Fix http://codereview.chromium.org/6869009 to ignore an existing object exactly once and land the...

base/metrics/histogram.cc

 // Copyright (c) 2011 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.
 
 // Histogram is an object that aggregates statistics, and can summarize them in
 // various forms, including ASCII graphical, HTML, and numerically (as a
 // vector of numbers corresponding to each of the aggregating buckets).
 // See header file for details and examples.
 
 #include "base/metrics/histogram.h"
 
 #include <math.h>
 
 #include <algorithm>
 #include <string>
 
+#include "base/debug/leak_annotations.h"
 #include "base/logging.h"
 #include "base/pickle.h"
 #include "base/stringprintf.h"
 #include "base/synchronization/lock.h"
 
 namespace base {
 
 // Static table of checksums for all possible 8 bit bytes.
 const uint32 Histogram::kCrcTable[256] = {0x0, 0x77073096L, 0xee0e612cL,
 0x990951baL, 0x76dc419L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0xedb8832L,
@@ skipping 63 matching lines @@
     // Extra variable is not needed... but this keeps this section basically
     // identical to other derived classes in this file (and compiler will
     // optimize away the extra variable.
     // To avoid racy destruction at shutdown, the following will be leaked.
     Histogram* tentative_histogram =
         new Histogram(name, minimum, maximum, bucket_count);
     tentative_histogram->InitializeBucketRange();
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(HISTOGRAM, histogram->histogram_type());
   DCHECK(histogram->HasConstructorArguments(minimum, maximum, bucket_count));
   return histogram;
 }
 
 Histogram* Histogram::FactoryTimeGet(const std::string& name,
                                      TimeDelta minimum,
                                      TimeDelta maximum,
@@ skipping 674 matching lines @@
     maximum = kSampleType_MAX - 1;
 
   if (!StatisticsRecorder::FindHistogram(name, &histogram)) {
     // To avoid racy destruction at shutdown, the following will be leaked.
     LinearHistogram* tentative_histogram =
         new LinearHistogram(name, minimum, maximum, bucket_count);
     tentative_histogram->InitializeBucketRange();
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(LINEAR_HISTOGRAM, histogram->histogram_type());
   DCHECK(histogram->HasConstructorArguments(minimum, maximum, bucket_count));
   return histogram;
 }
 
 Histogram* LinearHistogram::FactoryTimeGet(const std::string& name,
                                            TimeDelta minimum,
                                            TimeDelta maximum,
@@ skipping 71 matching lines @@
 Histogram* BooleanHistogram::FactoryGet(const std::string& name, Flags flags) {
   Histogram* histogram(NULL);
 
   if (!StatisticsRecorder::FindHistogram(name, &histogram)) {
     // To avoid racy destruction at shutdown, the following will be leaked.
     BooleanHistogram* tentative_histogram = new BooleanHistogram(name);
     tentative_histogram->InitializeBucketRange();
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(BOOLEAN_HISTOGRAM, histogram->histogram_type());
   return histogram;
 }
 
 Histogram::ClassType BooleanHistogram::histogram_type() const {
   return BOOLEAN_HISTOGRAM;
 }
 
@@ skipping 27 matching lines @@
 
   DCHECK_LT(ranges.back(), kSampleType_MAX);
 
   if (!StatisticsRecorder::FindHistogram(name, &histogram)) {
     // To avoid racy destruction at shutdown, the following will be leaked.
     CustomHistogram* tentative_histogram = new CustomHistogram(name, ranges);
     tentative_histogram->InitializedCustomBucketRange(ranges);
     tentative_histogram->SetFlags(flags);
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    if (histogram == tentative_histogram)
+        ANNOTATE_LEAKING_OBJECT_PTR(histogram);  // see crbug.com/79322
   }
 
   DCHECK_EQ(histogram->histogram_type(), CUSTOM_HISTOGRAM);
   DCHECK(histogram->HasConstructorArguments(ranges[1], ranges.back(),
                                             ranges.size()));
   return histogram;
 }
 
 Histogram::ClassType CustomHistogram::histogram_type() const {
   return CUSTOM_HISTOGRAM;
@@ skipping 196 matching lines @@
 }
 
 // static
 StatisticsRecorder::HistogramMap* StatisticsRecorder::histograms_ = NULL;
 // static
 base::Lock* StatisticsRecorder::lock_ = NULL;
 // static
 bool StatisticsRecorder::dump_on_exit_ = false;
 
 }  // namespace base