1 files changed, 169 insertions, 0 deletions
diff --git a/base/message_loop/incoming_task_queue.cc b/base/message_loop/incoming_task_queue.cc
new file mode 100644
index 0000000..db99d87
--- /dev/null
+++ b/base/message_loop/incoming_task_queue.cc
@@ -0,0 +1,169 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/message_loop/incoming_task_queue.h"
+
+#include "base/debug/trace_event.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop.h"
+#include "base/synchronization/waitable_event.h"
+
+namespace base {
+namespace internal {
+
+IncomingTaskQueue::IncomingTaskQueue(MessageLoop* message_loop)
+    : message_loop_(message_loop),
+      next_sequence_num_(0) {
+}
+
+bool IncomingTaskQueue::AddToIncomingQueue(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay,
+    bool nestable) {
+  AutoLock locked(incoming_queue_lock_);
+  PendingTask pending_task(
+      from_here, task, CalculateDelayedRuntime(delay), nestable);
+  return PostPendingTask(&pending_task);
+}
+
+bool IncomingTaskQueue::TryAddToIncomingQueue(
+    const tracked_objects::Location& from_here,
+    const Closure& task) {
+  if (!incoming_queue_lock_.Try()) {
+    // Reset |task|.
+    Closure local_task = task;
+    return false;
+  }
+
+  AutoLock locked(incoming_queue_lock_, AutoLock::AlreadyAcquired());
+  PendingTask pending_task(
+      from_here, task, CalculateDelayedRuntime(TimeDelta()), true);
+  return PostPendingTask(&pending_task);
+}
+
+bool IncomingTaskQueue::IsHighResolutionTimerEnabledForTesting() {
+#if defined(OS_WIN)
+  return !high_resolution_timer_expiration_.is_null();
+#else
+  return true;
+#endif
+}
+
+bool IncomingTaskQueue::IsIdleForTesting() {
+  AutoLock lock(incoming_queue_lock_);
+  return incoming_queue_.empty();
+}
+
+void IncomingTaskQueue::LockWaitUnLockForTesting(WaitableEvent* caller_wait,
+                                                 WaitableEvent* caller_signal) {
+  AutoLock lock(incoming_queue_lock_);
+  caller_wait->Signal();
+  caller_signal->Wait();
+}
+
+void IncomingTaskQueue::ReloadWorkQueue(TaskQueue* work_queue) {
+  // Make sure no tasks are lost.
+  DCHECK(work_queue->empty());
+
+  // Acquire all we can from the inter-thread queue with one lock acquisition.
+  AutoLock lock(incoming_queue_lock_);
+  if (!incoming_queue_.empty())
+    incoming_queue_.Swap(work_queue);  // Constant time
+
+  DCHECK(incoming_queue_.empty());
+}
+
+void IncomingTaskQueue::WillDestroyCurrentMessageLoop() {
+#if defined(OS_WIN)
+  // If we left the high-resolution timer activated, deactivate it now.
+  // Doing this is not-critical, it is mainly to make sure we track
+  // the high resolution timer activations properly in our unit tests.
+  if (!high_resolution_timer_expiration_.is_null()) {
+    Time::ActivateHighResolutionTimer(false);
+    high_resolution_timer_expiration_ = TimeTicks();
+  }
+#endif
+
+  AutoLock lock(incoming_queue_lock_);
+  message_loop_ = NULL;
+}
+
+IncomingTaskQueue::~IncomingTaskQueue() {
+  // Verify that WillDestroyCurrentMessageLoop() has been called.
+  DCHECK(!message_loop_);
+}
+
+TimeTicks IncomingTaskQueue::CalculateDelayedRuntime(TimeDelta delay) {
+  TimeTicks delayed_run_time;
+  if (delay > TimeDelta()) {
+    delayed_run_time = TimeTicks::Now() + delay;
+
+#if defined(OS_WIN)
+    if (high_resolution_timer_expiration_.is_null()) {
+      // Windows timers are granular to 15.6ms.  If we only set high-res
+      // timers for those under 15.6ms, then a 18ms timer ticks at ~32ms,
+      // which as a percentage is pretty inaccurate.  So enable high
+      // res timers for any timer which is within 2x of the granularity.
+      // This is a tradeoff between accuracy and power management.
+      bool needs_high_res_timers = delay.InMilliseconds() <
+          (2 * Time::kMinLowResolutionThresholdMs);
+      if (needs_high_res_timers) {
+        if (Time::ActivateHighResolutionTimer(true)) {
+          high_resolution_timer_expiration_ = TimeTicks::Now() +
+              TimeDelta::FromMilliseconds(
+                  MessageLoop::kHighResolutionTimerModeLeaseTimeMs);
+        }
+      }
+    }
+#endif
+  } else {
+    DCHECK_EQ(delay.InMilliseconds(), 0) << "delay should not be negative";
+  }
+
+#if defined(OS_WIN)
+  if (!high_resolution_timer_expiration_.is_null()) {
+    if (TimeTicks::Now() > high_resolution_timer_expiration_) {
+      Time::ActivateHighResolutionTimer(false);
+      high_resolution_timer_expiration_ = TimeTicks();
+    }
+  }
+#endif
+
+  return delayed_run_time;
+}
+
+bool IncomingTaskQueue::PostPendingTask(PendingTask* pending_task) {
+  // Warning: Don't try to short-circuit, and handle this thread's tasks more
+  // directly, as it could starve handling of foreign threads.  Put every task
+  // into this queue.
+
+  // This should only be called while the lock is taken.
+  incoming_queue_lock_.AssertAcquired();
+
+  if (!message_loop_) {
+    pending_task->task.Reset();
+    return false;
+  }
+
+  // Initialize the sequence number. The sequence number is used for delayed
+  // tasks (to faciliate FIFO sorting when two tasks have the same
+  // delayed_run_time value) and for identifying the task in about:tracing.
+  pending_task->sequence_num = next_sequence_num_++;
+
+  TRACE_EVENT_FLOW_BEGIN0("task", "MessageLoop::PostTask",
+      TRACE_ID_MANGLE(message_loop_->GetTaskTraceID(*pending_task)));
+
+  bool was_empty = incoming_queue_.empty();
+  incoming_queue_.push(*pending_task);
+  pending_task->task.Reset();
+
+  // Wake up the pump.
+  message_loop_->ScheduleWork(was_empty);
+
+  return true;
+}
+
+}  // namespace internal
+}  // namespace base