C++ 11 STL 线程库实现的线程同步与互斥

　　以前操作系统课程设计的时候，我们在Linux操作系统中用C语言和POSIX线程库编写过线程同步与互斥。

/*
 * thread_synchronization.c
 * 
 * Copyright 2012 叶剑飞
 *
 * 编译命令：
 *        gcc thread_synchronization.c -o thread_synchronization \
 *              -std=gnu99 -pedantic-errors -D_REENTRANT -pthread -Wall
 * 
 */


#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <pthread.h>
#include <unistd.h>
#include <semaphore.h>
#include <time.h>

typedef int COUNT;

sem_t p12, p13, p24, p25, p35, p46, p56;
int maxLoop[7];

void * thread1 ( void * args )
{
    for ( COUNT i = 0 ; i < maxLoop[1] ; i ++ )
    {
        puts( "I am thread one." );
        usleep(500000);
    }
    sem_post( &p12 );
    sem_post( &p13 );
    return NULL;
}

void * thread2 ( void * args )
{
    sem_wait( &p12 );
    for ( COUNT i = 0 ; i < maxLoop[2] ; i ++ )
    {
        puts( "I am thread two." );
        usleep(500000);
    }
    sem_post( &p24 );
    sem_post( &p25 );
    return NULL;
}

void * thread3 ( void * args )
{
    sem_wait( &p13 );
    for ( COUNT i = 0 ; i < maxLoop[3] ; i ++ )
    {
        puts( "I am thread three." );
        usleep(500000);
    }
    sem_post( &p35 );
    return NULL;
}

void * thread4 ( void * args )
{
    sem_wait( &p24 );
    for ( COUNT i = 0 ; i < maxLoop[4] ; i ++ )
    {
        puts( "I am thread four." );
        usleep(500000);
    }
    sem_post( &p46 );
    return NULL;
}

void * thread5 ( void * args )
{
    sem_wait( &p25 );
    sem_wait( &p35 );
    for ( COUNT i = 0 ; i < maxLoop[5] ; i ++ )
    {
        puts( "I am thread five." );
        usleep(500000);
    }
    sem_post( &p56 );
    return NULL;
}

void * thread6 ( void * args )
{
    sem_wait( &p46 );
    sem_wait( &p56 );
    for ( COUNT i = 0 ; i < maxLoop[6] ; i ++ )
    {
        puts( "I am thread six." );
        usleep(500000);
    }
    return NULL;
}

int main (void)
{
    pthread_t threadid[7];
    const int n = 10;

    srand( time(NULL) );

    for ( COUNT i = 1 ; i < 7 ; i ++ )
        maxLoop[i] = (rand() % n) + 1;

    if ( sem_init( &p12, 0, 0 ) == -1 )
    {
        fprintf( stderr, "Error Initializing Semaphore\n\n");
        return EXIT_FAILURE;
    }
    if ( sem_init( &p13, 0, 0 ) == -1 )
    {
        fprintf( stderr, "Error Initializing Semaphore\n\n");
        return EXIT_FAILURE;
    }
    if ( sem_init( &p24, 0, 0 ) == -1 )
    {
        fprintf( stderr, "Error Initializing Semaphore\n\n");
        return EXIT_FAILURE;
    }
    if ( sem_init( &p25, 0, 0 ) == -1 )
    {
        fprintf( stderr, "Error Initializing Semaphore\n\n");
        return EXIT_FAILURE;
    }
    if ( sem_init( &p35, 0, 0 ) == -1 )
    {
        fprintf( stderr, "Error Initializing Semaphore\n\n");
        return EXIT_FAILURE;
    }
    if ( sem_init( &p46, 0, 0 ) == -1 )
    {
        fprintf( stderr, "Error Initializing Semaphore\n\n");
        return EXIT_FAILURE;
    }
    if ( sem_init( &p56, 0, 0 ) == -1 )
    {
        fprintf( stderr, "Error Initializing Semaphore\n\n");
        return EXIT_FAILURE;
    }

    if ( pthread_create( &threadid[1], NULL, thread1, NULL ) )
    {
        fprintf( stderr, "Error Creating Thread.\n\n" );
        return EXIT_FAILURE;
    }
    if ( pthread_create( &threadid[2], NULL, thread2, NULL ) )
    {
        fprintf( stderr, "Error Creating Thread.\n\n" );
        return EXIT_FAILURE;
    }
    if ( pthread_create( &threadid[3], NULL, thread3, NULL ) )
    {
        fprintf( stderr, "Error Creating Thread.\n\n" );
        return EXIT_FAILURE;
    }
    if ( pthread_create( &threadid[4], NULL, thread4, NULL ) )
    {
        fprintf( stderr, "Error Creating Thread.\n\n" );
        return EXIT_FAILURE;
    }
    if ( pthread_create( &threadid[5], NULL, thread5, NULL ) )
    {
        fprintf( stderr, "Error Creating Thread.\n\n" );
        return EXIT_FAILURE;
    }
    if ( pthread_create( &threadid[6], NULL, thread6, NULL ) )
    {
        fprintf( stderr, "Error Creating Thread.\n\n" );
        return EXIT_FAILURE;
    }

    for ( COUNT i = 1 ; i < 7 ; i ++ )
    {
        if ( pthread_join( threadid[i] , NULL ) )
        {
            fprintf( stderr, "Error Joining Thread.\n\n" );
            return EXIT_FAILURE;
        }
    }

    return EXIT_SUCCESS;
}

　　今天突然想起此事，于是用C++ 11标准新引入的STL线程库重新实现一遍。

/*
 * thread_synchronization.cpp
 * 
 * Copyright 2013 叶剑飞
 *
 * 编译命令：
 *       g++ thread_synchronization.cpp -o thread_synchronization -Wall -std=c++11 -pthread 
 *
 */


#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <thread>
#include <mutex>
#include <chrono>

using namespace std;

typedef int COUNT;

mutex p12, p13, p24, p25, p35, p46, p56;
int maxLoop[7];

void thread1 ( )
{
    for ( COUNT i = 0 ; i < maxLoop[1] ; i ++ )
    {
        puts( "I am thread one." );
        this_thread::sleep_for(chrono::milliseconds(500));
    }
    p12.unlock( );
    p13.unlock( );
}

void thread2 ( )
{
    p12.lock( );
    for ( COUNT i = 0 ; i < maxLoop[2] ; i ++ )
    {
        puts( "I am thread two." );
        this_thread::sleep_for(chrono::milliseconds(500));
    }
    p24.unlock( );
    p25.unlock( );
}

void thread3 ( )
{
    p13.lock( );
    for ( COUNT i = 0 ; i < maxLoop[3] ; i ++ )
    {
        puts( "I am thread three." );
        this_thread::sleep_for(chrono::milliseconds(500));
    }
    p35.unlock( );
}

void thread4 (  )
{
    p24.lock( );
    for ( COUNT i = 0 ; i < maxLoop[4] ; i ++ )
    {
        puts( "I am thread four." );
        this_thread::sleep_for(chrono::milliseconds(500));
    }
    p46.unlock( );
}

void thread5 (  )
{
    p25.lock( );
    p35.lock( );
    for ( COUNT i = 0 ; i < maxLoop[5] ; i ++ )
    {
        puts( "I am thread five." );
        this_thread::sleep_for(chrono::milliseconds(500));
    }
    p56.unlock( );
}

void thread6 ( )
{
    p46.lock( );
    p56.lock( );
    for ( COUNT i = 0 ; i < maxLoop[6] ; i ++ )
    {
        puts( "I am thread six." );
        this_thread::sleep_for(chrono::milliseconds(500));
    }
}

bool LockAllMutex ( )
{
    try
    {
        p12.lock( );
        p13.lock( );
        p24.lock( );
        p25.lock( );
        p35.lock( );
        p46.lock( );
        p56.lock( );
    }
    catch ( ... )
    {
        return false;
    }

    return true;
}

bool CreateAllThread( thread * threadid )
{
    try
    {
        threadid[1] = thread( thread1 );
        threadid[2] = thread( thread2 );
        threadid[3] = thread( thread3 );
        threadid[4] = thread( thread4 );
        threadid[5] = thread( thread5 );
        threadid[6] = thread( thread6 );
    }
    catch( ... )
    {
        return false;
    }

    return true;
}

int main (void)
{
    thread threadid[7];
    const int n = 10;

    srand( time(NULL) );

    for ( COUNT i = 1 ; i < 7 ; i ++ )
        maxLoop[i] = (rand() % n) + 1;

    if ( !LockAllMutex ( ) )
    {
        fprintf( stderr, "Error Locking the Mutex \n\n");
        return EXIT_FAILURE;
    }

    if ( !CreateAllThread( threadid ) )
    {
        fprintf( stderr, "Error Creating Thread.\n\n" );
        return EXIT_FAILURE;
    }

    for ( COUNT i = 1 ; i < 7 ; i ++ )
    {
        try
        {
            threadid[i].join( );
        }
        catch( ... )
        {
            fprintf( stderr, "Error Joining Thread.\n\n" );
            return EXIT_FAILURE;
        }
    }

    return EXIT_SUCCESS;
}

　　发现C++ 11线程真心简单。