Reorganize histograms for persistence.

base/metrics/sparse_histogram.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 "base/metrics/sparse_histogram.h"
 
 #include <utility>
 
+#include "base/metrics/metrics_hashes.h"
 #include "base/metrics/sample_map.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/pickle.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
 
 namespace base {
 
 typedef HistogramBase::Count Count;
 typedef HistogramBase::Sample Sample;
 
 // static
 HistogramBase* SparseHistogram::FactoryGet(const std::string& name,
                                            int32 flags) {
   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
 
   if (!histogram) {
     // To avoid racy destruction at shutdown, the following will be leaked.
     HistogramBase* tentative_histogram = new SparseHistogram(name);
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
   }
   DCHECK_EQ(SPARSE_HISTOGRAM, histogram->GetHistogramType());
   return histogram;
 }
 
 SparseHistogram::~SparseHistogram() {}
 
+uint64_t SparseHistogram::name_hash() const {
+  return samples_.id();
+}
+
 HistogramType SparseHistogram::GetHistogramType() const {
   return SPARSE_HISTOGRAM;
 }
 
 bool SparseHistogram::HasConstructionArguments(
     Sample expected_minimum,
     Sample expected_maximum,
     size_t expected_bucket_count) const {
   // SparseHistogram never has min/max/bucket_count limit.
   return false;
@@ skipping 10 matching lines @@
   }
   {
     base::AutoLock auto_lock(lock_);
     samples_.Accumulate(value, count);
   }
 
   FindAndRunCallback(value);
 }
 
 scoped_ptr<HistogramSamples> SparseHistogram::SnapshotSamples() const {
-  scoped_ptr<SampleMap> snapshot(new SampleMap());
+  scoped_ptr<SampleMap> snapshot(new SampleMap(name_hash()));
 
   base::AutoLock auto_lock(lock_);
   snapshot->Add(samples_);
   return std::move(snapshot);
 }
 
 void SparseHistogram::AddSamples(const HistogramSamples& samples) {
   base::AutoLock auto_lock(lock_);
   samples_.Add(samples);
 }
@@ skipping 11 matching lines @@
 
 void SparseHistogram::WriteAscii(std::string* output) const {
   WriteAsciiImpl(true, "\n", output);
 }
 
 bool SparseHistogram::SerializeInfoImpl(Pickle* pickle) const {
   return pickle->WriteString(histogram_name()) && pickle->WriteInt(flags());
 }
 
 SparseHistogram::SparseHistogram(const std::string& name)
-    : HistogramBase(name) {}
+    : HistogramBase(name),
+      samples_(HashMetricName(name)) {}
 
 HistogramBase* SparseHistogram::DeserializeInfoImpl(PickleIterator* iter) {
   std::string histogram_name;
   int flags;
   if (!iter->ReadString(&histogram_name) || !iter->ReadInt(&flags)) {
     DLOG(ERROR) << "Pickle error decoding Histogram: " << histogram_name;
     return NULL;
   }
 
   DCHECK(flags & HistogramBase::kIPCSerializationSourceFlag);
@@ skipping 69 matching lines @@
                                        std::string* output) const {
   StringAppendF(output,
                 "Histogram: %s recorded %d samples",
                 histogram_name().c_str(),
                 total_count);
   if (flags() & ~kHexRangePrintingFlag)
     StringAppendF(output, " (flags = 0x%x)", flags() & ~kHexRangePrintingFlag);
 }
 
 }  // namespace base