diff options
Diffstat (limited to 'base/metrics/histogram.h')
| -rw-r--r-- | base/metrics/histogram.h | 61 |
1 files changed, 56 insertions, 5 deletions
diff --git a/base/metrics/histogram.h b/base/metrics/histogram.h index 20f67c2..000807a 100644 --- a/base/metrics/histogram.h +++ b/base/metrics/histogram.h @@ -36,6 +36,7 @@ #include <string> #include <vector> +#include "base/gtest_prod_util.h" #include "base/ref_counted.h" #include "base/logging.h" #include "base/time.h" @@ -243,8 +244,8 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { typedef std::vector<Count> Counts; typedef std::vector<Sample> Ranges; - /* These enums are meant to facilitate deserialization of renderer histograms - into the browser. */ + // These enums are used to facilitate deserialization of renderer histograms + // into the browser. enum ClassType { HISTOGRAM, LINEAR_HISTOGRAM, @@ -273,6 +274,16 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { kHexRangePrintingFlag = 0x8000, // Fancy bucket-naming supported. }; + enum Inconsistencies { + NO_INCONSISTENCIES = 0x0, + RANGE_CHECKSUM_ERROR = 0x1, + BUCKET_ORDER_ERROR = 0x2, + COUNT_HIGH_ERROR = 0x4, + COUNT_LOW_ERROR = 0x8, + + NEVER_EXCEEDED_VALUE = 0x10 + }; + struct DescriptionPair { Sample sample; const char* description; // Null means end of a list of pairs. @@ -298,6 +309,7 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { Count TotalCount() const; int64 sum() const { return sum_; } int64 square_sum() const { return square_sum_; } + int64 redundant_count() const { return redundant_count_; } // Arithmetic manipulation of corresponding elements of the set. void Add(const SampleSet& other); @@ -315,7 +327,21 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { // without shared memory at some point. int64 sum_; // sum of samples. int64 square_sum_; // sum of squares of samples. + + private: + // Allow tests to corrupt our innards for testing purposes. + FRIEND_TEST(HistogramTest, CorruptSampleCounts); + + // To help identify memory corruption, we reduntantly save the number of + // samples we've accumulated into all of our buckets. We can compare this + // count to the sum of the counts in all buckets, and detect problems. Note + // that due to races in histogram accumulation (if a histogram is indeed + // updated on several threads simultaneously), the tallies might mismatch, + // and also the snapshotting code may asynchronously get a mismatch (though + // generally either race based mismatch cause is VERY rare). + int64 redundant_count_; }; + //---------------------------------------------------------------------------- // minimum should start from 1. 0 is invalid as a minimum. 0 is an implicit // default underflow bucket. @@ -367,6 +393,13 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { // browser process. static bool DeserializeHistogramInfo(const std::string& histogram_info); + // Check to see if bucket ranges, counts and tallies in the snapshot are + // consistent with the bucket ranges and checksums in our histogram. This can + // produce a false-alarm if a race occurred in the reading of the data during + // a SnapShot process, but should otherwise be false at all times (unless we + // have memory over-writes, or DRAM failures). + Inconsistencies FindCorruption(const SampleSet& snapshot) const; + //---------------------------------------------------------------------------- // Accessors for factory constuction, serialization and testing. //---------------------------------------------------------------------------- @@ -375,6 +408,7 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { Sample declared_min() const { return declared_min_; } Sample declared_max() const { return declared_max_; } virtual Sample ranges(size_t i) const { return ranges_[i];} + Sample range_checksum() const { return range_checksum_; } virtual size_t bucket_count() const { return bucket_count_; } // Snapshot the current complete set of sample data. // Override with atomic/locked snapshot if needed. @@ -409,6 +443,9 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { // Get normalized size, relative to the ranges_[i]. virtual double GetBucketSize(Count current, size_t i) const; + // Recalculate range_checksum_. + void ResetRangeChecksum(); + // Return a string description of what goes in a given bucket. // Most commonly this is the numeric value, but in derived classes it may // be a name (or string description) given to the bucket. @@ -430,9 +467,18 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { bool ValidateBucketRanges() const; private: + // Allow tests to corrupt our innards for testing purposes. + FRIEND_TEST(HistogramTest, CorruptBucketBounds); + FRIEND_TEST(HistogramTest, CorruptSampleCounts); + // Post constructor initialization. void Initialize(); + // Return true iff the range_checksum_ matches current ranges_ vector. + bool HasValidRangeChecksum() const; + + Sample CalculateRangeChecksum() const; + //---------------------------------------------------------------------------- // Helpers for emitting Ascii graphic. Each method appends data to output. @@ -477,6 +523,11 @@ class Histogram : public base::RefCountedThreadSafe<Histogram> { // The dimension of ranges_ is bucket_count + 1. Ranges ranges_; + // For redundancy, we store the sum of all the sample ranges when ranges are + // generated. If ever there is ever a difference, then the histogram must + // have been corrupted. + Sample range_checksum_; + // Finally, provide the state that changes with the addition of each new // sample. SampleSet sample_; @@ -561,11 +612,11 @@ class CustomHistogram : public Histogram { virtual ClassType histogram_type() const; static scoped_refptr<Histogram> FactoryGet(const std::string& name, - const std::vector<int>& custom_ranges, Flags flags); + const std::vector<Sample>& custom_ranges, Flags flags); protected: CustomHistogram(const std::string& name, - const std::vector<int>& custom_ranges); + const std::vector<Sample>& custom_ranges); // Initialize ranges_ mapping. virtual void InitializeBucketRange(); @@ -573,7 +624,7 @@ class CustomHistogram : public Histogram { private: // Temporary pointer used during construction/initialization, and then NULLed. - const std::vector<int>* ranges_vector_; + const std::vector<Sample>* ranges_vector_; DISALLOW_COPY_AND_ASSIGN(CustomHistogram); }; |