ibatis里面流控的实现
ibatis里面的流控实现是通过Throttle这个类来实现，既信号量，实例化时指定最大的访问量，每次请求时从这里获取一个信号量，如果已经达到阈值将阻塞或者抛出异常，以免大量的请求导致服务当机，每次请求时申请一个，请求结束返回，既信号量的实现，代码如下
申请资源public void increment() { synchronized (LOCK) { long totalWaitTime = 0; while (count >= limit) { if (maxWait > 0) { long waitTime = System.currentTimeMillis(); try { LOCK.wait(maxWait - totalWaitTime); } catch (InterruptedException e) { //ignore } totalWaitTime += System.currentTimeMillis() - waitTime; if (totalWaitTime > maxWait) { throw new RuntimeException("Throttle waited too long (" + totalWaitTime + " milliseconds) for lock."); } } else { try { LOCK.wait(); } catch (InterruptedException e) { //ignore } } } count++; } }释放资源 /** * Remove a reference */ public void decrement() { synchronized (LOCK) { count--; LOCK.notify(); } }客户端调用方式 /** * Pop an object from the pool * @return - the Object */ public Object pop() { throttle.increment(); return pool.remove(0); } /** * Push an object onto the pool * @param o - the object to put into the pool */ public void push(Object o) { if (o != null && o.getClass() == type) { pool.add(o); throttle.decrement(); } }