Change the logic for discarding all non-histogram logs because of actions/omnibox events to truncat…

components/metrics/metrics_service.cc

 // Copyright 2014 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.
 
 //------------------------------------------------------------------------------
 // Description of the life cycle of a instance of MetricsService.
 //
 //  OVERVIEW
 //
 // A MetricsService instance is typically created at application startup.  It is
@@ skipping 144 matching lines @@
 #include "components/metrics/stability_metrics_provider.h"
 #include "components/metrics/url_constants.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
 #include "components/variations/entropy_provider.h"
 
 namespace metrics {
 
 namespace {
 
-// This drops records if the number of events (user action and omnibox) exceeds
-// the kEventLimit.
-const base::Feature kUMAThrottleEvents{"UMAThrottleEvents",
-                                       base::FEATURE_ENABLED_BY_DEFAULT};
-
 // The delay, in seconds, after starting recording before doing expensive
 // initialization work.
 #if defined(OS_ANDROID) || defined(OS_IOS)
 // On mobile devices, a significant portion of sessions last less than a minute.
 // Use a shorter timer on these platforms to avoid losing data.
 // TODO(dfalcantara): To avoid delaying startup, tighten up initialization so
 //                    that it occurs after the user gets their initial page.
 const int kInitializationDelaySeconds = 5;
 #else
 const int kInitializationDelaySeconds = 30;
 #endif
 
-// The maximum number of events in a log uploaded to the UMA server.
-const int kEventLimit = 2400;
-
 #if defined(OS_ANDROID) || defined(OS_IOS)
 void MarkAppCleanShutdownAndCommit(CleanExitBeacon* clean_exit_beacon,
                                    PrefService* local_state) {
   clean_exit_beacon->WriteBeaconValue(true);
   ExecutionPhaseManager(local_state).OnAppEnterBackground();
   // Start writing right away (write happens on a different thread).
   local_state->CommitPendingWrite();
 }
 #endif  // defined(OS_ANDROID) || defined(OS_IOS)
 
@@ skipping 444 matching lines @@
 void MetricsService::StartInitTask() {
   client_->InitializeSystemProfileMetrics(
       base::Bind(&MetricsService::FinishedInitTask,
                  self_ptr_factory_.GetWeakPtr()));
 }
 
 void MetricsService::CloseCurrentLog() {
   if (!log_manager_.current_log())
     return;
 
-  // TODO(rkaplow): Evaluate if this is needed.
-  if (log_manager_.current_log()->num_events() > kEventLimit) {
-    UMA_HISTOGRAM_COUNTS("UMA.Discarded Log Events",
-                         log_manager_.current_log()->num_events());
-    if (base::FeatureList::IsEnabled(kUMAThrottleEvents)) {
-      log_manager_.DiscardCurrentLog();
-      OpenNewLog();  // Start trivial log to hold our histograms.
-    }
-  }
-
   // If a persistent allocator is in use, update its internal histograms (such
   // as how much memory is being used) before reporting.
   base::PersistentHistogramAllocator* allocator =
       base::GlobalHistogramAllocator::Get();
   if (allocator)
     allocator->UpdateTrackingHistograms();
 
   // Put incremental data (histogram deltas, and realtime stats deltas) at the
   // end of all log transmissions (initial log handles this separately).
   // RecordIncrementalStabilityElements only exists on the derived
   // MetricsLog class.
   MetricsLog* current_log = log_manager_.current_log();
   DCHECK(current_log);
   RecordCurrentEnvironment(current_log);
   base::TimeDelta incremental_uptime;
   base::TimeDelta uptime;
   GetUptimes(local_state_, &incremental_uptime, &uptime);
   current_log->RecordStabilityMetrics(metrics_providers_, incremental_uptime,
                                       uptime);
 
   current_log->RecordGeneralMetrics(metrics_providers_);
   RecordCurrentHistograms();
+  current_log->TruncateEvents();
   DVLOG(1) << "Generated an ongoing log.";
   log_manager_.FinishCurrentLog(log_store());
 }
 
 void MetricsService::PushPendingLogsToPersistentStorage() {
   if (state_ < SENDING_LOGS)
     return;  // We didn't and still don't have time to get plugin list etc.
 
   CloseCurrentLog();
   log_store()->PersistUnsentLogs();
@@ skipping 302 matching lines @@
   // Redundant setting to assure that we always reset this value at shutdown
   // (and that we don't use some alternate path, and not call LogCleanShutdown).
   clean_shutdown_status_ = CLEANLY_SHUTDOWN;
   client_->OnLogCleanShutdown();
   clean_exit_beacon_.WriteBeaconValue(true);
   SetExecutionPhase(ExecutionPhase::SHUTDOWN_COMPLETE, local_state_);
   StabilityMetricsProvider(local_state_).MarkSessionEndCompleted(end_completed);
 }
 
 }  // namespace metrics