com.generallycloud.baseio.concurrent.ListQueueLink Maven / Gradle / Ivy
/*
* Copyright 2015-2017 GenerallyCloud.com
*
* 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 com.generallycloud.baseio.concurrent;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import com.generallycloud.baseio.component.Linkable;
public class ListQueueLink> implements ListQueue {
private ReentrantLock lock = new ReentrantLock();
private Condition empty = lock.newCondition();
private int size;
private Linkable head = null;
private Linkable tail = null;
@Override
public boolean offer(T object) {
ReentrantLock lock = this.lock;
lock.lock();
try {
if (size == 0) {
head = tail = object;
empty.signal();
} else {
tail.setNext(object);
tail = object;
}
size++;
return true;
} finally {
lock.unlock();
}
}
@Override
public T poll() {
ReentrantLock lock = this.lock;
lock.lock();
try {
if (size == 0) {
return null;
}
return get();
} finally {
lock.unlock();
}
}
@Override
public T poll(long timeout) {
ReentrantLock lock = this.lock;
lock.lock();
try {
if (size == 0) {
try {
empty.await(timeout, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
empty.signal();
}
if (size == 0) {
return null;
}
return get();
}
return get();
} finally {
lock.unlock();
}
}
private T get(){
Linkable t = head;
Linkable next = t.getNext();
if (next == null) {
head = tail = null;
} else {
head = next;
}
size--;
return t.getValue();
}
@Override
public int size() {
return size;
}
}