package mon;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReadWriteLock;

import java.util.concurrent.locks.ReentrantReadWriteLock;

import org.apache.log4j.Logger;

import cn.guagua.mobile.cache.redis.Redis;

/**

* 读写锁控制强制读取缓存同步

* @author shma

* @date 2014-10-11 15:04:28

*/

public class SynchCacheLock {

private static final Logger logger = Logger.getLogger(SynchCacheLock.class);

private static Redis.RedisClient redis1 = new Redis.RedisClient("1");

private ReadWriteLock lock = null;

private Lock readLock = null; // 读锁

private Lock writeLock = null; // 写锁

public SynchCacheLock() {

lock = new ReentrantReadWriteLock();

readLock = lock.readLock();

writeLock = lock.writeLock();

System.out.println(Thread.currentThread().getName() + ">>> cache lock init...");

}

public T getCache(String key, Runnable task) {

T obj = null;

readLock.lock();

try {

obj = (T) redis1.getObject(key);

if(obj == null) {

System.out.println(Thread.currentThread().getName() + " read request " + key + " is null, wait query...");

readLock.unlock();

writeLock.lock();

try {

obj = (T) redis1.getObject(key);

if(obj == null) {

task.run();//强制执行执行写缓存任务

System.out.println(Thread.currentThread().getName() + " read request " + key + " end...");

obj = (T) redis1.getObject(key);

}

} catch(Throwable e) {

System.out.println("readLock error...");

e.printStackTrace();

} finally {

readLock.lock();

writeLock.unlock();

}

}

System.out.println(Thread.currentThread().getName() + " read request " + key + " data...");

} catch(Throwable e) {

System.out.println("lock error...");

e.printStackTrace();

} finally {

readLock.unlock();

}

return obj;

}

}