| // Copyright 2019 The Cobalt Authors. All Rights Reserved. |
| // |
| // 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. |
| |
| #include "starboard/shared/pthread/thread_sampler_internal.h" |
| |
| #if SB_API_VERSION >= 11 |
| |
| #include <semaphore.h> |
| #include <signal.h> |
| |
| #include "starboard/common/log.h" |
| #include "starboard/common/mutex.h" |
| #include "starboard/shared/pthread/thread_context_internal.h" |
| #include "starboard/shared/pthread/types_internal.h" |
| #include "starboard/thread.h" |
| |
| namespace { |
| |
| class SignalHandler { |
| public: |
| static void AddSampler() { |
| starboard::ScopedLock lock(GetMutex()); |
| if (++sampler_count_ == 1) { |
| Install(); |
| } |
| } |
| |
| static void RemoveSampler() { |
| starboard::ScopedLock lock(GetMutex()); |
| if (--sampler_count_ == 0) { |
| Restore(); |
| } |
| } |
| |
| static SbThreadContext Freeze(SbThreadSampler sampler); |
| static bool Thaw(SbThreadSampler sampler); |
| |
| private: |
| // Getter with static local to lazily initialize the mutex once. |
| static const starboard::Mutex& GetMutex() { |
| static starboard::Mutex mutex; |
| return mutex; |
| } |
| |
| static void Install() { |
| sem_init(&freeze_semaphore_, 0, 0); |
| sem_init(&thaw_semaphore_, 0, 0); |
| struct sigaction sa; |
| sa.sa_sigaction = &HandleProfilerSignal; |
| sigemptyset(&sa.sa_mask); |
| sa.sa_flags = SA_RESTART | SA_SIGINFO; |
| signal_handler_installed_ = |
| (sigaction(SIGPROF, &sa, &old_signal_handler_) == 0); |
| } |
| |
| static void Restore() { |
| if (signal_handler_installed_) { |
| sigaction(SIGPROF, &old_signal_handler_, 0); |
| signal_handler_installed_ = false; |
| } |
| sem_destroy(&freeze_semaphore_); |
| sem_destroy(&thaw_semaphore_); |
| } |
| |
| static void HandleProfilerSignal(int signal, siginfo_t* info, void* context); |
| |
| static int sampler_count_; |
| static bool signal_handler_installed_; |
| static struct sigaction old_signal_handler_; |
| static SbThreadContextPrivate sb_context_; |
| static SbThreadSampler frozen_sampler_; |
| // POSIX semaphore can be used in signal handler. Other synchronization, |
| // including mutex, condition variable and Starboard's semaphore can't. |
| static sem_t freeze_semaphore_; |
| static sem_t thaw_semaphore_; |
| }; |
| |
| int SignalHandler::sampler_count_ = 0; |
| bool SignalHandler::signal_handler_installed_ = false; |
| struct sigaction SignalHandler::old_signal_handler_; |
| SbThreadContextPrivate SignalHandler::sb_context_; |
| SbThreadSampler SignalHandler::frozen_sampler_ = kSbThreadSamplerInvalid; |
| sem_t SignalHandler::freeze_semaphore_; |
| sem_t SignalHandler::thaw_semaphore_; |
| |
| SbThreadContext SignalHandler::Freeze(SbThreadSampler sampler) { |
| starboard::ScopedLock lock(GetMutex()); |
| SB_DCHECK(frozen_sampler_ != sampler) << "SbThreadSampler frozen twice."; |
| if (!signal_handler_installed_ || SbThreadSamplerIsValid(frozen_sampler_)) { |
| return kSbThreadContextInvalid; |
| } |
| frozen_sampler_ = sampler; |
| pthread_kill(SB_PTHREAD_INTERNAL_THREAD(sampler->thread()), SIGPROF); |
| sem_wait(&freeze_semaphore_); |
| return &sb_context_; |
| } |
| |
| bool SignalHandler::Thaw(SbThreadSampler sampler) { |
| starboard::ScopedLock lock(GetMutex()); |
| SB_DCHECK(frozen_sampler_ == sampler) << "SbThreadSampler didn't freeze."; |
| if (frozen_sampler_ != sampler) return false; |
| sb_context_ = SbThreadContextPrivate(); |
| sem_post(&thaw_semaphore_); |
| frozen_sampler_ = kSbThreadSamplerInvalid; |
| return true; |
| } |
| |
| void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info, |
| void* context) { |
| if (signal != SIGPROF) return; |
| sb_context_ = SbThreadContextPrivate(reinterpret_cast<ucontext_t*>(context)); |
| // |Freeze| can return the context now. |
| sem_post(&freeze_semaphore_); |
| // Keep this thread frozen until |Thaw| is called. |
| sem_wait(&thaw_semaphore_); |
| } |
| |
| } // namespace |
| |
| SbThreadSamplerPrivate::SbThreadSamplerPrivate(SbThread thread) |
| : thread_(thread) { |
| SignalHandler::AddSampler(); |
| } |
| |
| SbThreadSamplerPrivate::~SbThreadSamplerPrivate() { |
| SignalHandler::RemoveSampler(); |
| } |
| |
| SbThreadContext SbThreadSamplerPrivate::Freeze() { |
| return SignalHandler::Freeze(this); |
| } |
| |
| bool SbThreadSamplerPrivate::Thaw() { return SignalHandler::Thaw(this); } |
| |
| #endif // SB_API_VERSION >= 11 |