Domain Reliability: Add sample_rate field to Beacon

components/domain_reliability/context.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.
 
 #include "components/domain_reliability/context.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
+#include "base/rand_util.h"
 #include "base/values.h"
 #include "components/domain_reliability/dispatcher.h"
 #include "components/domain_reliability/uploader.h"
 #include "components/domain_reliability/util.h"
 #include "net/base/net_errors.h"
 #include "net/url_request/url_request_context_getter.h"
 
 using base::DictionaryValue;
 using base::ListValue;
 using base::Value;
@@ skipping 38 matching lines @@
       weak_factory_(this) {
 }
 
 DomainReliabilityContext::~DomainReliabilityContext() {
   ClearBeacons();
 }
 
 void DomainReliabilityContext::OnBeacon(
     scoped_ptr<DomainReliabilityBeacon> beacon) {
   bool success = (beacon->status == "ok");
-
-  bool reported = config().DecideIfShouldReportRequest(success);
-  UMA_HISTOGRAM_BOOLEAN("DomainReliability.BeaconReported", reported);
-  if (!reported) {
+  double sample_rate = config().GetSampleRate(success);
+  bool should_report = base::RandDouble() < sample_rate;
+  UMA_HISTOGRAM_BOOLEAN("DomainReliability.BeaconReported", should_report);
+  if (!should_report) {
     // If the beacon isn't queued to be reported, it definitely cannot evict
     // an older beacon. (This histogram is also logged below based on whether
     // an older beacon was actually evicted.)
     LogOnBeaconDidEvictHistogram(false);
     return;
   }
+  beacon->sample_rate = sample_rate;
 
   UMA_HISTOGRAM_SPARSE_SLOWLY("DomainReliability.ReportedBeaconError",
                               -beacon->chrome_error);
   if (!beacon->server_ip.empty()) {
     UMA_HISTOGRAM_SPARSE_SLOWLY(
         "DomainReliability.ReportedBeaconError_HasServerIP",
         -beacon->chrome_error);
   }
   // TODO(ttuttle): Histogram HTTP response code?
 
   // Allow beacons about reports, but don't schedule an upload for more than
   // one layer of recursion, to avoid infinite report loops.
   if (beacon->upload_depth <= kMaxUploadDepthToSchedule)
     scheduler_.OnBeaconAdded();
   beacons_.push_back(beacon.release());
-  bool evicted = beacons_.size() > kMaxQueuedBeacons;
-  if (evicted)
+  bool should_evict = beacons_.size() > kMaxQueuedBeacons;
+  if (should_evict)
     RemoveOldestBeacon();
 
-  LogOnBeaconDidEvictHistogram(evicted);
+  LogOnBeaconDidEvictHistogram(should_evict);
 }
 
 void DomainReliabilityContext::ClearBeacons() {
   STLDeleteElements(&beacons_);
   beacons_.clear();
   uploading_beacons_size_ = 0;
 }
 
 scoped_ptr<Value> DomainReliabilityContext::GetWebUIData() const {
   DictionaryValue* context_value = new DictionaryValue();
@@ skipping 134 matching lines @@
   delete beacons_.front();
   beacons_.pop_front();
 
   // If that just removed a beacon counted in uploading_beacons_size_, decrement
   // that.
   if (uploading_beacons_size_ > 0)
     --uploading_beacons_size_;
 }
 
 }  // namespace domain_reliability