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Diffstat (limited to 'msm8909/sdm/include/utils/sync_task.h')
-rw-r--r-- | msm8909/sdm/include/utils/sync_task.h | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/msm8909/sdm/include/utils/sync_task.h b/msm8909/sdm/include/utils/sync_task.h new file mode 100644 index 00000000..725460a1 --- /dev/null +++ b/msm8909/sdm/include/utils/sync_task.h @@ -0,0 +1,143 @@ +/* +* Copyright (c) 2017, The Linux Foundation. All rights reserved. +* +* Redistribution and use in source and binary forms, with or without +* modification, are permitted provided that the following conditions are +* met: +* * Redistributions of source code must retain the above copyright +* notice, this list of conditions and the following disclaimer. +* * Redistributions in binary form must reproduce the above +* copyright notice, this list of conditions and the following +* disclaimer in the documentation and/or other materials provided +* with the distribution. +* * Neither the name of The Linux Foundation nor the names of its +* contributors may be used to endorse or promote products derived +* from this software without specific prior written permission. +* +* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED +* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT +* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS +* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR +* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, +* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE +* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN +* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +*/ + +#ifndef __SYNC_TASK_H__ +#define __SYNC_TASK_H__ + +#include <thread> +#include <mutex> +#include <condition_variable> // NOLINT + +namespace sdm { + +template <class TaskCode> +class SyncTask { + public: + // This class need to be overridden by caller to pass on a task context. + class TaskContext { + public: + virtual ~TaskContext() { } + }; + + // Methods to callback into caller for command codes executions in worker thread. + class TaskHandler { + public: + virtual ~TaskHandler() { } + virtual void OnTask(const TaskCode &task_code, TaskContext *task_context) = 0; + }; + + explicit SyncTask(TaskHandler &task_handler) : task_handler_(task_handler) { + // Block caller thread until worker thread has started and ready to listen to task commands. + // Worker thread will signal as soon as callback is received in the new thread. + std::unique_lock<std::mutex> caller_lock(caller_mutex_); + std::thread worker_thread(SyncTaskThread, this); + worker_thread_.swap(worker_thread); + caller_cv_.wait(caller_lock); + } + + ~SyncTask() { + // Task code does not matter here. + PerformTask(task_code_, nullptr, true); + worker_thread_.join(); + } + + void PerformTask(const TaskCode &task_code, TaskContext *task_context) { + PerformTask(task_code, task_context, false); + } + + private: + void PerformTask(const TaskCode &task_code, TaskContext *task_context, bool terminate) { + std::unique_lock<std::mutex> caller_lock(caller_mutex_); + + // New scope to limit scope of worker lock to this block. + { + // Set task command code and notify worker thread. + std::unique_lock<std::mutex> worker_lock(worker_mutex_); + task_code_ = task_code; + task_context_ = task_context; + worker_thread_exit_ = terminate; + pending_code_ = true; + worker_cv_.notify_one(); + } + + // Wait for worker thread to finish and signal. + caller_cv_.wait(caller_lock); + } + + static void SyncTaskThread(SyncTask *sync_task) { + if (sync_task) { + sync_task->OnThreadCallback(); + } + } + + void OnThreadCallback() { + // Acquire worker lock and start waiting for events. + // Wait must start before caller thread can post events, otherwise posted events will be lost. + // Caller thread will be blocked until worker thread signals readiness. + std::unique_lock<std::mutex> worker_lock(worker_mutex_); + + // New scope to limit scope of caller lock to this block. + { + // Signal caller thread that worker thread is ready to listen to events. + std::unique_lock<std::mutex> caller_lock(caller_mutex_); + caller_cv_.notify_one(); + } + + while (!worker_thread_exit_) { + // Add predicate to handle spurious interrupts. + // Wait for caller thread to signal new command codes. + worker_cv_.wait(worker_lock, [this] { return pending_code_; }); + + // Call task handler which is implemented by the caller. + if (!worker_thread_exit_) { + task_handler_.OnTask(task_code_, task_context_); + } + + pending_code_ = false; + // Notify completion of current task to the caller thread which is blocked. + std::unique_lock<std::mutex> caller_lock(caller_mutex_); + caller_cv_.notify_one(); + } + } + + TaskHandler &task_handler_; + TaskCode task_code_; + TaskContext *task_context_ = nullptr; + std::thread worker_thread_; + std::mutex caller_mutex_; + std::mutex worker_mutex_; + std::condition_variable caller_cv_; + std::condition_variable worker_cv_; + bool worker_thread_exit_ = false; + bool pending_code_ = false; +}; + +} // namespace sdm + +#endif // __SYNC_TASK_H__ |