1 // Copyright 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/message_loop/incoming_task_queue.h" 6 7 #include "base/location.h" 8 #include "base/message_loop/message_loop.h" 9 #include "base/synchronization/waitable_event.h" 10 #include "base/time/time.h" 11 12 namespace base { 13 namespace internal { 14 15 IncomingTaskQueue::IncomingTaskQueue(MessageLoop* message_loop) 16 : high_res_task_count_(0), 17 message_loop_(message_loop), 18 next_sequence_num_(0) { 19 } 20 21 bool IncomingTaskQueue::AddToIncomingQueue( 22 const tracked_objects::Location& from_here, 23 const Closure& task, 24 TimeDelta delay, 25 bool nestable) { 26 AutoLock locked(incoming_queue_lock_); 27 PendingTask pending_task( 28 from_here, task, CalculateDelayedRuntime(delay), nestable); 29 #if defined(OS_WIN) 30 // We consider the task needs a high resolution timer if the delay is 31 // more than 0 and less than 32ms. This caps the relative error to 32 // less than 50% : a 33ms wait can wake at 48ms since the default 33 // resolution on Windows is between 10 and 15ms. 34 if (delay > TimeDelta() && 35 delay.InMilliseconds() < (2 * Time::kMinLowResolutionThresholdMs)) { 36 ++high_res_task_count_; 37 pending_task.is_high_res = true; 38 } 39 #endif 40 return PostPendingTask(&pending_task); 41 } 42 43 bool IncomingTaskQueue::HasHighResolutionTasks() { 44 AutoLock lock(incoming_queue_lock_); 45 return high_res_task_count_ > 0; 46 } 47 48 bool IncomingTaskQueue::IsIdleForTesting() { 49 AutoLock lock(incoming_queue_lock_); 50 return incoming_queue_.empty(); 51 } 52 53 int IncomingTaskQueue::ReloadWorkQueue(TaskQueue* work_queue) { 54 // Make sure no tasks are lost. 55 DCHECK(work_queue->empty()); 56 57 // Acquire all we can from the inter-thread queue with one lock acquisition. 58 AutoLock lock(incoming_queue_lock_); 59 if (!incoming_queue_.empty()) 60 incoming_queue_.Swap(work_queue); 61 62 // Reset the count of high resolution tasks since our queue is now empty. 63 int high_res_tasks = high_res_task_count_; 64 high_res_task_count_ = 0; 65 return high_res_tasks; 66 } 67 68 void IncomingTaskQueue::WillDestroyCurrentMessageLoop() { 69 AutoLock lock(incoming_queue_lock_); 70 message_loop_ = NULL; 71 } 72 73 IncomingTaskQueue::~IncomingTaskQueue() { 74 // Verify that WillDestroyCurrentMessageLoop() has been called. 75 DCHECK(!message_loop_); 76 } 77 78 TimeTicks IncomingTaskQueue::CalculateDelayedRuntime(TimeDelta delay) { 79 TimeTicks delayed_run_time; 80 if (delay > TimeDelta()) 81 delayed_run_time = TimeTicks::Now() + delay; 82 else 83 DCHECK_EQ(delay.InMilliseconds(), 0) << "delay should not be negative"; 84 return delayed_run_time; 85 } 86 87 bool IncomingTaskQueue::PostPendingTask(PendingTask* pending_task) { 88 // Warning: Don't try to short-circuit, and handle this thread's tasks more 89 // directly, as it could starve handling of foreign threads. Put every task 90 // into this queue. 91 92 // This should only be called while the lock is taken. 93 incoming_queue_lock_.AssertAcquired(); 94 95 if (!message_loop_) { 96 pending_task->task.Reset(); 97 return false; 98 } 99 100 // Initialize the sequence number. The sequence number is used for delayed 101 // tasks (to faciliate FIFO sorting when two tasks have the same 102 // delayed_run_time value) and for identifying the task in about:tracing. 103 pending_task->sequence_num = next_sequence_num_++; 104 105 message_loop_->task_annotator()->DidQueueTask("MessageLoop::PostTask", 106 *pending_task); 107 108 bool was_empty = incoming_queue_.empty(); 109 incoming_queue_.push(*pending_task); 110 pending_task->task.Reset(); 111 112 // Wake up the pump. 113 message_loop_->ScheduleWork(was_empty); 114 115 return true; 116 } 117 118 } // namespace internal 119 } // namespace base 120