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Diffstat (limited to 'ipc/chromium/src/base/histogram.cc')
| -rw-r--r-- | ipc/chromium/src/base/histogram.cc | 1176 |
1 files changed, 1176 insertions, 0 deletions
diff --git a/ipc/chromium/src/base/histogram.cc b/ipc/chromium/src/base/histogram.cc new file mode 100644 index 000000000..49561bf60 --- /dev/null +++ b/ipc/chromium/src/base/histogram.cc @@ -0,0 +1,1176 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +// 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/histogram.h" + +#include <math.h> + +#include <algorithm> +#include <string> + +#include "base/logging.h" +#include "base/pickle.h" +#include "base/string_util.h" +#include "base/logging.h" + +namespace base { + +#define DVLOG(x) CHROMIUM_LOG(ERROR) +#define CHECK_GT DCHECK_GT +#define CHECK_LT DCHECK_LT +typedef ::Lock Lock; +typedef ::AutoLock AutoLock; + +// Static table of checksums for all possible 8 bit bytes. +const uint32_t Histogram::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, +}; + +typedef Histogram::Count Count; + +// static +const size_t Histogram::kBucketCount_MAX = 16384u; + +Histogram* Histogram::FactoryGet(const std::string& name, + Sample minimum, + Sample maximum, + size_t bucket_count, + Flags flags) { + Histogram* histogram(NULL); + + // Defensive code. + if (minimum < 1) + minimum = 1; + if (maximum > kSampleType_MAX - 1) + maximum = kSampleType_MAX - 1; + + if (!StatisticsRecorder::FindHistogram(name, &histogram)) { + // 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. + Histogram* tentative_histogram = + new Histogram(name, minimum, maximum, bucket_count); + tentative_histogram->InitializeBucketRange(); + tentative_histogram->SetFlags(flags); + histogram = + StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram); + } + + 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, + size_t bucket_count, + Flags flags) { + return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(), + bucket_count, flags); +} + +void Histogram::Add(int value) { + if (value > kSampleType_MAX - 1) + value = kSampleType_MAX - 1; + if (value < 0) + value = 0; + size_t index = BucketIndex(value); + DCHECK_GE(value, ranges(index)); + DCHECK_LT(value, ranges(index + 1)); + Accumulate(value, 1, index); +} + +void Histogram::Subtract(int value) { + if (value > kSampleType_MAX - 1) + value = kSampleType_MAX - 1; + if (value < 0) + value = 0; + size_t index = BucketIndex(value); + DCHECK_GE(value, ranges(index)); + DCHECK_LT(value, ranges(index + 1)); + Accumulate(value, -1, index); +} + +void Histogram::AddBoolean(bool value) { + DCHECK(false); +} + +void Histogram::AddSampleSet(const SampleSet& sample) { + sample_.Add(sample); +} + +void Histogram::Clear() { + SampleSet ss; + ss.Resize(*this); + sample_ = ss; +} + +void Histogram::SetRangeDescriptions(const DescriptionPair descriptions[]) { + DCHECK(false); +} + +// The following methods provide a graphical histogram display. +void Histogram::WriteHTMLGraph(std::string* output) const { + // TBD(jar) Write a nice HTML bar chart, with divs an mouse-overs etc. + output->append("<PRE>"); + WriteAscii(true, "<br>", output); + output->append("</PRE>"); +} + +void Histogram::WriteAscii(bool graph_it, const std::string& newline, + std::string* output) const { + // Get local (stack) copies of all effectively volatile class data so that we + // are consistent across our output activities. + SampleSet snapshot; + SnapshotSample(&snapshot); + + Count sample_count = snapshot.TotalCount(); + + WriteAsciiHeader(snapshot, sample_count, output); + output->append(newline); + + // Prepare to normalize graphical rendering of bucket contents. + double max_size = 0; + if (graph_it) + max_size = GetPeakBucketSize(snapshot); + + // Calculate space needed to print bucket range numbers. Leave room to print + // nearly the largest bucket range without sliding over the histogram. + size_t largest_non_empty_bucket = bucket_count() - 1; + while (0 == snapshot.counts(largest_non_empty_bucket)) { + if (0 == largest_non_empty_bucket) + break; // All buckets are empty. + --largest_non_empty_bucket; + } + + // Calculate largest print width needed for any of our bucket range displays. + size_t print_width = 1; + for (size_t i = 0; i < bucket_count(); ++i) { + if (snapshot.counts(i)) { + size_t width = GetAsciiBucketRange(i).size() + 1; + if (width > print_width) + print_width = width; + } + } + + int64_t remaining = sample_count; + int64_t past = 0; + // Output the actual histogram graph. + for (size_t i = 0; i < bucket_count(); ++i) { + Count current = snapshot.counts(i); + if (!current && !PrintEmptyBucket(i)) + continue; + remaining -= current; + std::string range = GetAsciiBucketRange(i); + output->append(range); + for (size_t j = 0; range.size() + j < print_width + 1; ++j) + output->push_back(' '); + if (0 == current && + i < bucket_count() - 1 && 0 == snapshot.counts(i + 1)) { + while (i < bucket_count() - 1 && 0 == snapshot.counts(i + 1)) + ++i; + output->append("... "); + output->append(newline); + continue; // No reason to plot emptiness. + } + double current_size = GetBucketSize(current, i); + if (graph_it) + WriteAsciiBucketGraph(current_size, max_size, output); + WriteAsciiBucketContext(past, current, remaining, i, output); + output->append(newline); + past += current; + } + DCHECK_EQ(sample_count, past); +} + +//------------------------------------------------------------------------------ +// Methods for the validating a sample and a related histogram. +//------------------------------------------------------------------------------ + +Histogram::Inconsistencies +Histogram::FindCorruption(const SampleSet& snapshot) const +{ + int inconsistencies = NO_INCONSISTENCIES; + Sample previous_range = -1; // Bottom range is always 0. + int64_t count = 0; + for (size_t index = 0; index < bucket_count(); ++index) { + count += snapshot.counts(index); + int new_range = ranges(index); + if (previous_range >= new_range) + inconsistencies |= BUCKET_ORDER_ERROR; + previous_range = new_range; + } + + if (!HasValidRangeChecksum()) + inconsistencies |= RANGE_CHECKSUM_ERROR; + + int64_t delta64 = snapshot.redundant_count() - count; + if (delta64 != 0) { + int delta = static_cast<int>(delta64); + if (delta != delta64) + delta = INT_MAX; // Flag all giant errors as INT_MAX. + // Since snapshots of histograms are taken asynchronously relative to + // sampling (and snapped from different threads), it is pretty likely that + // we'll catch a redundant count that doesn't match the sample count. We + // allow for a certain amount of slop before flagging this as an + // inconsistency. Even with an inconsistency, we'll snapshot it again (for + // UMA in about a half hour, so we'll eventually get the data, if it was + // not the result of a corruption. If histograms show that 1 is "too tight" + // then we may try to use 2 or 3 for this slop value. + const int kCommonRaceBasedCountMismatch = 1; + if (delta > 0) { + UMA_HISTOGRAM_COUNTS("Histogram.InconsistentCountHigh", delta); + if (delta > kCommonRaceBasedCountMismatch) + inconsistencies |= COUNT_HIGH_ERROR; + } else { + DCHECK_GT(0, delta); + UMA_HISTOGRAM_COUNTS("Histogram.InconsistentCountLow", -delta); + if (-delta > kCommonRaceBasedCountMismatch) + inconsistencies |= COUNT_LOW_ERROR; + } + } + return static_cast<Inconsistencies>(inconsistencies); +} + +Histogram::ClassType Histogram::histogram_type() const { + return HISTOGRAM; +} + +Histogram::Sample Histogram::ranges(size_t i) const { + return ranges_[i]; +} + +size_t Histogram::bucket_count() const { + return bucket_count_; +} + +void Histogram::SnapshotSample(SampleSet* sample) const { + *sample = sample_; +} + +bool Histogram::HasConstructorArguments(Sample minimum, + Sample maximum, + size_t bucket_count) { + return ((minimum == declared_min_) && (maximum == declared_max_) && + (bucket_count == bucket_count_)); +} + +bool Histogram::HasConstructorTimeDeltaArguments(TimeDelta minimum, + TimeDelta maximum, + size_t bucket_count) { + return ((minimum.InMilliseconds() == declared_min_) && + (maximum.InMilliseconds() == declared_max_) && + (bucket_count == bucket_count_)); +} + +bool Histogram::HasValidRangeChecksum() const { + return CalculateRangeChecksum() == range_checksum_; +} + +size_t Histogram::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) +{ + size_t n = 0; + n += aMallocSizeOf(this); + // We're not allowed to do deep dives into STL data structures. This + // is as close as we can get to measuring this array. + n += aMallocSizeOf(&ranges_[0]); + n += sample_.SizeOfExcludingThis(aMallocSizeOf); + return n; +} + +size_t +Histogram::SampleSet::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) +{ + // We're not allowed to do deep dives into STL data structures. This + // is as close as we can get to measuring this array. + return aMallocSizeOf(&counts_[0]); +} + +Histogram::Histogram(const std::string& name, Sample minimum, + Sample maximum, size_t bucket_count) + : sample_(), + histogram_name_(name), + declared_min_(minimum), + declared_max_(maximum), + bucket_count_(bucket_count), + flags_(kNoFlags), + ranges_(bucket_count + 1, 0), + range_checksum_(0), + recording_enabled_(true) { + Initialize(); +} + +Histogram::Histogram(const std::string& name, TimeDelta minimum, + TimeDelta maximum, size_t bucket_count) + : sample_(), + histogram_name_(name), + declared_min_(static_cast<int> (minimum.InMilliseconds())), + declared_max_(static_cast<int> (maximum.InMilliseconds())), + bucket_count_(bucket_count), + flags_(kNoFlags), + ranges_(bucket_count + 1, 0), + range_checksum_(0), + recording_enabled_(true) { + Initialize(); +} + +Histogram::~Histogram() { + if (StatisticsRecorder::dump_on_exit()) { + std::string output; + WriteAscii(true, "\n", &output); + CHROMIUM_LOG(INFO) << output; + } + + // Just to make sure most derived class did this properly... + DCHECK(ValidateBucketRanges()); +} + +// Calculate what range of values are held in each bucket. +// We have to be careful that we don't pick a ratio between starting points in +// consecutive buckets that is sooo small, that the integer bounds are the same +// (effectively making one bucket get no values). We need to avoid: +// ranges_[i] == ranges_[i + 1] +// To avoid that, we just do a fine-grained bucket width as far as we need to +// until we get a ratio that moves us along at least 2 units at a time. From +// that bucket onward we do use the exponential growth of buckets. +void Histogram::InitializeBucketRange() { + double log_max = log(static_cast<double>(declared_max())); + double log_ratio; + double log_next; + size_t bucket_index = 1; + Sample current = declared_min(); + SetBucketRange(bucket_index, current); + while (bucket_count() > ++bucket_index) { + double log_current; + log_current = log(static_cast<double>(current)); + // Calculate the count'th root of the range. + log_ratio = (log_max - log_current) / (bucket_count() - bucket_index); + // See where the next bucket would start. + log_next = log_current + log_ratio; + int next; + next = static_cast<int>(floor(exp(log_next) + 0.5)); + if (next > current) + current = next; + else + ++current; // Just do a narrow bucket, and keep trying. + SetBucketRange(bucket_index, current); + } + ResetRangeChecksum(); + + DCHECK_EQ(bucket_count(), bucket_index); +} + +bool Histogram::PrintEmptyBucket(size_t index) const { + return true; +} + +size_t Histogram::BucketIndex(Sample value) const { + // Use simple binary search. This is very general, but there are better + // approaches if we knew that the buckets were linearly distributed. + DCHECK_LE(ranges(0), value); + DCHECK_GT(ranges(bucket_count()), value); + size_t under = 0; + size_t over = bucket_count(); + size_t mid; + + do { + DCHECK_GE(over, under); + mid = under + (over - under)/2; + if (mid == under) + break; + if (ranges(mid) <= value) + under = mid; + else + over = mid; + } while (true); + + DCHECK_LE(ranges(mid), value); + CHECK_GT(ranges(mid+1), value); + return mid; +} + +// Use the actual bucket widths (like a linear histogram) until the widths get +// over some transition value, and then use that transition width. Exponentials +// get so big so fast (and we don't expect to see a lot of entries in the large +// buckets), so we need this to make it possible to see what is going on and +// not have 0-graphical-height buckets. +double Histogram::GetBucketSize(Count current, size_t i) const { + DCHECK_GT(ranges(i + 1), ranges(i)); + static const double kTransitionWidth = 5; + double denominator = ranges(i + 1) - ranges(i); + if (denominator > kTransitionWidth) + denominator = kTransitionWidth; // Stop trying to normalize. + return current/denominator; +} + +void Histogram::ResetRangeChecksum() { + range_checksum_ = CalculateRangeChecksum(); +} + +const std::string Histogram::GetAsciiBucketRange(size_t i) const { + std::string result; + if (kHexRangePrintingFlag & flags_) + StringAppendF(&result, "%#x", ranges(i)); + else + StringAppendF(&result, "%d", ranges(i)); + return result; +} + +// Update histogram data with new sample. +void Histogram::Accumulate(Sample value, Count count, size_t index) { + sample_.Accumulate(value, count, index); +} + +void Histogram::SetBucketRange(size_t i, Sample value) { + DCHECK_GT(bucket_count_, i); + ranges_[i] = value; +} + +bool Histogram::ValidateBucketRanges() const { + // Standard assertions that all bucket ranges should satisfy. + DCHECK_EQ(bucket_count_ + 1, ranges_.size()); + DCHECK_EQ(0, ranges_[0]); + DCHECK_EQ(declared_min(), ranges_[1]); + DCHECK_EQ(declared_max(), ranges_[bucket_count_ - 1]); + DCHECK_EQ(kSampleType_MAX, ranges_[bucket_count_]); + return true; +} + +uint32_t Histogram::CalculateRangeChecksum() const { + DCHECK_EQ(ranges_.size(), bucket_count() + 1); + uint32_t checksum = static_cast<uint32_t>(ranges_.size()); // Seed checksum. + for (size_t index = 0; index < bucket_count(); ++index) + checksum = Crc32(checksum, ranges(index)); + return checksum; +} + +void Histogram::Initialize() { + sample_.Resize(*this); + if (declared_min_ < 1) + declared_min_ = 1; + if (declared_max_ > kSampleType_MAX - 1) + declared_max_ = kSampleType_MAX - 1; + DCHECK_LE(declared_min_, declared_max_); + DCHECK_GT(bucket_count_, 1u); + CHECK_LT(bucket_count_, kBucketCount_MAX); + size_t maximal_bucket_count = declared_max_ - declared_min_ + 2; + DCHECK_LE(bucket_count_, maximal_bucket_count); + DCHECK_EQ(0, ranges_[0]); + ranges_[bucket_count_] = kSampleType_MAX; +} + +// 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_t. 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. +uint32_t Histogram::Crc32(uint32_t sum, Histogram::Sample range) { + const bool kUseRealCrc = true; // TODO(jar): Switch to false and watch stats. + if (kUseRealCrc) { + union { + Histogram::Sample range; + unsigned char bytes[sizeof(Histogram::Sample)]; + } converter; + converter.range = range; + 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 { + Histogram::Sample range; + uint16_t ints[sizeof(Histogram::Sample) / 2]; + } converter; + DCHECK_EQ(sizeof(Histogram::Sample), sizeof(converter)); + converter.range = range; + sum += converter.ints[0]; + sum = (sum << 16) ^ sum ^ (static_cast<uint32_t>(converter.ints[1]) << 11); + sum += sum >> 11; + } + return sum; +} + +//------------------------------------------------------------------------------ +// Private methods + +double Histogram::GetPeakBucketSize(const SampleSet& snapshot) const { + double max = 0; + for (size_t i = 0; i < bucket_count() ; ++i) { + double current_size + = GetBucketSize(snapshot.counts(i), i); + if (current_size > max) + max = current_size; + } + return max; +} + +void Histogram::WriteAsciiHeader(const SampleSet& snapshot, + Count sample_count, + std::string* output) const { + StringAppendF(output, + "Histogram: %s recorded %d samples", + histogram_name().c_str(), + sample_count); + int64_t snapshot_sum = snapshot.sum(); + if (0 == sample_count) { + DCHECK_EQ(snapshot_sum, 0); + } else { + double average = static_cast<float>(snapshot_sum) / sample_count; + + StringAppendF(output, ", average = %.1f", average); + } + if (flags_ & ~kHexRangePrintingFlag) + StringAppendF(output, " (flags = 0x%x)", flags_ & ~kHexRangePrintingFlag); +} + +void Histogram::WriteAsciiBucketContext(const int64_t past, + const Count current, + const int64_t remaining, + const size_t i, + std::string* output) const { + double scaled_sum = (past + current + remaining) / 100.0; + WriteAsciiBucketValue(current, scaled_sum, output); + if (0 < i) { + double percentage = past / scaled_sum; + StringAppendF(output, " {%3.1f%%}", percentage); + } +} + +void Histogram::WriteAsciiBucketValue(Count current, double scaled_sum, + std::string* output) const { + StringAppendF(output, " (%d = %3.1f%%)", current, current/scaled_sum); +} + +void Histogram::WriteAsciiBucketGraph(double current_size, double max_size, + std::string* output) const { + const int k_line_length = 72; // Maximal horizontal width of graph. + int x_count = static_cast<int>(k_line_length * (current_size / max_size) + + 0.5); + int x_remainder = k_line_length - x_count; + + while (0 < x_count--) + output->append("-"); + output->append("O"); + while (0 < x_remainder--) + output->append(" "); +} + +//------------------------------------------------------------------------------ +// Methods for the Histogram::SampleSet class +//------------------------------------------------------------------------------ + +Histogram::SampleSet::SampleSet() + : counts_(), + sum_(0), + redundant_count_(0) { +} + +Histogram::SampleSet::~SampleSet() { +} + +void Histogram::SampleSet::Resize(const Histogram& histogram) { + counts_.resize(histogram.bucket_count(), 0); +} + +void Histogram::SampleSet::Accumulate(Sample value, Count count, + size_t index) { + DCHECK(count == 1 || count == -1); + counts_[index] += count; + redundant_count_ += count; + sum_ += static_cast<int64_t>(count) * value; + DCHECK_GE(counts_[index], 0); + DCHECK_GE(sum_, 0); + DCHECK_GE(redundant_count_, 0); +} + +Count Histogram::SampleSet::TotalCount() const { + Count total = 0; + for (Counts::const_iterator it = counts_.begin(); + it != counts_.end(); + ++it) { + total += *it; + } + return total; +} + +void Histogram::SampleSet::Add(const SampleSet& other) { + DCHECK_EQ(counts_.size(), other.counts_.size()); + sum_ += other.sum_; + redundant_count_ += other.redundant_count_; + for (size_t index = 0; index < counts_.size(); ++index) + counts_[index] += other.counts_[index]; +} + +//------------------------------------------------------------------------------ +// LinearHistogram: This histogram uses a traditional set of evenly spaced +// buckets. +//------------------------------------------------------------------------------ + +LinearHistogram::~LinearHistogram() { +} + +Histogram* LinearHistogram::FactoryGet(const std::string& name, + Sample minimum, + Sample maximum, + size_t bucket_count, + Flags flags) { + Histogram* histogram(NULL); + + if (minimum < 1) + minimum = 1; + if (maximum > kSampleType_MAX - 1) + maximum = kSampleType_MAX - 1; + + if (!StatisticsRecorder::FindHistogram(name, &histogram)) { + LinearHistogram* tentative_histogram = + new LinearHistogram(name, minimum, maximum, bucket_count); + tentative_histogram->InitializeBucketRange(); + tentative_histogram->SetFlags(flags); + histogram = + StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram); + } + + 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, + size_t bucket_count, + Flags flags) { + return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(), + bucket_count, flags); +} + +Histogram::ClassType LinearHistogram::histogram_type() const { + return LINEAR_HISTOGRAM; +} + +void LinearHistogram::Accumulate(Sample value, Count count, size_t index) { + sample_.Accumulate(value, count, index); +} + +void LinearHistogram::SetRangeDescriptions( + const DescriptionPair descriptions[]) { + for (int i =0; descriptions[i].description; ++i) { + bucket_description_[descriptions[i].sample] = descriptions[i].description; + } +} + +LinearHistogram::LinearHistogram(const std::string& name, + Sample minimum, + Sample maximum, + size_t bucket_count) + : Histogram(name, minimum >= 1 ? minimum : 1, maximum, bucket_count) { +} + +LinearHistogram::LinearHistogram(const std::string& name, + TimeDelta minimum, + TimeDelta maximum, + size_t bucket_count) + : Histogram(name, minimum >= TimeDelta::FromMilliseconds(1) ? + minimum : TimeDelta::FromMilliseconds(1), + maximum, bucket_count) { +} + +void LinearHistogram::InitializeBucketRange() { + DCHECK_GT(declared_min(), 0); // 0 is the underflow bucket here. + double min = declared_min(); + double max = declared_max(); + size_t i; + for (i = 1; i < bucket_count(); ++i) { + double linear_range = (min * (bucket_count() -1 - i) + max * (i - 1)) / + (bucket_count() - 2); + SetBucketRange(i, static_cast<int> (linear_range + 0.5)); + } + ResetRangeChecksum(); +} + +double LinearHistogram::GetBucketSize(Count current, size_t i) const { + DCHECK_GT(ranges(i + 1), ranges(i)); + // Adjacent buckets with different widths would have "surprisingly" many (few) + // samples in a histogram if we didn't normalize this way. + double denominator = ranges(i + 1) - ranges(i); + return current/denominator; +} + +const std::string LinearHistogram::GetAsciiBucketRange(size_t i) const { + int range = ranges(i); + BucketDescriptionMap::const_iterator it = bucket_description_.find(range); + if (it == bucket_description_.end()) + return Histogram::GetAsciiBucketRange(i); + return it->second; +} + +bool LinearHistogram::PrintEmptyBucket(size_t index) const { + return bucket_description_.find(ranges(index)) == bucket_description_.end(); +} + + +//------------------------------------------------------------------------------ +// This section provides implementation for BooleanHistogram. +//------------------------------------------------------------------------------ + +Histogram* BooleanHistogram::FactoryGet(const std::string& name, Flags flags) { + Histogram* histogram(NULL); + + if (!StatisticsRecorder::FindHistogram(name, &histogram)) { + BooleanHistogram* tentative_histogram = new BooleanHistogram(name); + tentative_histogram->InitializeBucketRange(); + tentative_histogram->SetFlags(flags); + histogram = + StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram); + } + + DCHECK_EQ(BOOLEAN_HISTOGRAM, histogram->histogram_type()); + return histogram; +} + +Histogram::ClassType BooleanHistogram::histogram_type() const { + return BOOLEAN_HISTOGRAM; +} + +void BooleanHistogram::AddBoolean(bool value) { + Add(value ? 1 : 0); +} + +BooleanHistogram::BooleanHistogram(const std::string& name) + : LinearHistogram(name, 1, 2, 3) { +} + +void +BooleanHistogram::Accumulate(Sample value, Count count, size_t index) +{ + // Callers will have computed index based on the non-booleanified value. + // So we need to adjust the index manually. + LinearHistogram::Accumulate(!!value, count, value ? 1 : 0); +} + +//------------------------------------------------------------------------------ +// FlagHistogram: +//------------------------------------------------------------------------------ + +Histogram * +FlagHistogram::FactoryGet(const std::string &name, Flags flags) +{ + Histogram *h(nullptr); + + if (!StatisticsRecorder::FindHistogram(name, &h)) { + FlagHistogram *fh = new FlagHistogram(name); + fh->InitializeBucketRange(); + fh->SetFlags(flags); + size_t zero_index = fh->BucketIndex(0); + fh->LinearHistogram::Accumulate(0, 1, zero_index); + h = StatisticsRecorder::RegisterOrDeleteDuplicate(fh); + } + + return h; +} + +FlagHistogram::FlagHistogram(const std::string &name) + : BooleanHistogram(name), mSwitched(false) { +} + +Histogram::ClassType +FlagHistogram::histogram_type() const +{ + return FLAG_HISTOGRAM; +} + +void +FlagHistogram::Accumulate(Sample value, Count count, size_t index) +{ + if (mSwitched) { + return; + } + + mSwitched = true; + DCHECK_EQ(value, 1); + LinearHistogram::Accumulate(value, 1, index); + size_t zero_index = BucketIndex(0); + LinearHistogram::Accumulate(0, -1, zero_index); +} + +void +FlagHistogram::AddSampleSet(const SampleSet& sample) { + DCHECK_EQ(bucket_count(), sample.size()); + // We can't be sure the SampleSet provided came from another FlagHistogram, + // so we take the following steps: + // - If our flag has already been set do nothing. + // - Set our flag if the following hold: + // - The sum of the counts in the provided SampleSet is 1. + // - The bucket index for that single value is the same as the index where we + // would place our set flag. + // - Otherwise, take no action. + + if (mSwitched) { + return; + } + + if (sample.sum() != 1) { + return; + } + + size_t one_index = BucketIndex(1); + if (sample.counts(one_index) == 1) { + Accumulate(1, 1, one_index); + } +} + +void +FlagHistogram::Clear() { + Histogram::Clear(); + + mSwitched = false; + size_t zero_index = BucketIndex(0); + LinearHistogram::Accumulate(0, 1, zero_index); +} + +//------------------------------------------------------------------------------ +// CountHistogram: +//------------------------------------------------------------------------------ + +Histogram * +CountHistogram::FactoryGet(const std::string &name, Flags flags) +{ + Histogram *h(nullptr); + + if (!StatisticsRecorder::FindHistogram(name, &h)) { + CountHistogram *fh = new CountHistogram(name); + fh->InitializeBucketRange(); + fh->SetFlags(flags); + h = StatisticsRecorder::RegisterOrDeleteDuplicate(fh); + } + + return h; +} + +CountHistogram::CountHistogram(const std::string &name) + : LinearHistogram(name, 1, 2, 3) { +} + +Histogram::ClassType +CountHistogram::histogram_type() const +{ + return COUNT_HISTOGRAM; +} + +void +CountHistogram::Accumulate(Sample value, Count count, size_t index) +{ + size_t zero_index = BucketIndex(0); + LinearHistogram::Accumulate(value, 1, zero_index); +} + +void +CountHistogram::AddSampleSet(const SampleSet& sample) { + DCHECK_EQ(bucket_count(), sample.size()); + // We can't be sure the SampleSet provided came from another CountHistogram, + // so we at least check that the unused buckets are empty. + + const size_t indices[] = { BucketIndex(0), BucketIndex(1), BucketIndex(2) }; + + if (sample.counts(indices[1]) != 0 || sample.counts(indices[2]) != 0) { + return; + } + + if (sample.counts(indices[0]) != 0) { + Accumulate(1, sample.counts(indices[0]), indices[0]); + } +} + + +//------------------------------------------------------------------------------ +// CustomHistogram: +//------------------------------------------------------------------------------ + +Histogram* CustomHistogram::FactoryGet(const std::string& name, + const std::vector<Sample>& custom_ranges, + Flags flags) { + Histogram* histogram(NULL); + + // Remove the duplicates in the custom ranges array. + std::vector<int> ranges = custom_ranges; + ranges.push_back(0); // Ensure we have a zero value. + std::sort(ranges.begin(), ranges.end()); + ranges.erase(std::unique(ranges.begin(), ranges.end()), ranges.end()); + if (ranges.size() <= 1) { + DCHECK(false); + // Note that we pushed a 0 in above, so for defensive code.... + ranges.push_back(1); // Put in some data so we can index to [1]. + } + + DCHECK_LT(ranges.back(), kSampleType_MAX); + + if (!StatisticsRecorder::FindHistogram(name, &histogram)) { + CustomHistogram* tentative_histogram = new CustomHistogram(name, ranges); + tentative_histogram->InitializedCustomBucketRange(ranges); + tentative_histogram->SetFlags(flags); + histogram = + StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram); + } + + 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; +} + +CustomHistogram::CustomHistogram(const std::string& name, + const std::vector<Sample>& custom_ranges) + : Histogram(name, custom_ranges[1], custom_ranges.back(), + custom_ranges.size()) { + DCHECK_GT(custom_ranges.size(), 1u); + DCHECK_EQ(custom_ranges[0], 0); +} + +void CustomHistogram::InitializedCustomBucketRange( + const std::vector<Sample>& custom_ranges) { + DCHECK_GT(custom_ranges.size(), 1u); + DCHECK_EQ(custom_ranges[0], 0); + DCHECK_LE(custom_ranges.size(), bucket_count()); + for (size_t index = 0; index < custom_ranges.size(); ++index) + SetBucketRange(index, custom_ranges[index]); + ResetRangeChecksum(); +} + +double CustomHistogram::GetBucketSize(Count current, size_t i) const { + return 1; +} + +//------------------------------------------------------------------------------ +// The next section handles global (central) support for all histograms, as well +// as startup/teardown of this service. +//------------------------------------------------------------------------------ + +// This singleton instance should be started during the single threaded portion +// of main(), and hence it is not thread safe. It initializes globals to +// provide support for all future calls. +StatisticsRecorder::StatisticsRecorder() { + DCHECK(!histograms_); + if (lock_ == NULL) { + // This will leak on purpose. It's the only way to make sure we won't race + // against the static uninitialization of the module while one of our + // static methods relying on the lock get called at an inappropriate time + // during the termination phase. Since it's a static data member, we will + // leak one per process, which would be similar to the instance allocated + // during static initialization and released only on process termination. + lock_ = new base::Lock; + } + base::AutoLock auto_lock(*lock_); + histograms_ = new HistogramMap; +} + +StatisticsRecorder::~StatisticsRecorder() { + DCHECK(histograms_ && lock_); + + if (dump_on_exit_) { + std::string output; + WriteGraph("", &output); + CHROMIUM_LOG(INFO) << output; + } + // Clean up. + HistogramMap* histograms = NULL; + { + base::AutoLock auto_lock(*lock_); + histograms = histograms_; + histograms_ = NULL; + for (HistogramMap::iterator it = histograms->begin(); + histograms->end() != it; + ++it) { + // No other clients permanently hold Histogram references, so we + // have the only one and it is safe to delete it. + delete it->second; + } + } + delete histograms; + // We don't delete lock_ on purpose to avoid having to properly protect + // against it going away after we checked for NULL in the static methods. +} + +// static +bool StatisticsRecorder::IsActive() { + if (lock_ == NULL) + return false; + base::AutoLock auto_lock(*lock_); + return NULL != histograms_; +} + +Histogram* StatisticsRecorder::RegisterOrDeleteDuplicate(Histogram* histogram) { + DCHECK(histogram->HasValidRangeChecksum()); + if (lock_ == NULL) + return histogram; + base::AutoLock auto_lock(*lock_); + if (!histograms_) + return histogram; + const std::string name = histogram->histogram_name(); + HistogramMap::iterator it = histograms_->find(name); + // Avoid overwriting a previous registration. + if (histograms_->end() == it) { + (*histograms_)[name] = histogram; + } else { + delete histogram; // We already have one by this name. + histogram = it->second; + } + return histogram; +} + +// static +void StatisticsRecorder::WriteHTMLGraph(const std::string& query, + std::string* output) { + if (!IsActive()) + return; + output->append("<html><head><title>About Histograms"); + if (!query.empty()) + output->append(" - " + query); + output->append("</title>" + // We'd like the following no-cache... but it doesn't work. + // "<META HTTP-EQUIV=\"Pragma\" CONTENT=\"no-cache\">" + "</head><body>"); + + Histograms snapshot; + GetSnapshot(query, &snapshot); + for (Histograms::iterator it = snapshot.begin(); + it != snapshot.end(); + ++it) { + (*it)->WriteHTMLGraph(output); + output->append("<br><hr><br>"); + } + output->append("</body></html>"); +} + +// static +void StatisticsRecorder::WriteGraph(const std::string& query, + std::string* output) { + if (!IsActive()) + return; + if (query.length()) + StringAppendF(output, "Collections of histograms for %s\n", query.c_str()); + else + output->append("Collections of all histograms\n"); + + Histograms snapshot; + GetSnapshot(query, &snapshot); + for (Histograms::iterator it = snapshot.begin(); + it != snapshot.end(); + ++it) { + (*it)->WriteAscii(true, "\n", output); + output->append("\n"); + } +} + +// static +void StatisticsRecorder::GetHistograms(Histograms* output) { + if (lock_ == NULL) + return; + base::AutoLock auto_lock(*lock_); + if (!histograms_) + return; + for (HistogramMap::iterator it = histograms_->begin(); + histograms_->end() != it; + ++it) { + DCHECK_EQ(it->first, it->second->histogram_name()); + output->push_back(it->second); + } +} + +bool StatisticsRecorder::FindHistogram(const std::string& name, + Histogram** histogram) { + if (lock_ == NULL) + return false; + base::AutoLock auto_lock(*lock_); + if (!histograms_) + return false; + HistogramMap::iterator it = histograms_->find(name); + if (histograms_->end() == it) + return false; + *histogram = it->second; + return true; +} + +// private static +void StatisticsRecorder::GetSnapshot(const std::string& query, + Histograms* snapshot) { + if (lock_ == NULL) + return; + base::AutoLock auto_lock(*lock_); + if (!histograms_) + return; + for (HistogramMap::iterator it = histograms_->begin(); + histograms_->end() != it; + ++it) { + if (it->first.find(query) != std::string::npos) + snapshot->push_back(it->second); + } +} + +// static +StatisticsRecorder::HistogramMap* StatisticsRecorder::histograms_ = NULL; +// static +base::Lock* StatisticsRecorder::lock_ = NULL; +// static +bool StatisticsRecorder::dump_on_exit_ = false; + +} // namespace base |