Function InitMutexOwnerMapEntry

src/bthread/mutex.cpp:705–731

static MutexOwnerMapEntry g_mutex_owner_map[MUTEX_MAP_SIZE] = {}; // zero-initialize

static void InitMutexOwnerMapEntry(pthread_mutex_t* mutex,
                                   const pthread_mutexattr_t* mutexattr) {
    int type = PTHREAD_MUTEX_DEFAULT;
    if (NULL != mutexattr) {
        pthread_mutexattr_gettype(mutexattr, &type);
    }
    // Only normal mutexes are tracked.
    if (type != PTHREAD_MUTEX_NORMAL) {
        return;
    }

    // Fast path: If the hash entry is not used, use it.
    MutexOwnerMapEntry& hash_entry =
        g_mutex_owner_map[hash_mutex_ptr(mutex) & (MUTEX_MAP_SIZE - 1)];
    if (!hash_entry.valid.exchange(true, butil::memory_order_relaxed)) {
        MUTEX_RESET_OWNER_COMMON(hash_entry.owner);
        return;
    }

    // Slow path: Find an unused entry.
    for (auto& entry : g_mutex_owner_map) {
        if (!entry.valid.exchange(true, butil::memory_order_relaxed)) {
            MUTEX_RESET_OWNER_COMMON(entry.owner);
            return;
        }
    }
}

static BUTIL_FORCE_INLINE
MutexOwnerMapEntry* FindMutexOwnerMapEntry(pthread_mutex_t* mutex) {