : object.hashCode();
}
@Override
public boolean equals(final K o1, final K o2) {
return o1.equals(o2);
}
private int hash(K key) {
return spread(myHashingStrategy.computeHashCode(key));
}
private boolean isEqual(@NotNull K key1, K key2) {
return isEqual(key1, key2, myHashingStrategy);
}
private static <K> boolean isEqual(@NotNull K key1, K key2, @NotNull TObjectHashingStrategy<K> hashingStrategy) {
return key1 == key2 || key2 != null && hashingStrategy.equals(key1, key2);
}
}