1 // Copyright (c) 2006-2008 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/histogram.h"
11
12 #include <math.h>
13 #include <string>
14
15 #include "base/logging.h"
16 #include "base/pickle.h"
17 #include "base/string_util.h"
18
19 using base::TimeDelta;
20
21 typedef Histogram::Count Count;
22
FactoryGet(const std::string & name,Sample minimum,Sample maximum,size_t bucket_count,Flags flags)23 scoped_refptr<Histogram> Histogram::FactoryGet(const std::string& name,
24 Sample minimum, Sample maximum, size_t bucket_count, Flags flags) {
25 scoped_refptr<Histogram> histogram(NULL);
26
27 // Defensive code.
28 if (minimum <= 0)
29 minimum = 1;
30 if (maximum >= kSampleType_MAX)
31 maximum = kSampleType_MAX - 1;
32
33 if (StatisticsRecorder::FindHistogram(name, &histogram)) {
34 DCHECK(histogram.get() != NULL);
35 } else {
36 histogram = new Histogram(name, minimum, maximum, bucket_count);
37 scoped_refptr<Histogram> registered_histogram(NULL);
38 StatisticsRecorder::FindHistogram(name, ®istered_histogram);
39 // Allow a NULL return to mean that the StatisticsRecorder was not started.
40 if (registered_histogram.get() != NULL &&
41 registered_histogram.get() != histogram.get())
42 histogram = registered_histogram;
43 }
44
45 DCHECK(HISTOGRAM == histogram->histogram_type());
46 DCHECK(histogram->HasConstructorArguments(minimum, maximum, bucket_count));
47 histogram->SetFlags(flags);
48 return histogram;
49 }
50
FactoryGet(const std::string & name,base::TimeDelta minimum,base::TimeDelta maximum,size_t bucket_count,Flags flags)51 scoped_refptr<Histogram> Histogram::FactoryGet(const std::string& name,
52 base::TimeDelta minimum, base::TimeDelta maximum, size_t bucket_count,
53 Flags flags) {
54 return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
55 bucket_count, flags);
56 }
57
Histogram(const std::string & name,Sample minimum,Sample maximum,size_t bucket_count)58 Histogram::Histogram(const std::string& name, Sample minimum,
59 Sample maximum, size_t bucket_count)
60 : histogram_name_(name),
61 declared_min_(minimum),
62 declared_max_(maximum),
63 bucket_count_(bucket_count),
64 flags_(kNoFlags),
65 ranges_(bucket_count + 1, 0),
66 sample_() {
67 Initialize();
68 }
69
Histogram(const std::string & name,TimeDelta minimum,TimeDelta maximum,size_t bucket_count)70 Histogram::Histogram(const std::string& name, TimeDelta minimum,
71 TimeDelta maximum, size_t bucket_count)
72 : histogram_name_(name),
73 declared_min_(static_cast<int> (minimum.InMilliseconds())),
74 declared_max_(static_cast<int> (maximum.InMilliseconds())),
75 bucket_count_(bucket_count),
76 flags_(kNoFlags),
77 ranges_(bucket_count + 1, 0),
78 sample_() {
79 Initialize();
80 }
81
~Histogram()82 Histogram::~Histogram() {
83 if (StatisticsRecorder::dump_on_exit()) {
84 std::string output;
85 WriteAscii(true, "\n", &output);
86 LOG(INFO) << output;
87 }
88
89 // Just to make sure most derived class did this properly...
90 DCHECK(ValidateBucketRanges());
91 }
92
Add(int value)93 void Histogram::Add(int value) {
94 if (value >= kSampleType_MAX)
95 value = kSampleType_MAX - 1;
96 if (value < 0)
97 value = 0;
98 size_t index = BucketIndex(value);
99 DCHECK(value >= ranges(index));
100 DCHECK(value < ranges(index + 1));
101 Accumulate(value, 1, index);
102 }
103
AddSampleSet(const SampleSet & sample)104 void Histogram::AddSampleSet(const SampleSet& sample) {
105 sample_.Add(sample);
106 }
107
108 // The following methods provide a graphical histogram display.
WriteHTMLGraph(std::string * output) const109 void Histogram::WriteHTMLGraph(std::string* output) const {
110 // TBD(jar) Write a nice HTML bar chart, with divs an mouse-overs etc.
111 output->append("<PRE>");
112 WriteAscii(true, "<br>", output);
113 output->append("</PRE>");
114 }
115
WriteAscii(bool graph_it,const std::string & newline,std::string * output) const116 void Histogram::WriteAscii(bool graph_it, const std::string& newline,
117 std::string* output) const {
118 // Get local (stack) copies of all effectively volatile class data so that we
119 // are consistent across our output activities.
120 SampleSet snapshot;
121 SnapshotSample(&snapshot);
122 Count sample_count = snapshot.TotalCount();
123
124 WriteAsciiHeader(snapshot, sample_count, output);
125 output->append(newline);
126
127 // Prepare to normalize graphical rendering of bucket contents.
128 double max_size = 0;
129 if (graph_it)
130 max_size = GetPeakBucketSize(snapshot);
131
132 // Calculate space needed to print bucket range numbers. Leave room to print
133 // nearly the largest bucket range without sliding over the histogram.
134 size_t largest_non_empty_bucket = bucket_count() - 1;
135 while (0 == snapshot.counts(largest_non_empty_bucket)) {
136 if (0 == largest_non_empty_bucket)
137 break; // All buckets are empty.
138 --largest_non_empty_bucket;
139 }
140
141 // Calculate largest print width needed for any of our bucket range displays.
142 size_t print_width = 1;
143 for (size_t i = 0; i < bucket_count(); ++i) {
144 if (snapshot.counts(i)) {
145 size_t width = GetAsciiBucketRange(i).size() + 1;
146 if (width > print_width)
147 print_width = width;
148 }
149 }
150
151 int64 remaining = sample_count;
152 int64 past = 0;
153 // Output the actual histogram graph.
154 for (size_t i = 0; i < bucket_count(); ++i) {
155 Count current = snapshot.counts(i);
156 if (!current && !PrintEmptyBucket(i))
157 continue;
158 remaining -= current;
159 std::string range = GetAsciiBucketRange(i);
160 output->append(range);
161 for (size_t j = 0; range.size() + j < print_width + 1; ++j)
162 output->push_back(' ');
163 if (0 == current && i < bucket_count() - 1 && 0 == snapshot.counts(i + 1)) {
164 while (i < bucket_count() - 1 && 0 == snapshot.counts(i + 1))
165 ++i;
166 output->append("... ");
167 output->append(newline);
168 continue; // No reason to plot emptiness.
169 }
170 double current_size = GetBucketSize(current, i);
171 if (graph_it)
172 WriteAsciiBucketGraph(current_size, max_size, output);
173 WriteAsciiBucketContext(past, current, remaining, i, output);
174 output->append(newline);
175 past += current;
176 }
177 DCHECK(past == sample_count);
178 }
179
ValidateBucketRanges() const180 bool Histogram::ValidateBucketRanges() const {
181 // Standard assertions that all bucket ranges should satisfy.
182 DCHECK(ranges_.size() == bucket_count_ + 1);
183 DCHECK_EQ(0, ranges_[0]);
184 DCHECK(declared_min() == ranges_[1]);
185 DCHECK(declared_max() == ranges_[bucket_count_ - 1]);
186 DCHECK(kSampleType_MAX == ranges_[bucket_count_]);
187 return true;
188 }
189
Initialize()190 void Histogram::Initialize() {
191 sample_.Resize(*this);
192 if (declared_min_ <= 0)
193 declared_min_ = 1;
194 if (declared_max_ >= kSampleType_MAX)
195 declared_max_ = kSampleType_MAX - 1;
196 DCHECK(declared_min_ <= declared_max_);
197 DCHECK_LT(1u, bucket_count_);
198 size_t maximal_bucket_count = declared_max_ - declared_min_ + 2;
199 DCHECK(bucket_count_ <= maximal_bucket_count);
200 DCHECK_EQ(0, ranges_[0]);
201 ranges_[bucket_count_] = kSampleType_MAX;
202 InitializeBucketRange();
203 DCHECK(ValidateBucketRanges());
204 StatisticsRecorder::Register(this);
205 }
206
207 // Calculate what range of values are held in each bucket.
208 // We have to be careful that we don't pick a ratio between starting points in
209 // consecutive buckets that is sooo small, that the integer bounds are the same
210 // (effectively making one bucket get no values). We need to avoid:
211 // (ranges_[i] == ranges_[i + 1]
212 // To avoid that, we just do a fine-grained bucket width as far as we need to
213 // until we get a ratio that moves us along at least 2 units at a time. From
214 // that bucket onward we do use the exponential growth of buckets.
InitializeBucketRange()215 void Histogram::InitializeBucketRange() {
216 double log_max = log(static_cast<double>(declared_max()));
217 double log_ratio;
218 double log_next;
219 size_t bucket_index = 1;
220 Sample current = declared_min();
221 SetBucketRange(bucket_index, current);
222 while (bucket_count() > ++bucket_index) {
223 double log_current;
224 log_current = log(static_cast<double>(current));
225 // Calculate the count'th root of the range.
226 log_ratio = (log_max - log_current) / (bucket_count() - bucket_index);
227 // See where the next bucket would start.
228 log_next = log_current + log_ratio;
229 int next;
230 next = static_cast<int>(floor(exp(log_next) + 0.5));
231 if (next > current)
232 current = next;
233 else
234 ++current; // Just do a narrow bucket, and keep trying.
235 SetBucketRange(bucket_index, current);
236 }
237
238 DCHECK(bucket_count() == bucket_index);
239 }
240
BucketIndex(Sample value) const241 size_t Histogram::BucketIndex(Sample value) const {
242 // Use simple binary search. This is very general, but there are better
243 // approaches if we knew that the buckets were linearly distributed.
244 DCHECK(ranges(0) <= value);
245 DCHECK(ranges(bucket_count()) > value);
246 size_t under = 0;
247 size_t over = bucket_count();
248 size_t mid;
249
250 do {
251 DCHECK(over >= under);
252 mid = (over + under)/2;
253 if (mid == under)
254 break;
255 if (ranges(mid) <= value)
256 under = mid;
257 else
258 over = mid;
259 } while (true);
260
261 DCHECK(ranges(mid) <= value && ranges(mid+1) > value);
262 return mid;
263 }
264
265 // Use the actual bucket widths (like a linear histogram) until the widths get
266 // over some transition value, and then use that transition width. Exponentials
267 // get so big so fast (and we don't expect to see a lot of entries in the large
268 // buckets), so we need this to make it possible to see what is going on and
269 // not have 0-graphical-height buckets.
GetBucketSize(Count current,size_t i) const270 double Histogram::GetBucketSize(Count current, size_t i) const {
271 DCHECK(ranges(i + 1) > ranges(i));
272 static const double kTransitionWidth = 5;
273 double denominator = ranges(i + 1) - ranges(i);
274 if (denominator > kTransitionWidth)
275 denominator = kTransitionWidth; // Stop trying to normalize.
276 return current/denominator;
277 }
278
279 //------------------------------------------------------------------------------
280 // The following two methods can be overridden to provide a thread safe
281 // version of this class. The cost of locking is low... but an error in each
282 // of these methods has minimal impact. For now, I'll leave this unlocked,
283 // and I don't believe I can loose more than a count or two.
284 // The vectors are NOT reallocated, so there is no risk of them moving around.
285
286 // Update histogram data with new sample.
Accumulate(Sample value,Count count,size_t index)287 void Histogram::Accumulate(Sample value, Count count, size_t index) {
288 // Note locking not done in this version!!!
289 sample_.Accumulate(value, count, index);
290 }
291
292 // Do a safe atomic snapshot of sample data.
293 // This implementation assumes we are on a safe single thread.
SnapshotSample(SampleSet * sample) const294 void Histogram::SnapshotSample(SampleSet* sample) const {
295 // Note locking not done in this version!!!
296 *sample = sample_;
297 }
298
299 //------------------------------------------------------------------------------
300 // Accessor methods
301
SetBucketRange(size_t i,Sample value)302 void Histogram::SetBucketRange(size_t i, Sample value) {
303 DCHECK(bucket_count_ > i);
304 ranges_[i] = value;
305 }
306
307 //------------------------------------------------------------------------------
308 // Private methods
309
GetPeakBucketSize(const SampleSet & snapshot) const310 double Histogram::GetPeakBucketSize(const SampleSet& snapshot) const {
311 double max = 0;
312 for (size_t i = 0; i < bucket_count() ; ++i) {
313 double current_size = GetBucketSize(snapshot.counts(i), i);
314 if (current_size > max)
315 max = current_size;
316 }
317 return max;
318 }
319
WriteAsciiHeader(const SampleSet & snapshot,Count sample_count,std::string * output) const320 void Histogram::WriteAsciiHeader(const SampleSet& snapshot,
321 Count sample_count,
322 std::string* output) const {
323 StringAppendF(output,
324 "Histogram: %s recorded %d samples",
325 histogram_name().c_str(),
326 sample_count);
327 if (0 == sample_count) {
328 DCHECK_EQ(0, snapshot.sum());
329 } else {
330 double average = static_cast<float>(snapshot.sum()) / sample_count;
331 double variance = static_cast<float>(snapshot.square_sum())/sample_count
332 - average * average;
333 double standard_deviation = sqrt(variance);
334
335 StringAppendF(output,
336 ", average = %.1f, standard deviation = %.1f",
337 average, standard_deviation);
338 }
339 if (flags_ & ~kHexRangePrintingFlag )
340 StringAppendF(output, " (flags = 0x%x)", flags_ & ~kHexRangePrintingFlag);
341 }
342
WriteAsciiBucketContext(const int64 past,const Count current,const int64 remaining,const size_t i,std::string * output) const343 void Histogram::WriteAsciiBucketContext(const int64 past,
344 const Count current,
345 const int64 remaining,
346 const size_t i,
347 std::string* output) const {
348 double scaled_sum = (past + current + remaining) / 100.0;
349 WriteAsciiBucketValue(current, scaled_sum, output);
350 if (0 < i) {
351 double percentage = past / scaled_sum;
352 StringAppendF(output, " {%3.1f%%}", percentage);
353 }
354 }
355
GetAsciiBucketRange(size_t i) const356 const std::string Histogram::GetAsciiBucketRange(size_t i) const {
357 std::string result;
358 if (kHexRangePrintingFlag & flags_)
359 StringAppendF(&result, "%#x", ranges(i));
360 else
361 StringAppendF(&result, "%d", ranges(i));
362 return result;
363 }
364
WriteAsciiBucketValue(Count current,double scaled_sum,std::string * output) const365 void Histogram::WriteAsciiBucketValue(Count current, double scaled_sum,
366 std::string* output) const {
367 StringAppendF(output, " (%d = %3.1f%%)", current, current/scaled_sum);
368 }
369
WriteAsciiBucketGraph(double current_size,double max_size,std::string * output) const370 void Histogram::WriteAsciiBucketGraph(double current_size, double max_size,
371 std::string* output) const {
372 const int k_line_length = 72; // Maximal horizontal width of graph.
373 int x_count = static_cast<int>(k_line_length * (current_size / max_size)
374 + 0.5);
375 int x_remainder = k_line_length - x_count;
376
377 while (0 < x_count--)
378 output->append("-");
379 output->append("O");
380 while (0 < x_remainder--)
381 output->append(" ");
382 }
383
384 // static
SerializeHistogramInfo(const Histogram & histogram,const SampleSet & snapshot)385 std::string Histogram::SerializeHistogramInfo(const Histogram& histogram,
386 const SampleSet& snapshot) {
387 DCHECK(histogram.histogram_type() != NOT_VALID_IN_RENDERER);
388
389 Pickle pickle;
390 pickle.WriteString(histogram.histogram_name());
391 pickle.WriteInt(histogram.declared_min());
392 pickle.WriteInt(histogram.declared_max());
393 pickle.WriteSize(histogram.bucket_count());
394 pickle.WriteInt(histogram.histogram_type());
395 pickle.WriteInt(histogram.flags());
396
397 snapshot.Serialize(&pickle);
398 return std::string(static_cast<const char*>(pickle.data()), pickle.size());
399 }
400
401 // static
DeserializeHistogramInfo(const std::string & histogram_info)402 bool Histogram::DeserializeHistogramInfo(const std::string& histogram_info) {
403 if (histogram_info.empty()) {
404 return false;
405 }
406
407 Pickle pickle(histogram_info.data(),
408 static_cast<int>(histogram_info.size()));
409 void* iter = NULL;
410 size_t bucket_count;
411 int declared_min;
412 int declared_max;
413 int histogram_type;
414 int pickle_flags;
415 std::string histogram_name;
416 SampleSet sample;
417
418 if (!pickle.ReadString(&iter, &histogram_name) ||
419 !pickle.ReadInt(&iter, &declared_min) ||
420 !pickle.ReadInt(&iter, &declared_max) ||
421 !pickle.ReadSize(&iter, &bucket_count) ||
422 !pickle.ReadInt(&iter, &histogram_type) ||
423 !pickle.ReadInt(&iter, &pickle_flags) ||
424 !sample.Histogram::SampleSet::Deserialize(&iter, pickle)) {
425 LOG(ERROR) << "Pickle error decoding Histogram: " << histogram_name;
426 return false;
427 }
428 DCHECK(pickle_flags & kIPCSerializationSourceFlag);
429 // Since these fields may have come from an untrusted renderer, do additional
430 // checks above and beyond those in Histogram::Initialize()
431 if (declared_max <= 0 || declared_min <= 0 || declared_max < declared_min ||
432 INT_MAX / sizeof(Count) <= bucket_count || bucket_count < 2) {
433 LOG(ERROR) << "Values error decoding Histogram: " << histogram_name;
434 return false;
435 }
436
437 Flags flags = static_cast<Flags>(pickle_flags & ~kIPCSerializationSourceFlag);
438
439 DCHECK(histogram_type != NOT_VALID_IN_RENDERER);
440
441 scoped_refptr<Histogram> render_histogram(NULL);
442
443 if (histogram_type == HISTOGRAM) {
444 render_histogram = Histogram::FactoryGet(
445 histogram_name, declared_min, declared_max, bucket_count, flags);
446 } else if (histogram_type == LINEAR_HISTOGRAM) {
447 render_histogram = LinearHistogram::FactoryGet(
448 histogram_name, declared_min, declared_max, bucket_count, flags);
449 } else if (histogram_type == BOOLEAN_HISTOGRAM) {
450 render_histogram = BooleanHistogram::FactoryGet(histogram_name, flags);
451 } else {
452 LOG(ERROR) << "Error Deserializing Histogram Unknown histogram_type: " <<
453 histogram_type;
454 return false;
455 }
456
457 DCHECK(declared_min == render_histogram->declared_min());
458 DCHECK(declared_max == render_histogram->declared_max());
459 DCHECK(bucket_count == render_histogram->bucket_count());
460 DCHECK(histogram_type == render_histogram->histogram_type());
461
462 if (render_histogram->flags() & kIPCSerializationSourceFlag) {
463 DLOG(INFO) << "Single process mode, histogram observed and not copied: " <<
464 histogram_name;
465 } else {
466 DCHECK(flags == (flags & render_histogram->flags()));
467 render_histogram->AddSampleSet(sample);
468 }
469
470 return true;
471 }
472
473 //------------------------------------------------------------------------------
474 // Methods for the Histogram::SampleSet class
475 //------------------------------------------------------------------------------
476
SampleSet()477 Histogram::SampleSet::SampleSet()
478 : counts_(),
479 sum_(0),
480 square_sum_(0) {
481 }
482
Resize(const Histogram & histogram)483 void Histogram::SampleSet::Resize(const Histogram& histogram) {
484 counts_.resize(histogram.bucket_count(), 0);
485 }
486
CheckSize(const Histogram & histogram) const487 void Histogram::SampleSet::CheckSize(const Histogram& histogram) const {
488 DCHECK(counts_.size() == histogram.bucket_count());
489 }
490
491
Accumulate(Sample value,Count count,size_t index)492 void Histogram::SampleSet::Accumulate(Sample value, Count count,
493 size_t index) {
494 DCHECK(count == 1 || count == -1);
495 counts_[index] += count;
496 sum_ += count * value;
497 square_sum_ += (count * value) * static_cast<int64>(value);
498 DCHECK_GE(counts_[index], 0);
499 DCHECK_GE(sum_, 0);
500 DCHECK_GE(square_sum_, 0);
501 }
502
TotalCount() const503 Count Histogram::SampleSet::TotalCount() const {
504 Count total = 0;
505 for (Counts::const_iterator it = counts_.begin();
506 it != counts_.end();
507 ++it) {
508 total += *it;
509 }
510 return total;
511 }
512
Add(const SampleSet & other)513 void Histogram::SampleSet::Add(const SampleSet& other) {
514 DCHECK(counts_.size() == other.counts_.size());
515 sum_ += other.sum_;
516 square_sum_ += other.square_sum_;
517 for (size_t index = 0; index < counts_.size(); ++index)
518 counts_[index] += other.counts_[index];
519 }
520
Subtract(const SampleSet & other)521 void Histogram::SampleSet::Subtract(const SampleSet& other) {
522 DCHECK(counts_.size() == other.counts_.size());
523 // Note: Race conditions in snapshotting a sum or square_sum may lead to
524 // (temporary) negative values when snapshots are later combined (and deltas
525 // calculated). As a result, we don't currently CHCEK() for positive values.
526 sum_ -= other.sum_;
527 square_sum_ -= other.square_sum_;
528 for (size_t index = 0; index < counts_.size(); ++index) {
529 counts_[index] -= other.counts_[index];
530 DCHECK_GE(counts_[index], 0);
531 }
532 }
533
Serialize(Pickle * pickle) const534 bool Histogram::SampleSet::Serialize(Pickle* pickle) const {
535 pickle->WriteInt64(sum_);
536 pickle->WriteInt64(square_sum_);
537 pickle->WriteSize(counts_.size());
538
539 for (size_t index = 0; index < counts_.size(); ++index) {
540 pickle->WriteInt(counts_[index]);
541 }
542
543 return true;
544 }
545
Deserialize(void ** iter,const Pickle & pickle)546 bool Histogram::SampleSet::Deserialize(void** iter, const Pickle& pickle) {
547 DCHECK_EQ(counts_.size(), 0u);
548 DCHECK_EQ(sum_, 0);
549 DCHECK_EQ(square_sum_, 0);
550
551 size_t counts_size;
552
553 if (!pickle.ReadInt64(iter, &sum_) ||
554 !pickle.ReadInt64(iter, &square_sum_) ||
555 !pickle.ReadSize(iter, &counts_size)) {
556 return false;
557 }
558
559 if (counts_size == 0)
560 return false;
561
562 for (size_t index = 0; index < counts_size; ++index) {
563 int i;
564 if (!pickle.ReadInt(iter, &i))
565 return false;
566 counts_.push_back(i);
567 }
568
569 return true;
570 }
571
572 //------------------------------------------------------------------------------
573 // LinearHistogram: This histogram uses a traditional set of evenly spaced
574 // buckets.
575 //------------------------------------------------------------------------------
576
FactoryGet(const std::string & name,Sample minimum,Sample maximum,size_t bucket_count,Flags flags)577 scoped_refptr<Histogram> LinearHistogram::FactoryGet(
578 const std::string& name, Sample minimum, Sample maximum,
579 size_t bucket_count, Flags flags) {
580 scoped_refptr<Histogram> histogram(NULL);
581
582 if (minimum <= 0)
583 minimum = 1;
584 if (maximum >= kSampleType_MAX)
585 maximum = kSampleType_MAX - 1;
586
587 if (StatisticsRecorder::FindHistogram(name, &histogram)) {
588 DCHECK(histogram.get() != NULL);
589 } else {
590 histogram = new LinearHistogram(name, minimum, maximum, bucket_count);
591 scoped_refptr<Histogram> registered_histogram(NULL);
592 StatisticsRecorder::FindHistogram(name, ®istered_histogram);
593 if (registered_histogram.get() != NULL &&
594 registered_histogram.get() != histogram.get())
595 histogram = registered_histogram;
596 }
597
598 DCHECK(LINEAR_HISTOGRAM == histogram->histogram_type());
599 DCHECK(histogram->HasConstructorArguments(minimum, maximum, bucket_count));
600 histogram->SetFlags(flags);
601 return histogram;
602 }
603
FactoryGet(const std::string & name,base::TimeDelta minimum,base::TimeDelta maximum,size_t bucket_count,Flags flags)604 scoped_refptr<Histogram> LinearHistogram::FactoryGet(const std::string& name,
605 base::TimeDelta minimum, base::TimeDelta maximum, size_t bucket_count,
606 Flags flags) {
607 return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
608 bucket_count, flags);
609 }
610
LinearHistogram(const std::string & name,Sample minimum,Sample maximum,size_t bucket_count)611 LinearHistogram::LinearHistogram(const std::string& name, Sample minimum,
612 Sample maximum, size_t bucket_count)
613 : Histogram(name, minimum >= 1 ? minimum : 1, maximum, bucket_count) {
614 InitializeBucketRange();
615 DCHECK(ValidateBucketRanges());
616 }
617
LinearHistogram(const std::string & name,TimeDelta minimum,TimeDelta maximum,size_t bucket_count)618 LinearHistogram::LinearHistogram(const std::string& name,
619 TimeDelta minimum, TimeDelta maximum, size_t bucket_count)
620 : Histogram(name, minimum >= TimeDelta::FromMilliseconds(1) ?
621 minimum : TimeDelta::FromMilliseconds(1),
622 maximum, bucket_count) {
623 // Do a "better" (different) job at init than a base classes did...
624 InitializeBucketRange();
625 DCHECK(ValidateBucketRanges());
626 }
627
SetRangeDescriptions(const DescriptionPair descriptions[])628 void LinearHistogram::SetRangeDescriptions(
629 const DescriptionPair descriptions[]) {
630 for (int i =0; descriptions[i].description; ++i) {
631 bucket_description_[descriptions[i].sample] = descriptions[i].description;
632 }
633 }
634
GetAsciiBucketRange(size_t i) const635 const std::string LinearHistogram::GetAsciiBucketRange(size_t i) const {
636 int range = ranges(i);
637 BucketDescriptionMap::const_iterator it = bucket_description_.find(range);
638 if (it == bucket_description_.end())
639 return Histogram::GetAsciiBucketRange(i);
640 return it->second;
641 }
642
PrintEmptyBucket(size_t index) const643 bool LinearHistogram::PrintEmptyBucket(size_t index) const {
644 return bucket_description_.find(ranges(index)) == bucket_description_.end();
645 }
646
647
InitializeBucketRange()648 void LinearHistogram::InitializeBucketRange() {
649 DCHECK_LT(0, declared_min()); // 0 is the underflow bucket here.
650 double min = declared_min();
651 double max = declared_max();
652 size_t i;
653 for (i = 1; i < bucket_count(); ++i) {
654 double linear_range = (min * (bucket_count() -1 - i) + max * (i - 1)) /
655 (bucket_count() - 2);
656 SetBucketRange(i, static_cast<int> (linear_range + 0.5));
657 }
658 }
659
GetBucketSize(Count current,size_t i) const660 double LinearHistogram::GetBucketSize(Count current, size_t i) const {
661 DCHECK(ranges(i + 1) > ranges(i));
662 // Adjacent buckets with different widths would have "surprisingly" many (few)
663 // samples in a histogram if we didn't normalize this way.
664 double denominator = ranges(i + 1) - ranges(i);
665 return current/denominator;
666 }
667
668 //------------------------------------------------------------------------------
669 // This section provides implementation for BooleanHistogram.
670 //------------------------------------------------------------------------------
671
FactoryGet(const std::string & name,Flags flags)672 scoped_refptr<Histogram> BooleanHistogram::FactoryGet(const std::string& name,
673 Flags flags) {
674 scoped_refptr<Histogram> histogram(NULL);
675
676 if (StatisticsRecorder::FindHistogram(name, &histogram)) {
677 DCHECK(histogram.get() != NULL);
678 } else {
679 histogram = new BooleanHistogram(name);
680 scoped_refptr<Histogram> registered_histogram(NULL);
681 StatisticsRecorder::FindHistogram(name, ®istered_histogram);
682 if (registered_histogram.get() != NULL &&
683 registered_histogram.get() != histogram.get())
684 histogram = registered_histogram;
685 }
686
687 DCHECK(BOOLEAN_HISTOGRAM == histogram->histogram_type());
688 histogram->SetFlags(flags);
689 return histogram;
690 }
691
692
693 //------------------------------------------------------------------------------
694 // The next section handles global (central) support for all histograms, as well
695 // as startup/teardown of this service.
696 //------------------------------------------------------------------------------
697
698 // This singleton instance should be started during the single threaded portion
699 // of main(), and hence it is not thread safe. It initializes globals to
700 // provide support for all future calls.
StatisticsRecorder()701 StatisticsRecorder::StatisticsRecorder() {
702 DCHECK(!histograms_);
703 lock_ = new Lock;
704 histograms_ = new HistogramMap;
705 }
706
~StatisticsRecorder()707 StatisticsRecorder::~StatisticsRecorder() {
708 DCHECK(histograms_);
709
710 if (dump_on_exit_) {
711 std::string output;
712 WriteGraph("", &output);
713 LOG(INFO) << output;
714 }
715
716 // Clean up.
717 delete histograms_;
718 histograms_ = NULL;
719 delete lock_;
720 lock_ = NULL;
721 }
722
723 // static
WasStarted()724 bool StatisticsRecorder::WasStarted() {
725 return NULL != histograms_;
726 }
727
728 // Note: We can't accept a ref_ptr to |histogram| because we *might* not keep a
729 // reference, and we are called while in the Histogram constructor. In that
730 // scenario, a ref_ptr would have incremented the ref count when the histogram
731 // was passed to us, decremented it when we returned, and the instance would be
732 // destroyed before assignment (when value was returned by new).
733 // static
Register(Histogram * histogram)734 void StatisticsRecorder::Register(Histogram* histogram) {
735 if (!histograms_)
736 return;
737 const std::string name = histogram->histogram_name();
738 AutoLock auto_lock(*lock_);
739
740 DCHECK(histograms_->end() == histograms_->find(name));
741
742 (*histograms_)[name] = histogram;
743 return;
744 }
745
746 // static
WriteHTMLGraph(const std::string & query,std::string * output)747 void StatisticsRecorder::WriteHTMLGraph(const std::string& query,
748 std::string* output) {
749 if (!histograms_)
750 return;
751 output->append("<html><head><title>About Histograms");
752 if (!query.empty())
753 output->append(" - " + query);
754 output->append("</title>"
755 // We'd like the following no-cache... but it doesn't work.
756 // "<META HTTP-EQUIV=\"Pragma\" CONTENT=\"no-cache\">"
757 "</head><body>");
758
759 Histograms snapshot;
760 GetSnapshot(query, &snapshot);
761 for (Histograms::iterator it = snapshot.begin();
762 it != snapshot.end();
763 ++it) {
764 (*it)->WriteHTMLGraph(output);
765 output->append("<br><hr><br>");
766 }
767 output->append("</body></html>");
768 }
769
770 // static
WriteGraph(const std::string & query,std::string * output)771 void StatisticsRecorder::WriteGraph(const std::string& query,
772 std::string* output) {
773 if (!histograms_)
774 return;
775 if (query.length())
776 StringAppendF(output, "Collections of histograms for %s\n", query.c_str());
777 else
778 output->append("Collections of all histograms\n");
779
780 Histograms snapshot;
781 GetSnapshot(query, &snapshot);
782 for (Histograms::iterator it = snapshot.begin();
783 it != snapshot.end();
784 ++it) {
785 (*it)->WriteAscii(true, "\n", output);
786 output->append("\n");
787 }
788 }
789
790 // static
GetHistograms(Histograms * output)791 void StatisticsRecorder::GetHistograms(Histograms* output) {
792 if (!histograms_)
793 return;
794 AutoLock auto_lock(*lock_);
795 for (HistogramMap::iterator it = histograms_->begin();
796 histograms_->end() != it;
797 ++it) {
798 output->push_back(it->second);
799 }
800 }
801
FindHistogram(const std::string & name,scoped_refptr<Histogram> * histogram)802 bool StatisticsRecorder::FindHistogram(const std::string& name,
803 scoped_refptr<Histogram>* histogram) {
804 if (!histograms_)
805 return false;
806 AutoLock auto_lock(*lock_);
807 HistogramMap::iterator it = histograms_->find(name);
808 if (histograms_->end() == it)
809 return false;
810 *histogram = it->second;
811 return true;
812 }
813
814 // private static
GetSnapshot(const std::string & query,Histograms * snapshot)815 void StatisticsRecorder::GetSnapshot(const std::string& query,
816 Histograms* snapshot) {
817 AutoLock auto_lock(*lock_);
818 for (HistogramMap::iterator it = histograms_->begin();
819 histograms_->end() != it;
820 ++it) {
821 if (it->first.find(query) != std::string::npos)
822 snapshot->push_back(it->second);
823 }
824 }
825
826 // static
827 StatisticsRecorder::HistogramMap* StatisticsRecorder::histograms_ = NULL;
828 // static
829 Lock* StatisticsRecorder::lock_ = NULL;
830 // static
831 bool StatisticsRecorder::dump_on_exit_ = false;
832