1190 lines
35 KiB
Java
1190 lines
35 KiB
Java
/*
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166
|
|
* Expert Group and released to the public domain, as explained at
|
|
* http://creativecommons.org/licenses/publicdomain
|
|
*/
|
|
|
|
/*
|
|
* This wasn't included until Android API level 9, so we're duplicating
|
|
* it here for backwards compatibility.
|
|
*/
|
|
|
|
package org.thoughtcrime.securesms.util.deque;
|
|
|
|
import java.util.AbstractQueue;
|
|
import java.util.Collection;
|
|
import java.util.Iterator;
|
|
import java.util.NoSuchElementException;
|
|
import java.util.concurrent.TimeUnit;
|
|
import java.util.concurrent.locks.Condition;
|
|
import java.util.concurrent.locks.ReentrantLock;
|
|
|
|
/**
|
|
* An optionally-bounded {@linkplain BlockingDeque blocking deque} based on
|
|
* linked nodes.
|
|
*
|
|
* <p> The optional capacity bound constructor argument serves as a
|
|
* way to prevent excessive expansion. The capacity, if unspecified,
|
|
* is equal to {@link Integer#MAX_VALUE}. Linked nodes are
|
|
* dynamically created upon each insertion unless this would bring the
|
|
* deque above capacity.
|
|
*
|
|
* <p>Most operations run in constant time (ignoring time spent
|
|
* blocking). Exceptions include {@link #remove(Object) remove},
|
|
* {@link #removeFirstOccurrence removeFirstOccurrence}, {@link
|
|
* #removeLastOccurrence removeLastOccurrence}, {@link #contains
|
|
* contains}, {@link #iterator iterator.remove()}, and the bulk
|
|
* operations, all of which run in linear time.
|
|
*
|
|
* <p>This class and its iterator implement all of the
|
|
* <em>optional</em> methods of the {@link Collection} and {@link
|
|
* Iterator} interfaces.
|
|
*
|
|
* <p>This class is a member of the
|
|
* <a href="{@docRoot}/../technotes/guides/collections/index.html">
|
|
* Java Collections Framework</a>.
|
|
*
|
|
* @since 1.6
|
|
* @author Doug Lea
|
|
* @param <E> the type of elements held in this collection
|
|
*/
|
|
public class LinkedBlockingDeque<E>
|
|
extends AbstractQueue<E>
|
|
implements BlockingDeque<E>, java.io.Serializable {
|
|
|
|
/*
|
|
* Implemented as a simple doubly-linked list protected by a
|
|
* single lock and using conditions to manage blocking.
|
|
*
|
|
* To implement weakly consistent iterators, it appears we need to
|
|
* keep all Nodes GC-reachable from a predecessor dequeued Node.
|
|
* That would cause two problems:
|
|
* - allow a rogue Iterator to cause unbounded memory retention
|
|
* - cause cross-generational linking of old Nodes to new Nodes if
|
|
* a Node was tenured while live, which generational GCs have a
|
|
* hard time dealing with, causing repeated major collections.
|
|
* However, only non-deleted Nodes need to be reachable from
|
|
* dequeued Nodes, and reachability does not necessarily have to
|
|
* be of the kind understood by the GC. We use the trick of
|
|
* linking a Node that has just been dequeued to itself. Such a
|
|
* self-link implicitly means to jump to "first" (for next links)
|
|
* or "last" (for prev links).
|
|
*/
|
|
|
|
/*
|
|
* We have "diamond" multiple interface/abstract class inheritance
|
|
* here, and that introduces ambiguities. Often we want the
|
|
* BlockingDeque javadoc combined with the AbstractQueue
|
|
* implementation, so a lot of method specs are duplicated here.
|
|
*/
|
|
|
|
private static final long serialVersionUID = -387911632671998426L;
|
|
|
|
/** Doubly-linked list node class */
|
|
static final class Node<E> {
|
|
/**
|
|
* The item, or null if this node has been removed.
|
|
*/
|
|
E item;
|
|
|
|
/**
|
|
* One of:
|
|
* - the real predecessor Node
|
|
* - this Node, meaning the predecessor is tail
|
|
* - null, meaning there is no predecessor
|
|
*/
|
|
Node<E> prev;
|
|
|
|
/**
|
|
* One of:
|
|
* - the real successor Node
|
|
* - this Node, meaning the successor is head
|
|
* - null, meaning there is no successor
|
|
*/
|
|
Node<E> next;
|
|
|
|
Node(E x) {
|
|
item = x;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Pointer to first node.
|
|
* Invariant: (first == null && last == null) ||
|
|
* (first.prev == null && first.item != null)
|
|
*/
|
|
transient Node<E> first;
|
|
|
|
/**
|
|
* Pointer to last node.
|
|
* Invariant: (first == null && last == null) ||
|
|
* (last.next == null && last.item != null)
|
|
*/
|
|
transient Node<E> last;
|
|
|
|
/** Number of items in the deque */
|
|
private transient int count;
|
|
|
|
/** Maximum number of items in the deque */
|
|
private final int capacity;
|
|
|
|
/** Main lock guarding all access */
|
|
final ReentrantLock lock = new ReentrantLock();
|
|
|
|
/** Condition for waiting takes */
|
|
private final Condition notEmpty = lock.newCondition();
|
|
|
|
/** Condition for waiting puts */
|
|
private final Condition notFull = lock.newCondition();
|
|
|
|
/**
|
|
* Creates a {@code LinkedBlockingDeque} with a capacity of
|
|
* {@link Integer#MAX_VALUE}.
|
|
*/
|
|
public LinkedBlockingDeque() {
|
|
this(Integer.MAX_VALUE);
|
|
}
|
|
|
|
/**
|
|
* Creates a {@code LinkedBlockingDeque} with the given (fixed) capacity.
|
|
*
|
|
* @param capacity the capacity of this deque
|
|
* @throws IllegalArgumentException if {@code capacity} is less than 1
|
|
*/
|
|
public LinkedBlockingDeque(int capacity) {
|
|
if (capacity <= 0) throw new IllegalArgumentException();
|
|
this.capacity = capacity;
|
|
}
|
|
|
|
/**
|
|
* Creates a {@code LinkedBlockingDeque} with a capacity of
|
|
* {@link Integer#MAX_VALUE}, initially containing the elements of
|
|
* the given collection, added in traversal order of the
|
|
* collection's iterator.
|
|
*
|
|
* @param c the collection of elements to initially contain
|
|
* @throws NullPointerException if the specified collection or any
|
|
* of its elements are null
|
|
*/
|
|
public LinkedBlockingDeque(Collection<? extends E> c) {
|
|
this(Integer.MAX_VALUE);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock(); // Never contended, but necessary for visibility
|
|
try {
|
|
for (E e : c) {
|
|
if (e == null)
|
|
throw new NullPointerException();
|
|
if (!linkLast(new Node<E>(e)))
|
|
throw new IllegalStateException("Deque full");
|
|
}
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
|
|
// Basic linking and unlinking operations, called only while holding lock
|
|
|
|
/**
|
|
* Links node as first element, or returns false if full.
|
|
*/
|
|
private boolean linkFirst(Node<E> node) {
|
|
// assert lock.isHeldByCurrentThread();
|
|
if (count >= capacity)
|
|
return false;
|
|
Node<E> f = first;
|
|
node.next = f;
|
|
first = node;
|
|
if (last == null)
|
|
last = node;
|
|
else
|
|
f.prev = node;
|
|
++count;
|
|
notEmpty.signal();
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Links node as last element, or returns false if full.
|
|
*/
|
|
private boolean linkLast(Node<E> node) {
|
|
// assert lock.isHeldByCurrentThread();
|
|
if (count >= capacity)
|
|
return false;
|
|
Node<E> l = last;
|
|
node.prev = l;
|
|
last = node;
|
|
if (first == null)
|
|
first = node;
|
|
else
|
|
l.next = node;
|
|
++count;
|
|
notEmpty.signal();
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Removes and returns first element, or null if empty.
|
|
*/
|
|
private E unlinkFirst() {
|
|
// assert lock.isHeldByCurrentThread();
|
|
Node<E> f = first;
|
|
if (f == null)
|
|
return null;
|
|
Node<E> n = f.next;
|
|
E item = f.item;
|
|
f.item = null;
|
|
f.next = f; // help GC
|
|
first = n;
|
|
if (n == null)
|
|
last = null;
|
|
else
|
|
n.prev = null;
|
|
--count;
|
|
notFull.signal();
|
|
return item;
|
|
}
|
|
|
|
/**
|
|
* Removes and returns last element, or null if empty.
|
|
*/
|
|
private E unlinkLast() {
|
|
// assert lock.isHeldByCurrentThread();
|
|
Node<E> l = last;
|
|
if (l == null)
|
|
return null;
|
|
Node<E> p = l.prev;
|
|
E item = l.item;
|
|
l.item = null;
|
|
l.prev = l; // help GC
|
|
last = p;
|
|
if (p == null)
|
|
first = null;
|
|
else
|
|
p.next = null;
|
|
--count;
|
|
notFull.signal();
|
|
return item;
|
|
}
|
|
|
|
/**
|
|
* Unlinks x.
|
|
*/
|
|
void unlink(Node<E> x) {
|
|
// assert lock.isHeldByCurrentThread();
|
|
Node<E> p = x.prev;
|
|
Node<E> n = x.next;
|
|
if (p == null) {
|
|
unlinkFirst();
|
|
} else if (n == null) {
|
|
unlinkLast();
|
|
} else {
|
|
p.next = n;
|
|
n.prev = p;
|
|
x.item = null;
|
|
// Don't mess with x's links. They may still be in use by
|
|
// an iterator.
|
|
--count;
|
|
notFull.signal();
|
|
}
|
|
}
|
|
|
|
// BlockingDeque methods
|
|
|
|
/**
|
|
* @throws IllegalStateException {@inheritDoc}
|
|
* @throws NullPointerException {@inheritDoc}
|
|
*/
|
|
public void addFirst(E e) {
|
|
if (!offerFirst(e))
|
|
throw new IllegalStateException("Deque full");
|
|
}
|
|
|
|
/**
|
|
* @throws IllegalStateException {@inheritDoc}
|
|
* @throws NullPointerException {@inheritDoc}
|
|
*/
|
|
public void addLast(E e) {
|
|
if (!offerLast(e))
|
|
throw new IllegalStateException("Deque full");
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
*/
|
|
public boolean offerFirst(E e) {
|
|
if (e == null) throw new NullPointerException();
|
|
Node<E> node = new Node<E>(e);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return linkFirst(node);
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
*/
|
|
public boolean offerLast(E e) {
|
|
if (e == null) throw new NullPointerException();
|
|
Node<E> node = new Node<E>(e);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return linkLast(node);
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws InterruptedException {@inheritDoc}
|
|
*/
|
|
public void putFirst(E e) throws InterruptedException {
|
|
if (e == null) throw new NullPointerException();
|
|
Node<E> node = new Node<E>(e);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
while (!linkFirst(node))
|
|
notFull.await();
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws InterruptedException {@inheritDoc}
|
|
*/
|
|
public void putLast(E e) throws InterruptedException {
|
|
if (e == null) throw new NullPointerException();
|
|
Node<E> node = new Node<E>(e);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
while (!linkLast(node))
|
|
notFull.await();
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws InterruptedException {@inheritDoc}
|
|
*/
|
|
public boolean offerFirst(E e, long timeout, TimeUnit unit)
|
|
throws InterruptedException {
|
|
if (e == null) throw new NullPointerException();
|
|
Node<E> node = new Node<E>(e);
|
|
long nanos = unit.toNanos(timeout);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lockInterruptibly();
|
|
try {
|
|
while (!linkFirst(node)) {
|
|
if (nanos <= 0)
|
|
return false;
|
|
nanos = notFull.awaitNanos(nanos);
|
|
}
|
|
return true;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws InterruptedException {@inheritDoc}
|
|
*/
|
|
public boolean offerLast(E e, long timeout, TimeUnit unit)
|
|
throws InterruptedException {
|
|
if (e == null) throw new NullPointerException();
|
|
Node<E> node = new Node<E>(e);
|
|
long nanos = unit.toNanos(timeout);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lockInterruptibly();
|
|
try {
|
|
while (!linkLast(node)) {
|
|
if (nanos <= 0)
|
|
return false;
|
|
nanos = notFull.awaitNanos(nanos);
|
|
}
|
|
return true;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws NoSuchElementException {@inheritDoc}
|
|
*/
|
|
public E removeFirst() {
|
|
E x = pollFirst();
|
|
if (x == null) throw new NoSuchElementException();
|
|
return x;
|
|
}
|
|
|
|
/**
|
|
* @throws NoSuchElementException {@inheritDoc}
|
|
*/
|
|
public E removeLast() {
|
|
E x = pollLast();
|
|
if (x == null) throw new NoSuchElementException();
|
|
return x;
|
|
}
|
|
|
|
public E pollFirst() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return unlinkFirst();
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public E pollLast() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return unlinkLast();
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public E takeFirst() throws InterruptedException {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
E x;
|
|
while ( (x = unlinkFirst()) == null)
|
|
notEmpty.await();
|
|
return x;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public E takeLast() throws InterruptedException {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
E x;
|
|
while ( (x = unlinkLast()) == null)
|
|
notEmpty.await();
|
|
return x;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public E pollFirst(long timeout, TimeUnit unit)
|
|
throws InterruptedException {
|
|
long nanos = unit.toNanos(timeout);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lockInterruptibly();
|
|
try {
|
|
E x;
|
|
while ( (x = unlinkFirst()) == null) {
|
|
if (nanos <= 0)
|
|
return null;
|
|
nanos = notEmpty.awaitNanos(nanos);
|
|
}
|
|
return x;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public E pollLast(long timeout, TimeUnit unit)
|
|
throws InterruptedException {
|
|
long nanos = unit.toNanos(timeout);
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lockInterruptibly();
|
|
try {
|
|
E x;
|
|
while ( (x = unlinkLast()) == null) {
|
|
if (nanos <= 0)
|
|
return null;
|
|
nanos = notEmpty.awaitNanos(nanos);
|
|
}
|
|
return x;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws NoSuchElementException {@inheritDoc}
|
|
*/
|
|
public E getFirst() {
|
|
E x = peekFirst();
|
|
if (x == null) throw new NoSuchElementException();
|
|
return x;
|
|
}
|
|
|
|
/**
|
|
* @throws NoSuchElementException {@inheritDoc}
|
|
*/
|
|
public E getLast() {
|
|
E x = peekLast();
|
|
if (x == null) throw new NoSuchElementException();
|
|
return x;
|
|
}
|
|
|
|
public E peekFirst() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return (first == null) ? null : first.item;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public E peekLast() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return (last == null) ? null : last.item;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public boolean removeFirstOccurrence(Object o) {
|
|
if (o == null) return false;
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
for (Node<E> p = first; p != null; p = p.next) {
|
|
if (o.equals(p.item)) {
|
|
unlink(p);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public boolean removeLastOccurrence(Object o) {
|
|
if (o == null) return false;
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
for (Node<E> p = last; p != null; p = p.prev) {
|
|
if (o.equals(p.item)) {
|
|
unlink(p);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
// BlockingQueue methods
|
|
|
|
/**
|
|
* Inserts the specified element at the end of this deque unless it would
|
|
* violate capacity restrictions. When using a capacity-restricted deque,
|
|
* it is generally preferable to use method {@link #offer offer}.
|
|
*
|
|
* <p>This method is equivalent to {@link #addLast}.
|
|
*
|
|
* @throws IllegalStateException if the element cannot be added at this
|
|
* time due to capacity restrictions
|
|
* @throws NullPointerException if the specified element is null
|
|
*/
|
|
@Override
|
|
public boolean add(E e) {
|
|
addLast(e);
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException if the specified element is null
|
|
*/
|
|
public boolean offer(E e) {
|
|
return offerLast(e);
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws InterruptedException {@inheritDoc}
|
|
*/
|
|
public void put(E e) throws InterruptedException {
|
|
putLast(e);
|
|
}
|
|
|
|
/**
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws InterruptedException {@inheritDoc}
|
|
*/
|
|
public boolean offer(E e, long timeout, TimeUnit unit)
|
|
throws InterruptedException {
|
|
return offerLast(e, timeout, unit);
|
|
}
|
|
|
|
/**
|
|
* Retrieves and removes the head of the queue represented by this deque.
|
|
* This method differs from {@link #poll poll} only in that it throws an
|
|
* exception if this deque is empty.
|
|
*
|
|
* <p>This method is equivalent to {@link #removeFirst() removeFirst}.
|
|
*
|
|
* @return the head of the queue represented by this deque
|
|
* @throws NoSuchElementException if this deque is empty
|
|
*/
|
|
@Override
|
|
public E remove() {
|
|
return removeFirst();
|
|
}
|
|
|
|
public E poll() {
|
|
return pollFirst();
|
|
}
|
|
|
|
public E take() throws InterruptedException {
|
|
return takeFirst();
|
|
}
|
|
|
|
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
|
|
return pollFirst(timeout, unit);
|
|
}
|
|
|
|
/**
|
|
* Retrieves, but does not remove, the head of the queue represented by
|
|
* this deque. This method differs from {@link #peek peek} only in that
|
|
* it throws an exception if this deque is empty.
|
|
*
|
|
* <p>This method is equivalent to {@link #getFirst() getFirst}.
|
|
*
|
|
* @return the head of the queue represented by this deque
|
|
* @throws NoSuchElementException if this deque is empty
|
|
*/
|
|
@Override
|
|
public E element() {
|
|
return getFirst();
|
|
}
|
|
|
|
public E peek() {
|
|
return peekFirst();
|
|
}
|
|
|
|
/**
|
|
* Returns the number of additional elements that this deque can ideally
|
|
* (in the absence of memory or resource constraints) accept without
|
|
* blocking. This is always equal to the initial capacity of this deque
|
|
* less the current {@code size} of this deque.
|
|
*
|
|
* <p>Note that you <em>cannot</em> always tell if an attempt to insert
|
|
* an element will succeed by inspecting {@code remainingCapacity}
|
|
* because it may be the case that another thread is about to
|
|
* insert or remove an element.
|
|
*/
|
|
public int remainingCapacity() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return capacity - count;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @throws UnsupportedOperationException {@inheritDoc}
|
|
* @throws ClassCastException {@inheritDoc}
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws IllegalArgumentException {@inheritDoc}
|
|
*/
|
|
public int drainTo(Collection<? super E> c) {
|
|
return drainTo(c, Integer.MAX_VALUE);
|
|
}
|
|
|
|
/**
|
|
* @throws UnsupportedOperationException {@inheritDoc}
|
|
* @throws ClassCastException {@inheritDoc}
|
|
* @throws NullPointerException {@inheritDoc}
|
|
* @throws IllegalArgumentException {@inheritDoc}
|
|
*/
|
|
public int drainTo(Collection<? super E> c, int maxElements) {
|
|
if (c == null)
|
|
throw new NullPointerException();
|
|
if (c == this)
|
|
throw new IllegalArgumentException();
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
int n = Math.min(maxElements, count);
|
|
for (int i = 0; i < n; i++) {
|
|
c.add(first.item); // In this order, in case add() throws.
|
|
unlinkFirst();
|
|
}
|
|
return n;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
// Stack methods
|
|
|
|
/**
|
|
* @throws IllegalStateException {@inheritDoc}
|
|
* @throws NullPointerException {@inheritDoc}
|
|
*/
|
|
public void push(E e) {
|
|
addFirst(e);
|
|
}
|
|
|
|
/**
|
|
* @throws NoSuchElementException {@inheritDoc}
|
|
*/
|
|
public E pop() {
|
|
return removeFirst();
|
|
}
|
|
|
|
// Collection methods
|
|
|
|
/**
|
|
* Removes the first occurrence of the specified element from this deque.
|
|
* If the deque does not contain the element, it is unchanged.
|
|
* More formally, removes the first element {@code e} such that
|
|
* {@code o.equals(e)} (if such an element exists).
|
|
* Returns {@code true} if this deque contained the specified element
|
|
* (or equivalently, if this deque changed as a result of the call).
|
|
*
|
|
* <p>This method is equivalent to
|
|
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}.
|
|
*
|
|
* @param o element to be removed from this deque, if present
|
|
* @return {@code true} if this deque changed as a result of the call
|
|
*/
|
|
@Override
|
|
public boolean remove(Object o) {
|
|
return removeFirstOccurrence(o);
|
|
}
|
|
|
|
/**
|
|
* Returns the number of elements in this deque.
|
|
*
|
|
* @return the number of elements in this deque
|
|
*/
|
|
@Override
|
|
public int size() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
return count;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Returns {@code true} if this deque contains the specified element.
|
|
* More formally, returns {@code true} if and only if this deque contains
|
|
* at least one element {@code e} such that {@code o.equals(e)}.
|
|
*
|
|
* @param o object to be checked for containment in this deque
|
|
* @return {@code true} if this deque contains the specified element
|
|
*/
|
|
@Override
|
|
public boolean contains(Object o) {
|
|
if (o == null) return false;
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
for (Node<E> p = first; p != null; p = p.next)
|
|
if (o.equals(p.item))
|
|
return true;
|
|
return false;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* TODO: Add support for more efficient bulk operations.
|
|
*
|
|
* We don't want to acquire the lock for every iteration, but we
|
|
* also want other threads a chance to interact with the
|
|
* collection, especially when count is close to capacity.
|
|
*/
|
|
|
|
// /**
|
|
// * Adds all of the elements in the specified collection to this
|
|
// * queue. Attempts to addAll of a queue to itself result in
|
|
// * {@code IllegalArgumentException}. Further, the behavior of
|
|
// * this operation is undefined if the specified collection is
|
|
// * modified while the operation is in progress.
|
|
// *
|
|
// * @param c collection containing elements to be added to this queue
|
|
// * @return {@code true} if this queue changed as a result of the call
|
|
// * @throws ClassCastException {@inheritDoc}
|
|
// * @throws NullPointerException {@inheritDoc}
|
|
// * @throws IllegalArgumentException {@inheritDoc}
|
|
// * @throws IllegalStateException {@inheritDoc}
|
|
// * @see #add(Object)
|
|
// */
|
|
// public boolean addAll(Collection<? extends E> c) {
|
|
// if (c == null)
|
|
// throw new NullPointerException();
|
|
// if (c == this)
|
|
// throw new IllegalArgumentException();
|
|
// final ReentrantLock lock = this.lock;
|
|
// lock.lock();
|
|
// try {
|
|
// boolean modified = false;
|
|
// for (E e : c)
|
|
// if (linkLast(e))
|
|
// modified = true;
|
|
// return modified;
|
|
// } finally {
|
|
// lock.unlock();
|
|
// }
|
|
// }
|
|
|
|
/**
|
|
* Returns an array containing all of the elements in this deque, in
|
|
* proper sequence (from first to last element).
|
|
*
|
|
* <p>The returned array will be "safe" in that no references to it are
|
|
* maintained by this deque. (In other words, this method must allocate
|
|
* a new array). The caller is thus free to modify the returned array.
|
|
*
|
|
* <p>This method acts as bridge between array-based and collection-based
|
|
* APIs.
|
|
*
|
|
* @return an array containing all of the elements in this deque
|
|
*/
|
|
@Override
|
|
@SuppressWarnings("unchecked")
|
|
public Object[] toArray() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
Object[] a = new Object[count];
|
|
int k = 0;
|
|
for (Node<E> p = first; p != null; p = p.next)
|
|
a[k++] = p.item;
|
|
return a;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Returns an array containing all of the elements in this deque, in
|
|
* proper sequence; the runtime type of the returned array is that of
|
|
* the specified array. If the deque fits in the specified array, it
|
|
* is returned therein. Otherwise, a new array is allocated with the
|
|
* runtime type of the specified array and the size of this deque.
|
|
*
|
|
* <p>If this deque fits in the specified array with room to spare
|
|
* (i.e., the array has more elements than this deque), the element in
|
|
* the array immediately following the end of the deque is set to
|
|
* {@code null}.
|
|
*
|
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between
|
|
* array-based and collection-based APIs. Further, this method allows
|
|
* precise control over the runtime type of the output array, and may,
|
|
* under certain circumstances, be used to save allocation costs.
|
|
*
|
|
* <p>Suppose {@code x} is a deque known to contain only strings.
|
|
* The following code can be used to dump the deque into a newly
|
|
* allocated array of {@code String}:
|
|
*
|
|
* <pre>
|
|
* String[] y = x.toArray(new String[0]);</pre>
|
|
*
|
|
* Note that {@code toArray(new Object[0])} is identical in function to
|
|
* {@code toArray()}.
|
|
*
|
|
* @param a the array into which the elements of the deque are to
|
|
* be stored, if it is big enough; otherwise, a new array of the
|
|
* same runtime type is allocated for this purpose
|
|
* @return an array containing all of the elements in this deque
|
|
* @throws ArrayStoreException if the runtime type of the specified array
|
|
* is not a supertype of the runtime type of every element in
|
|
* this deque
|
|
* @throws NullPointerException if the specified array is null
|
|
*/
|
|
@Override
|
|
@SuppressWarnings("unchecked")
|
|
public <T> T[] toArray(T[] a) {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
if (a.length < count)
|
|
a = (T[])java.lang.reflect.Array.newInstance
|
|
(a.getClass().getComponentType(), count);
|
|
|
|
int k = 0;
|
|
for (Node<E> p = first; p != null; p = p.next)
|
|
a[k++] = (T)p.item;
|
|
if (a.length > k)
|
|
a[k] = null;
|
|
return a;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
@Override
|
|
public String toString() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
Node<E> p = first;
|
|
if (p == null)
|
|
return "[]";
|
|
|
|
StringBuilder sb = new StringBuilder();
|
|
sb.append('[');
|
|
for (;;) {
|
|
E e = p.item;
|
|
sb.append(e == this ? "(this Collection)" : e);
|
|
p = p.next;
|
|
if (p == null)
|
|
return sb.append(']').toString();
|
|
sb.append(',').append(' ');
|
|
}
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Atomically removes all of the elements from this deque.
|
|
* The deque will be empty after this call returns.
|
|
*/
|
|
@Override
|
|
public void clear() {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
for (Node<E> f = first; f != null; ) {
|
|
f.item = null;
|
|
Node<E> n = f.next;
|
|
f.prev = null;
|
|
f.next = null;
|
|
f = n;
|
|
}
|
|
first = last = null;
|
|
count = 0;
|
|
notFull.signalAll();
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Returns an iterator over the elements in this deque in proper sequence.
|
|
* The elements will be returned in order from first (head) to last (tail).
|
|
*
|
|
* <p>The returned iterator is a "weakly consistent" iterator that
|
|
* will never throw {@link java.util.ConcurrentModificationException
|
|
* ConcurrentModificationException}, and guarantees to traverse
|
|
* elements as they existed upon construction of the iterator, and
|
|
* may (but is not guaranteed to) reflect any modifications
|
|
* subsequent to construction.
|
|
*
|
|
* @return an iterator over the elements in this deque in proper sequence
|
|
*/
|
|
@Override
|
|
public Iterator<E> iterator() {
|
|
return new Itr();
|
|
}
|
|
|
|
/**
|
|
* Returns an iterator over the elements in this deque in reverse
|
|
* sequential order. The elements will be returned in order from
|
|
* last (tail) to first (head).
|
|
*
|
|
* <p>The returned iterator is a "weakly consistent" iterator that
|
|
* will never throw {@link java.util.ConcurrentModificationException
|
|
* ConcurrentModificationException}, and guarantees to traverse
|
|
* elements as they existed upon construction of the iterator, and
|
|
* may (but is not guaranteed to) reflect any modifications
|
|
* subsequent to construction.
|
|
*
|
|
* @return an iterator over the elements in this deque in reverse order
|
|
*/
|
|
public Iterator<E> descendingIterator() {
|
|
return new DescendingItr();
|
|
}
|
|
|
|
/**
|
|
* Base class for Iterators for LinkedBlockingDeque
|
|
*/
|
|
private abstract class AbstractItr implements Iterator<E> {
|
|
/**
|
|
* The next node to return in next()
|
|
*/
|
|
Node<E> next;
|
|
|
|
/**
|
|
* nextItem holds on to item fields because once we claim that
|
|
* an element exists in hasNext(), we must return item read
|
|
* under lock (in advance()) even if it was in the process of
|
|
* being removed when hasNext() was called.
|
|
*/
|
|
E nextItem;
|
|
|
|
/**
|
|
* Node returned by most recent call to next. Needed by remove.
|
|
* Reset to null if this element is deleted by a call to remove.
|
|
*/
|
|
private Node<E> lastRet;
|
|
|
|
abstract Node<E> firstNode();
|
|
abstract Node<E> nextNode(Node<E> n);
|
|
|
|
AbstractItr() {
|
|
// set to initial position
|
|
final ReentrantLock lock = LinkedBlockingDeque.this.lock;
|
|
lock.lock();
|
|
try {
|
|
next = firstNode();
|
|
nextItem = (next == null) ? null : next.item;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Returns the successor node of the given non-null, but
|
|
* possibly previously deleted, node.
|
|
*/
|
|
private Node<E> succ(Node<E> n) {
|
|
// Chains of deleted nodes ending in null or self-links
|
|
// are possible if multiple interior nodes are removed.
|
|
for (;;) {
|
|
Node<E> s = nextNode(n);
|
|
if (s == null)
|
|
return null;
|
|
else if (s.item != null)
|
|
return s;
|
|
else if (s == n)
|
|
return firstNode();
|
|
else
|
|
n = s;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Advances next.
|
|
*/
|
|
void advance() {
|
|
final ReentrantLock lock = LinkedBlockingDeque.this.lock;
|
|
lock.lock();
|
|
try {
|
|
// assert next != null;
|
|
next = succ(next);
|
|
nextItem = (next == null) ? null : next.item;
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
public boolean hasNext() {
|
|
return next != null;
|
|
}
|
|
|
|
public E next() {
|
|
if (next == null)
|
|
throw new NoSuchElementException();
|
|
lastRet = next;
|
|
E x = nextItem;
|
|
advance();
|
|
return x;
|
|
}
|
|
|
|
public void remove() {
|
|
Node<E> n = lastRet;
|
|
if (n == null)
|
|
throw new IllegalStateException();
|
|
lastRet = null;
|
|
final ReentrantLock lock = LinkedBlockingDeque.this.lock;
|
|
lock.lock();
|
|
try {
|
|
if (n.item != null)
|
|
unlink(n);
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
}
|
|
|
|
/** Forward iterator */
|
|
private class Itr extends AbstractItr {
|
|
@Override
|
|
Node<E> firstNode() { return first; }
|
|
@Override
|
|
Node<E> nextNode(Node<E> n) { return n.next; }
|
|
}
|
|
|
|
/** Descending iterator */
|
|
private class DescendingItr extends AbstractItr {
|
|
@Override
|
|
Node<E> firstNode() { return last; }
|
|
@Override
|
|
Node<E> nextNode(Node<E> n) { return n.prev; }
|
|
}
|
|
|
|
/**
|
|
* Save the state of this deque to a stream (that is, serialize it).
|
|
*
|
|
* @serialData The capacity (int), followed by elements (each an
|
|
* {@code Object}) in the proper order, followed by a null
|
|
* @param s the stream
|
|
*/
|
|
private void writeObject(java.io.ObjectOutputStream s)
|
|
throws java.io.IOException {
|
|
final ReentrantLock lock = this.lock;
|
|
lock.lock();
|
|
try {
|
|
// Write out capacity and any hidden stuff
|
|
s.defaultWriteObject();
|
|
// Write out all elements in the proper order.
|
|
for (Node<E> p = first; p != null; p = p.next)
|
|
s.writeObject(p.item);
|
|
// Use trailing null as sentinel
|
|
s.writeObject(null);
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Reconstitute this deque from a stream (that is,
|
|
* deserialize it).
|
|
* @param s the stream
|
|
*/
|
|
private void readObject(java.io.ObjectInputStream s)
|
|
throws java.io.IOException, ClassNotFoundException {
|
|
s.defaultReadObject();
|
|
count = 0;
|
|
first = null;
|
|
last = null;
|
|
// Read in all elements and place in queue
|
|
for (;;) {
|
|
@SuppressWarnings("unchecked")
|
|
E item = (E)s.readObject();
|
|
if (item == null)
|
|
break;
|
|
add(item);
|
|
}
|
|
}
|
|
|
|
}
|