[scheduler] Add WakeupBudgetPool.

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

+// Copyright 2017 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/wake_up_budget_pool.h"
+
+#include <cstdint>
+
+#include "base/format_macros.h"
+#include "base/strings/stringprintf.h"
+#include "platform/scheduler/renderer/task_queue_throttler.h"
+
+namespace blink {
+namespace scheduler {
+
+namespace {
+
+std::string PointerToId(void* pointer) {
+  return base::StringPrintf(
+      "0x%" PRIx64,
+      static_cast<uint64_t>(reinterpret_cast<uintptr_t>(pointer)));
+}
+
+}  // namespace
+
+WakeUpBudgetPool::WakeUpBudgetPool(const char* name,
+                                   BudgetPoolController* budget_pool_controller,
+                                   base::TimeTicks now)
+    : BudgetPool(name, budget_pool_controller), wakeups_per_second_(1) {}
+
+WakeUpBudgetPool::~WakeUpBudgetPool() {}
+
+QueueBlockType WakeUpBudgetPool::GetBlockType() const {
+  return QueueBlockType::kNewTasksOnly;
+}
+
+void WakeUpBudgetPool::SetWakeUpRate(double wakeups_per_second) {
+  wakeups_per_second_ = wakeups_per_second;
+}
+
+void WakeUpBudgetPool::SetWakeUpDuration(base::TimeDelta duration) {
+  wakeup_duration_ = duration;
+}
+
+void WakeUpBudgetPool::RecordTaskRunTime(TaskQueue* queue,
+                                         base::TimeTicks start_time,
+                                         base::TimeTicks end_time) {
+  budget_pool_controller_->UpdateQueueThrottlingState(end_time, queue);
+}
+
+base::Optional<base::TimeTicks> WakeUpBudgetPool::NextWakeUp() const {
+  if (!last_wakeup_)
+    return base::nullopt;
+  // Subtract 1 microsecond to work with time alignment in task queue throttler.
+  // This is needed due to alignment mechanism in task queue throttler --
+  // whole seconds need to be aligned to the next second to deal with immediate
+  // tasks correctly. By subtracting 1 microsecond we ensure that next wakeup
+  // gets aligned to a correct time.
+  return last_wakeup_.value() +
+         base::TimeDelta::FromSeconds(1 / wakeups_per_second_) -
+         base::TimeDelta::FromMicroseconds(1);
+}
+
+bool WakeUpBudgetPool::CanRunTasksAt(base::TimeTicks moment,
+                                     bool is_wake_up) const {
+  if (!last_wakeup_)
+    return false;
+  // |is_wake_up| flag means that we're in the beginning of the wake-up and
+  // |OnWakeUp| has just been called. This is needed to support backwards
+  // compability with old throttling mechanism (when |wakeup_duration| is zero)
+  // and allow only one task to run.

[Sami, 2017/05/04 13:25:46]

We're not allowing just one task to run, but all tasks which were eligible to
run at the beginning of the wake-up, right? That's the old behavior.

+  if (last_wakeup_ == moment && is_wake_up)
+    return true;
+  return moment < last_wakeup_.value() + wakeup_duration_;
+}
+
+base::TimeTicks WakeUpBudgetPool::GetNextAllowedRunTime(
+    base::TimeTicks desired_run_time) const {
+  if (!last_wakeup_)
+    return desired_run_time;
+  if (desired_run_time < last_wakeup_.value() + wakeup_duration_)
+    return desired_run_time;
+  return std::max(desired_run_time, NextWakeUp().value());
+}
+
+void WakeUpBudgetPool::OnQueueNextWakeUpChanged(
+    TaskQueue* queue,
+    base::TimeTicks now,
+    base::TimeTicks desired_run_time) {
+  budget_pool_controller_->UpdateQueueThrottlingState(now, queue);
+}
+
+void WakeUpBudgetPool::OnWakeUp(base::TimeTicks now) {
+  last_wakeup_ = now;
+}
+
+void WakeUpBudgetPool::AsValueInto(base::trace_event::TracedValue* state,
+                                   base::TimeTicks now) const {
+  state->BeginDictionary(name_);
+
+  state->SetString("name", name_);
+  state->SetDouble("wakeups_per_second_rate", wakeups_per_second_);
+  state->SetDouble("wakeup_duration_in_seconds", wakeup_duration_.InSecondsF());
+  if (last_wakeup_) {
+    state->SetDouble("last_wakeup_seconds_ago",
+                     (now - last_wakeup_.value()).InSecondsF());
+  }
+  state->SetBoolean("is_enabled", is_enabled_);
+
+  state->BeginArray("task_queues");
+  for (TaskQueue* queue : associated_task_queues_) {
+    state->AppendString(PointerToId(queue));
+  }
+  state->EndArray();
+
+  state->EndDictionary();
+}
+
+}  // namespace scheduler
+}  // namespace blink