Make stack sampling profiler sample beyond startup.

components/metrics/call_stack_profile_metrics_provider.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 "components/metrics/call_stack_profile_metrics_provider.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <cstring>
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/singleton.h"
-#include "base/metrics/field_trial.h"
+#include "base/metrics/field_trial_params.h"
 #include "base/metrics/metrics_hashes.h"
 #include "base/profiler/stack_sampling_profiler.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
 
 using base::StackSamplingProfiler;
 
@@ skipping 16 matching lines @@
 
         ProcessPhase::SHUTDOWN_START,
 };
 
 // ProfilesState --------------------------------------------------------------
 
 // A set of profiles and the CallStackProfileMetricsProvider state associated
 // with them.
 struct ProfilesState {
   ProfilesState(const CallStackProfileParams& params,
-                StackSamplingProfiler::CallStackProfiles profiles,
-                base::TimeTicks start_timestamp);
+                StackSamplingProfiler::CallStackProfiles profiles);
   ProfilesState(ProfilesState&&);
   ProfilesState& operator=(ProfilesState&&);
 
   // The metrics-related parameters provided to
   // CallStackProfileMetricsProvider::GetProfilerCallback().
   CallStackProfileParams params;
 
   // The call stack profiles collected by the profiler.
   StackSamplingProfiler::CallStackProfiles profiles;
 
-  // The time at which the CallStackProfileMetricsProvider became aware of the
-  // request for profiling. In particular, this is when callback was requested
-  // via CallStackProfileMetricsProvider::GetProfilerCallback(). Used to
-  // determine if collection was disabled during the collection of the profile.
-  base::TimeTicks start_timestamp;
-
  private:
   DISALLOW_COPY_AND_ASSIGN(ProfilesState);
 };
 
 ProfilesState::ProfilesState(const CallStackProfileParams& params,
-                             StackSamplingProfiler::CallStackProfiles profiles,
-                             base::TimeTicks start_timestamp)
-    : params(params),
-      profiles(std::move(profiles)),
-      start_timestamp(start_timestamp) {}
+                             StackSamplingProfiler::CallStackProfiles profiles)
+    : params(params), profiles(std::move(profiles)) {}
 
 ProfilesState::ProfilesState(ProfilesState&&) = default;
 
 // Some versions of GCC need this for push_back to work with std::move.
 ProfilesState& ProfilesState::operator=(ProfilesState&&) = default;
 
 // PendingProfiles ------------------------------------------------------------
 
 // Singleton class responsible for retaining profiles received via the callback
 // created by CallStackProfileMetricsProvider::GetProfilerCallback(). These are
@@ skipping 76 matching lines @@
 }
 
 void PendingProfiles::CollectProfilesIfCollectionEnabled(
     ProfilesState profiles) {
   base::AutoLock scoped_lock(lock_);
 
   // Only collect if collection is not disabled and hasn't been disabled
   // since the start of collection for this profile.
   if (!collection_enabled_ ||
       (!last_collection_disable_time_.is_null() &&
-       last_collection_disable_time_ >= profiles.start_timestamp)) {
+       last_collection_disable_time_ >= profiles.params.start_timestamp)) {
     return;
   }
 
   profiles_.push_back(std::move(profiles));
 }
 
 void PendingProfiles::ResetToDefaultStateForTesting() {
   base::AutoLock scoped_lock(lock_);
 
   collection_enabled_ = true;
   last_collection_disable_time_ = base::TimeTicks();
   profiles_.clear();
 }
 
 // |collection_enabled_| is initialized to true to collect any profiles that are
 // generated prior to creation of the CallStackProfileMetricsProvider. The
 // ultimate disposition of these pre-creation collected profiles will be
 // determined by the initial recording state provided to
 // CallStackProfileMetricsProvider.
 PendingProfiles::PendingProfiles() : collection_enabled_(true) {}
 
 PendingProfiles::~PendingProfiles() {}
 
 // Functions to process completed profiles ------------------------------------
 
 // Will be invoked on either the main thread or the profiler's thread. Provides
 // the profiles to PendingProfiles to append, if the collecting state allows.
-void ReceiveCompletedProfilesImpl(
-    const CallStackProfileParams& params,
-    base::TimeTicks start_timestamp,
-    StackSamplingProfiler::CallStackProfiles profiles) {
+bool ReceiveCompletedProfilesImpl(
+    CallStackProfileParams* params,
+    StackSamplingProfiler::CallStackProfiles profiles,
+    StackSamplingProfiler::SamplingParams* sampling_params) {
   PendingProfiles::GetInstance()->CollectProfilesIfCollectionEnabled(
-      ProfilesState(params, std::move(profiles), start_timestamp));
+      ProfilesState(*params, std::move(profiles)));
+
+  // Now, schedule periodic sampling every 1s, if enabled by trial.
+  if (sampling_params &&
+      CallStackProfileMetricsProvider::IsPeriodicSamplingEnabled() &&
+      params->process == CallStackProfileParams::BROWSER_PROCESS &&
+      params->thread == CallStackProfileParams::UI_THREAD) {
+    params->trigger = metrics::CallStackProfileParams::PERIODIC_COLLECTION;
+    params->start_timestamp = base::TimeTicks::Now();
+    sampling_params->initial_delay = base::TimeDelta::FromSeconds(1);
+    sampling_params->bursts = 1;
+    sampling_params->samples_per_burst = 1;
+    // Below are unused:
+    sampling_params->burst_interval = base::TimeDelta::FromMilliseconds(0);
+    sampling_params->sampling_interval = base::TimeDelta::FromMilliseconds(0);
+    return true;
+  }
+  return false;
 }
 
 // Invoked on an arbitrary thread. Ignores the provided profiles.
-void IgnoreCompletedProfiles(
-    StackSamplingProfiler::CallStackProfiles profiles) {}
+bool IgnoreCompletedProfiles(
+    StackSamplingProfiler::CallStackProfiles profiles,
+    StackSamplingProfiler::SamplingParams* sampling_params) {
+  return false;
+}
 
 // Functions to encode protobufs ----------------------------------------------
 
 // The protobuf expects the MD5 checksum prefix of the module name.
 uint64_t HashModuleFilename(const base::FilePath& filename) {
   const base::FilePath::StringType basename = filename.BaseName().value();
   // Copy the bytes in basename into a string buffer.
   size_t basename_length_in_bytes =
       basename.size() * sizeof(base::FilePath::CharType);
   std::string name_bytes(basename_length_in_bytes, '\0');
@@ skipping 92 matching lines @@
   for (const StackSamplingProfiler::Module& module : profile.modules) {
     CallStackProfile::ModuleIdentifier* module_id =
         proto_profile->add_module_id();
     module_id->set_build_id(module.id);
     module_id->set_name_md5_prefix(HashModuleFilename(module.filename));
   }
 
   proto_profile->set_profile_duration_ms(
       profile.profile_duration.InMilliseconds());
   proto_profile->set_sampling_period_ms(
       profile.sampling_period.InMilliseconds());

[Alexei Svitkine (slow), 2017/06/20 20:57:39]

Note: I need to double check whether sampling period and profile duration are
set correctly.

iirc I think profiler duration wasn't being set correctly, but haven't looked
recently.

[Mike Wittman, 2017/06/21 14:49:06]

The sampling period is being set correctly, but the profile duration is not
currently. It's set to last_sample_time - first_sample_time but should be 
last_sample_time - first_sample_time + 1 * sampling_period to account for the
time period represented by the last sample.

[Alexei Svitkine (slow), 2017/06/29 20:51:04]

Done.

 }
 
 // Translates CallStackProfileParams's process to the corresponding
 // execution context Process.
 Process ToExecutionContextProcess(CallStackProfileParams::Process process) {
   switch (process) {
     case CallStackProfileParams::UNKNOWN_PROCESS:
       return UNKNOWN_PROCESS;
     case CallStackProfileParams::BROWSER_PROCESS:
       return BROWSER_PROCESS;
@@ skipping 53 matching lines @@
     CallStackProfileParams::Trigger trigger) {
   switch (trigger) {
     case CallStackProfileParams::UNKNOWN:
       return SampledProfile::UNKNOWN_TRIGGER_EVENT;
     case CallStackProfileParams::PROCESS_STARTUP:
       return SampledProfile::PROCESS_STARTUP;
     case CallStackProfileParams::JANKY_TASK:
       return SampledProfile::JANKY_TASK;
     case CallStackProfileParams::THREAD_HUNG:
       return SampledProfile::THREAD_HUNG;
+    case CallStackProfileParams::PERIODIC_COLLECTION:
+      return SampledProfile::PERIODIC_COLLECTION;
   }
   NOTREACHED();
   return SampledProfile::UNKNOWN_TRIGGER_EVENT;
 }
 
 }  // namespace
 
 // CallStackProfileMetricsProvider --------------------------------------------
 
-const char CallStackProfileMetricsProvider::kFieldTrialName[] =
-    "StackProfiling";
-const char CallStackProfileMetricsProvider::kReportProfilesGroupName[] =
-    "Report profiles";
+const base::Feature CallStackProfileMetricsProvider::kEnableReporting = {
+    "SamplingProfilerReporting", base::FEATURE_DISABLED_BY_DEFAULT};
 
 CallStackProfileMetricsProvider::CallStackProfileMetricsProvider() {
 }
 
 CallStackProfileMetricsProvider::~CallStackProfileMetricsProvider() {
 }
 
 // This function can be invoked on an abitrary thread.
 StackSamplingProfiler::CompletedCallback
 CallStackProfileMetricsProvider::GetProfilerCallback(
-    const CallStackProfileParams& params) {
+    CallStackProfileParams* params) {
   // Ignore the profiles if the collection is disabled. If the collection state
   // changes while collecting, this will be detected by the callback and
   // profiles will be ignored at that point.
   if (!PendingProfiles::GetInstance()->IsCollectionEnabled())
     return base::Bind(&IgnoreCompletedProfiles);
 
-  return base::Bind(&ReceiveCompletedProfilesImpl, params,
-                    base::TimeTicks::Now());
+  params->start_timestamp = base::TimeTicks::Now();
+  return base::Bind(&ReceiveCompletedProfilesImpl, params);
 }
 
 // static
 void CallStackProfileMetricsProvider::ReceiveCompletedProfiles(
-    const CallStackProfileParams& params,
-    base::TimeTicks start_timestamp,
-    StackSamplingProfiler::CallStackProfiles profiles) {
-  ReceiveCompletedProfilesImpl(params, start_timestamp, std::move(profiles));
+    CallStackProfileParams* params,
+    base::StackSamplingProfiler::CallStackProfiles profiles) {
+  ReceiveCompletedProfilesImpl(params, std::move(profiles), nullptr);
+}
+
+// static
+bool CallStackProfileMetricsProvider::IsPeriodicSamplingEnabled() {
+  return base::GetFieldTrialParamByFeatureAsBool(kEnableReporting, "periodic",
+                                                 false);
 }
 
 void CallStackProfileMetricsProvider::OnRecordingEnabled() {
   PendingProfiles::GetInstance()->SetCollectionEnabled(true);
 }
 
 void CallStackProfileMetricsProvider::OnRecordingDisabled() {
   PendingProfiles::GetInstance()->SetCollectionEnabled(false);
 }
 
 void CallStackProfileMetricsProvider::ProvideGeneralMetrics(
     ChromeUserMetricsExtension* uma_proto) {
   std::vector<ProfilesState> pending_profiles;
   PendingProfiles::GetInstance()->Swap(&pending_profiles);
 
   DCHECK(IsReportingEnabledByFieldTrial() || pending_profiles.empty());
 
   for (const ProfilesState& profiles_state : pending_profiles) {
     for (const StackSamplingProfiler::CallStackProfile& profile :
              profiles_state.profiles) {
       SampledProfile* sampled_profile = uma_proto->add_sampled_profile();
-      sampled_profile->set_process(ToExecutionContextProcess(
-          profiles_state.params.process));
-      sampled_profile->set_thread(ToExecutionContextThread(
-          profiles_state.params.thread));
-      sampled_profile->set_trigger_event(ToSampledProfileTriggerEvent(
-          profiles_state.params.trigger));
+      sampled_profile->set_process(
+          ToExecutionContextProcess(profiles_state.params.process));
+      sampled_profile->set_thread(
+          ToExecutionContextThread(profiles_state.params.thread));
+      sampled_profile->set_trigger_event(
+          ToSampledProfileTriggerEvent(profiles_state.params.trigger));
       CopyProfileToProto(profile, profiles_state.params.ordering_spec,
                          sampled_profile->mutable_call_stack_profile());
     }
   }
 }
 
 // static
 void CallStackProfileMetricsProvider::ResetStaticStateForTesting() {
   PendingProfiles::GetInstance()->ResetToDefaultStateForTesting();
 }
 
 // static
 bool CallStackProfileMetricsProvider::IsReportingEnabledByFieldTrial() {
-  const std::string group_name = base::FieldTrialList::FindFullName(
-      CallStackProfileMetricsProvider::kFieldTrialName);
-  return group_name ==
-      CallStackProfileMetricsProvider::kReportProfilesGroupName;
+  return base::FeatureList::IsEnabled(kEnableReporting);
 }
 
 }  // namespace metrics