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 #include "src/profiling/memory/scoped_spinlock.h" 18 19 #include <unistd.h> 20 21 #include <atomic> 22 23 #include "perfetto/ext/base/utils.h" 24 25 namespace { 26 // Wait for ~1s before timing out (+- spurious wakeups from the sleeps). 27 constexpr unsigned kSleepAttempts = 1000; 28 constexpr unsigned kLockAttemptsPerSleep = 1000; 29 constexpr unsigned kSleepDurationUs = 1000; 30 } // namespace 31 32 namespace perfetto { 33 namespace profiling { 34 LockSlow(Mode mode)35void ScopedSpinlock::LockSlow(Mode mode) { 36 for (size_t attempt = 0; mode == Mode::Blocking || 37 attempt < kLockAttemptsPerSleep * kSleepAttempts; 38 attempt++) { 39 if (!lock_->load(std::memory_order_relaxed) && 40 PERFETTO_LIKELY(!lock_->exchange(true, std::memory_order_acquire))) { 41 locked_ = true; 42 return; 43 } 44 if (attempt && attempt % kLockAttemptsPerSleep == 0) 45 usleep(kSleepDurationUs); 46 } 47 } 48 49 } // namespace profiling 50 } // namespace perfetto 51