sviolet.thistle.model.concurrent.lock.UnsafeSpinLock Maven / Gradle / Ivy
/*
* Copyright (C) 2015-2018 S.Violet
*
* 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.
*
* Project GitHub: https://github.com/shepherdviolet/thistle
* Email: [email protected]
*/
package sviolet.thistle.model.concurrent.lock;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
/**
* 慎用!!! 不规范的使用会导致严重的问题!!!
* IT'S UNSAFE !!! Irregular use can cause serious problems !!!
*
* 简易自旋锁, 未提供任何保护措施, 需要仔细阅读源码并谨慎使用.
*
*
* private UnsafeSpinLock spinLock = new UnsafeSpinLock();
*
* public void setXXX(int xxx) {
* try {
* spinLock.lock();
* //do something ...
* } finally {
* spinLock.unlock();
* }
* }
*
*
* @author S.Violet
*/
public class UnsafeSpinLock implements Lock {
private AtomicBoolean lock = new AtomicBoolean(false);
private Thread acquiredThread;
/**
* Lock, the thread will be blocked.
* IT'S UNSAFE !!! Irregular use can cause serious problems !!!
*
*
* private UnsafeSpinLock spinLock = new UnsafeSpinLock();
*
* public void setXXX(int xxx) {
* try {
* spinLock.lock();
* //do something ...
* } finally {
* spinLock.unlock();
* }
* }
*
*
*/
@Override
public void lock(){
while (true) {
if (tryLock()) {
break;
} else {
Thread.yield();
}
}
}
/**
* Unlock
* IT'S UNSAFE !!! Irregular use can cause serious problems !!!
*
*
* private UnsafeSpinLock spinLock = new UnsafeSpinLock();
*
* public void setXXX(int xxx) {
* try {
* spinLock.lock();
* //do something ...
* } finally {
* spinLock.unlock();
* }
* }
*
*
*/
@Override
public void unlock(){
if (Thread.currentThread() != this.acquiredThread) {
throw new IllegalStateException("The lock is not acquired by this thread");
}
this.acquiredThread = null;
lock.set(false);
}
/**
* Try to lock, return true if acquired successfully, return false if failed immediately, no blocking
*
*
* private UnsafeSpinLock spinLock = new UnsafeSpinLock();
*
* public void setXXX(int xxx) {
* if (spinLock.lock()) {
* try {
* //do something ...
* } finally {
* spinLock.unlock();
* }
* }
* }
*
*
* @return true: Acquired the lock successfully
*/
@Override
public boolean tryLock() {
if (lock.compareAndSet(false, true)) {
acquiredThread = Thread.currentThread();
return true;
}
return false;
}
/**
* Deprecated!!
* Lock, the thread will be blocked until acquired or interrupted
* IT'S UNSAFE !!! Irregular use can cause serious problems !!!
*
*
* private UnsafeSpinLock spinLock = new UnsafeSpinLock();
*
* public void setXXX(int xxx) {
* try {
* spinLock.lockInterruptibly();
* } catch (InterruptedException e) {
* //interrupted
* return;
* }
* try {
* //do something ...
* } finally {
* spinLock.unlock();
* }
* }
*
*
* @throws InterruptedException Thread interrupted
* @deprecated Although it is implemented, but it is not recommended to use
*/
@Override
@Deprecated
public void lockInterruptibly() throws InterruptedException {
while (!Thread.currentThread().isInterrupted()) {
if (tryLock()) {
break;
} else {
Thread.yield();
}
}
}
/**
* @deprecated Unsupported Operation
*/
@Override
@Deprecated
public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
throw new UnsupportedOperationException("tryLock method is unsupported in UnsafeSpinLock");
}
/**
* @deprecated Unsupported Operation
*/
@Override
@Deprecated
public Condition newCondition() {
throw new UnsupportedOperationException("newCondition method is unsupported in UnsafeSpinLock");
}
}