Domain Reliability: Omit empty, 0-count resources from uploads

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"
@@ skipping 21 matching lines @@
 class DomainReliabilityContext::ResourceState {
  public:
   ResourceState(DomainReliabilityContext* context,
                 const DomainReliabilityConfig::Resource* config)
       : context(context),
         config(config),
         successful_requests(0),
         failed_requests(0) {}
   ~ResourceState() {}
 
+  // Serializes the resource state into a Value to be included in an upload.
+  // If there is nothing to report (no beacons and all request counters are 0),
+  // returns a scoped_ptr to NULL instead so the resource can be omitted.
   scoped_ptr<base::Value> ToValue(base::TimeTicks upload_time) const {
+    if (beacons.empty() && successful_requests == 0 && failed_requests == 0)
+      return scoped_ptr<base::Value>();
+
     ListValue* beacons_value = new ListValue();
     for (BeaconConstIterator it = beacons.begin(); it != beacons.end(); ++it)
       beacons_value->Append(it->ToValue(upload_time));
 
     DictionaryValue* resource_value = new DictionaryValue();
     resource_value->SetString("resource_name", config->name);
     resource_value->SetInteger("successful_requests", successful_requests);
     resource_value->SetInteger("failed_requests", failed_requests);
     resource_value->Set("beacons", beacons_value);
 
@@ skipping 199 matching lines @@
   DCHECK(!upload_time_.is_null());
   UMA_HISTOGRAM_MEDIUM_TIMES("DomainReliability.UploadDuration",
                              time_->NowTicks() - upload_time_);
   last_upload_time_ = upload_time_;
   upload_time_ = base::TimeTicks();
 }
 
 scoped_ptr<const Value> DomainReliabilityContext::CreateReport(
     base::TimeTicks upload_time) const {
   ListValue* resources_value = new ListValue();
-  for (ResourceStateIterator it = states_.begin(); it != states_.end(); ++it)
-    resources_value->Append((*it)->ToValue(upload_time).release());
+  for (ResourceStateIterator it = states_.begin(); it != states_.end(); ++it) {
+    scoped_ptr<Value> resource_report = (*it)->ToValue(upload_time);
+    if (resource_report)
+      resources_value->Append(resource_report.release());
+  }
 
   DictionaryValue* report_value = new DictionaryValue();
   report_value->SetString("reporter", upload_reporter_string_);
   report_value->Set("resource_reports", resources_value);
 
   return scoped_ptr<const Value>(report_value);
 }
 
 void DomainReliabilityContext::MarkUpload() {
   for (ResourceStateIterator it = states_.begin(); it != states_.end(); ++it)
@@ skipping 28 matching lines @@
 
   min_resource->RemoveOldestBeacon();
   --beacon_count_;
   // If that just removed a beacon counted in uploading_beacon_count_, decrement
   // that.
   if (uploading_beacon_count_ > 0)
     --uploading_beacon_count_;
 }
 
 }  // namespace domain_reliability