Semaphore

最新推荐文章于 2025-06-24 08:30:00 发布

meng_lin

最新推荐文章于 2025-06-24 08:30:00 发布

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分类专栏：线程注意点文章标签： IE C C++ C# thread

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本文介绍了一个自定义同步队列的Java实现，该队列利用Semaphore来控制生产和消费操作，确保线程安全。文章详细展示了如何通过限制队列容量来防止资源过度使用，并提供了基本的队列操作方法。

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package projects.debug.learn;

import java.util.Collection;
import java.util.Iterator;
import java.util.Queue;
import java.util.concurrent.Semaphore;

public class SyncQueue implements Queue   
{   
    private final Queue mQueue;   
    private final int mCapacity;   
    private final Semaphore mSemProducer;   
    private final Semaphore mSemConsumer;      

    public SyncQueue(Queue queue)   
    {   
        this(queue, Integer.MAX_VALUE);   
    }   

    public SyncQueue(Queue queue, int capacity)   
    {   
        mQueue = queue;   
        mCapacity = capacity;   
        mSemProducer = new Semaphore(capacity);   
        mSemConsumer = new Semaphore(0);   
    }   

    public Object get()   
    {   
        // Accquire consumer's semaphore   
        try  
        {   
            mSemConsumer.acquire();   
        }   
        catch(InterruptedException ie)   
        {   
            Thread.currentThread().interrupt();   
            return null;   
        }   

        // Get the item   
        Object item = null;   
        synchronized(mQueue)   
        {          
            item = mQueue.poll();   
        }   

        //   
        mSemProducer.release();   
        return item;   
    }   

    public boolean put(Object item)   
    {   
        // Precondition checking   
        if(item == null)   
        {   
            return false;   
        }   

        // Accquire producer's semaphore   
        try  
        {   
            mSemProducer.acquire();   
        }   
        catch(InterruptedException ie)   
        {   
            Thread.currentThread().interrupt();   
            return false;   
        }   

        // Add the item   
        synchronized(mQueue)   
        {   
            mQueue.add(item);   
        }   

        // Release consumer's semaphore   
        mSemConsumer.release();   
        return true;   
    }

	public Object element()
	{
		// TODO Auto-generated method stub
		return null;
	}

	public boolean offer(Object o)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public Object peek()
	{
		// TODO Auto-generated method stub
		return null;
	}

	public Object poll()
	{
		// TODO Auto-generated method stub
		return null;
	}

	public Object remove()
	{
		// TODO Auto-generated method stub
		return null;
	}

	public boolean add(Object o)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public boolean addAll(Collection c)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public void clear()
	{
		// TODO Auto-generated method stub

	}

	public boolean contains(Object o)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public boolean containsAll(Collection c)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public boolean isEmpty()
	{
		// TODO Auto-generated method stub
		return false;
	}

	public Iterator iterator()
	{
		// TODO Auto-generated method stub
		return null;
	}

	public boolean remove(Object o)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public boolean removeAll(Collection c)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public boolean retainAll(Collection c)
	{
		// TODO Auto-generated method stub
		return false;
	}

	public int size()
	{
		// TODO Auto-generated method stub
		return 0;
	}

	public Object[] toArray()
	{
		// TODO Auto-generated method stub
		return null;
	}

	public Object[] toArray(Object[] a)
	{
		// TODO Auto-generated method stub
		return null;
	}   
}