platform_system_core/logd/rwlock.h
Tom Cherry 9b4246dc2d logd: fix various clang-tidy issues
In order of severity:
1) Add a CHECK() that a pointer is not nullptr, where the analyzer
   believes this is possible.
2) Add `final` appropriately to functions called from constructors.
3) Add missing cloexec flags.
4) Add missing `noexcept` and other subtle performance warnings

Test: build with clang-tidy
Change-Id: Ifd9a1299a51027a47382926b2224748b5750d6cf
2020-06-17 11:40:55 -07:00

56 lines
1.8 KiB
C++

/*
* Copyright (C) 2020 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/LICENSE2.0
*
* 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.
*/
#pragma once
#include <pthread.h>
#include <android-base/macros.h>
#include <android-base/thread_annotations.h>
// As of the end of May 2020, std::shared_mutex is *not* simply a pthread_rwlock, but rather a
// combination of std::mutex and std::condition variable, which is obviously less efficient. This
// immitates what std::shared_mutex should be doing and is compatible with RAII thread wrappers.
class SHARED_CAPABILITY("mutex") RwLock {
public:
RwLock() {}
~RwLock() {}
void lock() ACQUIRE() { pthread_rwlock_wrlock(&rwlock_); }
void lock_shared() ACQUIRE_SHARED() { pthread_rwlock_rdlock(&rwlock_); }
void unlock() RELEASE() { pthread_rwlock_unlock(&rwlock_); }
private:
pthread_rwlock_t rwlock_ = PTHREAD_RWLOCK_INITIALIZER;
};
// std::shared_lock does not have thread annotations, so we need our own.
class SCOPED_CAPABILITY SharedLock {
public:
explicit SharedLock(RwLock& lock) ACQUIRE_SHARED(lock) : lock_(lock) { lock_.lock_shared(); }
~SharedLock() RELEASE() { lock_.unlock(); }
void lock_shared() ACQUIRE_SHARED() { lock_.lock_shared(); }
void unlock() RELEASE() { lock_.unlock(); }
DISALLOW_IMPLICIT_CONSTRUCTORS(SharedLock);
private:
RwLock& lock_;
};