1
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2
// Use of this source code is governed by a BSD-style license that can be
3
// found in the LICENSE file.
5
// BucketRanges stores the vector of ranges that delimit what samples are
6
// tallied in the corresponding buckets of a histogram. Histograms that have
7
// same ranges for all their corresponding buckets should share the same
8
// BucketRanges object.
10
// E.g. A 5 buckets LinearHistogram with 1 as minimal value and 4 as maximal
11
// value will need a BucketRanges with 6 ranges:
12
// 0, 1, 2, 3, 4, INT_MAX
14
// TODO(kaiwang): Currently we keep all negative values in 0~1 bucket. Consider
15
// changing 0 to INT_MIN.
17
#ifndef BASE_METRICS_BUCKET_RANGES_H_
18
#define BASE_METRICS_BUCKET_RANGES_H_
22
#include "base/base_export.h"
23
#include "base/basictypes.h"
24
#include "base/gtest_prod_util.h"
25
#include "base/metrics/histogram_base.h"
29
class BASE_EXPORT BucketRanges {
31
typedef std::vector<HistogramBase::Sample> Ranges;
33
explicit BucketRanges(size_t num_ranges);
36
size_t size() const { return ranges_.size(); }
37
HistogramBase::Sample range(size_t i) const { return ranges_[i]; }
38
void set_range(size_t i, HistogramBase::Sample value);
39
uint32 checksum() const { return checksum_; }
40
void set_checksum(uint32 checksum) { checksum_ = checksum; }
42
// A bucket is defined by a consecutive pair of entries in |ranges|, so there
43
// is one fewer bucket than there are ranges. For example, if |ranges| is
44
// [0, 1, 3, 7, INT_MAX], then the buckets in this histogram are
45
// [0, 1), [1, 3), [3, 7), and [7, INT_MAX).
46
size_t bucket_count() const { return ranges_.size() - 1; }
48
// Checksum methods to verify whether the ranges are corrupted (e.g. bad
50
uint32 CalculateChecksum() const;
51
bool HasValidChecksum() const;
54
// Return true iff |other| object has same ranges_ as |this| object's ranges_.
55
bool Equals(const BucketRanges* other) const;
58
// A monotonically increasing list of values which determine which bucket to
59
// put a sample into. For each index, show the smallest sample that can be
60
// added to the corresponding bucket.
63
// Checksum for the conntents of ranges_. Used to detect random over-writes
64
// of our data, and to quickly see if some other BucketRanges instance is
65
// possibly Equal() to this instance.
66
// TODO(kaiwang): Consider change this to uint64. Because we see a lot of
67
// noise on UMA dashboard.
70
DISALLOW_COPY_AND_ASSIGN(BucketRanges);
73
//////////////////////////////////////////////////////////////////////////////
74
// Expose only for test.
75
BASE_EXPORT_PRIVATE extern const uint32 kCrcTable[256];
79
#endif // BASE_METRICS_BUCKET_RANGES_H_