metrics: Use absolute interval-based perf collection

chrome/browser/metrics/perf_provider_chromeos.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_METRICS_PERF_PROVIDER_CHROMEOS_H_
 #define CHROME_BROWSER_METRICS_PERF_PROVIDER_CHROMEOS_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "chromeos/login/login_state.h"
-#include "components/metrics/proto/perf_data.pb.h"
+#include "components/metrics/proto/sampled_profile.pb.h"
 
 namespace metrics {
 
 class WindowedIncognitoObserver;
 
 // Provides access to ChromeOS perf data. perf aka "perf events" is a
 // performance profiling infrastructure built into the linux kernel. For more
 // information, see: https://perf.wiki.kernel.org/index.php/Main_Page.
 class PerfProvider : public base::NonThreadSafe {
  public:
   PerfProvider();
   ~PerfProvider();
 
   // Writes collected perf data protobufs to |perf_data|. Clears all the stored
   // perf data. Returns true if it wrote to |perf_data|.
-  bool GetPerfData(std::vector<PerfDataProto>* perf_data);
+  bool GetPerfData(std::vector<SampledProfile>* perf_data);

[Ilya Sherman, 2014/05/29 22:56:49]

Optional nit: Perhaps name this "GetSampledProfile()", and name the variable
"sampled_profile"?

[Simon Que, 2014/05/30 01:21:45]

Done.

 
  private:
   // Class that listens for changes to the login state. When a normal user logs
   // in, it updates PerfProvider to start collecting data.
   class LoginObserver : public chromeos::LoginState::Observer {
    public:
     explicit LoginObserver(PerfProvider* perf_provider);
 
     // Called when either the login state or the logged in user type changes.
     // Activates |perf_provider_| to start collecting.
     virtual void LoggedInStateChanged() OVERRIDE;
 
    private:
     // Points to a PerfProvider instance that can be turned on or off based on
     // the login state.
     PerfProvider* perf_provider_;
   };
 
   // Turns on perf collection. Resets the timer that's used to schedule
   // collections.
   void Activate();
 
   // Turns off perf collection. Does not delete any data that was already
   // collected and stored in |cached_perf_data_|.
   void Deactivate();
 
   // Starts an internal timer to start collecting perf data. The timer is set to
-  // trigger |interval| after this function call.
-  void ScheduleCollection(const base::TimeDelta& interval);
+  // trigger at a random point in either the current or the next profiling
+  // interval.

[Ilya Sherman, 2014/05/29 22:56:49]

nit: Please update this comment.

[Simon Que, 2014/05/30 01:21:45]

Done.

+  void ScheduleCollection();
 
   // Collects perf data if it has not been consumed by calling GetPerfData()
   // (see above).
-  void CollectIfNecessary();
+  void CollectIfNecessary(SampledProfile::TriggerEvent trigger_event);

[Ilya Sherman, 2014/05/29 22:56:49]

nit: Please update the docs.

[Simon Que, 2014/05/30 01:21:45]

Done.

 
-  // Collects perf data by calling CollectIfNecessary() and reschedules it to be
-  // collected again.
-  void CollectIfNecessaryAndReschedule();
+  // Collects perf data on a repeating basis by calling CollectIfNecessary() and
+  // reschedules it to be collected again.
+  void DoPeriodicCollection();
 
-  // Parses a protobuf from the |data| passed in only if the
+  // Parses a perf data protobuf from the |data| passed in only if the
   // |incognito_observer| indicates that no incognito window had been opened
   // during the profile collection period.
+  // |trigger_event| is the cause of the perf data collection.
   void ParseProtoIfValid(
       scoped_ptr<WindowedIncognitoObserver> incognito_observer,
+      SampledProfile::TriggerEvent trigger_event,
       const std::vector<uint8>& data);
 
-  // Vector of perf data protobufs.
-  std::vector<PerfDataProto> cached_perf_data_;
+  // Vector of SampledProfile protobufs containing perf profiles.
+  std::vector<SampledProfile> cached_perf_data_;
 
   // For scheduling collection of perf data.
   base::OneShotTimer<PerfProvider> timer_;
 
   // For detecting when changes to the login state.
   LoginObserver login_observer_;
 
+  // Record of the last login time.
+  base::TimeTicks login_time_;
+
+  // Record of the start of the upcoming profiling interval.
+  base::TimeTicks next_profiling_interval_start_;
+
   // To pass around the "this" pointer across threads safely.
   base::WeakPtrFactory<PerfProvider> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PerfProvider);
 };
 
 }  // namespace metrics
 
 #endif  // CHROME_BROWSER_METRICS_PERF_PROVIDER_CHROMEOS_H_