Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 1 | #include "runtime.h" |
| 2 | #include "stl_util.h" |
| 3 | #include "thread.h" |
| 4 | #include "thread_pool.h" |
| 5 | |
| 6 | namespace art { |
| 7 | |
| 8 | ThreadPoolWorker::ThreadPoolWorker(ThreadPool* thread_pool, const std::string& name, |
| 9 | size_t stack_size) |
| 10 | : thread_pool_(thread_pool), |
| 11 | name_(name), |
| 12 | stack_size_(stack_size) { |
| 13 | const char* reason = "new thread pool worker thread"; |
| 14 | CHECK_PTHREAD_CALL(pthread_attr_init, (&attr), reason); |
| 15 | CHECK_PTHREAD_CALL(pthread_attr_setstacksize, (&attr, stack_size), reason); |
| 16 | CHECK_PTHREAD_CALL(pthread_create, (&pthread_, &attr, &Callback, this), reason); |
| 17 | CHECK_PTHREAD_CALL(pthread_attr_destroy, (&attr), reason); |
| 18 | } |
| 19 | |
| 20 | ThreadPoolWorker::~ThreadPoolWorker() { |
| 21 | CHECK_PTHREAD_CALL(pthread_join, (pthread_, NULL), "thread pool worker shutdown"); |
| 22 | } |
| 23 | |
| 24 | void ThreadPoolWorker::Run() { |
| 25 | Thread* self = Thread::Current(); |
| 26 | Closure* task = NULL; |
| 27 | while ((task = thread_pool_->GetTask(self)) != NULL) { |
| 28 | task->Run(self); |
| 29 | } |
| 30 | } |
| 31 | |
| 32 | void* ThreadPoolWorker::Callback(void* arg) { |
| 33 | ThreadPoolWorker* worker = reinterpret_cast<ThreadPoolWorker*>(arg); |
| 34 | Runtime* runtime = Runtime::Current(); |
| 35 | CHECK(runtime->AttachCurrentThread(worker->name_.c_str(), true, NULL)); |
| 36 | // Do work until its time to shut down. |
| 37 | worker->Run(); |
| 38 | runtime->DetachCurrentThread(); |
| 39 | return NULL; |
| 40 | } |
| 41 | |
| 42 | void ThreadPool::AddTask(Thread* self, Closure* task){ |
| 43 | MutexLock mu(self, task_queue_lock_); |
| 44 | tasks_.push_back(task); |
| 45 | // If we have any waiters, signal one. |
| 46 | if (waiting_count_ != 0) { |
| 47 | task_queue_condition_.Signal(self); |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | void ThreadPool::AddThread(size_t stack_size) { |
| 52 | threads_.push_back( |
| 53 | new ThreadPoolWorker( |
| 54 | this, |
| 55 | StringPrintf("Thread pool worker %d", static_cast<int>(GetThreadCount())), |
| 56 | stack_size)); |
| 57 | } |
| 58 | |
| 59 | ThreadPool::ThreadPool(size_t num_threads) |
| 60 | : task_queue_lock_("task queue lock"), |
| 61 | task_queue_condition_("task queue condition", task_queue_lock_), |
| 62 | completion_condition_("task completion condition", task_queue_lock_), |
| 63 | started_(false), |
| 64 | shutting_down_(false), |
| 65 | waiting_count_(0) { |
| 66 | while (GetThreadCount() < num_threads) { |
| 67 | AddThread(ThreadPoolWorker::kDefaultStackSize); |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | ThreadPool::~ThreadPool() { |
| 72 | // Tell any remaining workers to shut down. |
| 73 | shutting_down_ = true; |
| 74 | android_memory_barrier(); |
| 75 | // Broadcast to everyone waiting. |
| 76 | task_queue_condition_.Broadcast(Thread::Current()); |
| 77 | // Wait for the threads to finish. |
| 78 | STLDeleteElements(&threads_); |
| 79 | } |
| 80 | |
| 81 | void ThreadPool::StartWorkers(Thread* self) { |
| 82 | MutexLock mu(self, task_queue_lock_); |
| 83 | started_ = true; |
| 84 | android_memory_barrier(); |
| 85 | task_queue_condition_.Broadcast(self); |
| 86 | } |
| 87 | |
| 88 | void ThreadPool::StopWorkers(Thread* self) { |
| 89 | MutexLock mu(self, task_queue_lock_); |
| 90 | started_ = false; |
| 91 | android_memory_barrier(); |
| 92 | } |
| 93 | |
| 94 | Closure* ThreadPool::GetTask(Thread* self) { |
| 95 | MutexLock mu(self, task_queue_lock_); |
| 96 | while (!shutting_down_) { |
| 97 | if (started_ && !tasks_.empty()) { |
| 98 | Closure* task = tasks_.front(); |
| 99 | tasks_.pop_front(); |
| 100 | return task; |
| 101 | } |
| 102 | |
| 103 | waiting_count_++; |
| 104 | if (waiting_count_ == GetThreadCount() && tasks_.empty()) { |
| 105 | // We may be done, lets broadcast to the completion condition. |
| 106 | completion_condition_.Broadcast(self); |
| 107 | } |
| 108 | task_queue_condition_.Wait(self); |
| 109 | waiting_count_--; |
| 110 | } |
| 111 | |
| 112 | // We are shutting down, return NULL to tell the worker thread to stop looping. |
| 113 | return NULL; |
| 114 | } |
| 115 | |
| 116 | void ThreadPool::Wait(Thread* self) { |
| 117 | MutexLock mu(self, task_queue_lock_); |
| 118 | // Wait until each thread is waiting and the task list is empty. |
| 119 | while (waiting_count_ != GetThreadCount() || !tasks_.empty()) { |
| 120 | completion_condition_.Wait(self); |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | } // namespace art |