线程同步（老师在课堂上写的）

form:luozhiyong131.blog.chinaunix.net
/*
 * Produce/Consume using multithread
 */

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <string.h>
#include <assert.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>

#define BSIZE    30        //buffer size
#define PRODUCE_EXIT    '~'    //produce thread exit flag
#define CONSUME_EXIT    '@'    //consume thread exit flag
#define PRODUCE_NUMBER    3    //produce thread number
#define CONSUME_NUMBER    5    //consume thread number

typedef struct buffer_t
{
    char            buf[BSIZE];
    int                occupied;    //product number
    int                nextin;
    int                nextout;
    pthread_mutex_t    mutex;
    pthread_cond_t    less;
    pthread_cond_t    more;
}buffer_t;

pthread_once_t once = PTHREAD_ONCE_INIT;

buffer_t ware;

/*
 * initialization
 */
void init(void)
{
    memset(&ware, 0, sizeof(ware));
    pthread_mutex_init(&ware.mutex, NULL);
    pthread_cond_init(&ware.less, NULL);
    pthread_cond_init(&ware.more, NULL);
}
/*
 * destroy
 */
void destroy(void)
{
    pthread_mutex_destroy(&ware.mutex);
    pthread_cond_destroy(&ware.less);
    pthread_cond_destroy(&ware.more);
}

/*
 * The produce thread
 */
void * threadProduce(void * arg)
{
    char c = 0;
    struct timespec tt;
    int result;

    while(c != PRODUCE_EXIT)
    {
        //read product from keyboard
        c = getchar();
        if(c == '\n')
            continue;

        //lock mutex
        assert( pthread_mutex_lock(&ware.mutex) == 0);
        //condition wait
        tt.tv_sec = time(NULL)+1;
        tt.tv_nsec= 0;
        if(ware.occupied >= BSIZE)
        {
            result = pthread_cond_timedwait(
                        &ware.more,
                        &ware.mutex,
                        &tt);
            if(result == ETIMEDOUT)
            {
                assert( pthread_mutex_unlock(&ware.mutex) == 0);
                continue;
            }else if(result != 0)
            {
                printf("pthread_cond_timedwait ERROR.\n");
                assert( pthread_mutex_unlock(&ware.mutex) == 0);
                pthread_exit(NULL);
            }
        }
        //insert product into buf
        ware.buf[ware.nextin] = c;
        ware.occupied++;
        ware.nextin = (ware.nextin+1)%BSIZE;

        printf("produce: [tid=%u] [%c].\n",
                pthread_self(), c);

        //aware the consume thread
        pthread_cond_signal(&ware.less);
        //unlock mutex
        assert( pthread_mutex_unlock(&ware.mutex) == 0);
        sleep(1);
    }
    printf("produce [tid=%u] EXIT.\n", pthread_self());
    pthread_exit(NULL);
}

/*
 * The consume thread
 */
void * threadConsume(void * arg)
{
    char c = 0;
    struct timespec tt;
    int result;

    while(c != CONSUME_EXIT)
    {
        //lock mutex
        assert( pthread_mutex_lock(&ware.mutex) == 0);
        //condition wait
        tt.tv_sec = time(NULL)+1;
        tt.tv_nsec= 0;
        if(ware.occupied <= 0)
        {
            result = pthread_cond_timedwait(
                        &ware.less,
                        &ware.mutex,
                        &tt);
            if(result == ETIMEDOUT)
            {
                assert( pthread_mutex_unlock(&ware.mutex) == 0);
                continue;
            }else if(result != 0)
            {
                printf("pthread_cond_timedwait ERROR.\n");
                assert( pthread_mutex_unlock(&ware.mutex) == 0);
                pthread_exit(NULL);
            }
        }
        //read product from buf
        c = ware.buf[ware.nextout];
        ware.occupied--;
        ware.nextout = (ware.nextout+1)%BSIZE;
        printf("consume: [tid=%u] [%c].\n",
                pthread_self(), c);

        //aware the produce thread
        pthread_cond_signal(&ware.more);
        //unlock mutex
        assert( pthread_mutex_unlock(&ware.mutex) == 0);
        sleep(1);
    }
    printf("consume [tid=%u] EXIT.\n", pthread_self());
    pthread_exit(NULL);
}

int main(void)
{
    pthread_t tid[PRODUCE_NUMBER+CONSUME_NUMBER];
    int i;

    pthread_once(&once, init);
    for(i=0; i<PRODUCE_NUMBER; i++)
    {
        if( pthread_create(&tid[i], NULL,
                    threadProduce, NULL) )
        {
            printf("pthread_create ERROR.\n");
            destroy();
            exit(-1);
        }
    }
    for(; i<PRODUCE_NUMBER+CONSUME_NUMBER; i++)
    {
        if( pthread_create(&tid[i], NULL,
                    threadConsume, NULL) )
        {
            printf("pthread_create ERROR.\n");
            destroy();
            exit(-1);
        }
    }

    for(i=0; i<PRODUCE_NUMBER+CONSUME_NUMBER; i++)
    {
        pthread_join(tid[i], NULL);
    }
    destroy();

    pthread_exit(NULL);
}

/*
 * 线程同步
 */
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <assert.h>

int product = 0;

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;

/*
 * 线程函数 读
 */
void * threadRead(void * arg)
{
    int cnt = 0;
    while(cnt++ < 100)
    {
//        assert( pthread_mutex_lock(&mutex) == 0);
        assert( pthread_rwlock_rdlock(&rwlock) == 0);

        printf("Read: product = %d\n", product);

//        assert( pthread_mutex_unlock(&mutex) == 0);
        assert( pthread_rwlock_unlock(&rwlock) == 0);
        sleep(1);
    }
    pthread_exit(NULL);
}

/*
 * 线程函数 写 增加
 */
void * threadProduce(void * arg)
{
    int cnt = 0;
    while(cnt++ < 100)
    {
//        assert( pthread_mutex_lock(&mutex) == 0);
        assert( pthread_rwlock_wrlock(&rwlock) == 0);

        product++;
        printf("Produce: product = %d\n", product);

//        assert( pthread_mutex_unlock(&mutex) == 0);
        assert( pthread_rwlock_unlock(&rwlock) == 0);
        sleep(2);
    }
    pthread_exit(NULL);
}

/*
 * 线程函数 写 减少
 */
void * threadConsume(void * arg)
{
    int cnt = 0;
    while(cnt++ < 100)
    {
//        assert( pthread_mutex_lock(&mutex) == 0);
        assert( pthread_rwlock_wrlock(&rwlock) == 0);

        product--;
        printf("Consume: product = %d\n", product);

//        assert( pthread_mutex_unlock(&mutex) == 0);
        assert( pthread_rwlock_unlock(&rwlock) == 0);
        sleep(2);
    }
    pthread_exit(NULL);
}

int main(void)
{
    pthread_t tidRead[20], tidProduce, tidConsume;
    int i;

    for(i=0; i<20; i++)
        if( pthread_create(&tidRead[i], NULL,
                        threadRead, NULL) )
        {
            printf("pthread_create ERROR\n");
            exit(-1);
        }

    if( pthread_create(&tidProduce, NULL,
                    threadProduce, NULL) )
    {
        printf("pthread_create ERROR\n");
        exit(-1);
    }

    if( pthread_create(&tidConsume, NULL,
                    threadConsume, NULL) )
    {
        printf("pthread_create ERROR\n");
        exit(-1);
    }

    pthread_exit(NULL);
}