/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
* <p/>
* http://www.apache.org/licenses/LICENSE-2.0
* <p/>
* 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 org.apache.hadoop.hive.llap.daemon.impl;
import java.util.*;
import java.util.concurrent.BlockingDeque;
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
* a navigable set.
* <p/>
* <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}.
* <p/>
* <p>This class and its iterator implement all of the
* <em>optional</em> methods of the {@link Collection} and {@link
* Iterator} interfaces.
* <p/>
* This code is loosely based on the {@linkplain java.util.concurrent.LinkedBlockingDeque linked blocking deque} code.
*/
public class PriorityBlockingDeque<E>
extends AbstractQueue<E>
implements BlockingDeque<E>, java.io.Serializable {
/*
* Implemented as a navigable set protected by a
* single lock and using conditions to manage blocking.
*/
private final int capacity;
private final LinkedList<E> list;
/**
* Main lock guarding all access
*/
private 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();
private Comparator<E> comparator;
/**
* Creates a <tt>PriorityBlockingDeque</tt> with a capacity of
* {@link Integer#MAX_VALUE}.
*/
public PriorityBlockingDeque() {
this(null, Integer.MAX_VALUE);
}
/**
* Creates a <tt>PriorityBlockingDeque</tt> with the given (fixed) capacity.
*
* @param capacity the capacity of this deque
* @throws IllegalArgumentException if <tt>capacity</tt> is less than 1
*/
public PriorityBlockingDeque(int capacity) {
this(null, capacity);
}
public PriorityBlockingDeque(Comparator<E> comparator) {
this(comparator, Integer.MAX_VALUE);
}
public PriorityBlockingDeque(Comparator<E> comparator, int capacity) {
if (capacity <= 0) throw new IllegalArgumentException();
this.capacity = capacity;
this.list = new LinkedList<E>();
this.comparator = comparator;
}
// Basic adding and removing operations, called only while holding lock
/**
* Adds e or returns false if full.
*
* @param e The element to add.
* @return Whether adding was successful.
*/
private boolean innerAdd(E e) {
if (list.size() >= capacity)
return false;
int insertionPoint = Collections.binarySearch(list, e, comparator);
if (insertionPoint < 0) {
// this means the key didn't exist, so the insertion point is negative minus 1.
insertionPoint = -insertionPoint - 1;
}
list.add(insertionPoint, e);
// Inserted in sort order. Hence no explict sort.
notEmpty.signal();
return true;
}
/**
* Removes and returns first element, or null if empty.
*
* @return The removed element.
*/
private E innerRemoveFirst() {
E f = list.pollFirst();
if (f == null)
return null;
notFull.signal();
return f;
}
/**
* Removes and returns last element, or null if empty.
*
* @return The removed element.
*/
private E innerRemoveLast() {
E l = list.pollLast();
if (l == null)
return null;
notFull.signal();
return l;
}
// 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();
lock.lock();
try {
return innerAdd(e);
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
*/
@Override
public boolean offerLast(E e) {
if (e == null) throw new NullPointerException();
lock.lock();
try {
return innerAdd(e);
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
public void putFirst(E e) throws InterruptedException {
if (e == null) throw new NullPointerException();
lock.lock();
try {
while (!innerAdd(e))
notFull.await();
} finally {
lock.unlock();
}
}
/**
* @throws NullPointerException {@inheritDoc}
* @throws InterruptedException {@inheritDoc}
*/
public void putLast(E e) throws InterruptedException {
if (e == null) throw new NullPointerException();
lock.lock();
try {
while (!innerAdd(e))
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();
long nanos = unit.toNanos(timeout);
lock.lockInterruptibly();
try {
for (; ;) {
if (innerAdd(e))
return true;
if (nanos <= 0)
return false;
nanos = notFull.awaitNanos(nanos);
}
} 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();
long nanos = unit.toNanos(timeout);
lock.lockInterruptibly();
try {
for (; ;) {
if (innerAdd(e))
return true;
if (nanos <= 0)
return false;
nanos = notFull.awaitNanos(nanos);
}
} 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() {
lock.lock();
try {
return innerRemoveFirst();
} finally {
lock.unlock();
}
}
public E pollLast() {
lock.lock();
try {
return innerRemoveLast();
} finally {
lock.unlock();
}
}
public E takeFirst() throws InterruptedException {
lock.lock();
try {
E x;
while ((x = innerRemoveFirst()) == null)
notEmpty.await();
return x;
} finally {
lock.unlock();
}
}
public E takeLast() throws InterruptedException {
lock.lock();
try {
E x;
while ((x = innerRemoveLast()) == null)
notEmpty.await();
return x;
} finally {
lock.unlock();
}
}
public E pollFirst(long timeout, TimeUnit unit)
throws InterruptedException {
long nanos = unit.toNanos(timeout);
lock.lockInterruptibly();
try {
for (; ;) {
E x = innerRemoveFirst();
if (x != null)
return x;
if (nanos <= 0)
return null;
nanos = notEmpty.awaitNanos(nanos);
}
} finally {
lock.unlock();
}
}
public E pollLast(long timeout, TimeUnit unit)
throws InterruptedException {
long nanos = unit.toNanos(timeout);
lock.lockInterruptibly();
try {
for (; ;) {
E x = innerRemoveLast();
if (x != null)
return x;
if (nanos <= 0)
return null;
nanos = notEmpty.awaitNanos(nanos);
}
} 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() {
lock.lock();
try {
return list.size() == 0 ? null : list.peekFirst();
} finally {
lock.unlock();
}
}
public E peekLast() {
lock.lock();
try {
return list.size() == 0 ? null : list.peekLast();
} finally {
lock.unlock();
}
}
public boolean removeFirstOccurrence(Object o) {
if (o == null) return false;
lock.lock();
try {
for (Iterator<E> it = list.iterator(); it.hasNext();) {
E e = it.next();
if (o.equals(e)) {
it.remove();
return true;
}
}
return false;
} finally {
lock.unlock();
}
}
public boolean removeLastOccurrence(Object o) {
if (o == null) return false;
lock.lock();
try {
for (Iterator<E> it = list.descendingIterator(); it.hasNext();) {
E e = it.next();
if (o.equals(e)) {
it.remove();
return true;
}
}
return false;
} finally {
lock.unlock();
}
}
// BlockingQueue methods
/**
* Inserts the specified element to the deque unless it would
* violate capacity restrictions. When using a capacity-restricted deque,
* it is generally preferable to use method {@link #offer(Object) offer}.
* <p/>
* <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
*/
@Override
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/>
* <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/>
* <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 <tt>size</tt> of this deque.
* <p/>
* <p>Note that you <em>cannot</em> always tell if an attempt to insert
* an element will succeed by inspecting <tt>remainingCapacity</tt>
* because it may be the case that another thread is about to
* insert or remove an element.
*/
public int remainingCapacity() {
lock.lock();
try {
return capacity - list.size();
} finally {
lock.unlock();
}
}
/**
* @throws UnsupportedOperationException {@inheritDoc}
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
public int drainTo(Collection<? super E> c) {
if (c == null)
throw new NullPointerException();
if (c == this)
throw new IllegalArgumentException();
lock.lock();
try {
for (E e : list) {
c.add(e);
}
int n = list.size();
list.clear();
notFull.signalAll();
return n;
} finally {
lock.unlock();
}
}
/**
* @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();
lock.lock();
try {
int n = 0;
for (Iterator<E> it = list.iterator(); n < maxElements && it.hasNext();) {
E e = it.next();
c.add(e);
it.remove();
++n;
}
notFull.signalAll();
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 <tt>e</tt> such that
* <tt>o.equals(e)</tt> (if such an element exists).
* Returns <tt>true</tt> if this deque contained the specified element
* (or equivalently, if this deque changed as a result of the call).
* <p/>
* <p>This method is equivalent to
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}.
*
* @param o element to be removed from this deque, if present
* @return <tt>true</tt> 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() {
lock.lock();
try {
return list.size();
} finally {
lock.unlock();
}
}
/**
* Returns <tt>true</tt> if this deque contains the specified element.
* More formally, returns <tt>true</tt> if and only if this deque contains
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
*
* @param o object to be checked for containment in this deque
* @return <tt>true</tt> if this deque contains the specified element
*/
@Override
public boolean contains(Object o) {
if (o == null) return false;
lock.lock();
try {
return list.contains(o);
} finally {
lock.unlock();
}
}
/**
* Returns an array containing all of the elements in this deque, in
* proper sequence (from first to last element).
* <p/>
* <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/>
* <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
public Object[] toArray() {
lock.lock();
try {
return list.toArray();
} 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/>
* <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
* <tt>null</tt>.
* <p/>
* <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/>
* <p>Suppose <tt>x</tt> is a deque known to contain only strings.
* The following code can be used to dump the deque into a newly
* allocated array of <tt>String</tt>:
* <p/>
* <pre>
* String[] y = x.toArray(new String[0]);</pre>
* <p/>
* Note that <tt>toArray(new Object[0])</tt> is identical in function to
* <tt>toArray()</tt>.
*
* @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
public <T> T[] toArray(T[] a) {
lock.lock();
try {
return list.toArray(a);
} finally {
lock.unlock();
}
}
@Override
public String toString() {
lock.lock();
try {
return super.toString();
} 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() {
lock.lock();
try {
list.clear();
notFull.signalAll();
} finally {
lock.unlock();
}
}
@Override
public Iterator<E> iterator() {
return list.iterator();
}
public Iterator<E> descendingIterator() {
return list.descendingIterator();
}
}