一个高效率的线程池类

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最新推荐文章于 2025-05-21 11:52:39 发布

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分类专栏： vc/c++ 文章标签： thread 任务 null 多线程游戏工作

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MMORPG游戏服务端线程池类
线程池:
线程是一种比较昂贵的资源.有些系统为了重用线程.引入了线程池的机制.
线程池的工作原理如下：
首先.系统会启动一定数量的线程.这些线程就构成了一个线程池.当有任务要做的时候.系统就从线程池里面选一个空闲的线程.然后把这个线程标记为“正在运行”.然后把任务传给这个线程执行.线程执行任务完成之后.就把自己标记为"空闲".这个过程并不难以理解.难以理解的是.一般来说.线程执行完成之后.运行栈等系统资源就会释放.线程对象就被回收了.一个已经完成的线程.又如何能回到线程池的空闲线程队列中呢? 秘诀就在于.线程池里面的线程永远不会执行完成.线程池里面的线程都是一个无穷循环

ThreadStarter.h

#ifndef __THREADSTARTER_H__
#define __THREADSTARTER_H__

#include <windows.h>

//线程接口
class ThreadBase
{
public:
    ThreadBase() {}
    virtual ~ThreadBase() {}
    virtual bool run() = 0;//线程函数
    virtual void OnShutdown() {}
    HANDLE THREAD_HANDLE;
};

#endif

Threads.h

#ifndef __CTHREADS_H__
#define __CTHREADS_H__

#include "ThreadStarter.h"

//线程的状态
enum CThreadState
{
    THREADSTATE_TERMINATE = 0,//终止
    THREADSTATE_PAUSED    = 1,//暂停
    THREADSTATE_SLEEPING  = 2,//睡眠
    THREADSTATE_BUSY      = 3,//忙碌
    THREADSTATE_AWAITING  = 4,//等候
};

//线程基类
class CThread : public ThreadBase
{

public:
    CThread();
    ~CThread();
    virtual bool run();
    virtual void OnShutdown();

    //设置线程的状态
    __forceinline void SetThreadState(CThreadState thread_state)
    {
        ThreadState = thread_state;
    }
    //返回线程的状态
    __forceinline CThreadState GetThreadState()
    {
        return ThreadState;
    }
    //返回线程ID
    int GetThreadId()
    {
        return ThreadId;
    }
    time_t GetStartTime()
    {
        return start_time;
    }

protected:
    CThreadState ThreadState;//线程的状态
    time_t start_time;
    int ThreadId;//线程ID

};

#endif

Threads.cpp

#include "stdafx.h"
#include "CThreads.h"

CThread::CThread() : ThreadBase()
{
    //初试化线程的状态为等候
    ThreadState = THREADSTATE_AWAITING;
    start_time  = 0;
}

CThread::~CThread()
{

}

bool CThread::run()
{
    return false;
}

void CThread::OnShutdown()
{
    SetThreadState(THREADSTATE_TERMINATE);
}

Mutex.h

#ifndef __MUTEX_H__
#define __MUTEX_H__

#include <windows.h>

//多个线程操作相同的数据时，一般是需要按顺序访问的，否则会引导数据错乱
//为解决这个问题，就需要引入互斥变量，让每个线程都按顺序地访问变量。
class Mutex
{
public:
    Mutex();
    ~Mutex();

    __forceinline void Acquire()
    {
        EnterCriticalSection(&cs);
    }

    __forceinline void Release()
    {
        LeaveCriticalSection(&cs);
    }
    /*
    例如：
    线程操作函数。
    int AddCount(void)
    {
        EnterCriticalSection(&cs);
        int nRet = m_nCount++;
        LeaveCriticalSection(&cs);
        return nRet;
    }
    在函数AddCount里调用EnterCriticalSection和LeaveCriticalSection来互斥访问变量m_nCount。
    通过上面这种方法，就可以实现多线程按顺序地访问相同的变量
    */
    __forceinline bool AttemptAcquire()
    {
        //一个线程也可以调用TryEnterCriticalSection函数来请求某个临界区的所有权,此时即
        //使请求失败也不会被阻塞
        return 0;//(TryEnterCriticalSection(&cs) == TRUE ? true : false);
    }

protected:
    CRITICAL_SECTION cs;//临界区是一种防止多个线程同时执行一个特定代码节的机制

};

#endif

Mutex.cpp

#include "stdafx.h"
#include "Mutex.h"

Mutex::Mutex()
{
    //创建临界区对象
    InitializeCriticalSection(&cs);
}
Mutex::~Mutex()
{
    //删除临界区对象
    DeleteCriticalSection(&cs);
}

ThreadPool.h

#ifndef __THREADPOOL_H__
#define __THREADPOOL_H__

#include "ThreadStarter.h"
#include "Mutex.h"

#include <windows.h>
#include <assert.h>
#include <set>

typedef unsigned int uint32;
typedef signed __int32 int32;

//线程管理
class ThreadController
{
public:
    HANDLE hThread;
    uint32 thread_id;

    void Setup(HANDLE h)
    {
        hThread = h;
    }
    void Suspend()
    {
        assert(GetCurrentThreadId() == thread_id);
        //当线程做完任务或者现在想暂停线程运行，就需要使用SuspendThread来暂停线程的执行
        SuspendThread(hThread);

    }

    //恢复线程的执行就是使用ResumeThread函数了
    void Resume()
    {
        assert(GetCurrentThreadId() != thread_id);
        if(!ResumeThread(hThread))
        {
            DWORD le = GetLastError();
            printf("error: %u/n", le);
        }
    }

    void Join()
    {
        //WaitForSingleObject函数用来检测hHandle事件的信号状态，当函数的执行时间超过dwMilliseconds就返回
        WaitForSingleObject(hThread, INFINITE);
    }

    uint32 GetId()
    {
        return thread_id;
    }

};

struct Thread
{
    ThreadBase* ExecutionTarget;
    ThreadController ControlInterface;
    Mutex SetupMutex;//线程的互斥
    bool DeleteAfterExit;
};

typedef std::set<Thread*> ThreadSet;

//线程池类
class CThreadPool
{
    //uint32 _threadsRequestedSinceLastCheck;
    //uint32 _threadsFreedSinceLastCheck;
    //uint32 _threadsExitedSinceLastCheck;
    uint32 _threadsToExit;
    int32 _threadsEaten;//可用线程数量
    Mutex _mutex;

    ThreadSet m_activeThreads;//正在执行任务线程对列
    ThreadSet m_freeThreads;//可用线程对列

public:
    CThreadPool();

    void IntegrityCheck();

    //创建指定数量的线程并加到线程池
    void Startup();

    //销毁线程
    void Shutdown();


    bool ThreadExit(Thread * t);

    Thread* StartThread(ThreadBase * ExecutionTarget);

    //从线程池取得可用线程并执行任务
    void ExecuteTask(ThreadBase * ExecutionTarget);

    void ShowStats();


    void KillFreeThreads(uint32 count);


    //__forceinline void Gobble(){
    //    _threadsEaten=(int32)m_freeThreads.size();
    //}

    __forceinline uint32 GetActiveThreadCount(){
        return (uint32)m_activeThreads.size();
    }

    __forceinline uint32 GetFreeThreadCount(){
        return (uint32)m_freeThreads.size();
    }
};

extern CThreadPool ThreadPool;//线程池

#endif

ThreadPool.cpp

#include "stdafx.h"
#include "ThreadPool.h"
#include <process.h>

CThreadPool ThreadPool;

CThreadPool::CThreadPool()
{
    //_threadsExitedSinceLastCheck = 0;
    //_threadsRequestedSinceLastCheck = 0;
    _threadsEaten = 0;
    //_threadsFreedSinceLastCheck = 0;
}

bool CThreadPool::ThreadExit(Thread * t)
{
    _mutex.Acquire();

    m_activeThreads.erase(t);

    if(_threadsToExit > 0)
    {
        --_threadsToExit;
        //++_threadsExitedSinceLastCheck;
        if(t->DeleteAfterExit)
            m_freeThreads.erase(t);

        _mutex.Release();
        delete t;
        return false;
    }

    // enter the "suspended" pool
    //++_threadsExitedSinceLastCheck;
    ++_threadsEaten;
    std::set<Thread*>::iterator itr = m_freeThreads.find(t);

    if(itr != m_freeThreads.end())
    {

    }
    m_freeThreads.insert(t);

    _mutex.Release();

    return true;

}

void CThreadPool::ExecuteTask(ThreadBase * ExecutionTarget)
{

    Thread * t;
    _mutex.Acquire();
    //++_threadsRequestedSinceLastCheck;
    --_threadsEaten;

    //从线程池夺取一个线程
    if(m_freeThreads.size())//有可用线程
    {
        //得到一个可用线程
        t = *m_freeThreads.begin();
        //把它从可用线程对列里删掉
        m_freeThreads.erase(m_freeThreads.begin());

        //给这个线程一个任务
        t->ExecutionTarget = ExecutionTarget;

        //恢复线程的执行
        t->ControlInterface.Resume();
    }
    else
    {

        //创建一个新的线程并执行任务
        t = StartThread(ExecutionTarget);
    }

    //把线程加到执行任务线程对列
    m_activeThreads.insert(t);
    _mutex.Release();

}

void CThreadPool::Startup()
{
    int i;
    int tcount = 5;

    for(i=0; i < tcount; ++i)
        StartThread(NULL);

}

void CThreadPool::ShowStats()
{
    _mutex.Acquire();

    //在这里输出线程池的状态
    //

    _mutex.Release();
}

void CThreadPool::KillFreeThreads(uint32 count)
{
    _mutex.Acquire();
    Thread * t;
    ThreadSet::iterator itr;
    uint32 i;
    for(i = 0, itr = m_freeThreads.begin(); i < count && itr != m_freeThreads.end(); ++i, ++itr)
    {
        t = *itr;
        t->ExecutionTarget = NULL;
        t->DeleteAfterExit = true;
        ++_threadsToExit;
        t->ControlInterface.Resume();
    }
    _mutex.Release();
}

void CThreadPool::Shutdown()
{
    _mutex.Acquire();
    size_t tcount = m_activeThreads.size() + m_freeThreads.size();

    KillFreeThreads((uint32)m_freeThreads.size());
    _threadsToExit += (uint32)m_activeThreads.size();

    for(ThreadSet::iterator itr = m_activeThreads.begin(); itr != m_activeThreads.end(); ++itr)
    {
        if((*itr)->ExecutionTarget)
            (*itr)->ExecutionTarget->OnShutdown();
    }
    _mutex.Release();

    for(;;)
    {
        _mutex.Acquire();
        if(m_activeThreads.size() || m_freeThreads.size())
        {
            _mutex.Release();
            Sleep(1000);
            continue;
        }

        break;
    }
}

static unsigned long WINAPI thread_proc(void* param)
{
    Thread * t = (Thread*)param;
    t->SetupMutex.Acquire();
    uint32 tid = t->ControlInterface.GetId();
    bool ht = (t->ExecutionTarget != NULL);
    t->SetupMutex.Release();

    for(;;)
    {
        if(t->ExecutionTarget != NULL)
        {
            if(t->ExecutionTarget->run())//执行任务,返回true表示任务完成
                delete t->ExecutionTarget;

            t->ExecutionTarget = NULL;
        }

        if(!ThreadPool.ThreadExit(t))
        {
            //Log.Debug("ThreadPool", "Thread %u exiting.", tid);
            break;
        }
        else
        {
            //if(ht)
            //    printf("ThreadPool:线程%d正在等待新任务.", tid);
            t->ControlInterface.Suspend();//暂停线程运行
        }
    }

    ExitThread(0);

    return 0;
}

Thread * CThreadPool::StartThread(ThreadBase * ExecutionTarget)
{
    HANDLE h;
    Thread * t = new Thread;

    t->DeleteAfterExit = false;
    t->ExecutionTarget = ExecutionTarget;
    t->SetupMutex.Acquire();
    /*
    CreateThread(
    lpThreadAttributes是线程的属性,
    dwStackSize是线程的栈大小,
    lpStartAddress是线程函数的开始地址,
    lpParameter是传送给线程函数的参数,
    dwCreationFlags是创建线程标志，比如挂起线程,
    lpThreadId是标识这个线程的ID)
    */
    h = CreateThread(NULL, 0, &thread_proc, (LPVOID)t, 0, (LPDWORD)&t->ControlInterface.thread_id);
    t->ControlInterface.Setup(h);
    t->SetupMutex.Release();

    return t;
}