samples/common/include/Thread.h

/*
 * Copyright 2018 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.
 */

#pragma once

#include <cstdint>
#include <mutex>
#include <unordered_map>

#include "swappy/swappy_common.h"

// Enable thread safety attributes only with clang.
// The attributes can be safely erased when compiling with other compilers.
#if defined(__clang__) && (!defined(SWIG))
#define THREAD_ANNOTATION_ATTRIBUTE__(x) __attribute__((x))
#else
#define THREAD_ANNOTATION_ATTRIBUTE__(x)  // no-op
#endif

#define GUARDED_BY(x) THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))

#define REQUIRES(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(requires_capability(__VA_ARGS__))

namespace samples {

enum class Affinity { None, Even, Odd };

int32_t getNumCpus();

void setAffinity(int32_t cpu);

void setAffinity(Affinity affinity);

// This is a minimal demonstration of a thread manager that uses pthreads.
// It is not intended for production use!
struct ThreadManager {
  std::mutex threadMapMutex;
  std::unordered_map<SwappyThreadId, pthread_t> threads;
  ThreadManager() {}
  ThreadManager(const ThreadManager&) = delete;
  static std::atomic<SwappyThreadId> nextId;

 public:
  static ThreadManager& Instance();
  int Start(SwappyThreadId* thread_id, void* (*thread_func)(void*),
            void* user_data);
  void Join(SwappyThreadId thread_id);
  bool Joinable(SwappyThreadId thread_id);
};

}  // namespace samples