Function rwlock_tryrdlock

src/bthread/rwlock.cpp:86–101

Returns 0 if the lock was acquired, otherwise errno.

// Returns 0 if the lock was acquired, otherwise errno.
static  inline int rwlock_tryrdlock(bthread_rwlock_t* rwlock) {
    while (true) {
        int reader_count = ((butil::atomic<int>*)&rwlock->reader_count)
            ->load(butil::memory_order_relaxed);
        if (reader_count < 0) {
            // Failed to acquire the read lock because there is a writer.
            return EBUSY;
        }
        if (((butil::atomic<int>*)&rwlock->reader_count)
                ->compare_exchange_weak(reader_count, reader_count + 1,
                                        butil::memory_order_acquire,
                                        butil::memory_order_relaxed)) {
            return 0;
        }
    }
}

static inline int rwlock_unrdlock(bthread_rwlock_t* rwlock) {
    int reader_count = ((butil::atomic<int>*)&rwlock->reader_count)