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comparison: ipc/chromium/src/base/histogram.cc

ipc/chromium/src/base/histogram.cc

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1 // Copyright (c) 2011 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
14 #include <algorithm>
15 #include <string>
16
17 #include "base/logging.h"
18 #include "base/pickle.h"
19 #include "base/string_util.h"
20 #include "base/logging.h"
21
22 namespace base {
23
24 #define DVLOG(x) CHROMIUM_LOG(ERROR)
25 #define CHECK_GT DCHECK_GT
26 #define CHECK_LT DCHECK_LT
27 typedef ::Lock Lock;
28 typedef ::AutoLock AutoLock;
29
30 // Static table of checksums for all possible 8 bit bytes.
31 const uint32_t Histogram::kCrcTable[256] = {0x0, 0x77073096L, 0xee0e612cL,
32 0x990951baL, 0x76dc419L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0xedb8832L,
33 0x79dcb8a4L, 0xe0d5e91eL, 0x97d2d988L, 0x9b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
34 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, 0x1adad47dL,
35 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, 0x646ba8c0L, 0xfd62f97aL,
36 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L,
37 0x4c69105eL, 0xd56041e4L, 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL,
38 0xa50ab56bL, 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
39 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, 0xc8d75180L,
40 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, 0xb8bda50fL, 0x2802b89eL,
41 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL,
42 0xb6662d3dL, 0x76dc4190L, 0x1db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L,
43 0x6b6b51fL, 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0xf00f934L, 0x9609a88eL,
44 0xe10e9818L, 0x7f6a0dbbL, 0x86d3d2dL, 0x91646c97L, 0xe6635c01L, 0x6b6b51f4L,
45 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, 0x1b01a57bL, 0x8208f4c1L,
46 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL,
47 0x15da2d49L, 0x8cd37cf3L, 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L,
48 0xd4bb30e2L, 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
49 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, 0xaa0a4c5fL,
50 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, 0xc90c2086L, 0x5768b525L,
51 0x206f85b3L, 0xb966d409L, 0xce61e49fL, 0x5edef90eL, 0x29d9c998L, 0xb0d09822L,
52 0xc7d7a8b4L, 0x59b33d17L, 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L,
53 0x9abfb3b6L, 0x3b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x4db2615L,
54 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0xd6d6a3eL, 0x7a6a5aa8L, 0xe40ecf0bL,
55 0x9309ff9dL, 0xa00ae27L, 0x7d079eb1L, 0xf00f9344L, 0x8708a3d2L, 0x1e01f268L,
56 0x6906c2feL, 0xf762575dL, 0x806567cbL, 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L,
57 0x89d32be0L, 0x10da7a5aL, 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L,
58 0x60b08ed5L, 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
59 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, 0x36034af6L,
60 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, 0x4669be79L, 0xcb61b38cL,
61 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L,
62 0x5505262fL, 0xc5ba3bbeL, 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L,
63 0xb5d0cf31L, 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
64 0x26d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x5005713L, 0x95bf4a82L,
65 0xe2b87a14L, 0x7bb12baeL, 0xcb61b38L, 0x92d28e9bL, 0xe5d5be0dL, 0x7cdcefb7L,
66 0xbdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL,
67 0xf6b9265bL, 0x6fb077e1L, 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL,
68 0x11010b5cL, 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
69 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, 0x4969474dL,
70 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, 0x37d83bf0L, 0xa9bcae53L,
71 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L,
72 0x24b4a3a6L, 0xbad03605L, 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL,
73 0xc4614ab8L, 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
74 0x2d02ef8dL,
75 };
76
77 typedef Histogram::Count Count;
78
79 // static
80 const size_t Histogram::kBucketCount_MAX = 16384u;
81
82 Histogram* Histogram::FactoryGet(const std::string& name,
83 Sample minimum,
84 Sample maximum,
85 size_t bucket_count,
86 Flags flags) {
87 Histogram* histogram(NULL);
88
89 // Defensive code.
90 if (minimum < 1)
91 minimum = 1;
92 if (maximum > kSampleType_MAX - 1)
93 maximum = kSampleType_MAX - 1;
94
95 if (!StatisticsRecorder::FindHistogram(name, &histogram)) {
96 // Extra variable is not needed... but this keeps this section basically
97 // identical to other derived classes in this file (and compiler will
98 // optimize away the extra variable.
99 Histogram* tentative_histogram =
100 new Histogram(name, minimum, maximum, bucket_count);
101 tentative_histogram->InitializeBucketRange();
102 tentative_histogram->SetFlags(flags);
103 histogram =
104 StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
105 }
106
107 DCHECK_EQ(HISTOGRAM, histogram->histogram_type());
108 DCHECK(histogram->HasConstructorArguments(minimum, maximum, bucket_count));
109 return histogram;
110 }
111
112 Histogram* Histogram::FactoryTimeGet(const std::string& name,
113 TimeDelta minimum,
114 TimeDelta maximum,
115 size_t bucket_count,
116 Flags flags) {
117 return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
118 bucket_count, flags);
119 }
120
121 void Histogram::Add(int value) {
122 if (value > kSampleType_MAX - 1)
123 value = kSampleType_MAX - 1;
124 if (value < 0)
125 value = 0;
126 size_t index = BucketIndex(value);
127 DCHECK_GE(value, ranges(index));
128 DCHECK_LT(value, ranges(index + 1));
129 Accumulate(value, 1, index);
130 }
131
132 void Histogram::Subtract(int value) {
133 if (value > kSampleType_MAX - 1)
134 value = kSampleType_MAX - 1;
135 if (value < 0)
136 value = 0;
137 size_t index = BucketIndex(value);
138 DCHECK_GE(value, ranges(index));
139 DCHECK_LT(value, ranges(index + 1));
140 Accumulate(value, -1, index);
141 }
142
143 void Histogram::AddBoolean(bool value) {
144 DCHECK(false);
145 }
146
147 void Histogram::AddSampleSet(const SampleSet& sample) {
148 sample_.Add(sample);
149 }
150
151 void Histogram::Clear() {
152 SampleSet ss;
153 ss.Resize(*this);
154 sample_ = ss;
155 }
156
157 void Histogram::SetRangeDescriptions(const DescriptionPair descriptions[]) {
158 DCHECK(false);
159 }
160
161 // The following methods provide a graphical histogram display.
162 void Histogram::WriteHTMLGraph(std::string* output) const {
163 // TBD(jar) Write a nice HTML bar chart, with divs an mouse-overs etc.
164 output->append("<PRE>");
165 WriteAscii(true, "<br>", output);
166 output->append("</PRE>");
167 }
168
169 void Histogram::WriteAscii(bool graph_it, const std::string& newline,
170 std::string* output) const {
171 // Get local (stack) copies of all effectively volatile class data so that we
172 // are consistent across our output activities.
173 SampleSet snapshot;
174 SnapshotSample(&snapshot);
175 Count sample_count = snapshot.TotalCount();
176
177 WriteAsciiHeader(snapshot, sample_count, output);
178 output->append(newline);
179
180 // Prepare to normalize graphical rendering of bucket contents.
181 double max_size = 0;
182 if (graph_it)
183 max_size = GetPeakBucketSize(snapshot);
184
185 // Calculate space needed to print bucket range numbers. Leave room to print
186 // nearly the largest bucket range without sliding over the histogram.
187 size_t largest_non_empty_bucket = bucket_count() - 1;
188 while (0 == snapshot.counts(largest_non_empty_bucket)) {
189 if (0 == largest_non_empty_bucket)
190 break; // All buckets are empty.
191 --largest_non_empty_bucket;
192 }
193
194 // Calculate largest print width needed for any of our bucket range displays.
195 size_t print_width = 1;
196 for (size_t i = 0; i < bucket_count(); ++i) {
197 if (snapshot.counts(i)) {
198 size_t width = GetAsciiBucketRange(i).size() + 1;
199 if (width > print_width)
200 print_width = width;
201 }
202 }
203
204 int64_t remaining = sample_count;
205 int64_t past = 0;
206 // Output the actual histogram graph.
207 for (size_t i = 0; i < bucket_count(); ++i) {
208 Count current = snapshot.counts(i);
209 if (!current && !PrintEmptyBucket(i))
210 continue;
211 remaining -= current;
212 std::string range = GetAsciiBucketRange(i);
213 output->append(range);
214 for (size_t j = 0; range.size() + j < print_width + 1; ++j)
215 output->push_back(' ');
216 if (0 == current && i < bucket_count() - 1 && 0 == snapshot.counts(i + 1)) {
217 while (i < bucket_count() - 1 && 0 == snapshot.counts(i + 1))
218 ++i;
219 output->append("... ");
220 output->append(newline);
221 continue; // No reason to plot emptiness.
222 }
223 double current_size = GetBucketSize(current, i);
224 if (graph_it)
225 WriteAsciiBucketGraph(current_size, max_size, output);
226 WriteAsciiBucketContext(past, current, remaining, i, output);
227 output->append(newline);
228 past += current;
229 }
230 DCHECK_EQ(sample_count, past);
231 }
232
233 // static
234 std::string Histogram::SerializeHistogramInfo(const Histogram& histogram,
235 const SampleSet& snapshot) {
236 DCHECK_NE(NOT_VALID_IN_RENDERER, histogram.histogram_type());
237
238 Pickle pickle;
239 pickle.WriteString(histogram.histogram_name());
240 pickle.WriteInt(histogram.declared_min());
241 pickle.WriteInt(histogram.declared_max());
242 pickle.WriteSize(histogram.bucket_count());
243 pickle.WriteUInt32(histogram.range_checksum());
244 pickle.WriteInt(histogram.histogram_type());
245 pickle.WriteInt(histogram.flags());
246
247 snapshot.Serialize(&pickle);
248 return std::string(static_cast<const char*>(pickle.data()), pickle.size());
249 }
250
251 // static
252 bool Histogram::DeserializeHistogramInfo(const std::string& histogram_info) {
253 if (histogram_info.empty()) {
254 return false;
255 }
256
257 Pickle pickle(histogram_info.data(),
258 static_cast<int>(histogram_info.size()));
259 std::string histogram_name;
260 int declared_min;
261 int declared_max;
262 size_t bucket_count;
263 uint32_t range_checksum;
264 int histogram_type;
265 int pickle_flags;
266 SampleSet sample;
267
268 void* iter = NULL;
269 if (!pickle.ReadString(&iter, &histogram_name) ||
270 !pickle.ReadInt(&iter, &declared_min) ||
271 !pickle.ReadInt(&iter, &declared_max) ||
272 !pickle.ReadSize(&iter, &bucket_count) ||
273 !pickle.ReadUInt32(&iter, &range_checksum) ||
274 !pickle.ReadInt(&iter, &histogram_type) ||
275 !pickle.ReadInt(&iter, &pickle_flags) ||
276 !sample.Histogram::SampleSet::Deserialize(&iter, pickle)) {
277 CHROMIUM_LOG(ERROR) << "Pickle error decoding Histogram: " << histogram_name;
278 return false;
279 }
280 DCHECK(pickle_flags & kIPCSerializationSourceFlag);
281 // Since these fields may have come from an untrusted renderer, do additional
282 // checks above and beyond those in Histogram::Initialize()
283 if (declared_max <= 0 || declared_min <= 0 || declared_max < declared_min ||
284 INT_MAX / sizeof(Count) <= bucket_count || bucket_count < 2) {
285 CHROMIUM_LOG(ERROR) << "Values error decoding Histogram: " << histogram_name;
286 return false;
287 }
288
289 Flags flags = static_cast<Flags>(pickle_flags & ~kIPCSerializationSourceFlag);
290
291 DCHECK_NE(NOT_VALID_IN_RENDERER, histogram_type);
292
293 Histogram* render_histogram(NULL);
294
295 if (histogram_type == HISTOGRAM) {
296 render_histogram = Histogram::FactoryGet(
297 histogram_name, declared_min, declared_max, bucket_count, flags);
298 } else if (histogram_type == LINEAR_HISTOGRAM) {
299 render_histogram = LinearHistogram::FactoryGet(
300 histogram_name, declared_min, declared_max, bucket_count, flags);
301 } else if (histogram_type == BOOLEAN_HISTOGRAM) {
302 render_histogram = BooleanHistogram::FactoryGet(histogram_name, flags);
303 } else {
304 CHROMIUM_LOG(ERROR) << "Error Deserializing Histogram Unknown histogram_type: "
305 << histogram_type;
306 return false;
307 }
308
309 DCHECK_EQ(render_histogram->declared_min(), declared_min);
310 DCHECK_EQ(render_histogram->declared_max(), declared_max);
311 DCHECK_EQ(render_histogram->bucket_count(), bucket_count);
312 DCHECK_EQ(render_histogram->range_checksum(), range_checksum);
313 DCHECK_EQ(render_histogram->histogram_type(), histogram_type);
314
315 if (render_histogram->flags() & kIPCSerializationSourceFlag) {
316 DVLOG(1) << "Single process mode, histogram observed and not copied: "
317 << histogram_name;
318 } else {
319 DCHECK_EQ(flags & render_histogram->flags(), flags);
320 render_histogram->AddSampleSet(sample);
321 }
322
323 return true;
324 }
325
326 //------------------------------------------------------------------------------
327 // Methods for the validating a sample and a related histogram.
328 //------------------------------------------------------------------------------
329
330 Histogram::Inconsistencies Histogram::FindCorruption(
331 const SampleSet& snapshot) const {
332 int inconsistencies = NO_INCONSISTENCIES;
333 Sample previous_range = -1; // Bottom range is always 0.
334 int64_t count = 0;
335 for (size_t index = 0; index < bucket_count(); ++index) {
336 count += snapshot.counts(index);
337 int new_range = ranges(index);
338 if (previous_range >= new_range)
339 inconsistencies |= BUCKET_ORDER_ERROR;
340 previous_range = new_range;
341 }
342
343 if (!HasValidRangeChecksum())
344 inconsistencies |= RANGE_CHECKSUM_ERROR;
345
346 int64_t delta64 = snapshot.redundant_count() - count;
347 if (delta64 != 0) {
348 int delta = static_cast<int>(delta64);
349 if (delta != delta64)
350 delta = INT_MAX; // Flag all giant errors as INT_MAX.
351 // Since snapshots of histograms are taken asynchronously relative to
352 // sampling (and snapped from different threads), it is pretty likely that
353 // we'll catch a redundant count that doesn't match the sample count. We
354 // allow for a certain amount of slop before flagging this as an
355 // inconsistency. Even with an inconsistency, we'll snapshot it again (for
356 // UMA in about a half hour, so we'll eventually get the data, if it was
357 // not the result of a corruption. If histograms show that 1 is "too tight"
358 // then we may try to use 2 or 3 for this slop value.
359 const int kCommonRaceBasedCountMismatch = 1;
360 if (delta > 0) {
361 UMA_HISTOGRAM_COUNTS("Histogram.InconsistentCountHigh", delta);
362 if (delta > kCommonRaceBasedCountMismatch)
363 inconsistencies |= COUNT_HIGH_ERROR;
364 } else {
365 DCHECK_GT(0, delta);
366 UMA_HISTOGRAM_COUNTS("Histogram.InconsistentCountLow", -delta);
367 if (-delta > kCommonRaceBasedCountMismatch)
368 inconsistencies |= COUNT_LOW_ERROR;
369 }
370 }
371 return static_cast<Inconsistencies>(inconsistencies);
372 }
373
374 Histogram::ClassType Histogram::histogram_type() const {
375 return HISTOGRAM;
376 }
377
378 Histogram::Sample Histogram::ranges(size_t i) const {
379 return ranges_[i];
380 }
381
382 size_t Histogram::bucket_count() const {
383 return bucket_count_;
384 }
385
386 // Do a safe atomic snapshot of sample data.
387 // This implementation assumes we are on a safe single thread.
388 void Histogram::SnapshotSample(SampleSet* sample) const {
389 // Note locking not done in this version!!!
390 *sample = sample_;
391 }
392
393 bool Histogram::HasConstructorArguments(Sample minimum,
394 Sample maximum,
395 size_t bucket_count) {
396 return ((minimum == declared_min_) && (maximum == declared_max_) &&
397 (bucket_count == bucket_count_));
398 }
399
400 bool Histogram::HasConstructorTimeDeltaArguments(TimeDelta minimum,
401 TimeDelta maximum,
402 size_t bucket_count) {
403 return ((minimum.InMilliseconds() == declared_min_) &&
404 (maximum.InMilliseconds() == declared_max_) &&
405 (bucket_count == bucket_count_));
406 }
407
408 bool Histogram::HasValidRangeChecksum() const {
409 return CalculateRangeChecksum() == range_checksum_;
410 }
411
412 size_t Histogram::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf)
413 {
414 size_t n = 0;
415 n += aMallocSizeOf(this);
416 // We're not allowed to do deep dives into STL data structures. This
417 // is as close as we can get to measuring this array.
418 n += aMallocSizeOf(&ranges_[0]);
419 n += sample_.SizeOfExcludingThis(aMallocSizeOf);
420 return n;
421 }
422
423 size_t Histogram::SampleSet::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf)
424 {
425 // We're not allowed to do deep dives into STL data structures. This
426 // is as close as we can get to measuring this array.
427 return aMallocSizeOf(&counts_[0]);
428 }
429
430 Histogram::Histogram(const std::string& name, Sample minimum,
431 Sample maximum, size_t bucket_count)
432 : sample_(),
433 histogram_name_(name),
434 declared_min_(minimum),
435 declared_max_(maximum),
436 bucket_count_(bucket_count),
437 flags_(kNoFlags),
438 ranges_(bucket_count + 1, 0),
439 range_checksum_(0) {
440 Initialize();
441 }
442
443 Histogram::Histogram(const std::string& name, TimeDelta minimum,
444 TimeDelta maximum, size_t bucket_count)
445 : sample_(),
446 histogram_name_(name),
447 declared_min_(static_cast<int> (minimum.InMilliseconds())),
448 declared_max_(static_cast<int> (maximum.InMilliseconds())),
449 bucket_count_(bucket_count),
450 flags_(kNoFlags),
451 ranges_(bucket_count + 1, 0),
452 range_checksum_(0) {
453 Initialize();
454 }
455
456 Histogram::~Histogram() {
457 if (StatisticsRecorder::dump_on_exit()) {
458 std::string output;
459 WriteAscii(true, "\n", &output);
460 CHROMIUM_LOG(INFO) << output;
461 }
462
463 // Just to make sure most derived class did this properly...
464 DCHECK(ValidateBucketRanges());
465 }
466
467 // Calculate what range of values are held in each bucket.
468 // We have to be careful that we don't pick a ratio between starting points in
469 // consecutive buckets that is sooo small, that the integer bounds are the same
470 // (effectively making one bucket get no values). We need to avoid:
471 // ranges_[i] == ranges_[i + 1]
472 // To avoid that, we just do a fine-grained bucket width as far as we need to
473 // until we get a ratio that moves us along at least 2 units at a time. From
474 // that bucket onward we do use the exponential growth of buckets.
475 void Histogram::InitializeBucketRange() {
476 double log_max = log(static_cast<double>(declared_max()));
477 double log_ratio;
478 double log_next;
479 size_t bucket_index = 1;
480 Sample current = declared_min();
481 SetBucketRange(bucket_index, current);
482 while (bucket_count() > ++bucket_index) {
483 double log_current;
484 log_current = log(static_cast<double>(current));
485 // Calculate the count'th root of the range.
486 log_ratio = (log_max - log_current) / (bucket_count() - bucket_index);
487 // See where the next bucket would start.
488 log_next = log_current + log_ratio;
489 int next;
490 next = static_cast<int>(floor(exp(log_next) + 0.5));
491 if (next > current)
492 current = next;
493 else
494 ++current; // Just do a narrow bucket, and keep trying.
495 SetBucketRange(bucket_index, current);
496 }
497 ResetRangeChecksum();
498
499 DCHECK_EQ(bucket_count(), bucket_index);
500 }
501
502 bool Histogram::PrintEmptyBucket(size_t index) const {
503 return true;
504 }
505
506 size_t Histogram::BucketIndex(Sample value) const {
507 // Use simple binary search. This is very general, but there are better
508 // approaches if we knew that the buckets were linearly distributed.
509 DCHECK_LE(ranges(0), value);
510 DCHECK_GT(ranges(bucket_count()), value);
511 size_t under = 0;
512 size_t over = bucket_count();
513 size_t mid;
514
515 do {
516 DCHECK_GE(over, under);
517 mid = under + (over - under)/2;
518 if (mid == under)
519 break;
520 if (ranges(mid) <= value)
521 under = mid;
522 else
523 over = mid;
524 } while (true);
525
526 DCHECK_LE(ranges(mid), value);
527 CHECK_GT(ranges(mid+1), value);
528 return mid;
529 }
530
531 // Use the actual bucket widths (like a linear histogram) until the widths get
532 // over some transition value, and then use that transition width. Exponentials
533 // get so big so fast (and we don't expect to see a lot of entries in the large
534 // buckets), so we need this to make it possible to see what is going on and
535 // not have 0-graphical-height buckets.
536 double Histogram::GetBucketSize(Count current, size_t i) const {
537 DCHECK_GT(ranges(i + 1), ranges(i));
538 static const double kTransitionWidth = 5;
539 double denominator = ranges(i + 1) - ranges(i);
540 if (denominator > kTransitionWidth)
541 denominator = kTransitionWidth; // Stop trying to normalize.
542 return current/denominator;
543 }
544
545 void Histogram::ResetRangeChecksum() {
546 range_checksum_ = CalculateRangeChecksum();
547 }
548
549 const std::string Histogram::GetAsciiBucketRange(size_t i) const {
550 std::string result;
551 if (kHexRangePrintingFlag & flags_)
552 StringAppendF(&result, "%#x", ranges(i));
553 else
554 StringAppendF(&result, "%d", ranges(i));
555 return result;
556 }
557
558 // Update histogram data with new sample.
559 void Histogram::Accumulate(Sample value, Count count, size_t index) {
560 // Note locking not done in this version!!!
561 sample_.AccumulateWithExponentialStats(value, count, index,
562 flags_ & kExtendedStatisticsFlag);
563 }
564
565 void Histogram::SetBucketRange(size_t i, Sample value) {
566 DCHECK_GT(bucket_count_, i);
567 ranges_[i] = value;
568 }
569
570 bool Histogram::ValidateBucketRanges() const {
571 // Standard assertions that all bucket ranges should satisfy.
572 DCHECK_EQ(bucket_count_ + 1, ranges_.size());
573 DCHECK_EQ(0, ranges_[0]);
574 DCHECK_EQ(declared_min(), ranges_[1]);
575 DCHECK_EQ(declared_max(), ranges_[bucket_count_ - 1]);
576 DCHECK_EQ(kSampleType_MAX, ranges_[bucket_count_]);
577 return true;
578 }
579
580 uint32_t Histogram::CalculateRangeChecksum() const {
581 DCHECK_EQ(ranges_.size(), bucket_count() + 1);
582 uint32_t checksum = static_cast<uint32_t>(ranges_.size()); // Seed checksum.
583 for (size_t index = 0; index < bucket_count(); ++index)
584 checksum = Crc32(checksum, ranges(index));
585 return checksum;
586 }
587
588 void Histogram::Initialize() {
589 sample_.Resize(*this);
590 if (declared_min_ < 1)
591 declared_min_ = 1;
592 if (declared_max_ > kSampleType_MAX - 1)
593 declared_max_ = kSampleType_MAX - 1;
594 DCHECK_LE(declared_min_, declared_max_);
595 DCHECK_GT(bucket_count_, 1u);
596 CHECK_LT(bucket_count_, kBucketCount_MAX);
597 size_t maximal_bucket_count = declared_max_ - declared_min_ + 2;
598 DCHECK_LE(bucket_count_, maximal_bucket_count);
599 DCHECK_EQ(0, ranges_[0]);
600 ranges_[bucket_count_] = kSampleType_MAX;
601 }
602
603 // We generate the CRC-32 using the low order bits to select whether to XOR in
604 // the reversed polynomial 0xedb88320L. This is nice and simple, and allows us
605 // to keep the quotient in a uint32_t. Since we're not concerned about the nature
606 // of corruptions (i.e., we don't care about bit sequencing, since we are
607 // handling memory changes, which are more grotesque) so we don't bother to
608 // get the CRC correct for big-endian vs little-ending calculations. All we
609 // need is a nice hash, that tends to depend on all the bits of the sample, with
610 // very little chance of changes in one place impacting changes in another
611 // place.
612 uint32_t Histogram::Crc32(uint32_t sum, Histogram::Sample range) {
613 const bool kUseRealCrc = true; // TODO(jar): Switch to false and watch stats.
614 if (kUseRealCrc) {
615 union {
616 Histogram::Sample range;
617 unsigned char bytes[sizeof(Histogram::Sample)];
618 } converter;
619 converter.range = range;
620 for (size_t i = 0; i < sizeof(converter); ++i)
621 sum = kCrcTable[(sum & 0xff) ^ converter.bytes[i]] ^ (sum >> 8);
622 } else {
623 // Use hash techniques provided in ReallyFastHash, except we don't care
624 // about "avalanching" (which would worsten the hash, and add collisions),
625 // and we don't care about edge cases since we have an even number of bytes.
626 union {
627 Histogram::Sample range;
628 uint16_t ints[sizeof(Histogram::Sample) / 2];
629 } converter;
630 DCHECK_EQ(sizeof(Histogram::Sample), sizeof(converter));
631 converter.range = range;
632 sum += converter.ints[0];
633 sum = (sum << 16) ^ sum ^ (static_cast<uint32_t>(converter.ints[1]) << 11);
634 sum += sum >> 11;
635 }
636 return sum;
637 }
638
639 //------------------------------------------------------------------------------
640 // Private methods
641
642 double Histogram::GetPeakBucketSize(const SampleSet& snapshot) const {
643 double max = 0;
644 for (size_t i = 0; i < bucket_count() ; ++i) {
645 double current_size = GetBucketSize(snapshot.counts(i), i);
646 if (current_size > max)
647 max = current_size;
648 }
649 return max;
650 }
651
652 void Histogram::WriteAsciiHeader(const SampleSet& snapshot,
653 Count sample_count,
654 std::string* output) const {
655 StringAppendF(output,
656 "Histogram: %s recorded %d samples",
657 histogram_name().c_str(),
658 sample_count);
659 if (0 == sample_count) {
660 DCHECK_EQ(snapshot.sum(), 0);
661 } else {
662 double average = static_cast<float>(snapshot.sum()) / sample_count;
663
664 StringAppendF(output, ", average = %.1f", average);
665 }
666 if (flags_ & ~kHexRangePrintingFlag)
667 StringAppendF(output, " (flags = 0x%x)", flags_ & ~kHexRangePrintingFlag);
668 }
669
670 void Histogram::WriteAsciiBucketContext(const int64_t past,
671 const Count current,
672 const int64_t remaining,
673 const size_t i,
674 std::string* output) const {
675 double scaled_sum = (past + current + remaining) / 100.0;
676 WriteAsciiBucketValue(current, scaled_sum, output);
677 if (0 < i) {
678 double percentage = past / scaled_sum;
679 StringAppendF(output, " {%3.1f%%}", percentage);
680 }
681 }
682
683 void Histogram::WriteAsciiBucketValue(Count current, double scaled_sum,
684 std::string* output) const {
685 StringAppendF(output, " (%d = %3.1f%%)", current, current/scaled_sum);
686 }
687
688 void Histogram::WriteAsciiBucketGraph(double current_size, double max_size,
689 std::string* output) const {
690 const int k_line_length = 72; // Maximal horizontal width of graph.
691 int x_count = static_cast<int>(k_line_length * (current_size / max_size)
692 + 0.5);
693 int x_remainder = k_line_length - x_count;
694
695 while (0 < x_count--)
696 output->append("-");
697 output->append("O");
698 while (0 < x_remainder--)
699 output->append(" ");
700 }
701
702 //------------------------------------------------------------------------------
703 // Methods for the Histogram::SampleSet class
704 //------------------------------------------------------------------------------
705
706 Histogram::SampleSet::SampleSet()
707 : counts_(),
708 sum_(0),
709 sum_squares_(0),
710 log_sum_(0),
711 log_sum_squares_(0),
712 redundant_count_(0) {
713 }
714
715 Histogram::SampleSet::~SampleSet() {
716 }
717
718 void Histogram::SampleSet::Resize(const Histogram& histogram) {
719 counts_.resize(histogram.bucket_count(), 0);
720 }
721
722 void Histogram::SampleSet::CheckSize(const Histogram& histogram) const {
723 DCHECK_EQ(histogram.bucket_count(), counts_.size());
724 }
725
726 void Histogram::SampleSet::Accumulate(Sample value, Count count,
727 size_t index) {
728 DCHECK(count == 1 || count == -1);
729 counts_[index] += count;
730 redundant_count_ += count;
731 sum_ += static_cast<int64_t>(count) * value;
732 DCHECK_GE(counts_[index], 0);
733 DCHECK_GE(sum_, 0);
734 DCHECK_GE(redundant_count_, 0);
735 }
736
737 void Histogram::SampleSet::AccumulateWithLinearStats(Sample value,
738 Count count,
739 size_t index) {
740 Accumulate(value, count, index);
741 sum_squares_ += static_cast<int64_t>(count) * value * value;
742 }
743
744 void Histogram::SampleSet::AccumulateWithExponentialStats(Sample value,
745 Count count,
746 size_t index,
747 bool computeExtendedStatistics) {
748 Accumulate(value, count, index);
749 if (computeExtendedStatistics) {
750 DCHECK_GE(value, 0);
751 float value_log = logf(static_cast<float>(value) + 1.0f);
752 log_sum_ += count * value_log;
753 log_sum_squares_ += count * value_log * value_log;
754 }
755 }
756
757 Count Histogram::SampleSet::TotalCount() const {
758 Count total = 0;
759 for (Counts::const_iterator it = counts_.begin();
760 it != counts_.end();
761 ++it) {
762 total += *it;
763 }
764 return total;
765 }
766
767 void Histogram::SampleSet::Add(const SampleSet& other) {
768 DCHECK_EQ(counts_.size(), other.counts_.size());
769 sum_ += other.sum_;
770 sum_squares_ += other.sum_squares_;
771 log_sum_ += other.log_sum_;
772 log_sum_squares_ += other.log_sum_squares_;
773 redundant_count_ += other.redundant_count_;
774 for (size_t index = 0; index < counts_.size(); ++index)
775 counts_[index] += other.counts_[index];
776 }
777
778 void Histogram::SampleSet::Subtract(const SampleSet& other) {
779 DCHECK_EQ(counts_.size(), other.counts_.size());
780 // Note: Race conditions in snapshotting a sum may lead to (temporary)
781 // negative values when snapshots are later combined (and deltas calculated).
782 // As a result, we don't currently CHCEK() for positive values.
783 sum_ -= other.sum_;
784 sum_squares_ -= other.sum_squares_;
785 log_sum_ -= other.log_sum_;
786 log_sum_squares_ -= other.log_sum_squares_;
787 redundant_count_ -= other.redundant_count_;
788 for (size_t index = 0; index < counts_.size(); ++index) {
789 counts_[index] -= other.counts_[index];
790 DCHECK_GE(counts_[index], 0);
791 }
792 }
793
794 bool Histogram::SampleSet::Serialize(Pickle* pickle) const {
795 pickle->WriteInt64(sum_);
796 pickle->WriteInt64(redundant_count_);
797 pickle->WriteSize(counts_.size());
798
799 for (size_t index = 0; index < counts_.size(); ++index) {
800 pickle->WriteInt(counts_[index]);
801 }
802
803 return true;
804 }
805
806 bool Histogram::SampleSet::Deserialize(void** iter, const Pickle& pickle) {
807 DCHECK_EQ(counts_.size(), 0u);
808 DCHECK_EQ(sum_, 0);
809 DCHECK_EQ(redundant_count_, 0);
810
811 size_t counts_size;
812
813 if (!pickle.ReadInt64(iter, &sum_) ||
814 !pickle.ReadInt64(iter, &redundant_count_) ||
815 !pickle.ReadSize(iter, &counts_size)) {
816 return false;
817 }
818
819 if (counts_size == 0)
820 return false;
821
822 int count = 0;
823 for (size_t index = 0; index < counts_size; ++index) {
824 int i;
825 if (!pickle.ReadInt(iter, &i))
826 return false;
827 counts_.push_back(i);
828 count += i;
829 }
830
831 return true;
832 }
833
834 //------------------------------------------------------------------------------
835 // LinearHistogram: This histogram uses a traditional set of evenly spaced
836 // buckets.
837 //------------------------------------------------------------------------------
838
839 LinearHistogram::~LinearHistogram() {
840 }
841
842 Histogram* LinearHistogram::FactoryGet(const std::string& name,
843 Sample minimum,
844 Sample maximum,
845 size_t bucket_count,
846 Flags flags) {
847 Histogram* histogram(NULL);
848
849 if (minimum < 1)
850 minimum = 1;
851 if (maximum > kSampleType_MAX - 1)
852 maximum = kSampleType_MAX - 1;
853
854 if (!StatisticsRecorder::FindHistogram(name, &histogram)) {
855 LinearHistogram* tentative_histogram =
856 new LinearHistogram(name, minimum, maximum, bucket_count);
857 tentative_histogram->InitializeBucketRange();
858 tentative_histogram->SetFlags(flags);
859 histogram =
860 StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
861 }
862
863 DCHECK_EQ(LINEAR_HISTOGRAM, histogram->histogram_type());
864 DCHECK(histogram->HasConstructorArguments(minimum, maximum, bucket_count));
865 return histogram;
866 }
867
868 Histogram* LinearHistogram::FactoryTimeGet(const std::string& name,
869 TimeDelta minimum,
870 TimeDelta maximum,
871 size_t bucket_count,
872 Flags flags) {
873 return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
874 bucket_count, flags);
875 }
876
877 Histogram::ClassType LinearHistogram::histogram_type() const {
878 return LINEAR_HISTOGRAM;
879 }
880
881 void LinearHistogram::Accumulate(Sample value, Count count, size_t index) {
882 sample_.AccumulateWithLinearStats(value, count, index);
883 }
884
885 void LinearHistogram::SetRangeDescriptions(
886 const DescriptionPair descriptions[]) {
887 for (int i =0; descriptions[i].description; ++i) {
888 bucket_description_[descriptions[i].sample] = descriptions[i].description;
889 }
890 }
891
892 LinearHistogram::LinearHistogram(const std::string& name,
893 Sample minimum,
894 Sample maximum,
895 size_t bucket_count)
896 : Histogram(name, minimum >= 1 ? minimum : 1, maximum, bucket_count) {
897 }
898
899 LinearHistogram::LinearHistogram(const std::string& name,
900 TimeDelta minimum,
901 TimeDelta maximum,
902 size_t bucket_count)
903 : Histogram(name, minimum >= TimeDelta::FromMilliseconds(1) ?
904 minimum : TimeDelta::FromMilliseconds(1),
905 maximum, bucket_count) {
906 }
907
908 void LinearHistogram::InitializeBucketRange() {
909 DCHECK_GT(declared_min(), 0); // 0 is the underflow bucket here.
910 double min = declared_min();
911 double max = declared_max();
912 size_t i;
913 for (i = 1; i < bucket_count(); ++i) {
914 double linear_range = (min * (bucket_count() -1 - i) + max * (i - 1)) /
915 (bucket_count() - 2);
916 SetBucketRange(i, static_cast<int> (linear_range + 0.5));
917 }
918 ResetRangeChecksum();
919 }
920
921 double LinearHistogram::GetBucketSize(Count current, size_t i) const {
922 DCHECK_GT(ranges(i + 1), ranges(i));
923 // Adjacent buckets with different widths would have "surprisingly" many (few)
924 // samples in a histogram if we didn't normalize this way.
925 double denominator = ranges(i + 1) - ranges(i);
926 return current/denominator;
927 }
928
929 const std::string LinearHistogram::GetAsciiBucketRange(size_t i) const {
930 int range = ranges(i);
931 BucketDescriptionMap::const_iterator it = bucket_description_.find(range);
932 if (it == bucket_description_.end())
933 return Histogram::GetAsciiBucketRange(i);
934 return it->second;
935 }
936
937 bool LinearHistogram::PrintEmptyBucket(size_t index) const {
938 return bucket_description_.find(ranges(index)) == bucket_description_.end();
939 }
940
941
942 //------------------------------------------------------------------------------
943 // This section provides implementation for BooleanHistogram.
944 //------------------------------------------------------------------------------
945
946 Histogram* BooleanHistogram::FactoryGet(const std::string& name, Flags flags) {
947 Histogram* histogram(NULL);
948
949 if (!StatisticsRecorder::FindHistogram(name, &histogram)) {
950 BooleanHistogram* tentative_histogram = new BooleanHistogram(name);
951 tentative_histogram->InitializeBucketRange();
952 tentative_histogram->SetFlags(flags);
953 histogram =
954 StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
955 }
956
957 DCHECK_EQ(BOOLEAN_HISTOGRAM, histogram->histogram_type());
958 return histogram;
959 }
960
961 Histogram::ClassType BooleanHistogram::histogram_type() const {
962 return BOOLEAN_HISTOGRAM;
963 }
964
965 void BooleanHistogram::AddBoolean(bool value) {
966 Add(value ? 1 : 0);
967 }
968
969 BooleanHistogram::BooleanHistogram(const std::string& name)
970 : LinearHistogram(name, 1, 2, 3) {
971 }
972
973 void
974 BooleanHistogram::Accumulate(Sample value, Count count, size_t index)
975 {
976 // Callers will have computed index based on the non-booleanified value.
977 // So we need to adjust the index manually.
978 LinearHistogram::Accumulate(!!value, count, value ? 1 : 0);
979 }
980
981 //------------------------------------------------------------------------------
982 // FlagHistogram:
983 //------------------------------------------------------------------------------
984
985 Histogram *
986 FlagHistogram::FactoryGet(const std::string &name, Flags flags)
987 {
988 Histogram *h(nullptr);
989
990 if (!StatisticsRecorder::FindHistogram(name, &h)) {
991 FlagHistogram *fh = new FlagHistogram(name);
992 fh->InitializeBucketRange();
993 fh->SetFlags(flags);
994 size_t zero_index = fh->BucketIndex(0);
995 fh->LinearHistogram::Accumulate(0, 1, zero_index);
996 h = StatisticsRecorder::RegisterOrDeleteDuplicate(fh);
997 }
998
999 return h;
1000 }
1001
1002 FlagHistogram::FlagHistogram(const std::string &name)
1003 : BooleanHistogram(name), mSwitched(false) {
1004 }
1005
1006 Histogram::ClassType
1007 FlagHistogram::histogram_type() const
1008 {
1009 return FLAG_HISTOGRAM;
1010 }
1011
1012 void
1013 FlagHistogram::Accumulate(Sample value, Count count, size_t index)
1014 {
1015 if (mSwitched) {
1016 return;
1017 }
1018
1019 mSwitched = true;
1020 DCHECK_EQ(value, 1);
1021 LinearHistogram::Accumulate(value, 1, index);
1022 size_t zero_index = BucketIndex(0);
1023 LinearHistogram::Accumulate(0, -1, zero_index);
1024 }
1025
1026 void
1027 FlagHistogram::AddSampleSet(const SampleSet& sample) {
1028 DCHECK_EQ(bucket_count(), sample.size());
1029 // We can't be sure the SampleSet provided came from another FlagHistogram,
1030 // so we take the following steps:
1031 // - If our flag has already been set do nothing.
1032 // - Set our flag if the following hold:
1033 // - The sum of the counts in the provided SampleSet is 1.
1034 // - The bucket index for that single value is the same as the index where we
1035 // would place our set flag.
1036 // - Otherwise, take no action.
1037
1038 if (mSwitched) {
1039 return;
1040 }
1041
1042 if (sample.sum() != 1) {
1043 return;
1044 }
1045
1046 size_t one_index = BucketIndex(1);
1047 if (sample.counts(one_index) == 1) {
1048 Accumulate(1, 1, one_index);
1049 }
1050 }
1051 //------------------------------------------------------------------------------
1052 // CustomHistogram:
1053 //------------------------------------------------------------------------------
1054
1055 Histogram* CustomHistogram::FactoryGet(const std::string& name,
1056 const std::vector<Sample>& custom_ranges,
1057 Flags flags) {
1058 Histogram* histogram(NULL);
1059
1060 // Remove the duplicates in the custom ranges array.
1061 std::vector<int> ranges = custom_ranges;
1062 ranges.push_back(0); // Ensure we have a zero value.
1063 std::sort(ranges.begin(), ranges.end());
1064 ranges.erase(std::unique(ranges.begin(), ranges.end()), ranges.end());
1065 if (ranges.size() <= 1) {
1066 DCHECK(false);
1067 // Note that we pushed a 0 in above, so for defensive code....
1068 ranges.push_back(1); // Put in some data so we can index to [1].
1069 }
1070
1071 DCHECK_LT(ranges.back(), kSampleType_MAX);
1072
1073 if (!StatisticsRecorder::FindHistogram(name, &histogram)) {
1074 CustomHistogram* tentative_histogram = new CustomHistogram(name, ranges);
1075 tentative_histogram->InitializedCustomBucketRange(ranges);
1076 tentative_histogram->SetFlags(flags);
1077 histogram =
1078 StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
1079 }
1080
1081 DCHECK_EQ(histogram->histogram_type(), CUSTOM_HISTOGRAM);
1082 DCHECK(histogram->HasConstructorArguments(ranges[1], ranges.back(),
1083 ranges.size()));
1084 return histogram;
1085 }
1086
1087 Histogram::ClassType CustomHistogram::histogram_type() const {
1088 return CUSTOM_HISTOGRAM;
1089 }
1090
1091 CustomHistogram::CustomHistogram(const std::string& name,
1092 const std::vector<Sample>& custom_ranges)
1093 : Histogram(name, custom_ranges[1], custom_ranges.back(),
1094 custom_ranges.size()) {
1095 DCHECK_GT(custom_ranges.size(), 1u);
1096 DCHECK_EQ(custom_ranges[0], 0);
1097 }
1098
1099 void CustomHistogram::InitializedCustomBucketRange(
1100 const std::vector<Sample>& custom_ranges) {
1101 DCHECK_GT(custom_ranges.size(), 1u);
1102 DCHECK_EQ(custom_ranges[0], 0);
1103 DCHECK_LE(custom_ranges.size(), bucket_count());
1104 for (size_t index = 0; index < custom_ranges.size(); ++index)
1105 SetBucketRange(index, custom_ranges[index]);
1106 ResetRangeChecksum();
1107 }
1108
1109 double CustomHistogram::GetBucketSize(Count current, size_t i) const {
1110 return 1;
1111 }
1112
1113 //------------------------------------------------------------------------------
1114 // The next section handles global (central) support for all histograms, as well
1115 // as startup/teardown of this service.
1116 //------------------------------------------------------------------------------
1117
1118 // This singleton instance should be started during the single threaded portion
1119 // of main(), and hence it is not thread safe. It initializes globals to
1120 // provide support for all future calls.
1121 StatisticsRecorder::StatisticsRecorder() {
1122 DCHECK(!histograms_);
1123 if (lock_ == NULL) {
1124 // This will leak on purpose. It's the only way to make sure we won't race
1125 // against the static uninitialization of the module while one of our
1126 // static methods relying on the lock get called at an inappropriate time
1127 // during the termination phase. Since it's a static data member, we will
1128 // leak one per process, which would be similar to the instance allocated
1129 // during static initialization and released only on process termination.
1130 lock_ = new base::Lock;
1131 }
1132 base::AutoLock auto_lock(*lock_);
1133 histograms_ = new HistogramMap;
1134 }
1135
1136 StatisticsRecorder::~StatisticsRecorder() {
1137 DCHECK(histograms_ && lock_);
1138
1139 if (dump_on_exit_) {
1140 std::string output;
1141 WriteGraph("", &output);
1142 CHROMIUM_LOG(INFO) << output;
1143 }
1144 // Clean up.
1145 HistogramMap* histograms = NULL;
1146 {
1147 base::AutoLock auto_lock(*lock_);
1148 histograms = histograms_;
1149 histograms_ = NULL;
1150 for (HistogramMap::iterator it = histograms->begin();
1151 histograms->end() != it;
1152 ++it) {
1153 // No other clients permanently hold Histogram references, so we
1154 // have the only one and it is safe to delete it.
1155 delete it->second;
1156 }
1157 }
1158 delete histograms;
1159 // We don't delete lock_ on purpose to avoid having to properly protect
1160 // against it going away after we checked for NULL in the static methods.
1161 }
1162
1163 // static
1164 bool StatisticsRecorder::IsActive() {
1165 if (lock_ == NULL)
1166 return false;
1167 base::AutoLock auto_lock(*lock_);
1168 return NULL != histograms_;
1169 }
1170
1171 Histogram* StatisticsRecorder::RegisterOrDeleteDuplicate(Histogram* histogram) {
1172 DCHECK(histogram->HasValidRangeChecksum());
1173 if (lock_ == NULL)
1174 return histogram;
1175 base::AutoLock auto_lock(*lock_);
1176 if (!histograms_)
1177 return histogram;
1178 const std::string name = histogram->histogram_name();
1179 HistogramMap::iterator it = histograms_->find(name);
1180 // Avoid overwriting a previous registration.
1181 if (histograms_->end() == it) {
1182 (*histograms_)[name] = histogram;
1183 } else {
1184 delete histogram; // We already have one by this name.
1185 histogram = it->second;
1186 }
1187 return histogram;
1188 }
1189
1190 // static
1191 void StatisticsRecorder::WriteHTMLGraph(const std::string& query,
1192 std::string* output) {
1193 if (!IsActive())
1194 return;
1195 output->append("<html><head><title>About Histograms");
1196 if (!query.empty())
1197 output->append(" - " + query);
1198 output->append("</title>"
1199 // We'd like the following no-cache... but it doesn't work.
1200 // "<META HTTP-EQUIV=\"Pragma\" CONTENT=\"no-cache\">"
1201 "</head><body>");
1202
1203 Histograms snapshot;
1204 GetSnapshot(query, &snapshot);
1205 for (Histograms::iterator it = snapshot.begin();
1206 it != snapshot.end();
1207 ++it) {
1208 (*it)->WriteHTMLGraph(output);
1209 output->append("<br><hr><br>");
1210 }
1211 output->append("</body></html>");
1212 }
1213
1214 // static
1215 void StatisticsRecorder::WriteGraph(const std::string& query,
1216 std::string* output) {
1217 if (!IsActive())
1218 return;
1219 if (query.length())
1220 StringAppendF(output, "Collections of histograms for %s\n", query.c_str());
1221 else
1222 output->append("Collections of all histograms\n");
1223
1224 Histograms snapshot;
1225 GetSnapshot(query, &snapshot);
1226 for (Histograms::iterator it = snapshot.begin();
1227 it != snapshot.end();
1228 ++it) {
1229 (*it)->WriteAscii(true, "\n", output);
1230 output->append("\n");
1231 }
1232 }
1233
1234 // static
1235 void StatisticsRecorder::GetHistograms(Histograms* output) {
1236 if (lock_ == NULL)
1237 return;
1238 base::AutoLock auto_lock(*lock_);
1239 if (!histograms_)
1240 return;
1241 for (HistogramMap::iterator it = histograms_->begin();
1242 histograms_->end() != it;
1243 ++it) {
1244 DCHECK_EQ(it->first, it->second->histogram_name());
1245 output->push_back(it->second);
1246 }
1247 }
1248
1249 bool StatisticsRecorder::FindHistogram(const std::string& name,
1250 Histogram** histogram) {
1251 if (lock_ == NULL)
1252 return false;
1253 base::AutoLock auto_lock(*lock_);
1254 if (!histograms_)
1255 return false;
1256 HistogramMap::iterator it = histograms_->find(name);
1257 if (histograms_->end() == it)
1258 return false;
1259 *histogram = it->second;
1260 return true;
1261 }
1262
1263 // private static
1264 void StatisticsRecorder::GetSnapshot(const std::string& query,
1265 Histograms* snapshot) {
1266 if (lock_ == NULL)
1267 return;
1268 base::AutoLock auto_lock(*lock_);
1269 if (!histograms_)
1270 return;
1271 for (HistogramMap::iterator it = histograms_->begin();
1272 histograms_->end() != it;
1273 ++it) {
1274 if (it->first.find(query) != std::string::npos)
1275 snapshot->push_back(it->second);
1276 }
1277 }
1278
1279 // static
1280 StatisticsRecorder::HistogramMap* StatisticsRecorder::histograms_ = NULL;
1281 // static
1282 base::Lock* StatisticsRecorder::lock_ = NULL;
1283 // static
1284 bool StatisticsRecorder::dump_on_exit_ = false;
1285
1286 } // namespace base

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