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| 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/debug/trace_event.h" |
| 8 #include "base/location.h" |
| 9 #include "base/message_loop/message_loop.h" |
| 10 #include "base/synchronization/waitable_event.h" |
| 11 |
| 12 namespace base { |
| 13 namespace internal { |
| 14 |
| 15 IncomingTaskQueue::IncomingTaskQueue(MessageLoop* message_loop) |
| 16 : message_loop_(message_loop), |
| 17 next_sequence_num_(0) { |
| 18 } |
| 19 |
| 20 bool IncomingTaskQueue::AddToIncomingQueue( |
| 21 const tracked_objects::Location& from_here, |
| 22 const Closure& task, |
| 23 TimeDelta delay, |
| 24 bool nestable) { |
| 25 AutoLock locked(incoming_queue_lock_); |
| 26 PendingTask pending_task( |
| 27 from_here, task, CalculateDelayedRuntime(delay), nestable); |
| 28 return PostPendingTask(&pending_task); |
| 29 } |
| 30 |
| 31 bool IncomingTaskQueue::TryAddToIncomingQueue( |
| 32 const tracked_objects::Location& from_here, |
| 33 const Closure& task) { |
| 34 if (!incoming_queue_lock_.Try()) { |
| 35 // Reset |task|. |
| 36 Closure local_task = task; |
| 37 return false; |
| 38 } |
| 39 |
| 40 AutoLock locked(incoming_queue_lock_, AutoLock::AlreadyAcquired()); |
| 41 PendingTask pending_task( |
| 42 from_here, task, CalculateDelayedRuntime(TimeDelta()), true); |
| 43 return PostPendingTask(&pending_task); |
| 44 } |
| 45 |
| 46 bool IncomingTaskQueue::IsHighResolutionTimerEnabledForTesting() { |
| 47 #if defined(OS_WIN) |
| 48 return !high_resolution_timer_expiration_.is_null(); |
| 49 #else |
| 50 return true; |
| 51 #endif |
| 52 } |
| 53 |
| 54 bool IncomingTaskQueue::IsIdleForTesting() { |
| 55 AutoLock lock(incoming_queue_lock_); |
| 56 return incoming_queue_.empty(); |
| 57 } |
| 58 |
| 59 void IncomingTaskQueue::LockWaitUnLockForTesting(WaitableEvent* caller_wait, |
| 60 WaitableEvent* caller_signal) { |
| 61 AutoLock lock(incoming_queue_lock_); |
| 62 caller_wait->Signal(); |
| 63 caller_signal->Wait(); |
| 64 } |
| 65 |
| 66 void IncomingTaskQueue::ReloadWorkQueue(TaskQueue* work_queue) { |
| 67 // Make sure no tasks are lost. |
| 68 DCHECK(work_queue->empty()); |
| 69 |
| 70 // Acquire all we can from the inter-thread queue with one lock acquisition. |
| 71 AutoLock lock(incoming_queue_lock_); |
| 72 if (!incoming_queue_.empty()) |
| 73 incoming_queue_.Swap(work_queue); // Constant time |
| 74 |
| 75 DCHECK(incoming_queue_.empty()); |
| 76 } |
| 77 |
| 78 void IncomingTaskQueue::WillDestroyCurrentMessageLoop() { |
| 79 #if defined(OS_WIN) |
| 80 // If we left the high-resolution timer activated, deactivate it now. |
| 81 // Doing this is not-critical, it is mainly to make sure we track |
| 82 // the high resolution timer activations properly in our unit tests. |
| 83 if (!high_resolution_timer_expiration_.is_null()) { |
| 84 Time::ActivateHighResolutionTimer(false); |
| 85 high_resolution_timer_expiration_ = TimeTicks(); |
| 86 } |
| 87 #endif |
| 88 |
| 89 AutoLock lock(incoming_queue_lock_); |
| 90 message_loop_ = NULL; |
| 91 } |
| 92 |
| 93 IncomingTaskQueue::~IncomingTaskQueue() { |
| 94 // Verify that WillDestroyCurrentMessageLoop() has been called. |
| 95 DCHECK(!message_loop_); |
| 96 } |
| 97 |
| 98 TimeTicks IncomingTaskQueue::CalculateDelayedRuntime(TimeDelta delay) { |
| 99 TimeTicks delayed_run_time; |
| 100 if (delay > TimeDelta()) { |
| 101 delayed_run_time = TimeTicks::Now() + delay; |
| 102 |
| 103 #if defined(OS_WIN) |
| 104 if (high_resolution_timer_expiration_.is_null()) { |
| 105 // Windows timers are granular to 15.6ms. If we only set high-res |
| 106 // timers for those under 15.6ms, then a 18ms timer ticks at ~32ms, |
| 107 // which as a percentage is pretty inaccurate. So enable high |
| 108 // res timers for any timer which is within 2x of the granularity. |
| 109 // This is a tradeoff between accuracy and power management. |
| 110 bool needs_high_res_timers = delay.InMilliseconds() < |
| 111 (2 * Time::kMinLowResolutionThresholdMs); |
| 112 if (needs_high_res_timers) { |
| 113 if (Time::ActivateHighResolutionTimer(true)) { |
| 114 high_resolution_timer_expiration_ = TimeTicks::Now() + |
| 115 TimeDelta::FromMilliseconds( |
| 116 MessageLoop::kHighResolutionTimerModeLeaseTimeMs); |
| 117 } |
| 118 } |
| 119 } |
| 120 #endif |
| 121 } else { |
| 122 DCHECK_EQ(delay.InMilliseconds(), 0) << "delay should not be negative"; |
| 123 } |
| 124 |
| 125 #if defined(OS_WIN) |
| 126 if (!high_resolution_timer_expiration_.is_null()) { |
| 127 if (TimeTicks::Now() > high_resolution_timer_expiration_) { |
| 128 Time::ActivateHighResolutionTimer(false); |
| 129 high_resolution_timer_expiration_ = TimeTicks(); |
| 130 } |
| 131 } |
| 132 #endif |
| 133 |
| 134 return delayed_run_time; |
| 135 } |
| 136 |
| 137 bool IncomingTaskQueue::PostPendingTask(PendingTask* pending_task) { |
| 138 // Warning: Don't try to short-circuit, and handle this thread's tasks more |
| 139 // directly, as it could starve handling of foreign threads. Put every task |
| 140 // into this queue. |
| 141 |
| 142 // This should only be called while the lock is taken. |
| 143 incoming_queue_lock_.AssertAcquired(); |
| 144 |
| 145 if (!message_loop_) { |
| 146 pending_task->task.Reset(); |
| 147 return false; |
| 148 } |
| 149 |
| 150 // Initialize the sequence number. The sequence number is used for delayed |
| 151 // tasks (to faciliate FIFO sorting when two tasks have the same |
| 152 // delayed_run_time value) and for identifying the task in about:tracing. |
| 153 pending_task->sequence_num = next_sequence_num_++; |
| 154 |
| 155 TRACE_EVENT_FLOW_BEGIN0("task", "MessageLoop::PostTask", |
| 156 TRACE_ID_MANGLE(message_loop_->GetTaskTraceID(*pending_task))); |
| 157 |
| 158 bool was_empty = incoming_queue_.empty(); |
| 159 incoming_queue_.push(*pending_task); |
| 160 pending_task->task.Reset(); |
| 161 |
| 162 // Wake up the pump. |
| 163 message_loop_->ScheduleWork(was_empty); |
| 164 |
| 165 return true; |
| 166 } |
| 167 |
| 168 } // namespace internal |
| 169 } // namespace base |
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