org.apache.hadoop.hbase.procedure2.util.TimeoutBlockingQueue Maven / Gradle / Ivy
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* 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
*
* 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 org.apache.hadoop.hbase.procedure2.util;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.TimeUnit;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.classification.InterfaceStability;
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class TimeoutBlockingQueue {
public static interface TimeoutRetriever {
long getTimeout(T object);
TimeUnit getTimeUnit(T object);
}
private final ReentrantLock lock = new ReentrantLock();
private final Condition waitCond = lock.newCondition();
private final TimeoutRetriever timeoutRetriever;
private E[] objects;
private int head = 0;
private int tail = 0;
public TimeoutBlockingQueue(TimeoutRetriever timeoutRetriever) {
this(32, timeoutRetriever);
}
@SuppressWarnings("unchecked")
public TimeoutBlockingQueue(int capacity, TimeoutRetriever timeoutRetriever) {
this.objects = (E[])new Object[capacity];
this.timeoutRetriever = timeoutRetriever;
}
public void dump() {
for (int i = 0; i < objects.length; ++i) {
if (i == head) {
System.out.print("[" + objects[i] + "] ");
} else if (i == tail) {
System.out.print("]" + objects[i] + "[ ");
} else {
System.out.print(objects[i] + " ");
}
}
System.out.println();
}
public void clear() {
lock.lock();
try {
if (head != tail) {
for (int i = head; i < tail; ++i) {
objects[i] = null;
}
head = 0;
tail = 0;
waitCond.signal();
}
} finally {
lock.unlock();
}
}
public void add(E e) {
if (e == null) throw new NullPointerException();
lock.lock();
try {
addElement(e);
waitCond.signal();
} finally {
lock.unlock();
}
}
public boolean remove(E e) {
if (e == null) return false;
lock.lock();
try {
for (int i = 0; i < objects.length; ++i) {
if (e.equals(objects[i])) {
objects[i] = null;
return true;
}
}
return false;
} finally {
lock.unlock();
}
}
@edu.umd.cs.findbugs.annotations.SuppressWarnings("WA_AWAIT_NOT_IN_LOOP")
public E poll() {
lock.lock();
try {
if (isEmpty()) {
waitCond.await();
return null;
}
E elem = objects[head];
long nanos = getNanosTimeout(elem);
nanos = waitCond.awaitNanos(nanos);
return nanos > 0 ? null : removeFirst();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
return null;
} finally {
lock.unlock();
}
}
public int size() {
return tail - head;
}
public boolean isEmpty() {
return (tail - head) == 0;
}
public void signalAll() {
lock.lock();
try {
waitCond.signalAll();
} finally {
lock.unlock();
}
}
private void addElement(E elem) {
int size = (tail - head);
if ((objects.length - size) == 0) {
int capacity = size + ((size < 64) ? (size + 2) : (size >> 1));
E[] newObjects = (E[])new Object[capacity];
if (compareTimeouts(objects[tail - 1], elem) <= 0) {
// Append
System.arraycopy(objects, head, newObjects, 0, tail);
tail -= head;
newObjects[tail++] = elem;
} else if (compareTimeouts(objects[head], elem) > 0) {
// Prepend
System.arraycopy(objects, head, newObjects, 1, tail);
newObjects[0] = elem;
tail -= (head - 1);
} else {
// Insert in the middle
int index = upperBound(head, tail - 1, elem);
int newIndex = (index - head);
System.arraycopy(objects, head, newObjects, 0, newIndex);
newObjects[newIndex] = elem;
System.arraycopy(objects, index, newObjects, newIndex + 1, tail - index);
tail -= (head - 1);
}
head = 0;
objects = newObjects;
} else {
if (tail == objects.length) {
// shift down |-----AAAAAAA|
tail -= head;
System.arraycopy(objects, head, objects, 0, tail);
head = 0;
}
if (tail == head || compareTimeouts(objects[tail - 1], elem) <= 0) {
// Append
objects[tail++] = elem;
} else if (head > 0 && compareTimeouts(objects[head], elem) > 0) {
// Prepend
objects[--head] = elem;
} else {
// Insert in the middle
int index = upperBound(head, tail - 1, elem);
System.arraycopy(objects, index, objects, index + 1, tail - index);
objects[index] = elem;
tail++;
}
}
}
private E removeFirst() {
E elem = objects[head];
objects[head] = null;
head = (head + 1) % objects.length;
if (head == 0) tail = 0;
return elem;
}
private int upperBound(int start, int end, E key) {
while (start < end) {
int mid = (start + end) >>> 1;
E mitem = objects[mid];
int cmp = compareTimeouts(mitem, key);
if (cmp > 0) {
end = mid;
} else {
start = mid + 1;
}
}
return start;
}
private int compareTimeouts(final E a, final E b) {
long t1 = getNanosTimeout(a);
long t2 = getNanosTimeout(b);
return (t1 < t2) ? -1 : (t1 > t2) ? 1 : 0;
}
private long getNanosTimeout(final E obj) {
if (obj == null) return 0;
TimeUnit unit = timeoutRetriever.getTimeUnit(obj);
long timeout = timeoutRetriever.getTimeout(obj);
return unit.toNanos(timeout);
}
}
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