SimpleCache: more histograms watching how index is loaded.

net/disk_cache/simple/simple_index_file.cc

 // Copyright (c) 2013 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 "net/disk_cache/simple/simple_index_file.h"
 
 #include "base/file_util.h"
 #include "base/hash.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 283 matching lines @@
   scoped_ptr<SimpleIndex::EntrySet> index_file_entries;
 
   const bool index_file_exists = file_util::PathExists(index_file_path);
 
   // Only load if the index is not stale.
   const bool index_stale = IsIndexFileStale(index_file_path);
   if (!index_stale) {
     const base::TimeTicks start = base::TimeTicks::Now();
     index_file_entries = LoadFromDisk(index_file_path);
     UMA_HISTOGRAM_TIMES("SimpleCache.IndexLoadTime",
-                        (base::TimeTicks::Now() - start));
+                        base::TimeTicks::Now() - start);
+    UMA_HISTOGRAM_COUNTS("SimpleCache.IndexEntriesLoaded",
+                         index_file_entries->size());
   }
 
   UMA_HISTOGRAM_BOOLEAN("SimpleCache.IndexStale", index_stale);
 
   bool force_index_flush = false;
   if (!index_file_entries) {
     const base::TimeTicks start = base::TimeTicks::Now();
     index_file_entries = RestoreFromDisk(index_file_path);
-    UMA_HISTOGRAM_TIMES("SimpleCache.IndexRestoreTime",
-                        (base::TimeTicks::Now() - start));
+    UMA_HISTOGRAM_MEDIUM_TIMES("SimpleCache.IndexRestoreTime",
+                        base::TimeTicks::Now() - start);
+    UMA_HISTOGRAM_COUNTS("SimpleCache.IndexEntriesRestored",
+                         index_file_entries->size());
 
     // When we restore from disk we write the merged index file to disk right
     // away, this might save us from having to restore again next time.
     force_index_flush = true;
   }
   UMA_HISTOGRAM_BOOLEAN("SimpleCache.IndexCorrupt",
                         (!index_stale && force_index_flush));
 
   // Used in histograms. Please only add new values at the end.
   enum {
@@ skipping 78 matching lines @@
           index_file_entries.get());
     } else {
       // Summing up the total size of the entry through all the *_[0-2] files
       it->second.SetEntrySize(it->second.GetEntrySize() + file_size);
     }
   }
   return index_file_entries.Pass();
 }
 
 }  // namespace disk_cache