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/*******************************************************************************
* ___ _ ____ ____
* / _ \ _ _ ___ ___| |_| _ \| __ )
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* \__\_\\__,_|\___||___/\__|____/|____/
*
* Copyright (c) 2014-2019 Appsicle
* Copyright (c) 2019-2024 QuestDB
*
* 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.
*
******************************************************************************/
package io.questdb.std;
/*
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
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*
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/*
*
*
*
*
*
* 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/
*/
import org.jetbrains.annotations.NotNull;
import java.io.ObjectStreamField;
import java.io.Serializable;
import java.lang.ThreadLocal;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.LockSupport;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.LongFunction;
/**
* Same as {@link ConcurrentHashMap}, but with primitive type long keys.
*/
@SuppressWarnings("SynchronizationOnLocalVariableOrMethodParameter")
public class ConcurrentLongHashMap implements Serializable {
static final long EMPTY_KEY = Long.MIN_VALUE;
/*
* 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 referring 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 -------------- */
static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
/**
* The largest possible (non-power of two) array size.
* Needed by toArray and related methods.
*/
static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* 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.
*/
static final int MIN_TREEIFY_CAPACITY = 64;
/*
* Encodings for Node hash fields. See above for explanation.
*/
static final int MOVED = -1; // hash for forwarding nodes
/**
* Number of CPUS, to place bounds on some sizings
*/
static final int NCPU = Runtime.getRuntime().availableProcessors();
static final int RESERVED = -3; // hash for transient reservations
static final int TREEBIN = -2; // hash for roots of trees
/**
* 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.
*/
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.
*/
static final int UNTREEIFY_THRESHOLD = 6;
/* ---------------- Fields -------------- */
private static final long ABASE;
private static final int ASHIFT;
/*
* 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.
*/
private static final long BASECOUNT;
private static final long CELLSBUSY;
private static final long CELLVALUE;
/**
* The default initial table capacity. Must be a power of 2
* (i.e., at least 1) and at most MAXIMUM_CAPACITY.
*/
private static final int DEFAULT_CAPACITY = 16;
/**
* 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.
*/
private static final float LOAD_FACTOR = 0.75f;
/**
* 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;
/**
* 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;
private static final long PROBE;
/* ---------------- Nodes -------------- */
/**
* The increment for generating probe values
*/
private static final int PROBE_INCREMENT = 0x9e3779b9;
/* ---------------- Static utilities -------------- */
/**
* 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;
private static final long SEED;
/* ---------------- Table element access -------------- */
/**
* The increment of seeder per new instance
*/
private static final long SEEDER_INCREMENT = 0xbb67ae8584caa73bL;
private static final long SIZECTL;
private static final long TRANSFERINDEX;
/**
* Generates per-thread initialization/probe field
*/
private static final AtomicInteger probeGenerator = new AtomicInteger();
/**
* The next seed for default constructors.
*/
private static final AtomicLong seeder = new AtomicLong(initialSeed());
/**
* For serialization compatibility.
*/
private static final ObjectStreamField[] serialPersistentFields = {
new ObjectStreamField("segments", Segment[].class),
new ObjectStreamField("segmentMask", Integer.TYPE),
new ObjectStreamField("segmentShift", Integer.TYPE)
};
private static final long serialVersionUID = 7249069246763182397L;
private final java.lang.ThreadLocal> tlTraverser = ThreadLocal.withInitial(Traverser::new);
/**
* The array of bins. Lazily initialized upon first insertion.
* Size is always a power of two. Accessed directly by iterators.
*/
transient volatile Node[] table;
/**
* 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;
/**
* 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;
// Original (since JDK1.2) Map methods
private transient EntrySetView entrySet;
/* ---------------- Public operations -------------- */
// views
private transient KeySetView keySet;
/**
* The next table to use; non-null only while resizing.
*/
private transient volatile Node[] nextTable;
/**
* 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;
private transient ValuesView values;
/**
* 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
* @throws IllegalArgumentException if the initial capacity is
* negative or the load factor or concurrencyLevel are
* nonpositive
*/
public ConcurrentLongHashMap(int initialCapacity, float loadFactor) {
if (!(loadFactor > 0.0f) || initialCapacity < 0)
throw new IllegalArgumentException();
if (initialCapacity < 1) // Use at least as many bins
initialCapacity = 1; // as estimated threads
long size = (long) (1.0 + (long) initialCapacity / loadFactor);
this.sizeCtl = (size >= (long) MAXIMUM_CAPACITY) ?
MAXIMUM_CAPACITY : tableSizeFor((int) size);
}
/**
* Creates a new map with the same mappings as the given map.
*
* @param m the map
*/
public ConcurrentLongHashMap(ConcurrentLongHashMap m) {
this.sizeCtl = DEFAULT_CAPACITY;
putAll(m);
}
/**
* Creates a new, empty map with the default initial table size (16).
*/
public ConcurrentLongHashMap() {
}
/**
* 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 ConcurrentLongHashMap(int initialCapacity) {
if (initialCapacity < 0)
throw new IllegalArgumentException();
this.sizeCtl = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ?
MAXIMUM_CAPACITY :
tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
}
/**
* Creates a new {@link Set} backed by a ConcurrentLongHashMap
* from the given type to {@code Boolean.TRUE}.
*
* @return the new set
* @since 1.8
*/
public static KeySetView newKeySet() {
return new KeySetView<>(new ConcurrentLongHashMap<>(), Boolean.TRUE);
}
/**
* Creates a new {@link Set} backed by a ConcurrentLongHashMap
* from the given type to {@code Boolean.TRUE}.
*
* @param initialCapacity The implementation performs internal
* sizing to accommodate this many elements.
* @return the new set
* @throws IllegalArgumentException if the initial capacity of
* elements is negative
* @since 1.8
*/
public static KeySetView newKeySet(int initialCapacity) {
return new KeySetView<>(new ConcurrentLongHashMap<>(initialCapacity), Boolean.TRUE);
}
/**
* Removes all of the mappings from this map.
*/
public void clear() {
long delta = 0L; // negative number of deletions
int i = 0;
Node[] tab = table;
while (tab != null && i < tab.length) {
int fh;
Node f = tabAt(tab, i);
if (f == null)
++i;
else if ((fh = f.hash) == MOVED) {
tab = helpTransfer(tab, f);
i = 0; // restart
} else {
synchronized (f) {
if (tabAt(tab, i) == f) {
Node p = (fh >= 0 ? f :
(f instanceof TreeBin) ?
((TreeBin) f).first : null);
while (p != null) {
--delta;
p = p.next;
}
setTabAt(tab, i++, null);
}
}
}
}
if (delta != 0L)
addCount(delta, -1);
}
/**
* Attempts to compute a mapping for the specified key and its
* current mapped value (or {@code null} if there is no current
* mapping). The entire method invocation is performed atomically.
* Some attempted update operations on this map by other threads
* may be blocked while computation is in progress, so the
* computation should be short and simple, and must not attempt to
* update any other mappings of this Map.
*
* @param key key with which the specified value is to be associated
* @param remappingFunction the function to compute a value
* @return the new value associated with the specified key, or null if none
* @throws IllegalArgumentException if the specified key is negative
* @throws NullPointerException if the specified remappingFunction is null
* @throws IllegalStateException if the computation detectably
* attempts a recursive update to this map that would
* otherwise never complete
* @throws RuntimeException or Error if the remappingFunction does so,
* in which case the mapping is unchanged
*/
public V compute(long key, BiLongFunction remappingFunction) {
if (key < 0)
throw new IllegalArgumentException();
if (remappingFunction == null)
throw new NullPointerException();
int h = spread(keyHashCode(key));
V val = null;
int delta = 0;
int binCount = 0;
for (Node[] tab = table; ; ) {
Node f;
int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
Node r = new ReservationNode<>();
synchronized (r) {
if (casTabAt(tab, i, r)) {
binCount = 1;
Node node = null;
try {
if ((val = remappingFunction.apply(key, null)) != null) {
delta = 1;
node = new Node<>(h, key, val, null);
}
} finally {
setTabAt(tab, i, node);
}
}
}
if (binCount != 0)
break;
} else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node e = f, pred = null; ; ++binCount) {
if (e.hash == h && (e.key == key)) {
val = remappingFunction.apply(key, e.val);
if (val != null)
e.val = val;
else {
delta = -1;
Node en = e.next;
if (pred != null)
pred.next = en;
else
setTabAt(tab, i, en);
}
break;
}
pred = e;
if ((e = e.next) == null) {
val = remappingFunction.apply(key, null);
if (val != null) {
delta = 1;
pred.next = new Node<>(h, key, val, null);
}
break;
}
}
} else if (f instanceof TreeBin) {
binCount = 1;
TreeBin t = (TreeBin) f;
TreeNode r, p;
if ((r = t.root) != null)
p = r.findTreeNode(h, key);
else
p = null;
V pv = (p == null) ? null : p.val;
val = remappingFunction.apply(key, pv);
if (val != null) {
if (p != null)
p.val = val;
else {
delta = 1;
t.putTreeVal(h, key, val);
}
} else if (p != null) {
delta = -1;
if (t.removeTreeNode(p))
setTabAt(tab, i, untreeify(t.first));
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD)
treeifyBin(tab, i);
break;
}
}
}
if (delta != 0)
addCount(delta, binCount);
return val;
}
/**
* If the specified key is not already associated with a value,
* attempts to compute its value using the given mapping function
* and enters it into this map unless {@code null}. The entire
* method invocation is performed atomically, so the function is
* applied at most once per key. Some attempted update operations
* on this map by other threads may be blocked while computation
* is in progress, so the computation should be short and simple,
* and must not attempt to update any other mappings of this map.
*
* @param key key with which the specified value is to be associated
* @param token token to pass to the mapping function
* @param mappingFunction the function to compute a value
* @return the current (existing or computed) value associated with
* the specified key, or null if the computed value is null
* @throws IllegalArgumentException if the specified key is negative
* @throws NullPointerException if the specified mappingFunction is null
* @throws IllegalStateException if the computation detectably
* attempts a recursive update to this map that would
* otherwise never complete
* @throws RuntimeException or Error if the mappingFunction does so,
* in which case the mapping is left unestablished
*/
public V computeIfAbsent(long key, Object token, BiLongFunction mappingFunction) {
if (key < 0)
throw new IllegalArgumentException();
if (mappingFunction == null)
throw new NullPointerException();
int h = spread(keyHashCode(key));
V val = null;
int binCount = 0;
for (Node[] tab = table; ; ) {
Node f;
int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
Node r = new ReservationNode<>();
synchronized (r) {
if (casTabAt(tab, i, r)) {
binCount = 1;
Node node = null;
try {
if ((val = mappingFunction.apply(key, token)) != null)
node = new Node<>(h, key, val, null);
} finally {
setTabAt(tab, i, node);
}
}
}
if (binCount != 0)
break;
} else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
boolean added = false;
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node e = f; ; ++binCount) {
if (e.hash == h && e.key == key) {
val = e.val;
break;
}
Node pred = e;
if ((e = e.next) == null) {
if ((val = mappingFunction.apply(key, token)) != null) {
added = true;
pred.next = new Node<>(h, key, val, null);
}
break;
}
}
} else if (f instanceof TreeBin) {
binCount = 2;
TreeBin t = (TreeBin) f;
TreeNode r, p;
if ((r = t.root) != null &&
(p = r.findTreeNode(h, key)) != null)
val = p.val;
else if ((val = mappingFunction.apply(key, token)) != null) {
added = true;
t.putTreeVal(h, key, val);
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD)
treeifyBin(tab, i);
if (!added)
return val;
break;
}
}
}
if (val != null)
addCount(1L, binCount);
return val;
}
/**
* If the specified key is not already associated with a value,
* attempts to compute its value using the given mapping function
* and enters it into this map unless {@code null}. The entire
* method invocation is performed atomically, so the function is
* applied at most once per key. Some attempted update operations
* on this map by other threads may be blocked while computation
* is in progress, so the computation should be short and simple,
* and must not attempt to update any other mappings of this map.
*
* @param key key with which the specified value is to be associated
* @param mappingFunction the function to compute a value
* @return the current (existing or computed) value associated with
* the specified key, or null if the computed value is null
* @throws IllegalArgumentException if the specified key is negative
* @throws NullPointerException if the specified key or mappingFunction
* is null
* @throws IllegalStateException if the computation detectably
* attempts a recursive update to this map that would
* otherwise never complete
* @throws RuntimeException or Error if the mappingFunction does so,
* in which case the mapping is left unestablished
*/
public V computeIfAbsent(long key, LongFunction mappingFunction) {
if (key < 0)
throw new IllegalArgumentException();
if (mappingFunction == null)
throw new NullPointerException();
int h = spread(keyHashCode(key));
V val = null;
int binCount = 0;
for (Node[] tab = table; ; ) {
Node f;
int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
Node r = new ReservationNode<>();
synchronized (r) {
if (casTabAt(tab, i, r)) {
binCount = 1;
Node node = null;
try {
if ((val = mappingFunction.apply(key)) != null)
node = new Node<>(h, key, val, null);
} finally {
setTabAt(tab, i, node);
}
}
}
if (binCount != 0)
break;
} else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
boolean added = false;
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node e = f; ; ++binCount) {
if (e.hash == h && e.key == key) {
val = e.val;
break;
}
Node pred = e;
if ((e = e.next) == null) {
if ((val = mappingFunction.apply(key)) != null) {
added = true;
pred.next = new Node<>(h, key, val, null);
}
break;
}
}
} else if (f instanceof TreeBin) {
binCount = 2;
TreeBin t = (TreeBin) f;
TreeNode r, p;
if ((r = t.root) != null &&
(p = r.findTreeNode(h, key)) != null)
val = p.val;
else if ((val = mappingFunction.apply(key)) != null) {
added = true;
t.putTreeVal(h, key, val);
}
}
}
}
if (binCount != 0) {
if (binCount >= TREEIFY_THRESHOLD)
treeifyBin(tab, i);
if (!added)
return val;
break;
}
}
}
if (val != null)
addCount(1L, binCount);
return val;
}
/**
* If the value for the specified key is present, attempts to
* compute a new mapping given the key and its current mapped
* value. The entire method invocation is performed atomically.
* Some attempted update operations on this map by other threads
* may be blocked while computation is in progress, so the
* computation should be short and simple, and must not attempt to
* update any other mappings of this map.
*
* @param key key with which a value may be associated
* @param remappingFunction the function to compute a value
* @return the new value associated with the specified key, or null if none
* @throws IllegalArgumentException if the specified key is negative
* @throws NullPointerException if the specified remappingFunction is null
* @throws IllegalStateException if the computation detectably
* attempts a recursive update to this map that would
* otherwise never complete
* @throws RuntimeException or Error if the remappingFunction does so,
* in which case the mapping is unchanged
*/
public V computeIfPresent(long key, BiLongFunction remappingFunction) {
if (key < 0)
throw new IllegalArgumentException();
if (remappingFunction == null)
throw new NullPointerException();
int h = spread(keyHashCode(key));
V val = null;
int delta = 0;
int binCount = 0;
for (Node[] tab = table; ; ) {
Node f;
int n, i, fh;
if (tab == null || (n = tab.length) == 0)
tab = initTable();
else if ((f = tabAt(tab, i = (n - 1) & h)) == null)
break;
else if ((fh = f.hash) == MOVED)
tab = helpTransfer(tab, f);
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
if (fh >= 0) {
binCount = 1;
for (Node e = f, pred = null; ; ++binCount) {
if (e.hash == h && e.key == key) {
val = remappingFunction.apply(key, e.val);
if (val != null)
e.val = val;
else {
delta = -1;
Node en = e.next;
if (pred != null)
pred.next = en;
else
setTabAt(tab, i, en);
}
break;
}
pred = e;
if ((e = e.next) == null)
break;
}
} else if (f instanceof TreeBin) {
binCount = 2;
TreeBin t = (TreeBin) f;
TreeNode r, p;
if ((r = t.root) != null &&
(p = r.findTreeNode(h, key)) != null) {
val = remappingFunction.apply(key, p.val);
if (val != null)
p.val = val;
else {
delta = -1;
if (t.removeTreeNode(p))
setTabAt(tab, i, untreeify(t.first));
}
}
}
}
}
if (binCount != 0)
break;
}
}
if (delta != 0)
addCount(delta, binCount);
return val;
}
/**
* 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
*/
public boolean containsKey(long 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
*/
public boolean containsValue(V value) {
if (value == null)
throw new NullPointerException();
Node[] t = table;
if (t != null) {
Traverser it = getTraverser(t);
for (Node p; (p = it.advance()) != null; ) {
V v;
if ((v = p.val) == value || (value.equals(v)))
return true;
}
}
return false;
}
/**
* 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.
* The view's iterators and spliterators are
* weakly consistent.
*
* @return the set view
*/
@NotNull
public Set> entrySet() {
EntrySetView es;
return (es = entrySet) != null ? es : (entrySet = new EntrySetView<>(this));
}
/**
* 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
*/
public boolean equals(Object o) {
if (o != this) {
if (!(o instanceof ConcurrentLongHashMap))
return false;
ConcurrentLongHashMap m = (ConcurrentLongHashMap) o;
Traverser it = getTraverser(table);
for (Node 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 (LongEntry e : m.entrySet()) {
long mk;
Object mv, v;
if ((mk = e.getKey()) == EMPTY_KEY ||
(mv = e.getValue()) == null ||
(v = get(mk)) == null ||
(mv != v && !mv.equals(v)))
return false;
}
}
return true;
}
/**
* Returns the value to which the specified key is mapped,
* or {@code null} if this map contains no mapping for the key.
* 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.)
*
* @param key map key value
* @return value to which specified key is mapped
* @throws NullPointerException if the specified key is null
*/
public V get(long key) {
Node[] tab;
Node e, p;
int n, eh;
int h = spread(keyHashCode(key));
if ((tab = table) != null && (n = tab.length) > 0 &&
(e = tabAt(tab, (n - 1) & h)) != null) {
if ((eh = e.hash) == h) {
if (e.key == 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 && e.key == key)
return e.val;
}
}
return null;
}
/**
* 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
*/
public V getOrDefault(long key, V defaultValue) {
V v;
return (v = get(key)) == null ? defaultValue : v;
}
/**
* 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
*/
public int hashCode() {
int h = 0;
Node[] t = table;
if (t != null) {
Traverser it = getTraverser(t);
for (Node p; (p = it.advance()) != null; )
h += keyHashCode(p.key) ^ p.val.hashCode();
}
return h;
}
// ConcurrentMap methods
/**
* {@inheritDoc}
*/
public boolean isEmpty() {
return sumCount() <= 0L; // ignore transient negative values
}
/**
* Returns a {@link Set} view of the keys in this map, using the
* given common mapped value for any additions (i.e., {@link
* Collection#add} and {@link Collection#addAll(Collection)}).
* This is of course only appropriate if it is acceptable to use
* the same value for all additions from this view.
*
* @param mappedValue the mapped value to use for any additions
* @return the set view
* @throws NullPointerException if the mappedValue is null
*/
public KeySetView keySet(V mappedValue) {
if (mappedValue == null)
throw new NullPointerException();
return new KeySetView<>(this, mappedValue);
}
/**
* 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.
* The view's iterators and spliterators are
* weakly consistent.
*
*
* @return the set view
*/
@NotNull
public KeySetView keySet() {
KeySetView ks;
return (ks = keySet) != null ? ks : (keySet = new KeySetView<>(this, null));
}
/**
* Returns the number of mappings. This method should be used
* instead of {@link #size} because a ConcurrentLongHashMap 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
*/
public long mappingCount() {
return Math.max(sumCount(), 0L); // ignore transient negative values
}
// Overrides of JDK8+ Map extension method defaults
/**
* Maps the specified key to the specified value in this table.
* Neither the key nor the value can be null.
* 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
*/
public V put(long key, V value) {
return putVal(key, value, false);
}
/**
* 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
*/
public void putAll(@NotNull ConcurrentLongHashMap m) {
tryPresize(m.size());
for (LongEntry e : m.entrySet())
putVal(e.getKey(), e.getValue(), false);
}
/**
* {@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
*/
public V putIfAbsent(long key, V value) {
return putVal(key, value, true);
}
public boolean remove(long key, V value) {
return value != null && replaceNode(key, null, value) != null;
}
/**
* 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
*/
public V remove(long key) {
return replaceNode(key, null, null);
}
// Hashtable legacy methods
public boolean replace(long key, @NotNull V oldValue, @NotNull V newValue) {
return replaceNode(key, newValue, oldValue) != null;
}
// ConcurrentLongHashMap-only 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
*/
public V replace(long key, @NotNull V value) {
return replaceNode(key, value, null);
}
/**
* {@inheritDoc}
*/
public int size() {
long n = sumCount();
return ((n < 0L) ? 0 :
(n > (long) Integer.MAX_VALUE) ? Integer.MAX_VALUE :
(int) n);
}
/**
* 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
*/
public String toString() {
Traverser it = getTraverser(table);
StringBuilder sb = new StringBuilder();
sb.append('{');
Node p;
if ((p = it.advance()) != null) {
for (; ; ) {
long k = p.key;
V v = p.val;
sb.append(k);
sb.append('=');
sb.append(v == this ? "(this Map)" : v);
if ((p = it.advance()) == null)
break;
sb.append(',').append(' ');
}
}
return sb.append('}').toString();
}
/**
* 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.
* The view's iterators and spliterators are
* weakly consistent.
*
* @return the collection view
*/
@NotNull
public Collection values() {
ValuesView vs;
return (vs = values) != null ? vs : (values = new ValuesView<>(this));
}
/* ---------------- Special Nodes -------------- */
private static long initialSeed() {
String pp = System.getProperty("java.util.secureRandomSeed");
if (pp != null && pp.equalsIgnoreCase("true")) {
byte[] seedBytes = java.security.SecureRandom.getSeed(8);
long s = (long) (seedBytes[0]) & 0xffL;
for (int i = 1; i < 8; ++i)
s = (s << 8) | ((long) (seedBytes[i]) & 0xffL);
return s;
}
return (mix64(System.currentTimeMillis()) ^
mix64(System.nanoTime()));
}
/* ---------------- Table Initialization and Resizing -------------- */
private static int keyHashCode(final long key) {
return Hash.hashLong32(key);
}
private static long mix64(long z) {
z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
return z ^ (z >>> 33);
}
/**
* 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;
}
/**
* 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 || !Unsafe.cas(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[getProbe() & m]) == null ||
!(uncontended = Unsafe.cas(a, CELLVALUE, v = a.value, v + x))) {
fullAddCount(x, uncontended);
return;
}
if (check <= 1)
return;
s = sumCount();
}
if (check >= 0) {
Node[] 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 + MAX_RESIZERS || (nt = nextTable) == null || transferIndex <= 0)
break;
if (Unsafe.getUnsafe().compareAndSwapInt(this, SIZECTL, sc, sc + 1))
transfer(tab, nt);
} else if (Unsafe.getUnsafe().compareAndSwapInt(this, SIZECTL, sc,
(rs << RESIZE_STAMP_SHIFT) + 2))
transfer(tab, null);
s = sumCount();
}
}
}
// See LongAdder version for explanation
private void fullAddCount(long x, boolean wasUncontended) {
int h;
if ((h = getProbe()) == 0) {
localInit(); // force initialization
h = 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 &&
Unsafe.getUnsafe().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 (Unsafe.cas(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 &&
Unsafe.getUnsafe().compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
try {
if (counterCells == as) {// Expand table unless stale
CounterCell[] rs = new CounterCell[n << 1];
System.arraycopy(as, 0, rs, 0, n);
counterCells = rs;
}
} finally {
cellsBusy = 0;
}
collide = false;
continue; // Retry with expanded table
}
h = advanceProbe(h);
} else if (cellsBusy == 0 && counterCells == as &&
Unsafe.getUnsafe().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 (Unsafe.cas(this, BASECOUNT, v = baseCount, v + x))
break; // Fall back on using base
}
}
private Traverser getTraverser(Node[] tab) {
Traverser traverser = tlTraverser.get();
int len = tab == null ? 0 : tab.length;
traverser.of(tab, len, len);
return traverser;
}
/**
* Initializes table, using the size recorded in sizeCtl.
*/
private Node[] initTable() {
Node[] tab;
int sc;
while ((tab = table) == null || tab.length == 0) {
if ((sc = sizeCtl) < 0)
Os.pause(); // lost initialization race; just spin
else if (Unsafe.getUnsafe().compareAndSwapInt(this, SIZECTL, sc, -1)) {
try {
if ((tab = table) == null || tab.length == 0) {
int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
@SuppressWarnings("unchecked")
Node[] nt = (Node[]) new Node[n];
table = tab = nt;
sc = n - (n >>> 2);
}
} finally {
sizeCtl = sc;
}
break;
}
}
return tab;
}
/**
* Moves and/or copies the nodes in each bin to new table. See
* above for explanation.
*/
private void transfer(Node[] tab, Node[] 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[] nt = (Node[]) 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 fwd = new ForwardingNode<>(nextTab);
boolean advance = true;
boolean finishing = false; // to ensure sweep before committing nextTab
for (int i = 0, bound = 0; ; ) {
Node 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 (Unsafe.getUnsafe().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 (Unsafe.getUnsafe().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, fwd);
else if ((fh = f.hash) == MOVED)
advance = true; // already processed
else {
synchronized (f) {
if (tabAt(tab, i) == f) {
Node ln, hn;
if (fh >= 0) {
int runBit = fh & n;
Node lastRun = f;
for (Node 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 p = f; p != lastRun; p = p.next) {
int ph = p.hash;
long pk = p.key;
V pv = p.val;
if ((ph & n) == 0)
ln = new Node<>(ph, pk, pv, ln);
else
hn = new Node<>(ph, pk, pv, hn);
}
setTabAt(nextTab, i, ln);
setTabAt(nextTab, i + n, hn);
setTabAt(tab, i, fwd);
advance = true;
} else if (f instanceof TreeBin) {
TreeBin t = (TreeBin) f;
TreeNode lo = null, loTail = null;
TreeNode hi = null, hiTail = null;
int lc = 0, hc = 0;
for (Node e = t.first; e != null; e = e.next) {
int h = e.hash;
TreeNode p = new TreeNode<>(h, e.key, e.val, null, null);
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<>(lo) : t;
hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
(lc != 0) ? new TreeBin<>(hi) : t;
setTabAt(nextTab, i, ln);
setTabAt(nextTab, i + n, hn);
setTabAt(tab, i, fwd);
advance = true;
}
}
}
}
}
}
/* ---------------- Counter support -------------- */
/**
* Replaces all linked nodes in bin at given index unless table is
* too small, in which case resizes instead.
*/
private void treeifyBin(Node[] tab, int index) {
Node 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 hd = null, tl = null;
for (Node e = b; e != null; e = e.next) {
TreeNode p =
new TreeNode<>(e.hash, e.key, e.val, null, null);
if ((p.prev = tl) == null)
hd = p;
else
tl.next = p;
tl = p;
}
setTabAt(tab, index, new TreeBin<>(hd));
}
}
}
}
}
/**
* 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[] tab = table;
int n;
if (tab == null || (n = tab.length) == 0) {
n = Math.max(sc, c);
if (Unsafe.getUnsafe().compareAndSwapInt(this, SIZECTL, sc, -1)) {
try {
if (table == tab) {
@SuppressWarnings("unchecked")
Node[] nt = (Node[]) 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[] nt;
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
sc == rs + MAX_RESIZERS || (nt = nextTable) == null ||
transferIndex <= 0)
break;
if (Unsafe.getUnsafe().compareAndSwapInt(this, SIZECTL, sc, sc + 1))
transfer(tab, nt);
} else if (Unsafe.getUnsafe().compareAndSwapInt(this, SIZECTL, sc,
(rs << RESIZE_STAMP_SHIFT) + 2))
transfer(tab, null);
}
}
}
static int advanceProbe(int probe) {
probe ^= probe << 13; // xorshift
probe ^= probe >>> 17;
probe ^= probe << 5;
Unsafe.getUnsafe().putInt(Thread.currentThread(), PROBE, probe);
return probe;
}
/* ---------------- Conversion from/to TreeBins -------------- */
static boolean casTabAt(Node[] tab, int i,
Node v) {
return Unsafe.getUnsafe().compareAndSwapObject(tab, ((long) i << ASHIFT) + ABASE, null, v);
}
/**
* Returns x's Class if it is of the form "class C implements
* Comparable", else null.
*/
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;
}
/* ---------------- TreeNodes -------------- */
/**
* Returns k.compareTo(x) if x matches kc (k's screened comparable
* class), else 0.
*/
static int compareComparables(long k, long x) {
return Long.compare(k, x);
}
/* ---------------- TreeBins -------------- */
static int getProbe() {
return Unsafe.getUnsafe().getInt(Thread.currentThread(), PROBE);
}
/* ----------------Table Traversal -------------- */
/**
* Initialize Thread fields for the current thread. Called only
* when Thread.threadLocalRandomProbe is zero, indicating that a
* thread local seed value needs to be generated. Note that even
* though the initialization is purely thread-local, we need to
* rely on (static) atomic generators to initialize the values.
*/
static void localInit() {
int p = probeGenerator.addAndGet(PROBE_INCREMENT);
int probe = (p == 0) ? 1 : p; // skip 0
long seed = mix64(seeder.getAndAdd(SEEDER_INCREMENT));
Thread t = Thread.currentThread();
Unsafe.getUnsafe().putLong(t, SEED, seed);
Unsafe.getUnsafe().putInt(t, PROBE, probe);
}
/**
* Returns the stamp bits for resizing a table of size n.
* Must be negative when shifted left by RESIZE_STAMP_SHIFT.
*/
static int resizeStamp(int n) {
return Integer.numberOfLeadingZeros(n) | (1 << (RESIZE_STAMP_BITS - 1));
}
static void setTabAt(Node[] tab, int i, Node v) {
Unsafe.getUnsafe().putObjectVolatile(tab, ((long) i << ASHIFT) + ABASE, v);
}
/**
* 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.
*/
static int spread(int h) {
return (h ^ (h >>> 16)) & HASH_BITS;
}
@SuppressWarnings("unchecked")
static Node tabAt(Node[] tab, int i) {
return (Node) Unsafe.getUnsafe().getObjectVolatile(tab, ((long) i << ASHIFT) + ABASE);
}
/**
* Returns a list on non-TreeNodes replacing those in given list.
*/
static Node untreeify(Node b) {
Node hd = null, tl = null;
for (Node q = b; q != null; q = q.next) {
Node p = new Node<>(q.hash, q.key, q.val, null);
if (tl == null)
hd = p;
else
tl.next = p;
tl = p;
}
return hd;
}
/**
* Helps transfer if a resize is in progress.
*/
final Node[] helpTransfer(Node[] tab, Node f) {
Node[] nextTab;
int sc;
if (tab != null && (f instanceof ForwardingNode) &&
(nextTab = ((ForwardingNode) 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 (Unsafe.getUnsafe().compareAndSwapInt(this, SIZECTL, sc, sc + 1)) {
transfer(tab, nextTab);
break;
}
}
return nextTab;
}
return table;
}
/* ----------------Views -------------- */
/**
* Implementation for put and putIfAbsent
*/
final V putVal(long key, V value, boolean onlyIfAbsent) {
if (key < 0) throw new IllegalArgumentException();
if (value == null) throw new NullPointerException();
int hash = spread(keyHashCode(key));
int binCount = 0;
Node _new = null;
for (Node[] tab = table; ; ) {
Node 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 (_new == null) {
_new = new Node<>(hash, key, value, null);
}
if (casTabAt(tab, i, _new)) {
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 e = f; ; ++binCount) {
if (e.hash == hash && e.key == key) {
oldVal = e.val;
if (!onlyIfAbsent)
e.val = value;
break;
}
Node pred = e;
if ((e = e.next) == null) {
if (_new == null) {
pred.next = new Node<>(hash, key, value, null);
} else {
pred.next = _new;
}
break;
}
}
} else if (f instanceof TreeBin) {
Node p;
binCount = 2;
if ((p = ((TreeBin) 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;
}
/**
* 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.
*/
final V replaceNode(long key, V value, V cv) {
int hash = spread(keyHashCode(key));
for (Node[] tab = table; ; ) {
Node 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 e = f, pred = null; ; ) {
if (e.hash == hash && e.key == key) {
V ev = e.val;
if (cv == null || cv == ev || (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 t = (TreeBin) f;
TreeNode r, p;
if ((r = t.root) != null &&
(p = r.findTreeNode(hash, key)) != null) {
V pv = p.val;
if (cv == null || cv == pv || 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;
}
final 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;
}
public interface LongEntry {
boolean equals(Object var1);
long getKey();
V getValue();
int hashCode();
V setValue(V var1);
}
/**
* Base of key, value, and entry Iterators. Adds fields to
* Traverser to support iterator.remove.
*/
static class BaseIterator extends Traverser {
Node lastReturned;
ConcurrentLongHashMap map;
public final boolean hasNext() {
return next != null;
}
public final void remove() {
Node p;
if ((p = lastReturned) == null)
throw new IllegalStateException();
lastReturned = null;
map.replaceNode(p.key, null, null);
}
void of(ConcurrentLongHashMap map) {
Node[] tab = map.table;
int l = tab == null ? 0 : tab.length;
super.of(tab, l, l);
this.map = map;
advance();
}
}
/**
* Base class for views.
*/
abstract static class CollectionView
implements Collection, java.io.Serializable {
private static final String oomeMsg = "Required array size too large";
private static final long serialVersionUID = 7249069246763182397L;
final ConcurrentLongHashMap map;
CollectionView(ConcurrentLongHashMap map) {
this.map = map;
}
/**
* Removes all of the elements from this view, by removing all
* the mappings from the map backing this view.
*/
public final void clear() {
map.clear();
}
public abstract boolean contains(Object o);
public final boolean containsAll(@NotNull Collection c) {
if (c != this) {
for (Object e : c) {
if (e == null || !contains(e))
return false;
}
}
return true;
}
/**
* Returns the map backing this view.
*
* @return the map backing this view
*/
public ConcurrentLongHashMap getMap() {
return map;
}
public final boolean isEmpty() {
return map.isEmpty();
}
/**
* Returns an iterator over the elements in this collection.
* The returned iterator is
* weakly consistent.
*
* @return an iterator over the elements in this collection
*/
@NotNull
public abstract Iterator iterator();
public abstract boolean remove(Object o);
@Override
public final boolean removeAll(@NotNull Collection c) {
boolean modified = false;
for (Iterator it = iterator(); it.hasNext(); ) {
if (c.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
// implementations below rely on concrete classes supplying these
// abstract methods
@Override
public final boolean retainAll(@NotNull Collection c) {
boolean modified = false;
for (Iterator it = iterator(); it.hasNext(); ) {
if (!c.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
@Override
public final int size() {
return map.size();
}
@Override
public final Object @NotNull [] 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);
}
@Override
@SuppressWarnings("unchecked")
public final T @NotNull [] toArray(@NotNull T @NotNull [] 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 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();
}
}
/**
* A padded cell for distributing counts. Adapted from LongAdder
* and Striped64. See their internal docs for explanation.
*/
static final class CounterCell {
final long value;
CounterCell(long x) {
value = x;
}
}
static final class EntryIterator extends BaseIterator
implements Iterator> {
@Override
public LongEntry next() {
Node p;
if ((p = next) == null)
throw new NoSuchElementException();
long k = p.key;
V v = p.val;
lastReturned = p;
advance();
return new MapEntry<>(k, v, map);
}
}
/**
* A view of a ConcurrentLongHashMap as a {@link Set} of (key, value)
* entries. This class cannot be directly instantiated. See
* {@link #entrySet()}.
*/
static final class EntrySetView extends CollectionView>
implements Set>, java.io.Serializable {
private static final long serialVersionUID = 2249069246763182397L;
private final ThreadLocal> tlEntryIterator = ThreadLocal.withInitial(EntryIterator::new);
EntrySetView(ConcurrentLongHashMap map) {
super(map);
}
@Override
public boolean add(LongEntry e) {
return map.putVal(e.getKey(), e.getValue(), false) == null;
}
@Override
public boolean addAll(@NotNull Collection> c) {
boolean added = false;
for (LongEntry e : c) {
if (add(e))
added = true;
}
return added;
}
@Override
public boolean contains(Object o) {
long k;
Object v, r;
LongEntry e;
return ((o instanceof LongEntry) &&
(k = (e = (LongEntry) o).getKey()) != EMPTY_KEY &&
(r = map.get(k)) != null &&
(v = e.getValue()) != null &&
(v == r || v.equals(r)));
}
@Override
public boolean equals(Object o) {
Set c;
return ((o instanceof Set) &&
((c = (Set) o) == this ||
(containsAll(c) && c.containsAll(this))));
}
@Override
public int hashCode() {
int h = 0;
Node[] t = map.table;
if (t != null) {
Traverser it = map.getTraverser(t);
for (Node p; (p = it.advance()) != null; ) {
h += p.hashCode();
}
}
return h;
}
/**
* @return an iterator over the entries of the backing map
*/
@NotNull
public Iterator> iterator() {
EntryIterator it = tlEntryIterator.get();
it.of(map);
return it;
}
@Override
public boolean remove(Object o) {
long k;
Object v;
LongEntry e;
return ((o instanceof LongEntry) &&
(k = (e = (LongEntry) o).getKey()) != EMPTY_KEY &&
(v = e.getValue()) != null &&
map.remove(k, (V) v));
}
}
/**
* A node inserted at head of bins during transfer operations.
*/
static final class ForwardingNode extends Node {
final Node[] nextTable;
ForwardingNode(Node[] tab) {
super(MOVED, EMPTY_KEY, null, null);
this.nextTable = tab;
}
@Override
Node find(int h, long k) {
// loop to avoid arbitrarily deep recursion on forwarding nodes
outer:
for (Node[] tab = nextTable; ; ) {
Node e;
int n;
if (k == EMPTY_KEY || tab == null || (n = tab.length) == 0 ||
(e = tabAt(tab, (n - 1) & h)) == null)
return null;
for (; ; ) {
int eh;
if ((eh = e.hash) == h && e.key == k)
return e;
if (eh < 0) {
if (e instanceof ForwardingNode) {
tab = ((ForwardingNode) e).nextTable;
continue outer;
} else
return e.find(h, k);
}
if ((e = e.next) == null)
return null;
}
}
}
}
public static final class KeyIterator extends BaseIterator {
public long next() {
Node p;
if ((p = next) == null)
throw new NoSuchElementException();
long k = p.key;
lastReturned = p;
advance();
return k;
}
}
/**
* A view of a ConcurrentLongHashMap as a long 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()},
* {@link #keySet(Object) keySet(V)},
* {@link #newKeySet() newKeySet()},
* {@link #newKeySet(int) newKeySet(int)}.
*
* @since 1.8
*/
public static class KeySetView implements java.io.Serializable {
private static final long serialVersionUID = 7249069246763182397L;
private final ConcurrentLongHashMap map;
private final ThreadLocal> tlKeyIterator = ThreadLocal.withInitial(KeyIterator::new);
private final V value;
KeySetView(ConcurrentLongHashMap map, V value) { // non-public
this.map = map;
this.value = value;
}
/**
* Adds the specified key to this set view by mapping the key to
* the default mapped value in the backing map, if defined.
*
* @param k 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
*/
public boolean add(long k) {
V v;
if ((v = value) == null)
throw new UnsupportedOperationException();
return map.putVal(k, v, true) == null;
}
public final void clear() {
map.clear();
}
public boolean contains(long k) {
return map.containsKey(k);
}
@Override
public boolean equals(Object o) {
KeySetView c;
return ((o instanceof KeySetView) &&
((c = (KeySetView) o) == this ||
(containsAll(c) && c.containsAll(this))));
}
/**
* 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;
}
@Override
public int hashCode() {
int h = 0;
KeyIterator it = iterator();
if (it.hasNext()) {
do {
long k = it.next();
h += keyHashCode(k);
} while (it.hasNext());
}
return h;
}
public final boolean isEmpty() {
return map.isEmpty();
}
/**
* @return an iterator over the keys of the backing map
*/
@NotNull
public KeyIterator iterator() {
KeyIterator it = tlKeyIterator.get();
it.of(map);
return it;
}
/**
* 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 k 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
*/
public boolean remove(long k) {
return map.remove(k) != null;
}
public final int size() {
return map.size();
}
@Override
public final String toString() {
StringBuilder sb = new StringBuilder();
sb.append('[');
KeyIterator it = iterator();
if (it.hasNext()) {
for (; ; ) {
long k = it.next();
sb.append(k);
if (!it.hasNext())
break;
sb.append(',').append(' ');
}
}
return sb.append(']').toString();
}
private boolean containsAll(@NotNull KeySetView c) {
KeyIterator it = iterator();
if (it.hasNext()) {
do {
long k = it.next();
if (!contains(k))
return false;
} while (it.hasNext());
}
return true;
}
}
/**
* Exported Entry for EntryIterator
*/
static final class MapEntry implements LongEntry {
final long key; // != EMPTY_KEY
final ConcurrentLongHashMap map;
V val; // non-null
MapEntry(long key, V val, ConcurrentLongHashMap map) {
this.key = key;
this.val = val;
this.map = map;
}
@Override
public boolean equals(Object o) {
long k;
Object v;
LongEntry e;
return ((o instanceof LongEntry) &&
(k = (e = (LongEntry) o).getKey()) != EMPTY_KEY &&
(v = e.getValue()) != null &&
(k == key) &&
(v == val || v.equals(val)));
}
@Override
public long getKey() {
return key;
}
@Override
public V getValue() {
return val;
}
@Override
public int hashCode() {
return keyHashCode(key) ^ val.hashCode();
}
/**
* 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.
*/
@NotNull
public V setValue(V value) {
if (value == null) throw new NullPointerException();
V v = val;
val = value;
map.put(key, value);
return v;
}
@Override
public String toString() {
return key + "=" + val;
}
}
/**
* 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.
*/
static class Node implements LongEntry {
final int hash;
final long key;
volatile Node next;
volatile V val;
Node(int hash, long key, V val, Node next) {
this.hash = hash;
this.key = key;
this.val = val;
this.next = next;
}
@Override
public final boolean equals(Object o) {
long k;
Object v, u;
LongEntry e;
return ((o instanceof LongEntry) &&
(k = (e = (LongEntry) o).getKey()) != EMPTY_KEY &&
(v = e.getValue()) != null &&
(k == key) &&
(v == (u = val) || v.equals(u)));
}
@Override
public final long getKey() {
return key;
}
@Override
public final V getValue() {
return val;
}
@Override
public final int hashCode() {
return keyHashCode(key) ^ val.hashCode();
}
@Override
public final V setValue(V value) {
throw new UnsupportedOperationException();
}
@Override
public final String toString() {
return key + "=" + val;
}
/**
* Virtualized support for map.get(); overridden in subclasses.
*/
Node find(int h, long k) {
Node e = this;
if (k != EMPTY_KEY) {
do {
if (e.hash == h && (e.key == k))
return e;
} while ((e = e.next) != null);
}
return null;
}
}
/**
* A place-holder node used in computeIfAbsent and compute
*/
static final class ReservationNode extends Node {
ReservationNode() {
super(RESERVED, EMPTY_KEY, null, null);
}
@Override
Node find(int h, long k) {
return null;
}
}
/**
* Stripped-down version of helper class used in previous version,
* declared for the sake of serialization compatibility
*/
static class Segment extends ReentrantLock implements Serializable {
private static final long serialVersionUID = 2249069246763182397L;
final float loadFactor;
Segment() {
this.loadFactor = ConcurrentLongHashMap.LOAD_FACTOR;
}
}
/**
* 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.
*/
static final class TableStack {
int index;
int length;
TableStack next;
Node[] tab;
}
/**
* Encapsulates traversal for methods such as containsValue; also
* serves as a base class for other iterators and spliterators.
*
* 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.
*
* 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.
*/
static class Traverser {
int baseIndex; // current index of initial table
int baseLimit; // index bound for initial table
int baseSize; // initial table size
int index; // index of bin to use next
Node next; // the next entry to use
TableStack stack, spare; // to save/restore on ForwardingNodes
Node[] tab; // current table; updated if resized
/**
* Saves traversal state upon encountering a forwarding node.
*/
private void pushState(Node[] t, int i, int n) {
TableStack s = spare; // reuse if possible
if (s != null)
spare = s.next;
else
s = new TableStack<>();
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 s;
int len;
while ((s = stack) != null && (index += (len = s.length)) >= n) {
n = len;
index = s.index;
tab = s.tab;
s.tab = null;
TableStack next = s.next;
s.next = spare; // save for reuse
stack = next;
spare = s;
}
if (s == null && (index += baseSize) >= n)
index = ++baseIndex;
}
/**
* Advances if possible, returning next valid node, or null if none.
*/
final Node advance() {
Node e;
if ((e = next) != null)
e = e.next;
for (; ; ) {
Node[] 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) e).nextTable;
e = null;
pushState(t, i, n);
continue;
} else if (e instanceof TreeBin)
e = ((TreeBin) e).first;
else
e = null;
}
if (stack != null)
recoverState(n);
else if ((index = i + baseSize) >= n)
index = ++baseIndex; // visit upper slots if present
}
}
void of(Node[] tab, int size, int limit) {
this.tab = tab;
this.baseSize = size;
this.baseIndex = this.index = 0;
this.baseLimit = limit;
this.next = null;
}
}
/**
* 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.
*/
static final class TreeBin extends Node {
static final int READER = 4; // increment value for setting read lock
static final int WAITER = 2; // set when waiting for write lock
// values for lockState
static final int WRITER = 1; // set while holding write lock
private static final long LOCKSTATE;
private static final sun.misc.Unsafe U;
volatile TreeNode first;
volatile int lockState;
TreeNode root;
volatile Thread waiter;
/**
* Creates bin with initial set of nodes headed by b.
*/
TreeBin(TreeNode b) {
super(TREEBIN, EMPTY_KEY, null, null);
this.first = b;
TreeNode r = null;
for (TreeNode x = b, next; x != null; x = next) {
next = (TreeNode) x.next;
x.left = x.right = null;
if (r == null) {
x.parent = null;
x.red = false;
r = x;
} else {
long k = x.key;
int h = x.hash;
for (TreeNode p = r; ; ) {
int dir, ph;
long pk = p.key;
if ((ph = p.hash) > h)
dir = -1;
else if (ph < h)
dir = 1;
else if ((dir = compareComparables(k, pk)) == 0)
dir = tieBreakOrder(k, pk);
TreeNode 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);
}
/**
* 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);
}
}
/**
* 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;
}
static TreeNode balanceDeletion(TreeNode root,
TreeNode x) {
for (TreeNode 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 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) {
sl.red = false;
xpr.red = true;
root = rotateRight(root, xpr);
xpr = (xp = x.parent) == null ?
null : xp.right;
}
if (xpr != null) {
xpr.red = 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 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) {
sr.red = false;
xpl.red = true;
root = rotateLeft(root, xpl);
xpl = (xp = x.parent) == null ?
null : xp.left;
}
if (xpl != null) {
xpl.red = xp.red;
if ((sl = xpl.left) != null)
sl.red = false;
}
if (xp != null) {
xp.red = false;
root = rotateRight(root, xp);
}
x = root;
}
}
}
}
}
static TreeNode balanceInsertion(TreeNode root,
TreeNode x) {
x.red = true;
for (TreeNode 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);
}
}
}
}
}
}
/**
* Recursive invariant check
*/
@SuppressWarnings("SimplifiableIfStatement")
static