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fix redis null pointer exception

master
yihua.huang 2013-07-26 19:12:55 +08:00
parent 2c97dd90c7
commit 2bb6f84742
1 changed files with 6 additions and 30 deletions
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36
webmagic-plugin/webmagic-misc/src/main/java/us/codecraft/webmagic/scheduler/RedisScheduler.java
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@ -7,9 +7,6 @@ import us.codecraft.webmagic.Request;
import us.codecraft.webmagic.Task;
import us.codecraft.webmagic.schedular.Scheduler;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
/**
* 使用redis管理url，构建一个分布式的爬虫。<br>
*
@ -25,10 +22,6 @@ public class RedisScheduler implements Scheduler {
private static final String SET_PREFIX = "set_";
private ReentrantLock lock = new ReentrantLock();
private Condition condition = lock.newCondition();
public RedisScheduler(String host) {
pool = new JedisPool(new JedisPoolConfig(), host);
}
@ -38,15 +31,9 @@ public class RedisScheduler implements Scheduler {
Jedis jedis = pool.getResource();
//使用SortedSet进行url去重
if (jedis.zrank(SET_PREFIX + task.getUUID(), request.getUrl()) == null) {
try {
lock.lock();
//使用List保存队列
jedis.rpush(QUEUE_PREFIX + task.getUUID(), request.getUrl());
jedis.zadd(SET_PREFIX + task.getUUID(), System.currentTimeMillis(), request.getUrl());
condition.signal();
} finally {
lock.unlock();
}
//使用List保存队列
jedis.rpush(QUEUE_PREFIX + task.getUUID(), request.getUrl());
jedis.zadd(SET_PREFIX + task.getUUID(), System.currentTimeMillis(), request.getUrl());
}
pool.returnResource(jedis);
}
@ -55,21 +42,10 @@ public class RedisScheduler implements Scheduler {
public synchronized Request poll(Task task) {
Jedis jedis = pool.getResource();
String url = jedis.lpop(QUEUE_PREFIX + task.getUUID());
if (url == null) {
try {
lock.lock();
while (url == null) {
try {
condition.await();
url = jedis.lpop(QUEUE_PREFIX + task.getUUID());
} catch (InterruptedException e) {
}
}
} finally {
lock.unlock();
}
}
pool.returnResource(jedis);
if (url==null){
return null;
}
return new Request(url);
}
}