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 15 #include "pw_sync/counting_semaphore.h" 16 17 #include "pw_assert/check.h" 18 19 using pw::chrono::SystemClock; 20 21 namespace pw::sync { 22 release(ptrdiff_t update)23void CountingSemaphore::release(ptrdiff_t update) { 24 PW_DCHECK_UINT_GE(update, 0); 25 { 26 std::lock_guard lock(native_type_.mutex); 27 PW_DCHECK_UINT_LE(update, CountingSemaphore::max() - native_type_.count); 28 native_type_.count += update; 29 native_type_.condition.notify_one(); 30 } 31 } 32 acquire()33void CountingSemaphore::acquire() { 34 std::unique_lock lock(native_type_.mutex); 35 native_type_.condition.wait(lock, [&] { return native_type_.count != 0; }); 36 --native_type_.count; 37 } 38 try_acquire()39bool CountingSemaphore::try_acquire() noexcept { 40 std::lock_guard lock(native_type_.mutex); 41 if (native_type_.count != 0) { 42 --native_type_.count; 43 return true; 44 } 45 return false; 46 } 47 try_acquire_until(SystemClock::time_point deadline)48bool CountingSemaphore::try_acquire_until(SystemClock::time_point deadline) { 49 std::unique_lock lock(native_type_.mutex); 50 if (native_type_.condition.wait_until( 51 lock, deadline, [&] { return native_type_.count != 0; })) { 52 --native_type_.count; 53 return true; 54 } 55 return false; 56 } 57 58 } // namespace pw::sync 59