This is a copy of http://codereview.chromium.org/10796047/

It was reverted in https://chromiumcodereview.appspot.com/10807083/ because it unveiled a problem of build_nexe.py on Windows (http://crbug.com/138687).
Now the bug is fixed so submit this CL again.

Review URL: https://chromiumcodereview.appspot.com/10809076

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148391 0039d316-1c4b-4281-b951-d872f2087c98

base/base.gyp

@@ -436,6 +436,7 @@
         'message_loop_unittest.cc',
         'message_pump_glib_unittest.cc',
         'message_pump_libevent_unittest.cc',
+        'metrics/bucket_ranges_unittest.cc',
         'metrics/field_trial_unittest.cc',
         'metrics/histogram_unittest.cc',
         'metrics/stats_table_unittest.cc',
@@ -566,7 +567,7 @@
             # TODO(ios): Remove these as base/ is unforked.
             # For now, exclude everything that doesn't build as-is, just to
             # get a minimal target building.
-	    # Unittests that don't pass.
+            # Unittests that don't pass.
             ['exclude', '^message_loop_unittest\\.cc$'],
           ],
           'actions': [

base/base.gypi

@@ -236,6 +236,8 @@
           'message_pump_default.h',
           'message_pump_win.cc',
           'message_pump_win.h',
+          'metrics/bucket_ranges.cc',
+          'metrics/bucket_ranges.h',
           'metrics/histogram.cc',
           'metrics/histogram.h',
           'metrics/histogram_base.cc',

base/metrics/bucket_ranges.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/bucket_ranges.h"
+
+#include <cmath>
+
+#include "base/logging.h"
+
+namespace base {
+
+// Static table of checksums for all possible 8 bit bytes.
+static const uint32 kCrcTable[256] = { 0x0, 0x77073096L, 0xee0e612cL,
+0x990951baL, 0x76dc419L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0xedb8832L,
+0x79dcb8a4L, 0xe0d5e91eL, 0x97d2d988L, 0x9b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
+0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, 0x1adad47dL,
+0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, 0x646ba8c0L, 0xfd62f97aL,
+0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L,
+0x4c69105eL, 0xd56041e4L, 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL,
+0xa50ab56bL, 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
+0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, 0xc8d75180L,
+0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, 0xb8bda50fL, 0x2802b89eL,
+0x5f058808L, 0xc60cd9b2L, 0xb10be924L, 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL,
+0xb6662d3dL, 0x76dc4190L, 0x1db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L,
+0x6b6b51fL, 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0xf00f934L, 0x9609a88eL,
+0xe10e9818L, 0x7f6a0dbbL, 0x86d3d2dL, 0x91646c97L, 0xe6635c01L, 0x6b6b51f4L,
+0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, 0x1b01a57bL, 0x8208f4c1L,
+0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL,
+0x15da2d49L, 0x8cd37cf3L, 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L,
+0xd4bb30e2L, 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
+0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, 0xaa0a4c5fL,
+0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, 0xc90c2086L, 0x5768b525L,
+0x206f85b3L, 0xb966d409L, 0xce61e49fL, 0x5edef90eL, 0x29d9c998L, 0xb0d09822L,
+0xc7d7a8b4L, 0x59b33d17L, 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L,
+0x9abfb3b6L, 0x3b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x4db2615L,
+0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0xd6d6a3eL, 0x7a6a5aa8L, 0xe40ecf0bL,
+0x9309ff9dL, 0xa00ae27L, 0x7d079eb1L, 0xf00f9344L, 0x8708a3d2L, 0x1e01f268L,
+0x6906c2feL, 0xf762575dL, 0x806567cbL, 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L,
+0x89d32be0L, 0x10da7a5aL, 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L,
+0x60b08ed5L, 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
+0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, 0x36034af6L,
+0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, 0x4669be79L, 0xcb61b38cL,
+0xbc66831aL, 0x256fd2a0L, 0x5268e236L, 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L,
+0x5505262fL, 0xc5ba3bbeL, 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L,
+0xb5d0cf31L, 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
+0x26d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x5005713L, 0x95bf4a82L,
+0xe2b87a14L, 0x7bb12baeL, 0xcb61b38L, 0x92d28e9bL, 0xe5d5be0dL, 0x7cdcefb7L,
+0xbdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL,
+0xf6b9265bL, 0x6fb077e1L, 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL,
+0x11010b5cL, 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
+0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, 0x4969474dL,
+0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, 0x37d83bf0L, 0xa9bcae53L,
+0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L,
+0x24b4a3a6L, 0xbad03605L, 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL,
+0xc4614ab8L, 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
+0x2d02ef8dL,
+};
+
+// We generate the CRC-32 using the low order bits to select whether to XOR in
+// the reversed polynomial 0xedb88320L.  This is nice and simple, and allows us
+// to keep the quotient in a uint32.  Since we're not concerned about the nature
+// of corruptions (i.e., we don't care about bit sequencing, since we are
+// handling memory changes, which are more grotesque) so we don't bother to
+// get the CRC correct for big-endian vs little-ending calculations.  All we
+// need is a nice hash, that tends to depend on all the bits of the sample, with
+// very little chance of changes in one place impacting changes in another
+// place.
+static uint32 Crc32(uint32 sum, HistogramBase::Sample value) {
+  // TODO(jar): Switch to false and watch stats.
+  const bool kUseRealCrc = true;
+
+  if (kUseRealCrc) {
+    union {
+      HistogramBase::Sample range;
+      unsigned char bytes[sizeof(HistogramBase::Sample)];
+    } converter;
+    converter.range = value;
+    for (size_t i = 0; i < sizeof(converter); ++i)
+      sum = kCrcTable[(sum & 0xff) ^ converter.bytes[i]] ^ (sum >> 8);
+  } else {
+    // Use hash techniques provided in ReallyFastHash, except we don't care
+    // about "avalanching" (which would worsten the hash, and add collisions),
+    // and we don't care about edge cases since we have an even number of bytes.
+    union {
+      HistogramBase::Sample range;
+      uint16 ints[sizeof(HistogramBase::Sample) / 2];
+    } converter;
+    DCHECK_EQ(sizeof(HistogramBase::Sample), sizeof(converter));
+    converter.range = value;
+    sum += converter.ints[0];
+    sum = (sum << 16) ^ sum ^ (static_cast<uint32>(converter.ints[1]) << 11);
+    sum += sum >> 11;
+  }
+  return sum;
+}
+
+BucketRanges::BucketRanges(size_t num_ranges)
+    : ranges_(num_ranges, 0),
+      checksum_(0) {}
+
+BucketRanges::~BucketRanges() {}
+
+void BucketRanges::set_range(size_t i, HistogramBase::Sample value) {
+  DCHECK_LT(i, ranges_.size());
+  DCHECK_GE(value, 0);
+  ranges_[i] = value;
+}
+
+uint32 BucketRanges::CalculateChecksum() {
+  // Seed checksum.
+  uint32 checksum = static_cast<uint32>(ranges_.size());
+
+  for (size_t index = 0; index < ranges_.size(); ++index)
+    checksum = Crc32(checksum, ranges_[index]);
+  return checksum;
+}
+
+bool BucketRanges::HasValidChecksum() {
+  return CalculateChecksum() == checksum_;
+}
+
+void BucketRanges::ResetChecksum() {
+  checksum_ = CalculateChecksum();
+}
+
+bool BucketRanges::Equals(const BucketRanges* other) const {
+  if (checksum_ != other->checksum_)
+    return false;
+  if (ranges_.size() != other->ranges_.size())
+    return false;
+  for (size_t index = 0; index < ranges_.size(); ++index) {
+    if (ranges_[index] != other->ranges_[index])
+      return false;
+  }
+  return true;
+}
+
+}  // namespace base

base/metrics/bucket_ranges.h

+// 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.
+//
+// BucketRanges stores the vector of ranges that delimit what samples are
+// tallied in the corresponding buckets of a histogram. Histograms that have
+// same ranges for all their corresponding buckets should share the same
+// BucketRanges object.
+//
+// E.g. A 5 buckets LinearHistogram with 1 as minimal value and 4 as maximal
+// value will need a BucketRanges with 6 ranges:
+// 0, 1, 2, 3, 4, INT_MAX
+//
+// TODO(kaiwang): Currently we keep all negative values in 0~1 bucket. Consider
+// changing 0 to INT_MIN.
+
+#ifndef BASE_METRICS_BUCKET_RANGES_H_
+#define BASE_METRICS_BUCKET_RANGES_H_
+
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
+#include "base/metrics/histogram_base.h"
+
+namespace base {
+
+class BASE_EXPORT_PRIVATE BucketRanges {
+ public:
+  typedef std::vector<HistogramBase::Sample> Ranges;
+
+  BucketRanges(size_t num_ranges);
+  ~BucketRanges();
+
+  size_t size() const { return ranges_.size(); }
+  HistogramBase::Sample range(size_t i) const { return ranges_[i]; }
+  void set_range(size_t i, HistogramBase::Sample value);
+  uint32 checksum() const { return checksum_; }
+  void set_checksum(uint32 checksum) { checksum_ = checksum; }
+
+  // Checksum methods to verify whether the ranges are corrupted (e.g. bad
+  // memory access).
+  uint32 CalculateChecksum();
+  bool HasValidChecksum();
+  void ResetChecksum();
+
+  // Return true iff |other| object has same ranges_ as |this| object's ranges_.
+  bool Equals(const BucketRanges* other) const;
+
+ private:
+  // A monotonically increasing list of values which determine which bucket to
+  // put a sample into.  For each index, show the smallest sample that can be
+  // added to the corresponding bucket.
+  Ranges ranges_;
+
+  // Checksum for the conntents of ranges_.  Used to detect random over-writes
+  // of our data, and to quickly see if some other BucketRanges instance is
+  // possibly Equal() to this instance.
+  // TODO(kaiwang): Consider change this to uint64. Because we see a lot of
+  // noise on UMA dashboard.
+  uint32 checksum_;
+
+  DISALLOW_COPY_AND_ASSIGN(BucketRanges);
+};
+
+}  // namespace base
+
+#endif  // BASE_METRICS_BUCKET_RANGES_H_

base/metrics/bucket_ranges_unittest.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/bucket_ranges.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace {
+
+TEST(BucketRangesTest, NormalSetup) {
+  BucketRanges ranges(5);
+  ASSERT_EQ(5u, ranges.size());
+
+  for (int i = 0; i < 5; i++) {
+    EXPECT_EQ(0, ranges.range(i));
+  }
+  EXPECT_EQ(0u, ranges.checksum());
+
+  ranges.set_range(3, 100);
+  EXPECT_EQ(100, ranges.range(3));
+}
+
+TEST(BucketRangesTest, Equals) {
+  // Compare empty ranges.
+  BucketRanges ranges1(3);
+  BucketRanges ranges2(3);
+  BucketRanges ranges3(5);
+
+  EXPECT_TRUE(ranges1.Equals(&ranges2));
+  EXPECT_FALSE(ranges1.Equals(&ranges3));
+  EXPECT_FALSE(ranges2.Equals(&ranges3));
+
+  // Compare full filled ranges.
+  ranges1.set_range(0, 0);
+  ranges1.set_range(1, 1);
+  ranges1.set_range(2, 2);
+  ranges1.set_checksum(100);
+  ranges2.set_range(0, 0);
+  ranges2.set_range(1, 1);
+  ranges2.set_range(2, 2);
+  ranges2.set_checksum(100);
+
+  EXPECT_TRUE(ranges1.Equals(&ranges2));
+
+  // Checksum does not match.
+  ranges1.set_checksum(99);
+  EXPECT_FALSE(ranges1.Equals(&ranges2));
+  ranges1.set_checksum(100);
+
+  // Range does not match.
+  ranges1.set_range(1, 3);
+  EXPECT_FALSE(ranges1.Equals(&ranges2));
+}
+
+TEST(BucketRangesTest, Checksum) {
+  BucketRanges ranges(3);
+  ranges.set_range(0, 0);
+  ranges.set_range(1, 1);
+  ranges.set_range(2, 2);
+
+  ranges.ResetChecksum();
+  EXPECT_EQ(289217253u, ranges.checksum());
+
+  ranges.set_range(2, 3);
+  EXPECT_FALSE(ranges.HasValidChecksum());
+
+  ranges.ResetChecksum();
+  EXPECT_EQ(2843835776u, ranges.checksum());
+  EXPECT_TRUE(ranges.HasValidChecksum());
+}
+
+}  // namespace
+}  // namespace base

base/metrics/histogram.cc

@@ -383,7 +383,7 @@ Histogram::ClassType Histogram::histogram_type() const {
 }
 
 Histogram::Sample Histogram::ranges(size_t i) const {
-  return cached_ranges_->ranges(i);
+  return bucket_ranges_->range(i);
 }
 
 size_t Histogram::bucket_count() const {
@@ -423,7 +423,7 @@ Histogram::Histogram(const std::string& name, Sample minimum,
     declared_max_(maximum),
     bucket_count_(bucket_count),
     flags_(kNoFlags),
-    cached_ranges_(new CachedRanges(bucket_count + 1, 0)),
+    bucket_ranges_(new BucketRanges(bucket_count + 1)),
     range_checksum_(0),
     sample_() {
   Initialize();
@@ -436,7 +436,7 @@ Histogram::Histogram(const std::string& name, TimeDelta minimum,
     declared_max_(static_cast<int> (maximum.InMilliseconds())),
     bucket_count_(bucket_count),
     flags_(kNoFlags),
-    cached_ranges_(new CachedRanges(bucket_count + 1, 0)),
+    bucket_ranges_(new BucketRanges(bucket_count + 1)),
     range_checksum_(0),
     sample_() {
   Initialize();
@@ -557,12 +557,12 @@ void Histogram::Accumulate(Sample value, Count count, size_t index) {
 void Histogram::SetBucketRange(size_t i, Sample value) {
   DCHECK_GT(bucket_count_, i);
   DCHECK_GE(value, 0);
-  cached_ranges_->SetBucketRange(i, value);
+  bucket_ranges_->set_range(i, value);
 }
 
 bool Histogram::ValidateBucketRanges() const {
   // Standard assertions that all bucket ranges should satisfy.
-  DCHECK_EQ(bucket_count_ + 1, cached_ranges_->size());
+  DCHECK_EQ(bucket_count_ + 1, bucket_ranges_->size());
   DCHECK_EQ(0, ranges(0));
   DCHECK_EQ(declared_min(), ranges(1));
   DCHECK_EQ(declared_max(), ranges(bucket_count_ - 1));
@@ -571,9 +571,9 @@ bool Histogram::ValidateBucketRanges() const {
 }
 
 uint32 Histogram::CalculateRangeChecksum() const {
-  DCHECK_EQ(cached_ranges_->size(), bucket_count() + 1);
+  DCHECK_EQ(bucket_ranges_->size(), bucket_count() + 1);
   // Seed checksum.
-  uint32 checksum = static_cast<uint32>(cached_ranges_->size());
+  uint32 checksum = static_cast<uint32>(bucket_ranges_->size());
   for (size_t index = 0; index < bucket_count(); ++index)
     checksum = Crc32(checksum, ranges(index));
   return checksum;
@@ -591,7 +591,7 @@ void Histogram::Initialize() {
   size_t maximal_bucket_count = declared_max_ - declared_min_ + 2;
   DCHECK_LE(bucket_count_, maximal_bucket_count);
   DCHECK_EQ(0, ranges(0));
-  cached_ranges_->SetBucketRange(bucket_count_, kSampleType_MAX);
+  bucket_ranges_->set_range(bucket_count_, kSampleType_MAX);
 }
 
 // We generate the CRC-32 using the low order bits to select whether to XOR in
@@ -1000,8 +1000,8 @@ CustomHistogram::CustomHistogram(const std::string& name,
 }
 
 bool CustomHistogram::SerializeRanges(Pickle* pickle) const {
-  for (size_t i = 0; i < cached_ranges()->size(); ++i) {
-    if (!pickle->WriteInt(cached_ranges()->ranges(i)))
+  for (size_t i = 0; i < bucket_ranges()->size(); ++i) {
+    if (!pickle->WriteInt(bucket_ranges()->range(i)))
       return false;
   }
   return true;
@@ -1031,30 +1031,4 @@ double CustomHistogram::GetBucketSize(Count current, size_t i) const {
   return 1;
 }
 
-CachedRanges::CachedRanges(size_t bucket_count, int initial_value)
-    : ranges_(bucket_count, initial_value),
-      range_checksum_(0) {
-}
-
-CachedRanges::~CachedRanges() {
-}
-
-void CachedRanges::SetBucketRange(size_t i, Histogram::Sample value) {
-  DCHECK_LT(i, ranges_.size());
-  DCHECK_GE(value, 0);
-  ranges_[i] = value;
-}
-
-bool CachedRanges::Equals(CachedRanges* other) const {
-  if (range_checksum_ != other->range_checksum_)
-    return false;
-  if (ranges_.size() != other->ranges_.size())
-    return false;
-  for (size_t index = 0; index < ranges_.size(); ++index) {
-    if (ranges_[index] != other->ranges_[index])
-      return false;
-  }
-  return true;
-}
-
 }  // namespace base

base/metrics/histogram.h

@@ -49,6 +49,7 @@
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/logging.h"
+#include "base/metrics/bucket_ranges.h"
 #include "base/metrics/histogram_base.h"
 #include "base/time.h"
 
@@ -318,7 +319,7 @@ class Lock;
 //------------------------------------------------------------------------------
 
 class BooleanHistogram;
-class CachedRanges;
+class BucketRanges;
 class CustomHistogram;
 class Histogram;
 class LinearHistogram;
@@ -468,9 +469,6 @@ class BASE_EXPORT Histogram : public HistogramBase {
   // The following methods provide graphical histogram displays.
   virtual void WriteHTMLGraph(std::string* output) const OVERRIDE;
   virtual void WriteAscii(std::string* output) const OVERRIDE;
-  void WriteAsciiImpl(bool graph_it,
-                      const std::string& newline,
-                      std::string* output) const;
 
   // Support generic flagging of Histograms.
   // 0x1 Currently used to mark this histogram to be recorded by UMA..
@@ -511,9 +509,9 @@ class BASE_EXPORT Histogram : public HistogramBase {
   virtual Sample ranges(size_t i) const;
   uint32 range_checksum() const { return range_checksum_; }
   virtual size_t bucket_count() const;
-  CachedRanges* cached_ranges() const { return cached_ranges_; }
-  void set_cached_ranges(CachedRanges* cached_ranges) {
-    cached_ranges_ = cached_ranges;
+  BucketRanges* bucket_ranges() const { return bucket_ranges_; }
+  void set_bucket_ranges(BucketRanges* bucket_ranges) {
+    bucket_ranges_ = bucket_ranges;
   }
   // Snapshot the current complete set of sample data.
   // Override with atomic/locked snapshot if needed.
@@ -526,7 +524,7 @@ class BASE_EXPORT Histogram : public HistogramBase {
                                                 TimeDelta maximum,
                                                 size_t bucket_count);
   // Return true iff the range_checksum_ matches current |ranges_| vector in
-  // |cached_ranges_|.
+  // |bucket_ranges_|.
   bool HasValidRangeChecksum() const;
 
  protected:
@@ -543,7 +541,7 @@ class BASE_EXPORT Histogram : public HistogramBase {
   // serialized parameters.
   virtual bool SerializeRanges(Pickle* pickle) const;
 
-  // Initialize ranges_ mapping in cached_ranges_.
+  // Initialize ranges_ mapping in bucket_ranges_.
   void InitializeBucketRange();
 
   // Method to override to skip the display of the i'th bucket if it's empty.
@@ -576,7 +574,7 @@ class BASE_EXPORT Histogram : public HistogramBase {
   //----------------------------------------------------------------------------
   void SetBucketRange(size_t i, Sample value);
 
-  // Validate that ranges_ in cached_ranges_ was created sensibly (top and
+  // Validate that ranges_ in bucket_ranges_ was created sensibly (top and
   // bottom range values relate properly to the declared_min_ and
   // declared_max_).
   bool ValidateBucketRanges() const;
@@ -601,6 +599,10 @@ class BASE_EXPORT Histogram : public HistogramBase {
   //----------------------------------------------------------------------------
   // Helpers for emitting Ascii graphic.  Each method appends data to output.
 
+  void WriteAsciiImpl(bool graph_it,
+                      const std::string& newline,
+                      std::string* output) const;
+
   // Find out how large the (graphically) the largest bucket will appear to be.
   double GetPeakBucketSize(const SampleSet& snapshot) const;
 
@@ -639,8 +641,8 @@ class BASE_EXPORT Histogram : public HistogramBase {
   // For each index, show the least value that can be stored in the
   // corresponding bucket. We also append one extra element in this array,
   // containing kSampleType_MAX, to make calculations easy.
-  // The dimension of ranges_ in cached_ranges_ is bucket_count + 1.
-  CachedRanges* cached_ranges_;
+  // The dimension of ranges_ in bucket_ranges_ is bucket_count + 1.
+  BucketRanges* bucket_ranges_;
 
   // For redundancy, we store a checksum of all the sample ranges when ranges
   // are generated.  If ever there is ever a difference, then the histogram must
@@ -690,7 +692,7 @@ class BASE_EXPORT LinearHistogram : public Histogram {
   LinearHistogram(const std::string& name, TimeDelta minimum,
                   TimeDelta maximum, size_t bucket_count);
 
-  // Initialize ranges_ mapping in cached_ranges_.
+  // Initialize ranges_ mapping in bucket_ranges_.
   void InitializeBucketRange();
   virtual double GetBucketSize(Count current, size_t i) const OVERRIDE;
 
@@ -762,51 +764,13 @@ class BASE_EXPORT CustomHistogram : public Histogram {
 
   virtual bool SerializeRanges(Pickle* pickle) const OVERRIDE;
 
-  // Initialize ranges_ mapping in cached_ranges_.
+  // Initialize ranges_ mapping in bucket_ranges_.
   void InitializedCustomBucketRange(const std::vector<Sample>& custom_ranges);
   virtual double GetBucketSize(Count current, size_t i) const OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(CustomHistogram);
 };
 
-// CachedRanges stores the Ranges vector. Histograms that have same Ranges
-// vector will use the same CachedRanges object.
-class BASE_EXPORT CachedRanges {
- public:
-  typedef std::vector<Histogram::Sample> Ranges;
-
-  CachedRanges(size_t bucket_count, int initial_value);
-  ~CachedRanges();
-
-  //----------------------------------------------------------------------------
-  // Accessors methods for ranges_ and range_checksum_.
-  //----------------------------------------------------------------------------
-  size_t size() const { return ranges_.size(); }
-  Histogram::Sample ranges(size_t i) const { return ranges_[i]; }
-  void SetBucketRange(size_t i, Histogram::Sample value);
-  uint32 range_checksum(uint32 checksum) const { return range_checksum_; }
-  void SetRangeChecksum(uint32 checksum) { range_checksum_ = checksum; }
-
-  // Return true iff |other| object has same ranges_ as |this| object's ranges_.
-  bool Equals(CachedRanges* other) const;
-
- private:
-  // Allow tests to corrupt our innards for testing purposes.
-  FRIEND_TEST_ALL_PREFIXES(HistogramTest, CorruptBucketBounds);
-
-  // A monotonically increasing list of values which determine which bucket to
-  // put a sample into.  For each index, show the smallest sample that can be
-  // added to the corresponding bucket.
-  Ranges ranges_;
-
-  // Checksum for the conntents of ranges_.  Used to detect random over-writes
-  // of our data, and to quickly see if some other CachedRanges instance is
-  // possibly Equal() to this instance.
-  uint32 range_checksum_;
-
-  DISALLOW_COPY_AND_ASSIGN(CachedRanges);
-};
-
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_H_

base/metrics/histogram_unittest.cc

@@ -9,6 +9,7 @@
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/metrics/bucket_ranges.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/time.h"
@@ -382,26 +383,29 @@ TEST(HistogramTest, CorruptBucketBounds) {
   EXPECT_EQ(Histogram::NO_INCONSISTENCIES, 0);
   EXPECT_EQ(0, histogram->FindCorruption(snapshot));  // No default corruption.
 
-  CachedRanges* cached_ranges = histogram->cached_ranges();
-  std::swap(cached_ranges->ranges_[1], cached_ranges->ranges_[2]);
+  BucketRanges* bucket_ranges = histogram->bucket_ranges();
+  HistogramBase::Sample tmp = bucket_ranges->range(1);
+  bucket_ranges->set_range(1, bucket_ranges->range(2));
+  bucket_ranges->set_range(2, tmp);
   EXPECT_EQ(Histogram::BUCKET_ORDER_ERROR | Histogram::RANGE_CHECKSUM_ERROR,
             histogram->FindCorruption(snapshot));
 
-  std::swap(cached_ranges->ranges_[1], cached_ranges->ranges_[2]);
+  bucket_ranges->set_range(2, bucket_ranges->range(1));
+  bucket_ranges->set_range(1, tmp);
   EXPECT_EQ(0, histogram->FindCorruption(snapshot));
 
-  ++cached_ranges->ranges_[3];
+  bucket_ranges->set_range(3, bucket_ranges->range(3) + 1);
   EXPECT_EQ(Histogram::RANGE_CHECKSUM_ERROR,
             histogram->FindCorruption(snapshot));
 
   // Show that two simple changes don't offset each other
-  --cached_ranges->ranges_[4];
+  bucket_ranges->set_range(4, bucket_ranges->range(4) - 1);
   EXPECT_EQ(Histogram::RANGE_CHECKSUM_ERROR,
             histogram->FindCorruption(snapshot));
 
   // Repair histogram so that destructor won't DCHECK().
-  --cached_ranges->ranges_[3];
-  ++cached_ranges->ranges_[4];
+  bucket_ranges->set_range(3, bucket_ranges->range(3) - 1);
+  bucket_ranges->set_range(4, bucket_ranges->range(4) + 1);
 }
 
 // Table was generated similarly to sample code for CRC-32 given on:
@@ -420,9 +424,9 @@ TEST(HistogramTest, Crc32TableTest) {
   }
 }
 
-// RangeTest, CustomRangeTest and CorruptBucketBounds test CachedRanges class.
-// The following tests sharing of CachedRanges object.
-TEST(HistogramTest, CachedRangesTest) {
+// RangeTest, CustomRangeTest and CorruptBucketBounds test BucketRanges class.
+// The following tests sharing of BucketRanges object.
+TEST(HistogramTest, BucketRangesTest) {
   StatisticsRecorder recorder;
   StatisticsRecorder::Histograms histograms;
 
@@ -438,11 +442,11 @@ TEST(HistogramTest, CachedRangesTest) {
   Histogram* histogram3(Histogram::FactoryGet(
       "Histogram3", 1, 64, 16, Histogram::kNoFlags));
 
-  CachedRanges* cached_ranges1 = histogram1->cached_ranges();
-  CachedRanges* cached_ranges2 = histogram2->cached_ranges();
-  CachedRanges* cached_ranges3 = histogram3->cached_ranges();
-  EXPECT_TRUE(cached_ranges1->Equals(cached_ranges2));
-  EXPECT_FALSE(cached_ranges1->Equals(cached_ranges3));
+  BucketRanges* bucket_ranges1 = histogram1->bucket_ranges();
+  BucketRanges* bucket_ranges2 = histogram2->bucket_ranges();
+  BucketRanges* bucket_ranges3 = histogram3->bucket_ranges();
+  EXPECT_TRUE(bucket_ranges1->Equals(bucket_ranges2));
+  EXPECT_FALSE(bucket_ranges1->Equals(bucket_ranges3));
 }
 
 }  // namespace base

base/metrics/statistics_recorder.cc

@@ -121,32 +121,32 @@ Histogram* StatisticsRecorder::RegisterOrDeleteDuplicate(Histogram* histogram) {
 // static
 void StatisticsRecorder::RegisterOrDeleteDuplicateRanges(Histogram* histogram) {
   DCHECK(histogram);
-  CachedRanges* histogram_ranges = histogram->cached_ranges();
+  BucketRanges* histogram_ranges = histogram->bucket_ranges();
   DCHECK(histogram_ranges);
   uint32 checksum = histogram->range_checksum();
-  histogram_ranges->SetRangeChecksum(checksum);
+  histogram_ranges->set_checksum(checksum);
 
   RangesMap::iterator ranges_it = ranges_->find(checksum);
   if (ranges_->end() == ranges_it) {
-    // Register the new CachedRanges.
-    std::list<CachedRanges*>* checksum_matching_list(
-        new std::list<CachedRanges*>());
+    // Register the new BucketRanges.
+    std::list<BucketRanges*>* checksum_matching_list(
+        new std::list<BucketRanges*>());
     checksum_matching_list->push_front(histogram_ranges);
     (*ranges_)[checksum] = checksum_matching_list;
     return;
   }
 
-  // Use the registered CachedRanges if the registered CachedRanges has same
-  // ranges_ as |histogram|'s CachedRanges.
-  std::list<CachedRanges*>* checksum_matching_list = ranges_it->second;
-  std::list<CachedRanges*>::iterator checksum_matching_list_it;
+  // Use the registered BucketRanges if the registered BucketRanges has same
+  // ranges_ as |histogram|'s BucketRanges.
+  std::list<BucketRanges*>* checksum_matching_list = ranges_it->second;
+  std::list<BucketRanges*>::iterator checksum_matching_list_it;
   for (checksum_matching_list_it = checksum_matching_list->begin();
        checksum_matching_list_it != checksum_matching_list->end();
        ++checksum_matching_list_it) {
-    CachedRanges* existing_histogram_ranges = *checksum_matching_list_it;
+    BucketRanges* existing_histogram_ranges = *checksum_matching_list_it;
     DCHECK(existing_histogram_ranges);
     if (existing_histogram_ranges->Equals(histogram_ranges)) {
-      histogram->set_cached_ranges(existing_histogram_ranges);
+      histogram->set_bucket_ranges(existing_histogram_ranges);
       ++number_of_vectors_saved_;
       saved_ranges_size_ += histogram_ranges->size();
       delete histogram_ranges;
@@ -154,8 +154,8 @@ void StatisticsRecorder::RegisterOrDeleteDuplicateRanges(Histogram* histogram) {
     }
   }
 
-  // We haven't found a CachedRanges which has the same ranges. Register the
-  // new CachedRanges.
+  // We haven't found a BucketRanges which has the same ranges. Register the
+  // new BucketRanges.
   DCHECK(checksum_matching_list_it == checksum_matching_list->end());
   checksum_matching_list->push_front(histogram_ranges);
 }

base/metrics/statistics_recorder.h

@@ -21,7 +21,7 @@
 
 namespace base {
 
-class CachedRanges;
+class BucketRanges;
 class Histogram;
 class Lock;
 
@@ -41,12 +41,12 @@ class BASE_EXPORT StatisticsRecorder {
   // histogram (either the argument, or the pre-existing registered histogram).
   static Histogram* RegisterOrDeleteDuplicate(Histogram* histogram);
 
-  // Register, or add a new cached_ranges_ of |histogram|. If an identical
-  // cached_ranges_ is already registered, then the cached_ranges_ of
-  // |histogram| is deleted and the |histogram|'s cached_ranges_ is reset to the
-  // registered cached_ranges_.  The cached_ranges_ of |histogram| is always the
-  // registered CachedRanges (either the argument's cached_ranges_, or the
-  // pre-existing registered cached_ranges_).
+  // Register, or add a new bucket_ranges_ of |histogram|. If an identical
+  // bucket_ranges_ is already registered, then the bucket_ranges_ of
+  // |histogram| is deleted and the |histogram|'s bucket_ranges_ is reset to the
+  // registered bucket_ranges_.  The bucket_ranges_ of |histogram| is always the
+  // registered BucketRanges (either the argument's bucket_ranges_, or the
+  // pre-existing registered bucket_ranges_).
   static void RegisterOrDeleteDuplicateRanges(Histogram* histogram);
 
   // Method for collecting stats about histograms created in browser and
@@ -81,10 +81,10 @@ class BASE_EXPORT StatisticsRecorder {
   // We keep all registered histograms in a map, from name to histogram.
   typedef std::map<std::string, Histogram*> HistogramMap;
 
-  // We keep all |cached_ranges_| in a map, from checksum to a list of
-  // |cached_ranges_|.  Checksum is calculated from the |ranges_| in
-  // |cached_ranges_|.
-  typedef std::map<uint32, std::list<CachedRanges*>*> RangesMap;
+  // We keep all |bucket_ranges_| in a map, from checksum to a list of
+  // |bucket_ranges_|.  Checksum is calculated from the |ranges_| in
+  // |bucket_ranges_|.
+  typedef std::map<uint32, std::list<BucketRanges*>*> RangesMap;
 
   friend struct DefaultLazyInstanceTraits<StatisticsRecorder>;
 
@@ -93,7 +93,7 @@ class BASE_EXPORT StatisticsRecorder {
   FRIEND_TEST_ALL_PREFIXES(HistogramTest, RecordedStartupTest);
   FRIEND_TEST_ALL_PREFIXES(HistogramTest, RangeTest);
   FRIEND_TEST_ALL_PREFIXES(HistogramTest, CustomRangeTest);
-  FRIEND_TEST_ALL_PREFIXES(HistogramTest, CachedRangesTest);
+  FRIEND_TEST_ALL_PREFIXES(HistogramTest, BucketRangesTest);
 
   StatisticsRecorder();