[NoStatePrefetch] Track redirects in UMA

chrome/browser/prerender/prerender_histograms.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 "chrome/browser/prerender/prerender_histograms.h"
 
 #include <string>
 
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/prerender/prerender_util.h"
 
 namespace prerender {
 
 namespace {
 
 // This enum is used to define the buckets for the
 // "Prerender.NoStatePrefetchResourceCount" histogram family.
 // Hence, existing enumerated constants should never be deleted or reordered,
 // and new constants should only be appended at the end of the enumeration.
-enum NoStatePrefetchResourceType {
-  MAIN_RESOURCE_CACHEABLE = 0,
-  MAIN_RESOURCE_NO_STORE = 1,
-  SUB_RESOURCE_CACHEABLE = 2,
-  SUB_RESOURCE_NO_STORE = 3,
+enum NoStatePrefetchResponseType {
+  NO_STORE = 1 << 0,
+  REDIRECT = 1 << 1,
+  MAIN_RESOURCE = 1 << 2,
+  NO_STATE_PREFETCH_RESPONSE_TYPE_COUNT = 1 << 3
+};
 
-  NO_STATE_PREFETCH_RESOURCE_TYPE_COUNT  // Must be the last.
-};
+int GetResourceType(bool is_main_resource, bool is_redirect, bool is_no_store) {
+  return (is_no_store * NO_STORE) + (is_redirect * REDIRECT) +
+         (is_main_resource * MAIN_RESOURCE);
+}
+
+// Similar to UMA_HISTOGRAM_ENUMERATION but allows a dynamic histogram name.
+// Records a sample such as 0 <= sample < bucket_count, in a histogram with
+// |bucket_count| buckets of width 1 each.
+void RecordHistogramEnum(std::string histogram_name,
+                         base::HistogramBase::Sample sample,
+                         base::HistogramBase::Sample bucket_count) {
+  DCHECK_LT(sample, bucket_count);
+  base::HistogramBase* histogram_pointer = base::LinearHistogram::FactoryGet(
+      histogram_name, 1, bucket_count, bucket_count + 1,
+      base::HistogramBase::kUmaTargetedHistogramFlag);
+  histogram_pointer->Add(sample);
+}
 
 // Time window for which we will record windowed PLTs from the last observed
 // link rel=prefetch tag. This is not intended to be the same as the prerender
 // ttl, it's just intended to be a window during which a prerender has likely
 // affected performance.
 const int kWindowDurationSeconds = 30;
 
 std::string ComposeHistogramName(const std::string& prefix_type,
                                  const std::string& name) {
   if (prefix_type.empty())
@@ skipping 345 matching lines @@
             name, prerender_bytes, kHistogramMin, kHistogramMax, kBucketCount));
   } else {
     PREFIXED_HISTOGRAM(
         "NetworkBytesWasted",
         origin,
         UMA_HISTOGRAM_CUSTOM_COUNTS(
             name, prerender_bytes, kHistogramMin, kHistogramMax, kBucketCount));
   }
 }
 
-void PrerenderHistograms::RecordResourcePrefetch(Origin origin,
-                                                 bool is_main_resource,
-                                                 bool is_no_store) const {
+void PrerenderHistograms::RecordPrefetchResponseReceived(
+    Origin origin,
+    bool is_main_resource,
+    bool is_redirect,
+    bool is_no_store) const {
   DCHECK(thread_checker_.CalledOnValidThread());
-  NoStatePrefetchResourceType type =
-      is_main_resource
-          ? (is_no_store ? MAIN_RESOURCE_NO_STORE : MAIN_RESOURCE_CACHEABLE)
-          : (is_no_store ? SUB_RESOURCE_NO_STORE : SUB_RESOURCE_CACHEABLE);
-  DCHECK_LT(type, NO_STATE_PREFETCH_RESOURCE_TYPE_COUNT);
 
+  int sample = GetResourceType(is_main_resource, is_redirect, is_no_store);
   std::string histogram_name =
-      GetHistogramName(origin, IsOriginWash(), "NoStatePrefetchResourceTypes");
+      GetHistogramName(origin, IsOriginWash(), "NoStatePrefetchResponseTypes");
+  RecordHistogramEnum(histogram_name, sample,
+                      NO_STATE_PREFETCH_RESPONSE_TYPE_COUNT);
+}
 
-  // Unrolls UMA_HISTOGRAM_ENUMERATION, required to support dynamic histogram
-  // name.
-  base::HistogramBase* histogram_pointer = base::LinearHistogram::FactoryGet(
-      histogram_name, 1, NO_STATE_PREFETCH_RESOURCE_TYPE_COUNT,
-      NO_STATE_PREFETCH_RESOURCE_TYPE_COUNT + 1,
-      base::HistogramBase::kUmaTargetedHistogramFlag);
-  histogram_pointer->Add(type);
+void PrerenderHistograms::RecordPrefetchRedirectCount(
+    Origin origin,
+    bool is_main_resource,
+    int redirect_count) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  const int kMaxRedirectCount = 10;
+  std::string histogram_base_name = base::StringPrintf(
+      "NoStatePrefetch%sResourceRedirects", is_main_resource ? "Main" : "Sub");
+  std::string histogram_name =
+      GetHistogramName(origin, IsOriginWash(), histogram_base_name);
+  RecordHistogramEnum(histogram_name, redirect_count, kMaxRedirectCount);
 }
 
 bool PrerenderHistograms::IsOriginWash() const {
   if (!WithinWindow())
     return false;
   return origin_wash_;
 }
 
 }  // namespace prerender