Update from https://crrev.com/327068

base/profiler/stack_sampling_profiler.cc

Index: base/profiler/stack_sampling_profiler.cc
diff --git a/base/profiler/stack_sampling_profiler.cc b/base/profiler/stack_sampling_profiler.cc
index 57b7b355a080923b2acc4b2201d4e58d7bb666ab..9da662859fd9535cb4037d1d1302401b2566f5b3 100644
--- a/base/profiler/stack_sampling_profiler.cc
+++ b/base/profiler/stack_sampling_profiler.cc
@@ -9,114 +9,144 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/singleton.h"
+#include "base/profiler/native_stack_sampler.h"
 #include "base/synchronization/lock.h"
-#include "base/synchronization/waitable_event.h"
 #include "base/timer/elapsed_timer.h"
 
-template <typename T> struct DefaultSingletonTraits;
-
 namespace base {
 
+// DefaultProfileProcessor ----------------------------------------------------
+
 namespace {
 
-// Thread-safe singleton class that stores collected profiles waiting to be
-// processed.
-class PendingProfiles {
+// Singleton class responsible for providing the default processing for profiles
+// (i.e. for profiles generated by profilers without their own completed
+// callback).
+class DefaultProfileProcessor {
  public:
-  PendingProfiles();
-  ~PendingProfiles();
+  using CompletedCallback = StackSamplingProfiler::CompletedCallback;
+
+  ~DefaultProfileProcessor();
+
+  static DefaultProfileProcessor* GetInstance();
 
-  static PendingProfiles* GetInstance();
+  // Sets the callback to use for processing profiles captured without a
+  // per-profiler completed callback. Pending completed profiles are stored in
+  // this object until a non-null callback is provided here. This function is
+  // thread-safe.
+  void SetCompletedCallback(CompletedCallback callback);
 
-  // Appends |profiles|. This function is thread safe.
-  void PutProfiles(const std::vector<StackSamplingProfiler::Profile>& profiles);
-  // Gets the pending profiles into *|profiles|. This function is thread safe.
-  void GetProfiles(std::vector<StackSamplingProfiler::Profile>* profiles);
+  // Processes |profiles|. This function is thread safe.
+  void ProcessProfiles(
+      const StackSamplingProfiler::CallStackProfiles& profiles);
 
  private:
+  friend struct DefaultSingletonTraits<DefaultProfileProcessor>;
+
+  DefaultProfileProcessor();
+
+  // Copies the pending profiles from |profiles_| into |profiles|, and clears
+  // |profiles_|. This function may be called on any thread.
+  void GetAndClearPendingProfiles(
+      StackSamplingProfiler::CallStackProfiles* profiles);
+
+  // Gets the current completed callback, with proper locking.
+  CompletedCallback GetCompletedCallback() const;
+
+  mutable Lock callback_lock_;
+  CompletedCallback default_completed_callback_;
+
   Lock profiles_lock_;
-  std::vector<StackSamplingProfiler::Profile> profiles_;
+  StackSamplingProfiler::CallStackProfiles profiles_;
 
-  DISALLOW_COPY_AND_ASSIGN(PendingProfiles);
+  DISALLOW_COPY_AND_ASSIGN(DefaultProfileProcessor);
 };
 
-PendingProfiles::PendingProfiles() {}
-
-PendingProfiles::~PendingProfiles() {}
+DefaultProfileProcessor::~DefaultProfileProcessor() {}
 
 // static
-PendingProfiles* PendingProfiles::GetInstance() {
-  return Singleton<PendingProfiles>::get();
+DefaultProfileProcessor* DefaultProfileProcessor::GetInstance() {
+  return Singleton<DefaultProfileProcessor>::get();
 }
 
-void PendingProfiles::PutProfiles(
-    const std::vector<StackSamplingProfiler::Profile>& profiles) {
-  AutoLock scoped_lock(profiles_lock_);
-  profiles_.insert(profiles_.end(), profiles.begin(), profiles.end());
+void DefaultProfileProcessor::SetCompletedCallback(CompletedCallback callback) {
+  {
+    AutoLock scoped_lock(callback_lock_);
+    default_completed_callback_ = callback;
+  }
+
+  if (!callback.is_null()) {
+    // Provide any pending profiles to the callback immediately.
+    StackSamplingProfiler::CallStackProfiles profiles;
+    GetAndClearPendingProfiles(&profiles);
+    if (!profiles.empty())
+      callback.Run(profiles);
+  }
 }
 
-void PendingProfiles::GetProfiles(
-    std::vector<StackSamplingProfiler::Profile>* profiles) {
-  profiles->clear();
+void DefaultProfileProcessor::ProcessProfiles(
+    const StackSamplingProfiler::CallStackProfiles& profiles) {
+  CompletedCallback callback = GetCompletedCallback();
 
-  AutoLock scoped_lock(profiles_lock_);
-  profiles_.swap(*profiles);
+  // Store pending profiles if we don't have a valid callback.
+  if (!callback.is_null()) {
+    callback.Run(profiles);
+  } else {
+    AutoLock scoped_lock(profiles_lock_);
+    profiles_.insert(profiles_.end(), profiles.begin(), profiles.end());
+  }
 }
-}  // namespace
 
-StackSamplingProfiler::Module::Module() : base_address(nullptr) {}
+DefaultProfileProcessor::DefaultProfileProcessor() {}
 
-StackSamplingProfiler::Module::~Module() {}
+void DefaultProfileProcessor::GetAndClearPendingProfiles(
+    StackSamplingProfiler::CallStackProfiles* profiles) {
+  profiles->clear();
 
-StackSamplingProfiler::Frame::Frame()
-    : instruction_pointer(nullptr),
-      module_index(-1) {}
+  AutoLock scoped_lock(profiles_lock_);
+  profiles_.swap(*profiles);
+}
 
-StackSamplingProfiler::Frame::~Frame() {}
+DefaultProfileProcessor::CompletedCallback
+DefaultProfileProcessor::GetCompletedCallback() const {
+  AutoLock scoped_lock(callback_lock_);
+  return default_completed_callback_;
+}
 
-StackSamplingProfiler::Profile::Profile() : preserve_sample_ordering(false) {}
+}  // namespace
 
-StackSamplingProfiler::Profile::~Profile() {}
+// StackSamplingProfiler::Module ----------------------------------------------
 
-class StackSamplingProfiler::SamplingThread : public PlatformThread::Delegate {
- public:
-  // Samples stacks using |native_sampler|. When complete, invokes
-  // |profiles_callback| with the collected profiles. |profiles_callback| must
-  // be thread-safe and may consume the contents of the vector.
-  SamplingThread(
-      scoped_ptr<NativeStackSampler> native_sampler,
-      const SamplingParams& params,
-      Callback<void(const std::vector<Profile>&)> completed_callback);
-  ~SamplingThread() override;
+StackSamplingProfiler::Module::Module() : base_address(nullptr) {}
+StackSamplingProfiler::Module::Module(const void* base_address,
+                                      const std::string& id,
+                                      const FilePath& filename)
+    : base_address(base_address), id(id), filename(filename) {}
 
-  // Implementation of PlatformThread::Delegate:
-  void ThreadMain() override;
+StackSamplingProfiler::Module::~Module() {}
 
-  void Stop();
+// StackSamplingProfiler::Frame -----------------------------------------------
 
- private:
-  // Collects a profile from a single burst. Returns true if the profile was
-  // collected, or false if collection was stopped before it completed.
-  bool CollectProfile(Profile* profile, TimeDelta* elapsed_time);
-  // Collects profiles from all bursts, or until the sampling is stopped. If
-  // stopped before complete, |profiles| will contains only full bursts.
-  void CollectProfiles(std::vector<Profile>* profiles);
+StackSamplingProfiler::Frame::Frame(const void* instruction_pointer,
+                                    size_t module_index)
+    : instruction_pointer(instruction_pointer),
+      module_index(module_index) {}
 
-  scoped_ptr<NativeStackSampler> native_sampler_;
+StackSamplingProfiler::Frame::~Frame() {}
 
-  const SamplingParams params_;
+// StackSamplingProfiler::CallStackProfile ------------------------------------
 
-  WaitableEvent stop_event_;
+StackSamplingProfiler::CallStackProfile::CallStackProfile()
+    : preserve_sample_ordering(false), user_data(0) {}
 
-  Callback<void(const std::vector<Profile>&)> completed_callback_;
+StackSamplingProfiler::CallStackProfile::~CallStackProfile() {}
 
-  DISALLOW_COPY_AND_ASSIGN(SamplingThread);
-};
+// StackSamplingProfiler::SamplingThread --------------------------------------
 
 StackSamplingProfiler::SamplingThread::SamplingThread(
     scoped_ptr<NativeStackSampler> native_sampler,
     const SamplingParams& params,
-    Callback<void(const std::vector<Profile>&)> completed_callback)
+    CompletedCallback completed_callback)
     : native_sampler_(native_sampler.Pass()),
       params_(params),
       stop_event_(false, false),
@@ -128,61 +158,79 @@ StackSamplingProfiler::SamplingThread::~SamplingThread() {}
 void StackSamplingProfiler::SamplingThread::ThreadMain() {
   PlatformThread::SetName("Chrome_SamplingProfilerThread");
 
-  std::vector<Profile> profiles;
+  CallStackProfiles profiles;
   CollectProfiles(&profiles);
   completed_callback_.Run(profiles);
 }
 
+// Depending on how long the sampling takes and the length of the sampling
+// interval, a burst of samples could take arbitrarily longer than
+// samples_per_burst * sampling_interval. In this case, we (somewhat
+// arbitrarily) honor the number of samples requested rather than strictly
+// adhering to the sampling intervals. Once we have established users for the
+// StackSamplingProfiler and the collected data to judge, we may go the other
+// way or make this behavior configurable.
 bool StackSamplingProfiler::SamplingThread::CollectProfile(
-    Profile* profile,
+    CallStackProfile* profile,
     TimeDelta* elapsed_time) {
   ElapsedTimer profile_timer;
-  Profile current_profile;
-  native_sampler_->ProfileRecordingStarting(&current_profile);
+  CallStackProfile current_profile;
+  native_sampler_->ProfileRecordingStarting(&current_profile.modules);
   current_profile.sampling_period = params_.sampling_interval;
-  bool stopped_early = false;
+  bool burst_completed = true;
+  TimeDelta previous_elapsed_sample_time;
   for (int i = 0; i < params_.samples_per_burst; ++i) {
-    ElapsedTimer sample_timer;
-    current_profile.samples.push_back(Sample());
-    native_sampler_->RecordStackSample(&current_profile.samples.back());
-    TimeDelta elapsed_sample_time = sample_timer.Elapsed();
-    if (i != params_.samples_per_burst - 1) {
+    if (i != 0) {
+      // Always wait, even if for 0 seconds, so we can observe a signal on
+      // stop_event_.
       if (stop_event_.TimedWait(
-              std::max(params_.sampling_interval - elapsed_sample_time,
+              std::max(params_.sampling_interval - previous_elapsed_sample_time,
                        TimeDelta()))) {
-        stopped_early = true;
+        burst_completed = false;
         break;
       }
     }
+    ElapsedTimer sample_timer;
+    current_profile.samples.push_back(Sample());
+    native_sampler_->RecordStackSample(&current_profile.samples.back());
+    previous_elapsed_sample_time = sample_timer.Elapsed();
   }
 
   *elapsed_time = profile_timer.Elapsed();
   current_profile.profile_duration = *elapsed_time;
+  current_profile.preserve_sample_ordering = params_.preserve_sample_ordering;
+  current_profile.user_data = params_.user_data;
   native_sampler_->ProfileRecordingStopped();
 
-  if (!stopped_early)
+  if (burst_completed)
     *profile = current_profile;
 
-  return !stopped_early;
+  return burst_completed;
 }
 
+// In an analogous manner to CollectProfile() and samples exceeding the expected
+// total sampling time, bursts may also exceed the burst_interval. We adopt the
+// same wait-and-see approach here.
 void StackSamplingProfiler::SamplingThread::CollectProfiles(
-    std::vector<Profile>* profiles) {
+    CallStackProfiles* profiles) {
   if (stop_event_.TimedWait(params_.initial_delay))
     return;
 
+  TimeDelta previous_elapsed_profile_time;
   for (int i = 0; i < params_.bursts; ++i) {
-    Profile profile;
-    TimeDelta elapsed_profile_time;
-    if (CollectProfile(&profile, &elapsed_profile_time))
-      profiles->push_back(profile);
-    else
-      return;
+    if (i != 0) {
+      // Always wait, even if for 0 seconds, so we can observe a signal on
+      // stop_event_.
+      if (stop_event_.TimedWait(
+              std::max(params_.burst_interval - previous_elapsed_profile_time,
+                       TimeDelta())))
+        return;
+    }
 
-    if (stop_event_.TimedWait(
-            std::max(params_.burst_interval - elapsed_profile_time,
-                     TimeDelta())))
+    CallStackProfile profile;
+    if (!CollectProfile(&profile, &previous_elapsed_profile_time))
       return;
+    profiles->push_back(profile);
   }
 }
 
@@ -190,14 +238,7 @@ void StackSamplingProfiler::SamplingThread::Stop() {
   stop_event_.Signal();
 }
 
-void StackSamplingProfiler::SamplingThreadDeleter::operator()(
-    SamplingThread* thread) const {
-  delete thread;
-}
-
-StackSamplingProfiler::NativeStackSampler::NativeStackSampler() {}
-
-StackSamplingProfiler::NativeStackSampler::~NativeStackSampler() {}
+// StackSamplingProfiler ------------------------------------------------------
 
 StackSamplingProfiler::SamplingParams::SamplingParams()
     : initial_delay(TimeDelta::FromMilliseconds(0)),
@@ -205,29 +246,40 @@ StackSamplingProfiler::SamplingParams::SamplingParams()
       burst_interval(TimeDelta::FromMilliseconds(10000)),
       samples_per_burst(300),
       sampling_interval(TimeDelta::FromMilliseconds(100)),
-      preserve_sample_ordering(false) {
+      preserve_sample_ordering(false),
+      user_data(0) {
 }
 
 StackSamplingProfiler::StackSamplingProfiler(PlatformThreadId thread_id,
                                              const SamplingParams& params)
     : thread_id_(thread_id), params_(params) {}
 
-StackSamplingProfiler::~StackSamplingProfiler() {}
+StackSamplingProfiler::StackSamplingProfiler(PlatformThreadId thread_id,
+                                             const SamplingParams& params,
+                                             CompletedCallback callback)
+    : thread_id_(thread_id), params_(params), completed_callback_(callback) {}
+
+StackSamplingProfiler::~StackSamplingProfiler() {
+  Stop();
+  if (!sampling_thread_handle_.is_null())
+    PlatformThread::Join(sampling_thread_handle_);
+}
 
 void StackSamplingProfiler::Start() {
-  native_sampler_ = NativeStackSampler::Create(thread_id_);
-  if (!native_sampler_)
+  scoped_ptr<NativeStackSampler> native_sampler =
+      NativeStackSampler::Create(thread_id_);
+  if (!native_sampler)
     return;
 
+  CompletedCallback callback =
+      !completed_callback_.is_null() ? completed_callback_ :
+      Bind(&DefaultProfileProcessor::ProcessProfiles,
+           Unretained(DefaultProfileProcessor::GetInstance()));
   sampling_thread_.reset(
-      new SamplingThread(
-          native_sampler_.Pass(), params_,
-          (custom_completed_callback_.is_null() ?
-           Bind(&PendingProfiles::PutProfiles,
-                Unretained(PendingProfiles::GetInstance())) :
-           custom_completed_callback_)));
-  if (!PlatformThread::CreateNonJoinable(0, sampling_thread_.get()))
-    LOG(ERROR) << "failed to create thread";
+      new SamplingThread(native_sampler.Pass(), params_, callback));
+  if (!PlatformThread::Create(0, sampling_thread_.get(),
+                              &sampling_thread_handle_))
+    sampling_thread_.reset();
 }
 
 void StackSamplingProfiler::Stop() {
@@ -236,14 +288,12 @@ void StackSamplingProfiler::Stop() {
 }
 
 // static
-void StackSamplingProfiler::GetPendingProfiles(std::vector<Profile>* profiles) {
-  PendingProfiles::GetInstance()->GetProfiles(profiles);
+void StackSamplingProfiler::SetDefaultCompletedCallback(
+    CompletedCallback callback) {
+  DefaultProfileProcessor::GetInstance()->SetCompletedCallback(callback);
 }
 
-void StackSamplingProfiler::SetCustomCompletedCallback(
-    Callback<void(const std::vector<Profile>&)> callback) {
-  custom_completed_callback_ = callback;
-}
+// StackSamplingProfiler::Frame global functions ------------------------------
 
 bool operator==(const StackSamplingProfiler::Frame &a,
                 const StackSamplingProfiler::Frame &b) {