Optimize away updatable_queue_set_

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"
 #include "platform/scheduler/base/work_queue.h"
 
 namespace blink {
 namespace scheduler {
 
 TimeDomain::TimeDomain(Observer* observer) : observer_(observer) {}
 
 TimeDomain::~TimeDomain() {
   DCHECK(main_thread_checker_.CalledOnValidThread());
 }
 
 void TimeDomain::RegisterQueue(internal::TaskQueueImpl* queue) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(queue->GetTimeDomain(), this);
 }
 
 void TimeDomain::UnregisterQueue(internal::TaskQueueImpl* queue) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(queue->GetTimeDomain(), this);
-  UnregisterAsUpdatableTaskQueue(queue);
+
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    has_incoming_immediate_work_.erase(queue);
+  }
 
   // If no wakeup has been requested then bail out.
   if (!queue->heap_handle().IsValid())
     return;
 
   DCHECK_NE(queue->scheduled_time_domain_wakeup(), base::TimeTicks());
 
   // O(log n)
   delayed_wakeup_queue_.erase(queue->heap_handle());
 }
 
 void TimeDomain::MigrateQueue(internal::TaskQueueImpl* queue,
                               TimeDomain* destination_time_domain) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(queue->GetTimeDomain(), this);
   DCHECK(destination_time_domain);
 
   // Make sure we remember to update |queue| if it's got incoming immediate
   // work.
-  if (UnregisterAsUpdatableTaskQueue(queue))
-    destination_time_domain->updatable_queue_set_.insert(queue);
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    if (has_incoming_immediate_work_.erase(queue)) {
+      destination_time_domain->has_incoming_immediate_work_.insert(queue);

[Sami, 2017/01/18 17:57:04]

Looks like we need to grab the destination lock here. Could add insert/erase
helpers that handle locking for this too if you prefer.

[alex clarke (OOO till 29th), 2017/01/19 08:50:52]

I'd like has_incoming_immediate_work_ to end up on the TaskQueueManager, which
means this code will go away. 

[Sami, 2017/01/19 11:57:38]

That sounds fine, but for the time being don't we need to grab the lock on
|destination_time_domain|?

[alex clarke (OOO till 29th), 2017/01/19 12:34:31]

Done.

+    }
+  }
 
   // If no wakeup has been requested then bail out.
   if (!queue->heap_handle().IsValid())
     return;
 
   base::TimeTicks wake_up_time = queue->scheduled_time_domain_wakeup();
   DCHECK_NE(wake_up_time, base::TimeTicks());
 
   // O(log n)
   delayed_wakeup_queue_.erase(queue->heap_handle());
@@ skipping 25 matching lines @@
   // If |queue| is the first wakeup then request the wakeup.
   if (delayed_wakeup_queue_.min().queue == queue) {
     base::TimeDelta delay = std::max(base::TimeDelta(), delayed_run_time - now);
     RequestWakeup(now, delay);
   }
 
   if (observer_)
     observer_->OnTimeDomainHasDelayedWork(queue);
 }
 
-void TimeDomain::RegisterAsUpdatableTaskQueue(internal::TaskQueueImpl* queue) {
+void TimeDomain::OnQueueHasIncomingImmediateWork(
+    internal::TaskQueueImpl* queue) {
   {
-    base::AutoLock lock(newly_updatable_lock_);
-    newly_updatable_.push_back(queue);
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    has_incoming_immediate_work_.insert(queue);
   }
+
   if (observer_)
     observer_->OnTimeDomainHasImmediateWork(queue);
 }
 
-bool TimeDomain::UnregisterAsUpdatableTaskQueue(
-    internal::TaskQueueImpl* queue) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-
-  bool was_updatable = updatable_queue_set_.erase(queue) != 0;
-
-  base::AutoLock lock(newly_updatable_lock_);
-  // Remove all copies of |queue| from |newly_updatable_|.
-  for (size_t i = 0; i < newly_updatable_.size();) {
-    if (newly_updatable_[i] == queue) {
-      // Move last element into slot #i and then compact.
-      newly_updatable_[i] = newly_updatable_.back();
-      newly_updatable_.pop_back();
-      was_updatable = true;
-    } else {
-      i++;
-    }
-  }
-  return was_updatable;
-}
-
 void TimeDomain::UpdateWorkQueues(LazyNow lazy_now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
 
   // Move any ready delayed tasks into the Incoming queues.
   WakeupReadyDelayedQueues(&lazy_now);
 
-  MoveNewlyUpdatableQueuesIntoUpdatableQueueSet();
+  std::set<internal::TaskQueueImpl*> queues_to_reload_if_empty;
 
-  std::set<internal::TaskQueueImpl*>::iterator iter =
-      updatable_queue_set_.begin();
-  while (iter != updatable_queue_set_.end()) {
-    std::set<internal::TaskQueueImpl*>::iterator queue_it = iter++;
-    internal::TaskQueueImpl* queue = *queue_it;
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    std::swap(queues_to_reload_if_empty, has_incoming_immediate_work_);
+  }
 
-    // Update the queue and remove from the set if subsequent updates are not
-    // required.
-    if (!queue->MaybeUpdateImmediateWorkQueues())
-      updatable_queue_set_.erase(queue_it);
-  }
-}
-
-void TimeDomain::MoveNewlyUpdatableQueuesIntoUpdatableQueueSet() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  base::AutoLock lock(newly_updatable_lock_);
-  while (!newly_updatable_.empty()) {
-    updatable_queue_set_.insert(newly_updatable_.back());
-    newly_updatable_.pop_back();
-  }
+  for (internal::TaskQueueImpl* queue : queues_to_reload_if_empty)
+    queue->ReloadImmediateWorkQueueIfEmpty();
 }
 
 void TimeDomain::WakeupReadyDelayedQueues(LazyNow* lazy_now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   // Wake up any queues with pending delayed work.  Note std::multipmap 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;
@@ skipping 18 matching lines @@
   if (delayed_wakeup_queue_.empty())
     return false;
 
   *out_task_queue = delayed_wakeup_queue_.min().queue;
   return true;
 }
 
 void TimeDomain::AsValueInto(base::trace_event::TracedValue* state) const {
   state->BeginDictionary();
   state->SetString("name", GetName());
-  state->BeginArray("updatable_queue_set");
-  for (auto* queue : updatable_queue_set_)
-    state->AppendString(queue->GetName());
-  state->EndArray();
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    state->BeginArray("has_incoming_immediate_work");
+    for (internal::TaskQueueImpl* queue : has_incoming_immediate_work_)
+      state->AppendString(queue->GetName());
+    state->EndArray();
+  }
   state->SetInteger("registered_delay_count", delayed_wakeup_queue_.size());
   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