锁-swMutex

现在看swoole_init中创建锁。

typedef struct _swLock
{
    int type;
    union
    {
        swMutex mutex;
#ifdef HAVE_RWLOCK
        swRWLock rwlock;
#endif
#ifdef HAVE_SPINLOCK
        swSpinLock spinlock;
#endif
        swFileLock filelock;
        swSem sem;
        swAtomicLock atomlock;
    } object;

    int (*lock_rd)(struct _swLock *);
    int (*lock)(struct _swLock *);
    int (*unlock)(struct _swLock *);
    int (*trylock_rd)(struct _swLock *);
    int (*trylock)(struct _swLock *);
    int (*free)(struct _swLock *);
} swLock;

swLock结构体同样是定义一个‘接口’，需要注意的是里面使用了union。

typedef struct _swMutex
{
    pthread_mutex_t _lock;
    pthread_mutexattr_t attr;
} swMutex;

上是swoole封装的互斥锁。我们看swMutex创建

int swMutex_create(swLock *lock, int use_in_process)
{
    int ret;
    bzero(lock, sizeof(swLock));
    lock->type = SW_MUTEX;
    pthread_mutexattr_init(&lock->object.mutex.attr);
    if (use_in_process == 1)
    {
        pthread_mutexattr_setpshared(&lock->object.mutex.attr, PTHREAD_PROCESS_SHARED);
    }
    if ((ret = pthread_mutex_init(&lock->object.mutex._lock, &lock->object.mutex.attr)) < 0)
    {
        return SW_ERR;
    }
    lock->lock = swMutex_lock;
    lock->unlock = swMutex_unlock;
    lock->trylock = swMutex_trylock;
    lock->free = swMutex_free;
    return SW_OK;
}

基本是调用linux的api做初始化操作。几个函数中swMutex_lockwait有额外的逻辑。

int swMutex_lockwait(swLock *lock, int timeout_msec)
{
    int sub = 1;
    int sleep_ms = 1000;

    if (timeout_msec > 100)
    {
        sub = 10;
        sleep_ms = 10000;
    }

    while( timeout_msec > 0)
    {
        if (pthread_mutex_trylock(&lock->object.mutex._lock) == 0)
        {
            return 0;
        }
        else
        {
            usleep(sleep_ms);
            timeout_msec -= sub;
        }
    }
    return ETIMEDOUT;
}

如果timeout_msec大于100，相应的基数也变大。循环尝试解锁。

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