[scheduler] Implement time-based cpu throttling.

third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.cc

Index: third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.cc b/third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.cc
deleted file mode 100644
index 20ff3a1116f6628a01002daf48055ed181c184e0..0000000000000000000000000000000000000000
--- a/third_party/WebKit/Source/platform/scheduler/renderer/throttling_helper.cc
+++ /dev/null
@@ -1,225 +0,0 @@
-// 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/renderer/throttling_helper.h"
-
-#include "base/logging.h"
-#include "platform/scheduler/base/real_time_domain.h"
-#include "platform/scheduler/child/scheduler_tqm_delegate.h"
-#include "platform/scheduler/renderer/auto_advancing_virtual_time_domain.h"
-#include "platform/scheduler/renderer/renderer_scheduler_impl.h"
-#include "platform/scheduler/renderer/throttled_time_domain.h"
-#include "platform/scheduler/renderer/web_frame_scheduler_impl.h"
-#include "public/platform/WebFrameScheduler.h"
-
-namespace blink {
-namespace scheduler {
-
-ThrottlingHelper::ThrottlingHelper(RendererSchedulerImpl* renderer_scheduler,
-                                   const char* tracing_category)
-    : task_runner_(renderer_scheduler->ControlTaskRunner()),
-      renderer_scheduler_(renderer_scheduler),
-      tick_clock_(renderer_scheduler->tick_clock()),
-      tracing_category_(tracing_category),
-      time_domain_(new ThrottledTimeDomain(this, tracing_category)),
-      virtual_time_(false),
-      weak_factory_(this) {
-  pump_throttled_tasks_closure_.Reset(base::Bind(
-      &ThrottlingHelper::PumpThrottledTasks, weak_factory_.GetWeakPtr()));
-  forward_immediate_work_closure_ =
-      base::Bind(&ThrottlingHelper::OnTimeDomainHasImmediateWork,
-                 weak_factory_.GetWeakPtr());
-
-  renderer_scheduler_->RegisterTimeDomain(time_domain_.get());
-}
-
-ThrottlingHelper::~ThrottlingHelper() {
-  // It's possible for queues to be still throttled, so we need to tidy up
-  // before unregistering the time domain.
-  for (const TaskQueueMap::value_type& map_entry : throttled_queues_) {
-    TaskQueue* task_queue = map_entry.first;
-    task_queue->SetTimeDomain(renderer_scheduler_->real_time_domain());
-    task_queue->RemoveFence();
-  }
-
-  renderer_scheduler_->UnregisterTimeDomain(time_domain_.get());
-}
-
-void ThrottlingHelper::SetQueueEnabled(TaskQueue* task_queue, bool enabled) {
-  TaskQueueMap::iterator find_it = throttled_queues_.find(task_queue);
-
-  if (find_it == throttled_queues_.end()) {
-    task_queue->SetQueueEnabled(enabled);
-    return;
-  }
-
-  find_it->second.enabled = enabled;
-
-  // We don't enable the queue here because it's throttled and there might be
-  // tasks in it's work queue that would execute immediatly rather than after
-  // PumpThrottledTasks runs.
-  if (!enabled)
-    task_queue->SetQueueEnabled(false);
-}
-
-void ThrottlingHelper::IncreaseThrottleRefCount(TaskQueue* task_queue) {
-  DCHECK_NE(task_queue, task_runner_.get());
-
-  if (virtual_time_)
-    return;
-
-  std::pair<TaskQueueMap::iterator, bool> insert_result =
-      throttled_queues_.insert(std::make_pair(
-          task_queue, Metadata(1, task_queue->IsQueueEnabled())));
-
-  if (insert_result.second) {
-    // The insert was succesful so we need to throttle the queue.
-    task_queue->SetTimeDomain(time_domain_.get());
-    task_queue->RemoveFence();
-    task_queue->SetQueueEnabled(false);
-
-    if (!task_queue->IsEmpty()) {
-      if (task_queue->HasPendingImmediateWork()) {
-        OnTimeDomainHasImmediateWork();
-      } else {
-        OnTimeDomainHasDelayedWork();
-      }
-    }
-  } else {
-    // An entry already existed in the map so we need to increment the refcount.
-    insert_result.first->second.throttling_ref_count++;
-  }
-}
-
-void ThrottlingHelper::DecreaseThrottleRefCount(TaskQueue* task_queue) {
-  if (virtual_time_)
-    return;
-
-  TaskQueueMap::iterator iter = throttled_queues_.find(task_queue);
-
-  if (iter != throttled_queues_.end() &&
-      --iter->second.throttling_ref_count == 0) {
-    bool enabled = iter->second.enabled;
-    // The refcount has become zero, we need to unthrottle the queue.
-    throttled_queues_.erase(iter);
-
-    task_queue->SetTimeDomain(renderer_scheduler_->real_time_domain());
-    task_queue->RemoveFence();
-    task_queue->SetQueueEnabled(enabled);
-  }
-}
-
-bool ThrottlingHelper::IsThrottled(TaskQueue* task_queue) const {
-  return throttled_queues_.find(task_queue) != throttled_queues_.end();
-}
-
-void ThrottlingHelper::UnregisterTaskQueue(TaskQueue* task_queue) {
-  throttled_queues_.erase(task_queue);
-}
-
-void ThrottlingHelper::OnTimeDomainHasImmediateWork() {
-  // Forward to the main thread if called from another thread.
-  if (!task_runner_->RunsTasksOnCurrentThread()) {
-    task_runner_->PostTask(FROM_HERE, forward_immediate_work_closure_);
-    return;
-  }
-  TRACE_EVENT0(tracing_category_,
-               "ThrottlingHelper::OnTimeDomainHasImmediateWork");
-  base::TimeTicks now = tick_clock_->NowTicks();
-  MaybeSchedulePumpThrottledTasksLocked(FROM_HERE, now, now);
-}
-
-void ThrottlingHelper::OnTimeDomainHasDelayedWork() {
-  TRACE_EVENT0(tracing_category_,
-               "ThrottlingHelper::OnTimeDomainHasDelayedWork");
-  base::TimeTicks next_scheduled_delayed_task;
-  bool has_delayed_task =
-      time_domain_->NextScheduledRunTime(&next_scheduled_delayed_task);
-  DCHECK(has_delayed_task);
-  base::TimeTicks now = tick_clock_->NowTicks();
-  MaybeSchedulePumpThrottledTasksLocked(FROM_HERE, now,
-                                        next_scheduled_delayed_task);
-}
-
-void ThrottlingHelper::PumpThrottledTasks() {
-  TRACE_EVENT0(tracing_category_, "ThrottlingHelper::PumpThrottledTasks");
-  pending_pump_throttled_tasks_runtime_ = base::TimeTicks();
-
-  LazyNow lazy_low(tick_clock_);
-  for (const TaskQueueMap::value_type& map_entry : throttled_queues_) {
-    TaskQueue* task_queue = map_entry.first;
-    if (!map_entry.second.enabled || task_queue->IsEmpty())
-      continue;
-
-    task_queue->SetQueueEnabled(true);
-    task_queue->InsertFence();
-  }
-  // Make sure NextScheduledRunTime gives us an up-to date result.
-  time_domain_->ClearExpiredWakeups();
-
-  base::TimeTicks next_scheduled_delayed_task;
-  // Maybe schedule a call to ThrottlingHelper::PumpThrottledTasks if there is
-  // a pending delayed task. NOTE posting a non-delayed task in the future will
-  // result in ThrottlingHelper::OnTimeDomainHasImmediateWork being called.
-  if (time_domain_->NextScheduledRunTime(&next_scheduled_delayed_task)) {
-    MaybeSchedulePumpThrottledTasksLocked(FROM_HERE, lazy_low.Now(),
-                                          next_scheduled_delayed_task);
-  }
-}
-
-/* static */
-base::TimeTicks ThrottlingHelper::ThrottledRunTime(
-    base::TimeTicks unthrottled_runtime) {
-  const base::TimeDelta one_second = base::TimeDelta::FromSeconds(1);
-  return unthrottled_runtime + one_second -
-         ((unthrottled_runtime - base::TimeTicks()) % one_second);
-}
-
-void ThrottlingHelper::MaybeSchedulePumpThrottledTasksLocked(
-    const tracked_objects::Location& from_here,
-    base::TimeTicks now,
-    base::TimeTicks unthrottled_runtime) {
-  if (virtual_time_)
-    return;
-
-  base::TimeTicks throttled_runtime =
-      ThrottledRunTime(std::max(now, unthrottled_runtime));
-  // If there is a pending call to PumpThrottledTasks and it's sooner than
-  // |unthrottled_runtime| then return.
-  if (!pending_pump_throttled_tasks_runtime_.is_null() &&
-      throttled_runtime >= pending_pump_throttled_tasks_runtime_) {
-    return;
-  }
-
-  pending_pump_throttled_tasks_runtime_ = throttled_runtime;
-
-  pump_throttled_tasks_closure_.Cancel();
-
-  base::TimeDelta delay = pending_pump_throttled_tasks_runtime_ - now;
-  TRACE_EVENT1(tracing_category_,
-               "ThrottlingHelper::MaybeSchedulePumpThrottledTasksLocked",
-               "delay_till_next_pump_ms", delay.InMilliseconds());
-  task_runner_->PostDelayedTask(
-      from_here, pump_throttled_tasks_closure_.callback(), delay);
-}
-
-void ThrottlingHelper::EnableVirtualTime() {
-  virtual_time_ = true;
-
-  pump_throttled_tasks_closure_.Cancel();
-
-  while (!throttled_queues_.empty()) {
-    TaskQueue* task_queue = throttled_queues_.begin()->first;
-    bool enabled = throttled_queues_.begin()->second.enabled;
-
-    throttled_queues_.erase(throttled_queues_.begin());
-
-    task_queue->SetTimeDomain(renderer_scheduler_->GetVirtualTimeDomain());
-    task_queue->RemoveFence();
-    task_queue->SetQueueEnabled(enabled);
-  }
-}
-
-}  // namespace scheduler
-}  // namespace blink