1 // Copyright 2020 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 #pragma once 15 16 #include "pw_chrono/system_clock.h" 17 #include "pw_sync/binary_semaphore.h" 18 19 namespace pw::sync { 20 BinarySemaphore()21inline BinarySemaphore::BinarySemaphore() 22 : native_type_{.mutex = {}, .condition = {}, .count = 0} {} 23 ~BinarySemaphore()24inline BinarySemaphore::~BinarySemaphore() {} 25 try_acquire_for(chrono::SystemClock::duration timeout)26inline bool BinarySemaphore::try_acquire_for( 27 chrono::SystemClock::duration timeout) { 28 // Due to spurious condition variable wakeups we prefer not to use wait_for() 29 // as we may grossly extend the effective deadline after a spruious wakeup. 30 // Ergo we instead use the derived deadline which can be re-used many times 31 // without shifting the effective deadline. For more details on spurious 32 // wakeups and CVs on Windows and POSIX see: 33 // https://en.wikipedia.org/wiki/Spurious_wakeup 34 return try_acquire_until(chrono::SystemClock::TimePointAfterAtLeast(timeout)); 35 } 36 native_handle()37inline BinarySemaphore::native_handle_type BinarySemaphore::native_handle() { 38 return native_type_; 39 } 40 41 } // namespace pw::sync 42