1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef INCLUDE_PERFETTO_EXT_BASE_WAITABLE_EVENT_H_ 18 #define INCLUDE_PERFETTO_EXT_BASE_WAITABLE_EVENT_H_ 19 20 #include "perfetto/base/thread_annotations.h" 21 22 #include <stdint.h> 23 24 #include <condition_variable> 25 #include <mutex> 26 27 namespace perfetto { 28 namespace base { 29 30 // A waitable event for cross-thread synchronization. 31 // All methods on this class can be called from any thread. 32 class WaitableEvent { 33 public: 34 WaitableEvent(); 35 ~WaitableEvent(); 36 WaitableEvent(const WaitableEvent&) = delete; 37 WaitableEvent operator=(const WaitableEvent&) = delete; 38 39 // Synchronously block until the event is notified `notification` times. 40 void Wait(uint64_t notifications = 1); 41 42 // Signal the event, waking up blocked waiters. 43 void Notify(); 44 45 private: 46 std::mutex mutex_; 47 std::condition_variable event_ PERFETTO_GUARDED_BY(mutex_); 48 uint64_t notifications_ PERFETTO_GUARDED_BY(mutex_) = 0; 49 }; 50 51 } // namespace base 52 } // namespace perfetto 53 54 #endif // INCLUDE_PERFETTO_EXT_BASE_WAITABLE_EVENT_H_ 55