Roll Chrome into Mojo.

base/debug/trace_event_synthetic_delay.cc

-// Copyright 2014 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/debug/trace_event_synthetic_delay.h"
-#include "base/memory/singleton.h"
-
-namespace {
-const int kMaxSyntheticDelays = 32;
-}  // namespace
-
-namespace base {
-namespace debug {
-
-TraceEventSyntheticDelayClock::TraceEventSyntheticDelayClock() {}
-TraceEventSyntheticDelayClock::~TraceEventSyntheticDelayClock() {}
-
-class TraceEventSyntheticDelayRegistry : public TraceEventSyntheticDelayClock {
- public:
-  static TraceEventSyntheticDelayRegistry* GetInstance();
-
-  TraceEventSyntheticDelay* GetOrCreateDelay(const char* name);
-  void ResetAllDelays();
-
-  // TraceEventSyntheticDelayClock implementation.
-  base::TimeTicks Now() override;
-
- private:
-  TraceEventSyntheticDelayRegistry();
-
-  friend struct DefaultSingletonTraits<TraceEventSyntheticDelayRegistry>;
-
-  Lock lock_;
-  TraceEventSyntheticDelay delays_[kMaxSyntheticDelays];
-  TraceEventSyntheticDelay dummy_delay_;
-  base::subtle::Atomic32 delay_count_;
-
-  DISALLOW_COPY_AND_ASSIGN(TraceEventSyntheticDelayRegistry);
-};
-
-TraceEventSyntheticDelay::TraceEventSyntheticDelay()
-    : mode_(STATIC), begin_count_(0), trigger_count_(0), clock_(NULL) {}
-
-TraceEventSyntheticDelay::~TraceEventSyntheticDelay() {}
-
-TraceEventSyntheticDelay* TraceEventSyntheticDelay::Lookup(
-    const std::string& name) {
-  return TraceEventSyntheticDelayRegistry::GetInstance()->GetOrCreateDelay(
-      name.c_str());
-}
-
-void TraceEventSyntheticDelay::Initialize(
-    const std::string& name,
-    TraceEventSyntheticDelayClock* clock) {
-  name_ = name;
-  clock_ = clock;
-}
-
-void TraceEventSyntheticDelay::SetTargetDuration(
-    base::TimeDelta target_duration) {
-  AutoLock lock(lock_);
-  target_duration_ = target_duration;
-  trigger_count_ = 0;
-  begin_count_ = 0;
-}
-
-void TraceEventSyntheticDelay::SetMode(Mode mode) {
-  AutoLock lock(lock_);
-  mode_ = mode;
-}
-
-void TraceEventSyntheticDelay::SetClock(TraceEventSyntheticDelayClock* clock) {
-  AutoLock lock(lock_);
-  clock_ = clock;
-}
-
-void TraceEventSyntheticDelay::Begin() {
-  // Note that we check for a non-zero target duration without locking to keep
-  // things quick for the common case when delays are disabled. Since the delay
-  // calculation is done with a lock held, it will always be correct. The only
-  // downside of this is that we may fail to apply some delays when the target
-  // duration changes.
-  ANNOTATE_BENIGN_RACE(&target_duration_, "Synthetic delay duration");
-  if (!target_duration_.ToInternalValue())
-    return;
-
-  base::TimeTicks start_time = clock_->Now();
-  {
-    AutoLock lock(lock_);
-    if (++begin_count_ != 1)
-      return;
-    end_time_ = CalculateEndTimeLocked(start_time);
-  }
-}
-
-void TraceEventSyntheticDelay::BeginParallel(base::TimeTicks* out_end_time) {
-  // See note in Begin().
-  ANNOTATE_BENIGN_RACE(&target_duration_, "Synthetic delay duration");
-  if (!target_duration_.ToInternalValue()) {
-    *out_end_time = base::TimeTicks();
-    return;
-  }
-
-  base::TimeTicks start_time = clock_->Now();
-  {
-    AutoLock lock(lock_);
-    *out_end_time = CalculateEndTimeLocked(start_time);
-  }
-}
-
-void TraceEventSyntheticDelay::End() {
-  // See note in Begin().
-  ANNOTATE_BENIGN_RACE(&target_duration_, "Synthetic delay duration");
-  if (!target_duration_.ToInternalValue())
-    return;
-
-  base::TimeTicks end_time;
-  {
-    AutoLock lock(lock_);
-    if (!begin_count_ || --begin_count_ != 0)
-      return;
-    end_time = end_time_;
-  }
-  if (!end_time.is_null())
-    ApplyDelay(end_time);
-}
-
-void TraceEventSyntheticDelay::EndParallel(base::TimeTicks end_time) {
-  if (!end_time.is_null())
-    ApplyDelay(end_time);
-}
-
-base::TimeTicks TraceEventSyntheticDelay::CalculateEndTimeLocked(
-    base::TimeTicks start_time) {
-  if (mode_ == ONE_SHOT && trigger_count_++)
-    return base::TimeTicks();
-  else if (mode_ == ALTERNATING && trigger_count_++ % 2)
-    return base::TimeTicks();
-  return start_time + target_duration_;
-}
-
-void TraceEventSyntheticDelay::ApplyDelay(base::TimeTicks end_time) {
-  TRACE_EVENT0("synthetic_delay", name_.c_str());
-  while (clock_->Now() < end_time) {
-    // Busy loop.
-  }
-}
-
-TraceEventSyntheticDelayRegistry*
-TraceEventSyntheticDelayRegistry::GetInstance() {
-  return Singleton<
-      TraceEventSyntheticDelayRegistry,
-      LeakySingletonTraits<TraceEventSyntheticDelayRegistry> >::get();
-}
-
-TraceEventSyntheticDelayRegistry::TraceEventSyntheticDelayRegistry()
-    : delay_count_(0) {}
-
-TraceEventSyntheticDelay* TraceEventSyntheticDelayRegistry::GetOrCreateDelay(
-    const char* name) {
-  // Try to find an existing delay first without locking to make the common case
-  // fast.
-  int delay_count = base::subtle::Acquire_Load(&delay_count_);
-  for (int i = 0; i < delay_count; ++i) {
-    if (!strcmp(name, delays_[i].name_.c_str()))
-      return &delays_[i];
-  }
-
-  AutoLock lock(lock_);
-  delay_count = base::subtle::Acquire_Load(&delay_count_);
-  for (int i = 0; i < delay_count; ++i) {
-    if (!strcmp(name, delays_[i].name_.c_str()))
-      return &delays_[i];
-  }
-
-  DCHECK(delay_count < kMaxSyntheticDelays)
-      << "must increase kMaxSyntheticDelays";
-  if (delay_count >= kMaxSyntheticDelays)
-    return &dummy_delay_;
-
-  delays_[delay_count].Initialize(std::string(name), this);
-  base::subtle::Release_Store(&delay_count_, delay_count + 1);
-  return &delays_[delay_count];
-}
-
-base::TimeTicks TraceEventSyntheticDelayRegistry::Now() {
-  return base::TimeTicks::HighResNow();
-}
-
-void TraceEventSyntheticDelayRegistry::ResetAllDelays() {
-  AutoLock lock(lock_);
-  int delay_count = base::subtle::Acquire_Load(&delay_count_);
-  for (int i = 0; i < delay_count; ++i) {
-    delays_[i].SetTargetDuration(base::TimeDelta());
-    delays_[i].SetClock(this);
-  }
-}
-
-void ResetTraceEventSyntheticDelays() {
-  TraceEventSyntheticDelayRegistry::GetInstance()->ResetAllDelays();
-}
-
-}  // namespace debug
-}  // namespace base
-
-namespace trace_event_internal {
-
-ScopedSyntheticDelay::ScopedSyntheticDelay(const char* name,
-                                           base::subtle::AtomicWord* impl_ptr)
-    : delay_impl_(GetOrCreateDelay(name, impl_ptr)) {
-  delay_impl_->BeginParallel(&end_time_);
-}
-
-ScopedSyntheticDelay::~ScopedSyntheticDelay() {
-  delay_impl_->EndParallel(end_time_);
-}
-
-base::debug::TraceEventSyntheticDelay* GetOrCreateDelay(
-    const char* name,
-    base::subtle::AtomicWord* impl_ptr) {
-  base::debug::TraceEventSyntheticDelay* delay_impl =
-      reinterpret_cast<base::debug::TraceEventSyntheticDelay*>(
-          base::subtle::Acquire_Load(impl_ptr));
-  if (!delay_impl) {
-    delay_impl = base::debug::TraceEventSyntheticDelayRegistry::GetInstance()
-                     ->GetOrCreateDelay(name);
-    base::subtle::Release_Store(
-        impl_ptr, reinterpret_cast<base::subtle::AtomicWord>(delay_impl));
-  }
-  return delay_impl;
-}
-
-}  // namespace trace_event_internal