cn.hutool.core.thread.BlockPolicy Maven / Gradle / Ivy
package cn.hutool.core.thread;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.function.Consumer;
/**
* 当任务队列过长时处于阻塞状态，直到添加到队列中
* 如果阻塞过程中被中断，就会抛出{@link InterruptedException}异常
* 有时候在线程池内访问第三方接口，只希望固定并发数去访问，并且不希望丢弃任务时使用此策略，队列满的时候会处于阻塞状态(例如刷库的场景)
*
* @author luozongle
* @since 5.8.0
*/
public class BlockPolicy implements RejectedExecutionHandler {
/**
* 线程池关闭时，为避免任务丢失，留下处理方法
* 如果需要由调用方来运行，可以{@code new BlockPolicy(Runnable::run)}
*/
private final Consumer handlerwhenshutdown;
/**
* 构造
*
* @param handlerwhenshutdown 线程池关闭后的执行策略
*/
public BlockPolicy(final Consumer handlerwhenshutdown) {
this.handlerwhenshutdown = handlerwhenshutdown;
}
/**
* 构造
*/
public BlockPolicy() {
this(null);
}
@Override
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
// 线程池未关闭时，阻塞等待
if (false == e.isShutdown()) {
try {
e.getQueue().put(r);
} catch (InterruptedException ex) {
throw new RejectedExecutionException("Task " + r + " rejected from " + e);
}
} else if (null != handlerwhenshutdown) {
// 当设置了关闭时候的处理
handlerwhenshutdown.accept(r);
}
// 线程池关闭后，丢弃任务
}
}