base/metrics/histogram.cc

   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.
   4
   5 // Histogram is an object that aggregates statistics, and can summarize them in
   6 // various forms, including ASCII graphical, HTML, and numerically (as a
   7 // vector of numbers corresponding to each of the aggregating buckets).
   8 // See header file for details and examples.
   9
  10 #include "base/metrics/histogram.h"
  11
  12 #include <math.h>
  13
  14 #include <algorithm>
  15 #include <string>
  16
  17 #include "base/compiler_specific.h"
  18 #include "base/debug/alias.h"
  19 #include "base/logging.h"
  20 #include "base/metrics/sample_vector.h"
  21 #include "base/metrics/statistics_recorder.h"
  22 #include "base/pickle.h"
  23 #include "base/strings/string_util.h"
  24 #include "base/strings/stringprintf.h"
  25 #include "base/synchronization/lock.h"
  26 #include "base/values.h"
  27
  28 using std::string;
  29 using std::vector;
  30
  31 namespace base {
  32
  33 namespace {
  34
  35 bool ReadHistogramArguments(PickleIterator* iter,
  36                             string* histogram_name,
  37                             int* flags,
  38                             int* declared_min,
  39                             int* declared_max,
  40                             uint64* bucket_count,
  41                             uint32* range_checksum) {
  42   if (!iter->ReadString(histogram_name) ||
  43       !iter->ReadInt(flags) ||
  44       !iter->ReadInt(declared_min) ||
  45       !iter->ReadInt(declared_max) ||
  46       !iter->ReadUInt64(bucket_count) ||
  47       !iter->ReadUInt32(range_checksum)) {
  48     DLOG(ERROR) << "Pickle error decoding Histogram: " << *histogram_name;
  49     return false;
  50   }
  51
  52   // Since these fields may have come from an untrusted renderer, do additional
  53   // checks above and beyond those in Histogram::Initialize()
  54   if (*declared_max <= 0 ||
  55       *declared_min <= 0 ||
  56       *declared_max < *declared_min ||
  57       INT_MAX / sizeof(HistogramBase::Count) <= *bucket_count ||
  58       *bucket_count < 2) {
  59     DLOG(ERROR) << "Values error decoding Histogram: " << histogram_name;
  60     return false;
  61   }
  62
  63   // We use the arguments to find or create the local version of the histogram
  64   // in this process, so we need to clear the IPC flag.
  65   DCHECK(*flags & HistogramBase::kIPCSerializationSourceFlag);
  66   *flags &= ~HistogramBase::kIPCSerializationSourceFlag;
  67
  68   return true;
  69 }
  70
  71 bool ValidateRangeChecksum(const HistogramBase& histogram,
  72                            uint32 range_checksum) {
  73   const Histogram& casted_histogram =
  74       static_cast<const Histogram&>(histogram);
  75
  76   return casted_histogram.bucket_ranges()->checksum() == range_checksum;
  77 }
  78
  79 }  // namespace
  80
  81 typedef HistogramBase::Count Count;
  82 typedef HistogramBase::Sample Sample;
  83
  84 // static
  85 const size_t Histogram::kBucketCount_MAX = 16384u;
  86
  87 HistogramBase* Histogram::FactoryGet(const string& name,
  88                                      Sample minimum,
  89                                      Sample maximum,
  90                                      size_t bucket_count,
  91                                      int32 flags) {
  92   bool valid_arguments =
  93       InspectConstructionArguments(name, &minimum, &maximum, &bucket_count);
  94   DCHECK(valid_arguments);
  95
  96   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
  97   if (!histogram) {
  98     // To avoid racy destruction at shutdown, the following will be leaked.
  99     BucketRanges* ranges = new BucketRanges(bucket_count + 1);
 100     InitializeBucketRanges(minimum, maximum, ranges);
 101     const BucketRanges* registered_ranges =
 102         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges);
 103
 104     Histogram* tentative_histogram =
 105         new Histogram(name, minimum, maximum, registered_ranges);
 106
 107     tentative_histogram->SetFlags(flags);
 108     histogram =
 109         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
 110   }
 111
 112   DCHECK_EQ(HISTOGRAM, histogram->GetHistogramType());
 113   if (!histogram->HasConstructionArguments(minimum, maximum, bucket_count)) {
 114     // The construction arguments do not match the existing histogram.  This can
 115     // come about if an extension updates in the middle of a chrome run and has
 116     // changed one of them, or simply by bad code within Chrome itself.  We
 117     // return NULL here with the expectation that bad code in Chrome will crash
 118     // on dereference, but extension/Pepper APIs will guard against NULL and not
 119     // crash.
 120     DLOG(ERROR) << "Histogram " << name << " has bad construction arguments";
 121     return NULL;
 122   }
 123   return histogram;
 124 }
 125
 126 HistogramBase* Histogram::FactoryTimeGet(const string& name,
 127                                          TimeDelta minimum,
 128                                          TimeDelta maximum,
 129                                          size_t bucket_count,
 130                                          int32 flags) {
 131   return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
 132                     bucket_count, flags);
 133 }
 134
 135 // Calculate what range of values are held in each bucket.
 136 // We have to be careful that we don't pick a ratio between starting points in
 137 // consecutive buckets that is sooo small, that the integer bounds are the same
 138 // (effectively making one bucket get no values).  We need to avoid:
 139 //   ranges(i) == ranges(i + 1)
 140 // To avoid that, we just do a fine-grained bucket width as far as we need to
 141 // until we get a ratio that moves us along at least 2 units at a time.  From
 142 // that bucket onward we do use the exponential growth of buckets.
 143 //
 144 // static
 145 void Histogram::InitializeBucketRanges(Sample minimum,
 146                                        Sample maximum,
 147                                        BucketRanges* ranges) {
 148   double log_max = log(static_cast<double>(maximum));
 149   double log_ratio;
 150   double log_next;
 151   size_t bucket_index = 1;
 152   Sample current = minimum;
 153   ranges->set_range(bucket_index, current);
 154   size_t bucket_count = ranges->bucket_count();
 155   while (bucket_count > ++bucket_index) {
 156     double log_current;
 157     log_current = log(static_cast<double>(current));
 158     // Calculate the count'th root of the range.
 159     log_ratio = (log_max - log_current) / (bucket_count - bucket_index);
 160     // See where the next bucket would start.
 161     log_next = log_current + log_ratio;
 162     Sample next;
 163     next = static_cast<int>(floor(exp(log_next) + 0.5));
 164     if (next > current)
 165       current = next;
 166     else
 167       ++current;  // Just do a narrow bucket, and keep trying.
 168     ranges->set_range(bucket_index, current);
 169   }
 170   ranges->set_range(ranges->bucket_count(), HistogramBase::kSampleType_MAX);
 171   ranges->ResetChecksum();
 172 }
 173
 174 // static
 175 const int Histogram::kCommonRaceBasedCountMismatch = 5;
 176
 177 int Histogram::FindCorruption(const HistogramSamples& samples) const {
 178   int inconsistencies = NO_INCONSISTENCIES;
 179   Sample previous_range = -1;  // Bottom range is always 0.
 180   for (size_t index = 0; index < bucket_count(); ++index) {
 181     int new_range = ranges(index);
 182     if (previous_range >= new_range)
 183       inconsistencies |= BUCKET_ORDER_ERROR;
 184     previous_range = new_range;
 185   }
 186
 187   if (!bucket_ranges()->HasValidChecksum())
 188     inconsistencies |= RANGE_CHECKSUM_ERROR;
 189
 190   int64 delta64 = samples.redundant_count() - samples.TotalCount();
 191   if (delta64 != 0) {
 192     int delta = static_cast<int>(delta64);
 193     if (delta != delta64)
 194       delta = INT_MAX;  // Flag all giant errors as INT_MAX.
 195     if (delta > 0) {
 196       UMA_HISTOGRAM_COUNTS("Histogram.InconsistentCountHigh", delta);
 197       if (delta > kCommonRaceBasedCountMismatch)
 198         inconsistencies |= COUNT_HIGH_ERROR;
 199     } else {
 200       DCHECK_GT(0, delta);
 201       UMA_HISTOGRAM_COUNTS("Histogram.InconsistentCountLow", -delta);
 202       if (-delta > kCommonRaceBasedCountMismatch)
 203         inconsistencies |= COUNT_LOW_ERROR;
 204     }
 205   }
 206   return inconsistencies;
 207 }
 208
 209 Sample Histogram::ranges(size_t i) const {
 210   return bucket_ranges_->range(i);
 211 }
 212
 213 size_t Histogram::bucket_count() const {
 214   return bucket_ranges_->bucket_count();
 215 }
 216
 217 // static
 218 bool Histogram::InspectConstructionArguments(const string& name,
 219                                              Sample* minimum,
 220                                              Sample* maximum,
 221                                              size_t* bucket_count) {
 222   // Defensive code for backward compatibility.
 223   if (*minimum < 1) {
 224     DVLOG(1) << "Histogram: " << name << " has bad minimum: " << *minimum;
 225     *minimum = 1;
 226   }
 227   if (*maximum >= kSampleType_MAX) {
 228     DVLOG(1) << "Histogram: " << name << " has bad maximum: " << *maximum;
 229     *maximum = kSampleType_MAX - 1;
 230   }
 231   if (*bucket_count >= kBucketCount_MAX) {
 232     DVLOG(1) << "Histogram: " << name << " has bad bucket_count: "
 233              << *bucket_count;
 234     *bucket_count = kBucketCount_MAX - 1;
 235   }
 236
 237   if (*minimum >= *maximum)
 238     return false;
 239   if (*bucket_count < 3)
 240     return false;
 241   if (*bucket_count > static_cast<size_t>(*maximum - *minimum + 2))
 242     return false;
 243   return true;
 244 }
 245
 246 HistogramType Histogram::GetHistogramType() const {
 247   return HISTOGRAM;
 248 }
 249
 250 bool Histogram::HasConstructionArguments(Sample expected_minimum,
 251                                          Sample expected_maximum,
 252                                          size_t expected_bucket_count) const {
 253   return ((expected_minimum == declared_min_) &&
 254           (expected_maximum == declared_max_) &&
 255           (expected_bucket_count == bucket_count()));
 256 }
 257
 258 void Histogram::Add(int value) {
 259   DCHECK_EQ(0, ranges(0));
 260   DCHECK_EQ(kSampleType_MAX, ranges(bucket_count()));
 261
 262   if (value > kSampleType_MAX - 1)
 263     value = kSampleType_MAX - 1;
 264   if (value < 0)
 265     value = 0;
 266   samples_->Accumulate(value, 1);
 267 }
 268
 269 scoped_ptr<HistogramSamples> Histogram::SnapshotSamples() const {
 270   return SnapshotSampleVector().PassAs<HistogramSamples>();
 271 }
 272
 273 void Histogram::AddSamples(const HistogramSamples& samples) {
 274   samples_->Add(samples);
 275 }
 276
 277 bool Histogram::AddSamplesFromPickle(PickleIterator* iter) {
 278   return samples_->AddFromPickle(iter);
 279 }
 280
 281 // The following methods provide a graphical histogram display.
 282 void Histogram::WriteHTMLGraph(string* output) const {
 283   // TBD(jar) Write a nice HTML bar chart, with divs an mouse-overs etc.
 284   output->append("<PRE>");
 285   WriteAsciiImpl(true, "<br>", output);
 286   output->append("</PRE>");
 287 }
 288
 289 void Histogram::WriteAscii(string* output) const {
 290   WriteAsciiImpl(true, "\n", output);
 291 }
 292
 293 bool Histogram::SerializeInfoImpl(Pickle* pickle) const {
 294   DCHECK(bucket_ranges()->HasValidChecksum());
 295   return pickle->WriteString(histogram_name()) &&
 296       pickle->WriteInt(flags()) &&
 297       pickle->WriteInt(declared_min()) &&
 298       pickle->WriteInt(declared_max()) &&
 299       pickle->WriteUInt64(bucket_count()) &&
 300       pickle->WriteUInt32(bucket_ranges()->checksum());
 301 }
 302
 303 Histogram::Histogram(const string& name,
 304                      Sample minimum,
 305                      Sample maximum,
 306                      const BucketRanges* ranges)
 307   : HistogramBase(name),
 308     bucket_ranges_(ranges),
 309     declared_min_(minimum),
 310     declared_max_(maximum) {
 311   if (ranges)
 312     samples_.reset(new SampleVector(ranges));
 313 }
 314
 315 Histogram::~Histogram() {
 316 }
 317
 318 bool Histogram::PrintEmptyBucket(size_t index) const {
 319   return true;
 320 }
 321
 322 // Use the actual bucket widths (like a linear histogram) until the widths get
 323 // over some transition value, and then use that transition width.  Exponentials
 324 // get so big so fast (and we don't expect to see a lot of entries in the large
 325 // buckets), so we need this to make it possible to see what is going on and
 326 // not have 0-graphical-height buckets.
 327 double Histogram::GetBucketSize(Count current, size_t i) const {
 328   DCHECK_GT(ranges(i + 1), ranges(i));
 329   static const double kTransitionWidth = 5;
 330   double denominator = ranges(i + 1) - ranges(i);
 331   if (denominator > kTransitionWidth)
 332     denominator = kTransitionWidth;  // Stop trying to normalize.
 333   return current/denominator;
 334 }
 335
 336 const string Histogram::GetAsciiBucketRange(size_t i) const {
 337   return GetSimpleAsciiBucketRange(ranges(i));
 338 }
 339
 340 //------------------------------------------------------------------------------
 341 // Private methods
 342
 343 // static
 344 HistogramBase* Histogram::DeserializeInfoImpl(PickleIterator* iter) {
 345   string histogram_name;
 346   int flags;
 347   int declared_min;
 348   int declared_max;
 349   uint64 bucket_count;
 350   uint32 range_checksum;
 351
 352   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
 353                               &declared_max, &bucket_count, &range_checksum)) {
 354     return NULL;
 355   }
 356
 357   // Find or create the local version of the histogram in this process.
 358   HistogramBase* histogram = Histogram::FactoryGet(
 359       histogram_name, declared_min, declared_max, bucket_count, flags);
 360
 361   if (!ValidateRangeChecksum(*histogram, range_checksum)) {
 362     // The serialized histogram might be corrupted.
 363     return NULL;
 364   }
 365   return histogram;
 366 }
 367
 368 scoped_ptr<SampleVector> Histogram::SnapshotSampleVector() const {
 369   scoped_ptr<SampleVector> samples(new SampleVector(bucket_ranges()));
 370   samples->Add(*samples_);
 371   return samples.Pass();
 372 }
 373
 374 void Histogram::WriteAsciiImpl(bool graph_it,
 375                                const string& newline,
 376                                string* output) const {
 377   // Get local (stack) copies of all effectively volatile class data so that we
 378   // are consistent across our output activities.
 379   scoped_ptr<SampleVector> snapshot = SnapshotSampleVector();
 380   Count sample_count = snapshot->TotalCount();
 381
 382   WriteAsciiHeader(*snapshot, sample_count, output);
 383   output->append(newline);
 384
 385   // Prepare to normalize graphical rendering of bucket contents.
 386   double max_size = 0;
 387   if (graph_it)
 388     max_size = GetPeakBucketSize(*snapshot);
 389
 390   // Calculate space needed to print bucket range numbers.  Leave room to print
 391   // nearly the largest bucket range without sliding over the histogram.
 392   size_t largest_non_empty_bucket = bucket_count() - 1;
 393   while (0 == snapshot->GetCountAtIndex(largest_non_empty_bucket)) {
 394     if (0 == largest_non_empty_bucket)
 395       break;  // All buckets are empty.
 396     --largest_non_empty_bucket;
 397   }
 398
 399   // Calculate largest print width needed for any of our bucket range displays.
 400   size_t print_width = 1;
 401   for (size_t i = 0; i < bucket_count(); ++i) {
 402     if (snapshot->GetCountAtIndex(i)) {
 403       size_t width = GetAsciiBucketRange(i).size() + 1;
 404       if (width > print_width)
 405         print_width = width;
 406     }
 407   }
 408
 409   int64 remaining = sample_count;
 410   int64 past = 0;
 411   // Output the actual histogram graph.
 412   for (size_t i = 0; i < bucket_count(); ++i) {
 413     Count current = snapshot->GetCountAtIndex(i);
 414     if (!current && !PrintEmptyBucket(i))
 415       continue;
 416     remaining -= current;
 417     string range = GetAsciiBucketRange(i);
 418     output->append(range);
 419     for (size_t j = 0; range.size() + j < print_width + 1; ++j)
 420       output->push_back(' ');
 421     if (0 == current && i < bucket_count() - 1 &&
 422         0 == snapshot->GetCountAtIndex(i + 1)) {
 423       while (i < bucket_count() - 1 &&
 424              0 == snapshot->GetCountAtIndex(i + 1)) {
 425         ++i;
 426       }
 427       output->append("... ");
 428       output->append(newline);
 429       continue;  // No reason to plot emptiness.
 430     }
 431     double current_size = GetBucketSize(current, i);
 432     if (graph_it)
 433       WriteAsciiBucketGraph(current_size, max_size, output);
 434     WriteAsciiBucketContext(past, current, remaining, i, output);
 435     output->append(newline);
 436     past += current;
 437   }
 438   DCHECK_EQ(sample_count, past);
 439 }
 440
 441 double Histogram::GetPeakBucketSize(const SampleVector& samples) const {
 442   double max = 0;
 443   for (size_t i = 0; i < bucket_count() ; ++i) {
 444     double current_size = GetBucketSize(samples.GetCountAtIndex(i), i);
 445     if (current_size > max)
 446       max = current_size;
 447   }
 448   return max;
 449 }
 450
 451 void Histogram::WriteAsciiHeader(const SampleVector& samples,
 452                                  Count sample_count,
 453                                  string* output) const {
 454   StringAppendF(output,
 455                 "Histogram: %s recorded %d samples",
 456                 histogram_name().c_str(),
 457                 sample_count);
 458   if (0 == sample_count) {
 459     DCHECK_EQ(samples.sum(), 0);
 460   } else {
 461     double average = static_cast<float>(samples.sum()) / sample_count;
 462
 463     StringAppendF(output, ", average = %.1f", average);
 464   }
 465   if (flags() & ~kHexRangePrintingFlag)
 466     StringAppendF(output, " (flags = 0x%x)", flags() & ~kHexRangePrintingFlag);
 467 }
 468
 469 void Histogram::WriteAsciiBucketContext(const int64 past,
 470                                         const Count current,
 471                                         const int64 remaining,
 472                                         const size_t i,
 473                                         string* output) const {
 474   double scaled_sum = (past + current + remaining) / 100.0;
 475   WriteAsciiBucketValue(current, scaled_sum, output);
 476   if (0 < i) {
 477     double percentage = past / scaled_sum;
 478     StringAppendF(output, " {%3.1f%%}", percentage);
 479   }
 480 }
 481
 482 void Histogram::GetParameters(DictionaryValue* params) const {
 483   params->SetString("type", HistogramTypeToString(GetHistogramType()));
 484   params->SetInteger("min", declared_min());
 485   params->SetInteger("max", declared_max());
 486   params->SetInteger("bucket_count", static_cast<int>(bucket_count()));
 487 }
 488
 489 void Histogram::GetCountAndBucketData(Count* count,
 490                                       int64* sum,
 491                                       ListValue* buckets) const {
 492   scoped_ptr<SampleVector> snapshot = SnapshotSampleVector();
 493   *count = snapshot->TotalCount();
 494   *sum = snapshot->sum();
 495   size_t index = 0;
 496   for (size_t i = 0; i < bucket_count(); ++i) {
 497     Sample count = snapshot->GetCountAtIndex(i);
 498     if (count > 0) {
 499       scoped_ptr<DictionaryValue> bucket_value(new DictionaryValue());
 500       bucket_value->SetInteger("low", ranges(i));
 501       if (i != bucket_count() - 1)
 502         bucket_value->SetInteger("high", ranges(i + 1));
 503       bucket_value->SetInteger("count", count);
 504       buckets->Set(index, bucket_value.release());
 505       ++index;
 506     }
 507   }
 508 }
 509
 510 //------------------------------------------------------------------------------
 511 // LinearHistogram: This histogram uses a traditional set of evenly spaced
 512 // buckets.
 513 //------------------------------------------------------------------------------
 514
 515 LinearHistogram::~LinearHistogram() {}
 516
 517 HistogramBase* LinearHistogram::FactoryGet(const string& name,
 518                                            Sample minimum,
 519                                            Sample maximum,
 520                                            size_t bucket_count,
 521                                            int32 flags) {
 522   return FactoryGetWithRangeDescription(
 523       name, minimum, maximum, bucket_count, flags, NULL);
 524 }
 525
 526 HistogramBase* LinearHistogram::FactoryTimeGet(const string& name,
 527                                                TimeDelta minimum,
 528                                                TimeDelta maximum,
 529                                                size_t bucket_count,
 530                                                int32 flags) {
 531   return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
 532                     bucket_count, flags);
 533 }
 534
 535 HistogramBase* LinearHistogram::FactoryGetWithRangeDescription(
 536       const std::string& name,
 537       Sample minimum,
 538       Sample maximum,
 539       size_t bucket_count,
 540       int32 flags,
 541       const DescriptionPair descriptions[]) {
 542   bool valid_arguments = Histogram::InspectConstructionArguments(
 543       name, &minimum, &maximum, &bucket_count);
 544   DCHECK(valid_arguments);
 545
 546   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
 547   if (!histogram) {
 548     // To avoid racy destruction at shutdown, the following will be leaked.
 549     BucketRanges* ranges = new BucketRanges(bucket_count + 1);
 550     InitializeBucketRanges(minimum, maximum, ranges);
 551     const BucketRanges* registered_ranges =
 552         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges);
 553
 554     LinearHistogram* tentative_histogram =
 555         new LinearHistogram(name, minimum, maximum, registered_ranges);
 556
 557     // Set range descriptions.
 558     if (descriptions) {
 559       for (int i = 0; descriptions[i].description; ++i) {
 560         tentative_histogram->bucket_description_[descriptions[i].sample] =
 561             descriptions[i].description;
 562       }
 563     }
 564
 565     tentative_histogram->SetFlags(flags);
 566     histogram =
 567         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
 568   }
 569
 570   DCHECK_EQ(LINEAR_HISTOGRAM, histogram->GetHistogramType());
 571   if (!histogram->HasConstructionArguments(minimum, maximum, bucket_count)) {
 572     // The construction arguments do not match the existing histogram.  This can
 573     // come about if an extension updates in the middle of a chrome run and has
 574     // changed one of them, or simply by bad code within Chrome itself.  We
 575     // return NULL here with the expectation that bad code in Chrome will crash
 576     // on dereference, but extension/Pepper APIs will guard against NULL and not
 577     // crash.
 578     DLOG(ERROR) << "Histogram " << name << " has bad construction arguments";
 579     return NULL;
 580   }
 581   return histogram;
 582 }
 583
 584 HistogramType LinearHistogram::GetHistogramType() const {
 585   return LINEAR_HISTOGRAM;
 586 }
 587
 588 LinearHistogram::LinearHistogram(const string& name,
 589                                  Sample minimum,
 590                                  Sample maximum,
 591                                  const BucketRanges* ranges)
 592     : Histogram(name, minimum, maximum, ranges) {
 593 }
 594
 595 double LinearHistogram::GetBucketSize(Count current, size_t i) const {
 596   DCHECK_GT(ranges(i + 1), ranges(i));
 597   // Adjacent buckets with different widths would have "surprisingly" many (few)
 598   // samples in a histogram if we didn't normalize this way.
 599   double denominator = ranges(i + 1) - ranges(i);
 600   return current/denominator;
 601 }
 602
 603 const string LinearHistogram::GetAsciiBucketRange(size_t i) const {
 604   int range = ranges(i);
 605   BucketDescriptionMap::const_iterator it = bucket_description_.find(range);
 606   if (it == bucket_description_.end())
 607     return Histogram::GetAsciiBucketRange(i);
 608   return it->second;
 609 }
 610
 611 bool LinearHistogram::PrintEmptyBucket(size_t index) const {
 612   return bucket_description_.find(ranges(index)) == bucket_description_.end();
 613 }
 614
 615 // static
 616 void LinearHistogram::InitializeBucketRanges(Sample minimum,
 617                                              Sample maximum,
 618                                              BucketRanges* ranges) {
 619   double min = minimum;
 620   double max = maximum;
 621   size_t bucket_count = ranges->bucket_count();
 622   for (size_t i = 1; i < bucket_count; ++i) {
 623     double linear_range =
 624         (min * (bucket_count - 1 - i) + max * (i - 1)) / (bucket_count - 2);
 625     ranges->set_range(i, static_cast<Sample>(linear_range + 0.5));
 626   }
 627   ranges->set_range(ranges->bucket_count(), HistogramBase::kSampleType_MAX);
 628   ranges->ResetChecksum();
 629 }
 630
 631 // static
 632 HistogramBase* LinearHistogram::DeserializeInfoImpl(PickleIterator* iter) {
 633   string histogram_name;
 634   int flags;
 635   int declared_min;
 636   int declared_max;
 637   uint64 bucket_count;
 638   uint32 range_checksum;
 639
 640   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
 641                               &declared_max, &bucket_count, &range_checksum)) {
 642     return NULL;
 643   }
 644
 645   HistogramBase* histogram = LinearHistogram::FactoryGet(
 646       histogram_name, declared_min, declared_max, bucket_count, flags);
 647   if (!ValidateRangeChecksum(*histogram, range_checksum)) {
 648     // The serialized histogram might be corrupted.
 649     return NULL;
 650   }
 651   return histogram;
 652 }
 653
 654 //------------------------------------------------------------------------------
 655 // This section provides implementation for BooleanHistogram.
 656 //------------------------------------------------------------------------------
 657
 658 HistogramBase* BooleanHistogram::FactoryGet(const string& name, int32 flags) {
 659   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
 660   if (!histogram) {
 661     // To avoid racy destruction at shutdown, the following will be leaked.
 662     BucketRanges* ranges = new BucketRanges(4);
 663     LinearHistogram::InitializeBucketRanges(1, 2, ranges);
 664     const BucketRanges* registered_ranges =
 665         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges);
 666
 667     BooleanHistogram* tentative_histogram =
 668         new BooleanHistogram(name, registered_ranges);
 669
 670     tentative_histogram->SetFlags(flags);
 671     histogram =
 672         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
 673   }
 674
 675   DCHECK_EQ(BOOLEAN_HISTOGRAM, histogram->GetHistogramType());
 676   return histogram;
 677 }
 678
 679 HistogramType BooleanHistogram::GetHistogramType() const {
 680   return BOOLEAN_HISTOGRAM;
 681 }
 682
 683 BooleanHistogram::BooleanHistogram(const string& name,
 684                                    const BucketRanges* ranges)
 685     : LinearHistogram(name, 1, 2, ranges) {}
 686
 687 HistogramBase* BooleanHistogram::DeserializeInfoImpl(PickleIterator* iter) {
 688   string histogram_name;
 689   int flags;
 690   int declared_min;
 691   int declared_max;
 692   uint64 bucket_count;
 693   uint32 range_checksum;
 694
 695   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
 696                               &declared_max, &bucket_count, &range_checksum)) {
 697     return NULL;
 698   }
 699
 700   HistogramBase* histogram = BooleanHistogram::FactoryGet(
 701       histogram_name, flags);
 702   if (!ValidateRangeChecksum(*histogram, range_checksum)) {
 703     // The serialized histogram might be corrupted.
 704     return NULL;
 705   }
 706   return histogram;
 707 }
 708
 709 //------------------------------------------------------------------------------
 710 // CustomHistogram:
 711 //------------------------------------------------------------------------------
 712
 713 HistogramBase* CustomHistogram::FactoryGet(const string& name,
 714                                            const vector<Sample>& custom_ranges,
 715                                            int32 flags) {
 716   CHECK(ValidateCustomRanges(custom_ranges));
 717
 718   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
 719   if (!histogram) {
 720     BucketRanges* ranges = CreateBucketRangesFromCustomRanges(custom_ranges);
 721     const BucketRanges* registered_ranges =
 722         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges);
 723
 724     // To avoid racy destruction at shutdown, the following will be leaked.
 725     CustomHistogram* tentative_histogram =
 726         new CustomHistogram(name, registered_ranges);
 727
 728     tentative_histogram->SetFlags(flags);
 729
 730     histogram =
 731         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
 732   }
 733
 734   DCHECK_EQ(histogram->GetHistogramType(), CUSTOM_HISTOGRAM);
 735   return histogram;
 736 }
 737
 738 HistogramType CustomHistogram::GetHistogramType() const {
 739   return CUSTOM_HISTOGRAM;
 740 }
 741
 742 // static
 743 vector<Sample> CustomHistogram::ArrayToCustomRanges(
 744     const Sample* values, size_t num_values) {
 745   vector<Sample> all_values;
 746   for (size_t i = 0; i < num_values; ++i) {
 747     Sample value = values[i];
 748     all_values.push_back(value);
 749
 750     // Ensure that a guard bucket is added. If we end up with duplicate
 751     // values, FactoryGet will take care of removing them.
 752     all_values.push_back(value + 1);
 753   }
 754   return all_values;
 755 }
 756
 757 CustomHistogram::CustomHistogram(const string& name,
 758                                  const BucketRanges* ranges)
 759     : Histogram(name,
 760                 ranges->range(1),
 761                 ranges->range(ranges->bucket_count() - 1),
 762                 ranges) {}
 763
 764 bool CustomHistogram::SerializeInfoImpl(Pickle* pickle) const {
 765   if (!Histogram::SerializeInfoImpl(pickle))
 766     return false;
 767
 768   // Serialize ranges. First and last ranges are alwasy 0 and INT_MAX, so don't
 769   // write them.
 770   for (size_t i = 1; i < bucket_ranges()->bucket_count(); ++i) {
 771     if (!pickle->WriteInt(bucket_ranges()->range(i)))
 772       return false;
 773   }
 774   return true;
 775 }
 776
 777 double CustomHistogram::GetBucketSize(Count current, size_t i) const {
 778   return 1;
 779 }
 780
 781 // static
 782 HistogramBase* CustomHistogram::DeserializeInfoImpl(PickleIterator* iter) {
 783   string histogram_name;
 784   int flags;
 785   int declared_min;
 786   int declared_max;
 787   uint64 bucket_count;
 788   uint32 range_checksum;
 789
 790   if (!ReadHistogramArguments(iter, &histogram_name, &flags, &declared_min,
 791                               &declared_max, &bucket_count, &range_checksum)) {
 792     return NULL;
 793   }
 794
 795   // First and last ranges are not serialized.
 796   vector<Sample> sample_ranges(bucket_count - 1);
 797
 798   for (size_t i = 0; i < sample_ranges.size(); ++i) {
 799     if (!iter->ReadInt(&sample_ranges[i]))
 800       return NULL;
 801   }
 802
 803   HistogramBase* histogram = CustomHistogram::FactoryGet(
 804       histogram_name, sample_ranges, flags);
 805   if (!ValidateRangeChecksum(*histogram, range_checksum)) {
 806     // The serialized histogram might be corrupted.
 807     return NULL;
 808   }
 809   return histogram;
 810 }
 811
 812 // static
 813 bool CustomHistogram::ValidateCustomRanges(
 814     const vector<Sample>& custom_ranges) {
 815   bool has_valid_range = false;
 816   for (size_t i = 0; i < custom_ranges.size(); i++) {
 817     Sample sample = custom_ranges[i];
 818     if (sample < 0 || sample > HistogramBase::kSampleType_MAX - 1)
 819       return false;
 820     if (sample != 0)
 821       has_valid_range = true;
 822   }
 823   return has_valid_range;
 824 }
 825
 826 // static
 827 BucketRanges* CustomHistogram::CreateBucketRangesFromCustomRanges(
 828       const vector<Sample>& custom_ranges) {
 829   // Remove the duplicates in the custom ranges array.
 830   vector<int> ranges = custom_ranges;
 831   ranges.push_back(0);  // Ensure we have a zero value.
 832   ranges.push_back(HistogramBase::kSampleType_MAX);
 833   std::sort(ranges.begin(), ranges.end());
 834   ranges.erase(std::unique(ranges.begin(), ranges.end()), ranges.end());
 835
 836   BucketRanges* bucket_ranges = new BucketRanges(ranges.size());
 837   for (size_t i = 0; i < ranges.size(); i++) {
 838     bucket_ranges->set_range(i, ranges[i]);
 839   }
 840   bucket_ranges->ResetChecksum();
 841   return bucket_ranges;
 842 }
 843
 844 }  // namespace base