【自定义线程池逻辑实现】

【自定义线程池逻辑实现】

package cn.itcast.n8;

import lombok.extern.slf4j.Slf4j;
import org.springframework.core.log.LogDelegateFactory;

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.HashSet;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

@Slf4j(topic = "c.TestPool")
public class TestPool {
    
    
    public static void main(String[] args) {
    
    
        ThreadPool threadPool = new ThreadPool(1,
                1000, TimeUnit.MILLISECONDS, 1, (queue, task)->{
    
    
            // 1. 死等
//            queue.put(task);
            // 2) 带超时等待
//            queue.offer(task, 1500, TimeUnit.MILLISECONDS);
            // 3) 让调用者放弃任务执行
//            log.debug("放弃{}", task);
            // 4) 让调用者抛出异常
//            throw new RuntimeException("任务执行失败 " + task);
            // 5) 让调用者自己执行任务
            task.run();
        });
        for (int i = 0; i < 4; i++) {
    
    
            int j = i;
            threadPool.execute(() -> {
    
    
                try {
    
    
                    Thread.sleep(1000L);
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }
                log.debug("{}", j);

            });
        }
    }
}

@FunctionalInterface // 拒绝策略
interface RejectPolicy<T> {
    
    
    void reject(BlockingQueue<T> queue, T task);
}

@Slf4j(topic = "c.ThreadPool")
class ThreadPool {
    
    
    // 任务队列
    private BlockingQueue<Runnable> taskQueue;

    // 线程集合
    private HashSet<Worker> workers = new HashSet<>();

    // 核心线程数
    private int coreSize;

    // 获取任务时的超时时间
    private long timeout;

    private TimeUnit timeUnit;

    private RejectPolicy<Runnable> rejectPolicy;

    // 执行任务
    public void execute(Runnable task) {
    
    
        // 当任务数没有超过 coreSize 时，直接交给 worker 对象执行
        // 如果任务数超过 coreSize 时，加入任务队列暂存
        synchronized (workers) {
    
    
            if(workers.size() < coreSize) {
    
    
                Worker worker = new Worker(task);
                log.debug("新增 worker{}, {}", worker, task);
                workers.add(worker);
                worker.start();
            } else {
    
    
//                taskQueue.put(task);
                // 1) 死等
                // 2) 带超时等待
                // 3) 让调用者放弃任务执行
                // 4) 让调用者抛出异常
                // 5) 让调用者自己执行任务
                taskQueue.tryPut(rejectPolicy, task);
            }
        }
    }

    public ThreadPool(int coreSize, long timeout, TimeUnit timeUnit, int queueCapcity, RejectPolicy<Runnable> rejectPolicy) {
    
    
        this.coreSize = coreSize;
        this.timeout = timeout;
        this.timeUnit = timeUnit;
        this.taskQueue = new BlockingQueue<>(queueCapcity);
        this.rejectPolicy = rejectPolicy;
    }

    class Worker extends Thread{
    
    
        private Runnable task;

        public Worker(Runnable task) {
    
    
            this.task = task;
        }

        @Override
        public void run() {
    
    
            // 执行任务
            // 1) 当 task 不为空，执行任务
            // 2) 当 task 执行完毕，再接着从任务队列获取任务并执行
//            while(task != null || (task = taskQueue.take()) != null) {
    
    
            while(task != null || (task = taskQueue.poll(timeout, timeUnit)) != null) {
    
    
                try {
    
    
                    log.debug("正在执行...{}", task);
                    task.run();
                } catch (Exception e) {
    
    
                    e.printStackTrace();
                } finally {
    
    
                    task = null;
                }
            }
            synchronized (workers) {
    
    
                log.debug("worker 被移除{}", this);
                workers.remove(this);
            }
        }
    }
}
@Slf4j(topic = "c.BlockingQueue")
class BlockingQueue<T> {
    
    
    // 1. 任务队列
    private Deque<T> queue = new ArrayDeque<>();

    // 2. 锁
    private ReentrantLock lock = new ReentrantLock();

    // 3. 生产者条件变量
    private Condition fullWaitSet = lock.newCondition();

    // 4. 消费者条件变量
    private Condition emptyWaitSet = lock.newCondition();

    // 5. 容量
    private int capcity;

    public BlockingQueue(int capcity) {
    
    
        this.capcity = capcity;
    }

    // 带超时阻塞获取
    public T poll(long timeout, TimeUnit unit) {
    
    
        lock.lock();
        try {
    
    
            // 将 timeout 统一转换为 纳秒
            long nanos = unit.toNanos(timeout);
            while (queue.isEmpty()) {
    
    
                try {
    
    
                    // 返回值是剩余时间
                    if (nanos <= 0) {
    
    
                        return null;
                    }
                    nanos = emptyWaitSet.awaitNanos(nanos);
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }
            }
            T t = queue.removeFirst();
            fullWaitSet.signal();
            return t;
        } finally {
    
    
            lock.unlock();
        }
    }

    // 阻塞获取
    public T take() {
    
    
        lock.lock();
        try {
    
    
            while (queue.isEmpty()) {
    
    
                try {
    
    
                    emptyWaitSet.await();
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }
            }
            T t = queue.removeFirst();
            fullWaitSet.signal();
            return t;
        } finally {
    
    
            lock.unlock();
        }
    }

    // 阻塞添加
    public void put(T task) {
    
    
        lock.lock();
        try {
    
    
            while (queue.size() == capcity) {
    
    
                try {
    
    
                    log.debug("等待加入任务队列 {} ...", task);
                    fullWaitSet.await();
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }
            }
            log.debug("加入任务队列 {}", task);
            queue.addLast(task);
            emptyWaitSet.signal();
        } finally {
    
    
            lock.unlock();
        }
    }

    // 带超时时间阻塞添加
    public boolean offer(T task, long timeout, TimeUnit timeUnit) {
    
    
        lock.lock();
        try {
    
    
            long nanos = timeUnit.toNanos(timeout);
            while (queue.size() == capcity) {
    
    
                try {
    
    
                    if(nanos <= 0) {
    
    
                        return false;
                    }
                    log.debug("等待加入任务队列 {} ...", task);
                    nanos = fullWaitSet.awaitNanos(nanos);
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }
            }
            log.debug("加入任务队列 {}", task);
            queue.addLast(task);
            emptyWaitSet.signal();
            return true;
        } finally {
    
    
            lock.unlock();
        }
    }

    public int size() {
    
    
        lock.lock();
        try {
    
    
            return queue.size();
        } finally {
    
    
            lock.unlock();
        }
    }
	//  线程池满了怎么添加任务
    public void tryPut(RejectPolicy<T> rejectPolicy, T task) {
    
    
        lock.lock();
        try {
    
    
            // 判断队列是否满
            if(queue.size() == capcity) {
    
    
                rejectPolicy.reject(this, task);
            } else {
    
      // 有空闲
                log.debug("加入任务队列 {}", task);
                queue.addLast(task);
                emptyWaitSet.signal();
            }
        } finally {
    
    
            lock.unlock();
        }
    }
}