cc/gapic/android/mutex.cpp

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <gapic/mutex.h>
#include <gapic/assert.h>

#include <pthread.h>

namespace gapic {

Mutex::Mutex() {
    auto mutex = new pthread_mutex_t();
    GAPID_ASSERT(pthread_mutex_init(mutex, nullptr) == 0);
    _ = mutex;
}

Mutex::~Mutex() {
    auto mutex = reinterpret_cast<pthread_mutex_t*>(_);
    GAPID_ASSERT(pthread_mutex_destroy(mutex) == 0);
    delete mutex;
}

void Mutex::lock() {
    auto mutex = reinterpret_cast<pthread_mutex_t*>(_);
    GAPID_ASSERT(pthread_mutex_lock(mutex) == 0);
}

void Mutex::unlock() {
    auto mutex = reinterpret_cast<pthread_mutex_t*>(_);
    GAPID_ASSERT(pthread_mutex_unlock(mutex) == 0);
}

CycleMutex::CycleMutex() : count(0) {
    auto mutex = new pthread_mutex_t();
    // Make a recursive lock, so that we can detect cyclic locking.
    pthread_mutexattr_t attr;
    GAPID_ASSERT(pthread_mutexattr_init(&attr) == 0);
    GAPID_ASSERT(pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE) == 0);
    GAPID_ASSERT(pthread_mutex_init(mutex, &attr) == 0);
    GAPID_ASSERT(pthread_mutexattr_destroy(&attr) == 0);
    _ = mutex;
}

CycleMutex::~CycleMutex() {
    auto mutex = reinterpret_cast<pthread_mutex_t*>(_);
    GAPID_ASSERT(pthread_mutex_destroy(mutex) == 0);
    delete mutex;
    _ = nullptr;
}

bool CycleMutex::lock() {
    auto mutex = reinterpret_cast<pthread_mutex_t*>(_);
    GAPID_ASSERT(pthread_mutex_lock(mutex) == 0);
    ++count;
    // As we have PTHREAD_MUTEX_RECURSIVE we can get the lock more than once,
    // but only in the same thread.
    if (count > 1) {
        --count;
        GAPID_ASSERT(pthread_mutex_unlock(mutex) == 0);
        // We already have the lock
        return false;
    }
    return true;
}

void CycleMutex::unlock() {
    auto mutex = reinterpret_cast<pthread_mutex_t*>(_);
    --count;
    GAPID_ASSERT(pthread_mutex_unlock(mutex) == 0);
}

}  // namespace gapic