metrics: Add random delays to perf collection

chrome/browser/metrics/perf_provider_chromeos.cc

Index: chrome/browser/metrics/perf_provider_chromeos.cc
diff --git a/chrome/browser/metrics/perf_provider_chromeos.cc b/chrome/browser/metrics/perf_provider_chromeos.cc
index 72bf423077d56459d7769b1bbbee2b0a13fd5c2b..1ca0ccf9afede4cb7b420de86cbf5962d57e0f90 100644
--- a/chrome/browser/metrics/perf_provider_chromeos.cc
+++ b/chrome/browser/metrics/perf_provider_chromeos.cc
@@ -54,6 +54,16 @@ const int kRestoreSessionSamplingFactor = 10;
 // 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 {
@@ -185,19 +195,23 @@ void PerfProvider::SuspendDone(const base::TimeDelta& sleep_duration) {
   if (!IsNormalUserLoggedIn())
     return;
 
+  // Do not collect if there is an existing collection scheduled.
+  if (resume_timer_.IsRunning())
+    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());
+  // Randomly pick a delay before doing the collection.
+  uint64 collection_delay_ms = base::RandGenerator(kMaxResumeCollectionDelayMs);
+  resume_timer_.Start(FROM_HERE,
+                      base::TimeDelta::FromMilliseconds(collection_delay_ms),
+                      base::Bind(&PerfProvider::DoResumeCollection,
+                                 weak_factory_.GetWeakPtr(),
+                                 sleep_duration.InMilliseconds(),
+                                 collection_delay_ms));
 }
 
 void PerfProvider::Observe(int type,
@@ -206,6 +220,10 @@ void PerfProvider::Observe(int type,
   // Only handle session restore notifications.
   DCHECK_EQ(type, chrome::NOTIFICATION_SESSION_RESTORE_DONE);
 
+  // Do not collect if there is an existing collection scheduled.
+  if (restore_session_timer_.IsRunning())
+    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)
@@ -223,16 +241,15 @@ void PerfProvider::Observe(int type,
     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.
+  uint64 collection_delay_ms =
+      base::RandGenerator(kMaxRestoreSessionCollectionDelayMs);
+  restore_session_timer_.Start(
+      FROM_HERE,
+      base::TimeDelta::FromMilliseconds(collection_delay_ms),
+      base::Bind(&PerfProvider::DoRestoreSessionCollection,
+                 weak_factory_.GetWeakPtr(),
+                 collection_delay_ms));
 }
 
 void PerfProvider::OnUserLoggedIn() {
@@ -242,12 +259,12 @@ void PerfProvider::OnUserLoggedIn() {
 
 void PerfProvider::Deactivate() {
   // Stop the timer, but leave |cached_perf_data_| intact.
-  timer_.Stop();
+  interval_timer_.Stop();

[Ilya Sherman, 2014/07/03 00:12:47]

Should this stop the other timers as well?  In fact, do you really need multiple
timers, or can you just use a single timer for all three use cases?

[Simon Que, 2014/07/07 19:45:26]

Done. I think the three timers are needed so that they run independently.

[Ilya Sherman, 2014/07/08 00:06:40]

Why do the timers need to run independently?

 }
 
 void PerfProvider::ScheduleCollection() {
   DCHECK(CalledOnValidThread());
-  if (timer_.IsRunning())
+  if (interval_timer_.IsRunning())
     return;
 
   // Pick a random time in the current interval.
@@ -262,8 +279,8 @@ void PerfProvider::ScheduleCollection() {
   if (scheduled_time < now)
     scheduled_time = now;
 
-  timer_.Start(FROM_HERE, scheduled_time - now, this,
-               &PerfProvider::DoPeriodicCollection);
+  interval_timer_.Start(FROM_HERE, scheduled_time - now, this,
+                        &PerfProvider::DoPeriodicCollection);
 
   // Update the profiling interval tracker to the start of the next interval.
   next_profiling_interval_start_ +=
@@ -316,6 +333,27 @@ void PerfProvider::DoPeriodicCollection() {
   ScheduleCollection();
 }
 
+void PerfProvider::DoResumeCollection(uint64 sleep_duration_ms,
+                                      uint64 time_after_resume_ms) {
+  // 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_ms);
+  sampled_profile->set_ms_after_resume(time_after_resume_ms);
+
+  CollectIfNecessary(sampled_profile.Pass());
+}
+
+void PerfProvider::DoRestoreSessionCollection(uint64 time_after_restore_ms) {
+  // 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_ms);
+
+  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,