利用Linux系统函数实现线程池(C++)

昨天在笔试freewheel遇到一个编程题，要求实现C语言的线程池，可以利用Linux的系统函数，自己尝试写了写，但是由于函数调用回调的参数不知道该怎么写，实现的并不好。今天在博客上搜了搜，发现有人给出了实现，但是代码贴得太乱，所以自己转载过来，方便自己和他人以后用的时候看一下。

Thread.h

#ifndef __THREAD_H
#define __THREAD_H

#include <vector>
#include <string>
#include <pthread.h>

using namespace std;

/**
* 执行任务的类，设置任务数据并执行
*/
class CTask
{
protected:
string m_strTaskName;  /** 任务的名称 */
void* m_ptrData;       /** 要执行的任务的具体数据 */
public:
CTask(){}
CTask(string taskName)
{
m_strTaskName = taskName;
m_ptrData = NULL;
}
virtual int Run()= 0;
void SetData(void* data);    /** 设置任务数据 */

public:
virtual ~CTask(){}
};

/**
* 线程池管理类的实现
*/
class CThreadPool
{
private:
static 	vector<CTask*> m_vecTaskList;     /** 任务列表 */
static	bool shutdown;                    /** 线程退出标志 */
int 	m_iThreadNum;                     /** 线程池中启动的线程数 */
pthread_t	*pthread_id;

static pthread_mutex_t m_pthreadMutex;    /** 线程同步锁 */
static pthread_cond_t m_pthreadCond;      /** 线程同步的条件变量 */

protected:
static void* ThreadFunc(void * threadData); /** 新线程的线程回调函数 */
static int MoveToIdle(pthread_t tid);       /** 线程执行结束后，把自己放入到空闲线程中 */
static int MoveToBusy(pthread_t tid);       /** 移入到忙碌线程中去 */

int Create();          /** 创建线程池中的线程 */

public:
CThreadPool(int threadNum = 10);
int AddTask(CTask *task);      /** 把任务添加到任务队列中 */
int StopAll();                 /** 使线程池中的线程退出 */
int getTaskSize();             /** 获取当前任务队列中的任务数 */
};

#endif

实现文件
Thread.cpp

#include "Thread.h"
#include <iostream>

void CTask::SetData(void * data)
{
m_ptrData = data;
}

vector<CTask*> CThreadPool::m_vecTaskList;         //任务列表
bool CThreadPool::shutdown = false;

pthread_mutex_t CThreadPool::m_pthreadMutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t CThreadPool::m_pthreadCond = PTHREAD_COND_INITIALIZER;

/**
* 线程池管理类构造函数
*/
CThreadPool::CThreadPool(int threadNum)
{
this->m_iThreadNum = threadNum;
cout << "I will create " << threadNum << " threads" << endl;
Create();
}

/**
* 线程回调函数
*/
void* CThreadPool::ThreadFunc(void* threadData)
{
pthread_t tid = pthread_self();
while (1)
{
pthread_mutex_lock(&m_pthreadMutex);
while (m_vecTaskList.size() == 0 && !shutdown)
{
pthread_cond_wait(&m_pthreadCond, &m_pthreadMutex);
}

if (shutdown)
{
pthread_mutex_unlock(&m_pthreadMutex);
printf("thread %lu will exit/n", pthread_self());
pthread_exit(NULL);
}

printf("tid %lu run/n", tid);
vector<CTask*>::iterator iter = m_vecTaskList.begin();

/**
* 取出一个任务并处理之
*/
CTask* task = *iter;
if (iter != m_vecTaskList.end())
{
task = *iter;
m_vecTaskList.erase(iter);
}

pthread_mutex_unlock(&m_pthreadMutex);

task->Run(); /** 执行任务 */
printf("tid:%lu idle/n", tid);
}
return (void*)0;
}

/**
* 往任务队列里边添加任务并发出线程同步信号
*/
int CThreadPool::AddTask(CTask *task)
{
pthread_mutex_lock(&m_pthreadMutex);
this->m_vecTaskList.push_back(task);
pthread_mutex_unlock(&m_pthreadMutex);
pthread_cond_signal(&m_pthreadCond);
return 0;
}

/**
* 创建线程
*/
int CThreadPool::Create()
{
pthread_id = (pthread_t*)malloc(sizeof(pthread_t) * m_iThreadNum);
for(int i = 0; i < m_iThreadNum; i++)
{
pthread_create(&pthread_id[i], NULL, ThreadFunc, NULL);
}
return 0;
}

/**
* 停止所有线程
*/
int CThreadPool::StopAll()
{
/** 避免重复调用 */
if (shutdown)
{
return -1;
}
printf("Now I will end all threads!!/n");
/** 唤醒所有等待线程，线程池要销毁了 */
shutdown = true;
pthread_cond_broadcast(&m_pthreadCond);

/** 阻塞等待线程退出，否则就成僵尸了 */
for (int i = 0; i < m_iThreadNum; i++)
{
pthread_join(pthread_id[i], NULL);
}

free(pthread_id);
pthread_id = NULL;

/** 销毁条件变量和互斥体 */
pthread_mutex_destroy(&m_pthreadMutex);
pthread_cond_destroy(&m_pthreadCond);

return 0;
}

/**
* 获取当前队列中任务数
*/
int CThreadPool::getTaskSize()
{
return m_vecTaskList.size();
}

Main函数文件

#include "Thread.h"
#include <iostream>

class CMyTask: public CTask
{
public:
CMyTask(){}

inline int Run()
{
printf("%s/n", (char*)this->m_ptrData);
sleep(10);
return 0;
}
};

int main()
{
CMyTask taskObj;

char szTmp[] = "this is the first thread running";
taskObj.SetData((void*)szTmp);
CThreadPool threadPool(10);

for(int i = 0; i < 20; i++)
{
threadPool.AddTask(&taskObj);
}

while(1)
{
printf("there are still %d tasks need to handle/n", threadPool.getTaskSize());
if (threadPool.getTaskSize() == 0)
{
if (threadPool.StopAll() == -1)
{
printf("Now I will exit from main/n");
exit(0);
}
}
sleep(2);
}

return 0;
}

Makefile文件

CC := g++
TARGET := threadpool
INCLUDE := -I./
LIBS := -lpthread

# C++语言编译参数
CXXFLAGS := -g -Wall -D_REENTRANT

# C预处理参数
# CPPFLAGS :=

OBJECTS := test.o Thread.o

$(TARGET): $(OBJECTS)
$(CC) -o $(TARGET) $(OBJECTS) $(LIBS)

# $@表示所有目标集
%.o:%.cpp
$(CC) -c $(CXXFLAGS) $(INCLUDE) $< -o $@

.PHONY : clean
clean:
-rm -f $(OBJECTS) $(TARGET)

Linux上输出

I will create 10 threads
there are still 10 tasks need to handle
tid 3086535568 run
this is the first thread running
tid 3084434320 run
this is the first thread running
tid 3082333072 run
this is the first thread running
tid 3080231824 run
this is the first thread running
tid 3078130576 run
this is the first thread running
tid 3076029328 run
this is the first thread running
tid 3073928080 run
this is the first thread running
tid 3071826832 run
this is the first thread running
tid 3069725584 run
this is the first thread running
tid 3067624336 run
this is the first thread running
there are still 0 tasks need to handle
Now I will end all threads!!
tid:3086535568 idle
tid:3078130576 idle
thread 3078130576 will exit
tid:3076029328 idle
thread 3076029328 will exit
tid:3073928080 idle
thread 3073928080 will exit
tid:3071826832 idle
thread 3071826832 will exit
tid:3069725584 idle
thread 3069725584 will exit
tid:3067624336 idle
thread 3067624336 will exit
tid:3084434320 idle
thread 3084434320 will exit
thread 3086535568 will exit
tid:3082333072 idle
thread 3082333072 will exit
tid:3080231824 idle
thread 3080231824 will exit
there are still 0 tasks need to handle
Now I will exit from main