scheduler: Ensure consistent delayed task ordering between task queues

third_party/WebKit/Source/platform/scheduler/base/time_domain.cc

 // Copyright 2015 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 "platform/scheduler/base/time_domain.h"
 
 #include <set>
 
 #include "platform/scheduler/base/task_queue_impl.h"
 #include "platform/scheduler/base/task_queue_manager_delegate.h"
@@ skipping 15 matching lines @@
 
 void TimeDomain::UnregisterQueue(internal::TaskQueueImpl* queue) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(queue->GetTimeDomain(), this);
 
   CancelDelayedWork(queue);
 }
 
 void TimeDomain::ScheduleDelayedWork(internal::TaskQueueImpl* queue,
                                      base::TimeTicks delayed_run_time,
+                                     int sequence_num,
                                      base::TimeTicks now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(queue->GetTimeDomain(), this);
   DCHECK(queue->IsQueueEnabled());
   // We only want to store a single wakeup per queue, so we need to remove any
   // previously registered wake up for |queue|.
   if (queue->heap_handle().IsValid()) {
     DCHECK_NE(queue->scheduled_time_domain_wakeup(), base::TimeTicks());
 
     // O(log n)
     delayed_wakeup_queue_.ChangeKey(queue->heap_handle(),
-                                    {delayed_run_time, queue});
+                                    {delayed_run_time, sequence_num, queue});
   } else {
     // O(log n)
-    delayed_wakeup_queue_.insert({delayed_run_time, queue});
+    delayed_wakeup_queue_.insert({delayed_run_time, sequence_num, queue});
   }
 
   queue->set_scheduled_time_domain_wakeup(delayed_run_time);
 
   // If |queue| is the first wakeup then request the wakeup.
   if (delayed_wakeup_queue_.min().queue == queue)
     RequestWakeupAt(now, delayed_run_time);
 
   if (observer_)
     observer_->OnTimeDomainHasDelayedWork(queue);
@@ skipping 22 matching lines @@
   if (delayed_wakeup_queue_.empty()) {
     CancelWakeupAt(prev_first_wakeup);
   } else if (prev_first_wakeup != delayed_wakeup_queue_.min().time) {
     CancelWakeupAt(prev_first_wakeup);
     RequestWakeupAt(Now(), delayed_wakeup_queue_.min().time);
   }
 }
 
 void TimeDomain::WakeupReadyDelayedQueues(LazyNow* lazy_now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
-  // Wake up any queues with pending delayed work.  Note std::multipmap stores
+  // Wake up any queues with pending delayed work.  Note std::multimap stores
   // the elements sorted by key, so the begin() iterator points to the earliest
   // queue to wakeup.
   while (!delayed_wakeup_queue_.empty() &&
          delayed_wakeup_queue_.min().time <= lazy_now->Now()) {
     internal::TaskQueueImpl* queue = delayed_wakeup_queue_.min().queue;
-    base::Optional<base::TimeTicks> next_wakeup =
-        queue->WakeUpForDelayedWork(lazy_now);
+    base::TimeTicks next_wake_up_time;
+    int next_wake_up_sequence_num;
+    bool needs_wake_up = queue->WakeUpForDelayedWork(
+        lazy_now, &next_wake_up_time, &next_wake_up_sequence_num);
 
-    if (next_wakeup) {
+    if (needs_wake_up) {
       // O(log n)
-      delayed_wakeup_queue_.ReplaceMin({next_wakeup.value(), queue});
-      queue->set_scheduled_time_domain_wakeup(next_wakeup.value());
+      delayed_wakeup_queue_.ReplaceMin(
+          {next_wake_up_time, next_wake_up_sequence_num, queue});
+      queue->set_scheduled_time_domain_wakeup(next_wake_up_time);
     } else {
       // O(log n)
       delayed_wakeup_queue_.pop();
       DCHECK_EQ(queue->scheduled_time_domain_wakeup(), base::TimeTicks());
     }
   }
 }
 
 bool TimeDomain::NextScheduledRunTime(base::TimeTicks* out_time) const {
   DCHECK(main_thread_checker_.CalledOnValidThread());
@@ skipping 20 matching lines @@
   if (!delayed_wakeup_queue_.empty()) {
     base::TimeDelta delay = delayed_wakeup_queue_.min().time - Now();
     state->SetDouble("next_delay_ms", delay.InMillisecondsF());
   }
   AsValueIntoInternal(state);
   state->EndDictionary();
 }
 
 }  // namespace scheduler
 }  // namespace blink