metrics: Add random delays to perf collection

chrome/browser/metrics/perf_provider_chromeos.cc

 // 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.
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/command_line.h"
@@ skipping 36 matching lines @@
 // There may be too many session restores to collect a profile each time. Limit
 // the collection rate by collecting one per 10 restores. Adjust this number as
 // needed.
 const int kRestoreSessionSamplingFactor = 10;
 
 // This is used to space out session restore collections in the face of several
 // notifications in a short period of time. There should be no less than this
 // much time between collections. The current value is 30 seconds.
 const int kMinIntervalBetweenSessionRestoreCollectionsMs = 30 * 1000;
 
+// If collecting after a resume, add a random delay before collecting. The delay
+// should be randomly selected between 0 and this value. Currently the value is
+// equal to 5 seconds.
+const int kMaxResumeCollectionDelayMs = 5 * 1000;
+
+// If collecting after a session restore, add a random delay before collecting.
+// The delay should be randomly selected between 0 and this value. Currently the
+// value is equal to 10 seconds.
+const int kMaxRestoreSessionCollectionDelayMs = 10 * 1000;
+
 // Enumeration representing success and various failure modes for collecting and
 // sending perf data.
 enum GetPerfDataOutcome {
   SUCCESS,
   NOT_READY_TO_UPLOAD,
   NOT_READY_TO_COLLECT,
   INCOGNITO_ACTIVE,
   INCOGNITO_LAUNCHED,
   PROTOBUF_NOT_PARSED,
   NUM_OUTCOMES
@@ skipping 116 matching lines @@
   // the lid or idling when not logged in is currently to shut down instead of
   // suspending. But it's good to enforce the rule here in case that changes.
   if (!IsNormalUserLoggedIn())
     return;
 
   // Collect a profile only 1/|kResumeSamplingFactor| of the time, to avoid
   // collecting too much data.
   if (base::RandGenerator(kResumeSamplingFactor) != 0)
     return;
 
-  // Fill out a SampledProfile protobuf that will contain the collected data.
-  scoped_ptr<SampledProfile> sampled_profile(new SampledProfile);
-  sampled_profile->set_trigger_event(SampledProfile::RESUME_FROM_SUSPEND);
-  sampled_profile->set_suspend_duration_ms(sleep_duration.InMilliseconds());
-  // TODO(sque): Vary the time after resume at which to collect a profile.
-  // http://crbug.com/358778.
-  sampled_profile->set_ms_after_resume(0);
-  CollectIfNecessary(sampled_profile.Pass());
+  // Override any existing profiling.
+  if (timer_.IsRunning())
+    timer_.Stop();
+
+  // Randomly pick a delay before doing the collection.
+  base::TimeDelta collection_delay =
+      base::TimeDelta::FromMilliseconds(
+          base::RandGenerator(kMaxResumeCollectionDelayMs));
+  timer_.Start(FROM_HERE,
+               collection_delay,
+               base::Bind(&PerfProvider::CollectPerfDataAfterResume,
+                          weak_factory_.GetWeakPtr(),
+                          sleep_duration,
+                          collection_delay));
 }
 
 void PerfProvider::Observe(int type,
                            const content::NotificationSource& source,
                            const content::NotificationDetails& details) {
   // Only handle session restore notifications.
   DCHECK_EQ(type, chrome::NOTIFICATION_SESSION_RESTORE_DONE);
 
+  // Do not collect a profile unless logged in as a normal user.
+  if (!IsNormalUserLoggedIn())
+    return;
+
   // Collect a profile only 1/|kRestoreSessionSamplingFactor| of the time, to
   // avoid collecting too much data and potentially causing UI latency.
   if (base::RandGenerator(kRestoreSessionSamplingFactor) != 0)
     return;
 
+  // Stop any existing scheduled collection.
+  if (timer_.IsRunning())
+    timer_.Stop();

[Ilya Sherman, 2014/07/12 03:11:56]

It looks like if the early-return below is reached, then no periodic samples
will be collected.  I think you probably want to move this down below the final
early return.

[Simon Que, 2014/07/14 21:08:30]

Done.

+
   const base::TimeDelta min_interval =
       base::TimeDelta::FromMilliseconds(
           kMinIntervalBetweenSessionRestoreCollectionsMs);
   const base::TimeDelta time_since_last_collection =
       (base::TimeTicks::Now() - last_session_restore_collection_time_);
   // Do not collect if there hasn't been enough elapsed time since the last
   // collection.
   if (!last_session_restore_collection_time_.is_null() &&
       time_since_last_collection < min_interval) {
     return;
   }
 
-  // Fill out a SampledProfile protobuf that will contain the collected data.
-  scoped_ptr<SampledProfile> sampled_profile(new SampledProfile);
-  sampled_profile->set_trigger_event(SampledProfile::RESTORE_SESSION);
-  // TODO(sque): Vary the time after restore at which to collect a profile,
-  // and find a way to determine the number of tabs restored.
-  // http://crbug.com/358778.
-  sampled_profile->set_ms_after_restore(0);
-
-  CollectIfNecessary(sampled_profile.Pass());
-  last_session_restore_collection_time_ = base::TimeTicks::Now();
+  // Randomly pick a delay before doing the collection.
+  base::TimeDelta collection_delay =
+      base::TimeDelta::FromMilliseconds(
+          base::RandGenerator(kMaxRestoreSessionCollectionDelayMs));
+  timer_.Start(
+      FROM_HERE,
+      collection_delay,
+      base::Bind(&PerfProvider::CollectPerfDataAfterSessionRestore,
+                 weak_factory_.GetWeakPtr(),
+                 collection_delay));
 }
 
 void PerfProvider::OnUserLoggedIn() {
   login_time_ = base::TimeTicks::Now();
-  ScheduleCollection();
+  ScheduleIntervalCollection();
 }
 
 void PerfProvider::Deactivate() {
   // Stop the timer, but leave |cached_perf_data_| intact.
   timer_.Stop();
 }
 
-void PerfProvider::ScheduleCollection() {
+void PerfProvider::ScheduleIntervalCollection() {
   DCHECK(CalledOnValidThread());
   if (timer_.IsRunning())
     return;
 
   // Pick a random time in the current interval.
   base::TimeTicks scheduled_time =
       next_profiling_interval_start_ +
       base::TimeDelta::FromMilliseconds(
           base::RandGenerator(kPerfProfilingIntervalMs));
 
@@ skipping 47 matching lines @@
                                  weak_factory_.GetWeakPtr(),
                                  base::Passed(&incognito_observer),
                                  base::Passed(&sampled_profile)));
 }
 
 void PerfProvider::DoPeriodicCollection() {
   scoped_ptr<SampledProfile> sampled_profile(new SampledProfile);
   sampled_profile->set_trigger_event(SampledProfile::PERIODIC_COLLECTION);
 
   CollectIfNecessary(sampled_profile.Pass());
-  ScheduleCollection();
+}
+
+void PerfProvider::CollectPerfDataAfterResume(
+    const base::TimeDelta& sleep_duration,
+    const base::TimeDelta& time_after_resume) {
+  // Fill out a SampledProfile protobuf that will contain the collected data.
+  scoped_ptr<SampledProfile> sampled_profile(new SampledProfile);
+  sampled_profile->set_trigger_event(SampledProfile::RESUME_FROM_SUSPEND);
+  sampled_profile->set_suspend_duration_ms(sleep_duration.InMilliseconds());
+  sampled_profile->set_ms_after_resume(time_after_resume.InMilliseconds());
+
+  CollectIfNecessary(sampled_profile.Pass());
+}
+
+void PerfProvider::CollectPerfDataAfterSessionRestore(
+    const base::TimeDelta& time_after_restore) {
+  // Fill out a SampledProfile protobuf that will contain the collected data.
+  scoped_ptr<SampledProfile> sampled_profile(new SampledProfile);
+  sampled_profile->set_trigger_event(SampledProfile::RESTORE_SESSION);
+  sampled_profile->set_ms_after_restore(time_after_restore.InMilliseconds());
+
+  CollectIfNecessary(sampled_profile.Pass());
+  last_session_restore_collection_time_ = base::TimeTicks::Now();
 }
 
 void PerfProvider::ParseProtoIfValid(
     scoped_ptr<WindowedIncognitoObserver> incognito_observer,
     scoped_ptr<SampledProfile> sampled_profile,
     const std::vector<uint8>& data) {
   DCHECK(CalledOnValidThread());
 
   if (incognito_observer->incognito_launched()) {
     AddToPerfHistogram(INCOGNITO_LAUNCHED);
@@ skipping 16 matching lines @@
   collection_data.set_ms_after_boot(
       perf_data_proto.timestamp_sec() * base::Time::kMillisecondsPerSecond);
 
   DCHECK(!login_time_.is_null());
   collection_data.
       set_ms_after_login((base::TimeTicks::Now() - login_time_)
           .InMilliseconds());
 
   // Finally, store the perf data itself.
   collection_data.mutable_perf_data()->Swap(&perf_data_proto);
+
+  // Schedule another interval collection. This call makes sense regardless of
+  // whether or not the current collection was interval-triggered. If it had
+  // been another type of trigger event, the interval timer would have been
+  // halted, so it makes sense to reschedule a new interval collection.
+  ScheduleIntervalCollection();

[Ilya Sherman, 2014/07/12 03:11:56]

What if there was an early return from CollectIfNecessary?  It looks like that
will suspend collection indefinitely.  Is that intentional?

[Simon Que, 2014/07/14 21:08:30]

Done.

 }
 
 }  // namespace metrics