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| 1 // Copyright (c) 2015 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 #include "base/metrics/histogram_persistence.h" | |
| 6 | |
| 7 #include "base/lazy_instance.h" | |
| 8 #include "base/logging.h" | |
| 9 #include "base/memory/scoped_ptr.h" | |
| 10 #include "base/metrics/histogram.h" | |
| 11 #include "base/metrics/histogram_base.h" | |
| 12 #include "base/metrics/histogram_samples.h" | |
| 13 #include "base/metrics/statistics_recorder.h" | |
| 14 #include "base/synchronization/lock.h" | |
| 15 | |
| 16 namespace base { | |
| 17 | |
| 18 namespace { | |
| 19 | |
| 20 // Enumerate possible creation results for reporting. | |
| 21 enum CreateHistogramResultType { | |
| 22 // Everything was fine. | |
| 23 CREATE_HISTOGRAM_SUCCESS = 0, | |
| 24 | |
| 25 // Pointer to metadata was not valid. | |
| 26 CREATE_HISTOGRAM_INVALID_METADATA_POINTER, | |
| 27 | |
| 28 // Histogram metadata was not valid. | |
| 29 CREATE_HISTOGRAM_INVALID_METADATA, | |
| 30 | |
| 31 // Ranges information was not valid. | |
| 32 CREATE_HISTOGRAM_INVALID_RANGES_ARRAY, | |
| 33 | |
| 34 // Counts information was not valid. | |
| 35 CREATE_HISTOGRAM_INVALID_COUNTS_ARRAY, | |
| 36 | |
| 37 // Could not allocate histogram memory due to corruption. | |
| 38 CREATE_HISTOGRAM_ALLOCATOR_CORRUPT, | |
| 39 | |
| 40 // Could not allocate histogram memory due to lack of space. | |
| 41 CREATE_HISTOGRAM_ALLOCATOR_FULL, | |
| 42 | |
| 43 // Could not allocate histogram memory due to unknown error. | |
| 44 CREATE_HISTOGRAM_ALLOCATOR_ERROR, | |
| 45 | |
| 46 // Histogram was of unknown type. | |
| 47 CREATE_HISTOGRAM_UNKNOWN_TYPE, | |
| 48 | |
| 49 // Instance has detected a corrupt allocator (recorded only once). | |
| 50 CREATE_HISTOGRAM_ALLOCATOR_NEWLY_CORRUPT, | |
| 51 | |
| 52 // Always keep this at the end. | |
| 53 CREATE_HISTOGRAM_MAX | |
| 54 }; | |
| 55 | |
| 56 // Name of histogram for storing results of local operations. | |
| 57 const char kResultHistogram[] = "UMA.CreatePersistentHistogram.Result"; | |
| 58 | |
| 59 // Type identifiers used when storing in persistent memory so they can be | |
| 60 // identified during extraction; the first 4 bytes of the SHA1 of the name | |
| 61 // is used as a unique integer. A "version number" is added to the base | |
| 62 // so that, if the structure of that object changes, stored older versions | |
| 63 // will be safely ignored. | |
| 64 enum : uint32_t { | |
| 65 kTypeIdHistogram = 0xF1645910 + 2, // SHA1(Histogram) v2 | |
| 66 kTypeIdRangesArray = 0xBCEA225A + 1, // SHA1(RangesArray) v1 | |
| 67 kTypeIdCountsArray = 0x53215530 + 1, // SHA1(CountsArray) v1 | |
| 68 }; | |
| 69 | |
| 70 // This data must be held in persistent memory in order for processes to | |
| 71 // locate and use histograms created elsewhere. All elements must be of a | |
| 72 // fixed width to ensure 32/64-bit interoperability. | |
| 73 struct PersistentHistogramData { | |
| 74 int32_t histogram_type; | |
| 75 int32_t flags; | |
| 76 int32_t minimum; | |
| 77 int32_t maximum; | |
| 78 uint32_t bucket_count; | |
| 79 PersistentMemoryAllocator::Reference ranges_ref; | |
| 80 uint32_t ranges_checksum; | |
| 81 PersistentMemoryAllocator::Reference counts_ref; | |
| 82 HistogramSamples::Metadata samples_metadata; | |
| 83 HistogramSamples::Metadata logged_metadata; | |
| 84 | |
| 85 // Space for the histogram name will be added during the actual allocation | |
| 86 // request. This must be the last field of the structure. A zero-size array | |
| 87 // or a "flexible" array would be preferred but is not (yet) valid C++. | |
| 88 char name[1]; | |
| 89 }; | |
| 90 | |
| 91 // The object held here will obviously not be destructed at process exit | |
| 92 // but that's okay since PersistentMemoryAllocator objects are explicitly | |
| 93 // forbidden from doing anything essential at exit anyway due to the fact | |
| 94 // that they depend on data managed elsewhere and which could be destructed | |
| 95 // first. | |
| 96 PersistentMemoryAllocator* g_allocator = nullptr; | |
| 97 | |
| 98 // Take an array of range boundaries and create a proper BucketRanges object | |
| 99 // which is returned to the caller. A return of nullptr indicates that the | |
| 100 // passed boundaries are invalid. | |
| 101 BucketRanges* CreateRangesFromData(HistogramBase::Sample* ranges_data, | |
| 102 uint32_t ranges_checksum, | |
| 103 size_t count) { | |
| 104 scoped_ptr<BucketRanges> ranges(new BucketRanges(count)); | |
| 105 DCHECK_EQ(count, ranges->size()); | |
| 106 for (size_t i = 0; i < count; ++i) { | |
| 107 if (i > 0 && ranges_data[i] <= ranges_data[i - 1]) | |
| 108 return nullptr; | |
| 109 ranges->set_range(i, ranges_data[i]); | |
| 110 } | |
| 111 | |
| 112 ranges->ResetChecksum(); | |
| 113 if (ranges->checksum() != ranges_checksum) | |
| 114 return nullptr; | |
| 115 | |
| 116 return ranges.release(); | |
| 117 } | |
| 118 | |
| 119 // Calculate the number of bytes required to store all of a histogram's | |
| 120 // "counts". This will return zero (0) if |bucket_count| is not valid. | |
| 121 size_t CalculateRequiredCountsBytes(size_t bucket_count) { | |
| 122 // 2 because each "sample count" also requires a backup "logged count" | |
| 123 // used for calculating the delta during snapshot operations. | |
| 124 const unsigned kBytesPerBucket = 2 * sizeof(HistogramBase::AtomicCount); | |
| 125 | |
| 126 // If the |bucket_count| is such that it would overflow the return type, | |
| 127 // perhaps as the result of a malicious actor, then return zero to | |
| 128 // indicate the problem to the caller. | |
| 129 if (bucket_count > std::numeric_limits<uint32_t>::max() / kBytesPerBucket) | |
| 130 return 0; | |
| 131 | |
| 132 return bucket_count * kBytesPerBucket; | |
| 133 } | |
| 134 | |
| 135 } // namespace | |
| 136 | |
| 137 const Feature kPersistentHistogramsFeature{ | |
| 138 "PersistentHistograms", FEATURE_DISABLED_BY_DEFAULT | |
| 139 }; | |
| 140 | |
| 141 // Get the histogram in which create results are stored. This is copied almost | |
| 142 // exactly from the STATIC_HISTOGRAM_POINTER_BLOCK macro but with added code | |
| 143 // to prevent recursion (a likely occurance because the creation of a new | |
| 144 // histogram can end up calling this.) | |
| 145 HistogramBase* GetCreateHistogramResultHistogram() { | |
| 146 static base::subtle::AtomicWord atomic_histogram_pointer = 0; | |
| 147 HistogramBase* histogram_pointer( | |
| 148 reinterpret_cast<HistogramBase*>( | |
| 149 base::subtle::Acquire_Load(&atomic_histogram_pointer))); | |
| 150 if (!histogram_pointer) { | |
| 151 // It's possible for multiple threads to make it here in parallel but | |
| 152 // they'll always return the same result as there is a mutex in the Get. | |
| 153 // The purpose of the "initialized" variable is just to ensure that | |
| 154 // the same thread doesn't recurse which is also why it doesn't have | |
| 155 // to be atomic. | |
| 156 static bool initialized = false; | |
| 157 if (!initialized) { | |
| 158 initialized = true; | |
| 159 if (g_allocator) { | |
| 160 DLOG(WARNING) << "Creating the results-histogram inside persistent" | |
| 161 << " memory can cause future allocations to crash if" | |
| 162 << " that memory is ever released (for testing)."; | |
| 163 } | |
| 164 | |
| 165 histogram_pointer = LinearHistogram::FactoryGet( | |
| 166 kResultHistogram, 1, CREATE_HISTOGRAM_MAX, CREATE_HISTOGRAM_MAX + 1, | |
| 167 HistogramBase::kUmaTargetedHistogramFlag); | |
| 168 base::subtle::Release_Store( | |
| 169 &atomic_histogram_pointer, | |
| 170 reinterpret_cast<base::subtle::AtomicWord>(histogram_pointer)); | |
| 171 } | |
| 172 } | |
| 173 return histogram_pointer; | |
| 174 } | |
| 175 | |
| 176 // Record the result of a histogram creation. | |
| 177 void RecordCreateHistogramResult(CreateHistogramResultType result) { | |
| 178 HistogramBase* result_histogram = GetCreateHistogramResultHistogram(); | |
| 179 if (result_histogram) | |
| 180 result_histogram->Add(result); | |
| 181 } | |
| 182 | |
| 183 void SetPersistentHistogramMemoryAllocator( | |
| 184 PersistentMemoryAllocator* allocator) { | |
| 185 // Releasing or changing an allocator is extremely dangerous because it | |
| 186 // likely has histograms stored within it. If the backing memory is also | |
| 187 // also released, future accesses to those histograms will seg-fault. | |
| 188 CHECK(!g_allocator); | |
| 189 g_allocator = allocator; | |
| 190 } | |
| 191 | |
| 192 PersistentMemoryAllocator* GetPersistentHistogramMemoryAllocator() { | |
| 193 return g_allocator; | |
| 194 } | |
| 195 | |
| 196 PersistentMemoryAllocator* | |
| 197 ReleasePersistentHistogramMemoryAllocatorForTesting() { | |
| 198 PersistentMemoryAllocator* allocator = g_allocator; | |
| 199 if (!allocator) | |
| 200 return nullptr; | |
| 201 | |
| 202 // Before releasing the memory, it's necessary to have the Statistics- | |
| 203 // Recorder forget about the histograms contained therein; otherwise, | |
| 204 // some operations will try to access them and the released memory. | |
| 205 PersistentMemoryAllocator::Iterator iter; | |
| 206 PersistentMemoryAllocator::Reference ref; | |
| 207 uint32_t type_id; | |
| 208 allocator->CreateIterator(&iter); | |
| 209 while ((ref = allocator->GetNextIterable(&iter, &type_id)) != 0) { | |
| 210 if (type_id == kTypeIdHistogram) { | |
| 211 PersistentHistogramData* histogram_data = | |
| 212 allocator->GetAsObject<PersistentHistogramData>( | |
| 213 ref, kTypeIdHistogram); | |
| 214 DCHECK(histogram_data); | |
| 215 StatisticsRecorder::ForgetHistogramForTesting(histogram_data->name); | |
| 216 | |
| 217 // If a test breaks here then a memory region containing a histogram | |
| 218 // actively used by this code is being released back to the test. | |
| 219 // If that memory segment were to be deleted, future calls to create | |
| 220 // persistent histograms would crash. To avoid this, have the test call | |
| 221 // the method GetCreateHistogramResultHistogram() *before* setting the | |
| 222 // (temporary) memory allocator via SetPersistentMemoryAllocator() so | |
| 223 // that the histogram is instead allocated from the process heap. | |
| 224 DCHECK_NE(kResultHistogram, histogram_data->name); | |
| 225 } | |
| 226 } | |
| 227 | |
| 228 g_allocator = nullptr; | |
| 229 return allocator; | |
| 230 }; | |
| 231 | |
| 232 HistogramBase* CreatePersistentHistogram( | |
| 233 PersistentMemoryAllocator* allocator, | |
| 234 PersistentHistogramData* histogram_data_ptr) { | |
| 235 if (!histogram_data_ptr) { | |
| 236 RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_METADATA_POINTER); | |
| 237 NOTREACHED(); | |
| 238 return nullptr; | |
| 239 } | |
| 240 | |
| 241 // Copy the histogram_data to local storage because anything in persistent | |
| 242 // memory cannot be trusted as it could be changed at any moment by a | |
| 243 // malicious actor that shares access. The contents of histogram_data are | |
| 244 // validated below; the local copy is to ensure that the contents cannot | |
| 245 // be externally changed between validation and use. | |
| 246 PersistentHistogramData histogram_data = *histogram_data_ptr; | |
| 247 | |
| 248 HistogramBase::Sample* ranges_data = | |
| 249 allocator->GetAsObject<HistogramBase::Sample>(histogram_data.ranges_ref, | |
| 250 kTypeIdRangesArray); | |
| 251 if (!ranges_data || histogram_data.bucket_count < 2 || | |
| 252 histogram_data.bucket_count + 1 > | |
| 253 std::numeric_limits<uint32_t>::max() / | |
| 254 sizeof(HistogramBase::Sample) || | |
| 255 allocator->GetAllocSize(histogram_data.ranges_ref) < | |
| 256 (histogram_data.bucket_count + 1) * sizeof(HistogramBase::Sample)) { | |
| 257 RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_RANGES_ARRAY); | |
| 258 NOTREACHED(); | |
| 259 return nullptr; | |
| 260 } | |
| 261 // To avoid racy destruction at shutdown, the following will be leaked. | |
| 262 const BucketRanges* ranges = CreateRangesFromData( | |
| 263 ranges_data, | |
| 264 histogram_data.ranges_checksum, | |
| 265 histogram_data.bucket_count + 1); | |
| 266 if (!ranges) { | |
| 267 RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_RANGES_ARRAY); | |
| 268 NOTREACHED(); | |
| 269 return nullptr; | |
| 270 } | |
| 271 ranges = StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges); | |
| 272 | |
| 273 HistogramBase::AtomicCount* counts_data = | |
| 274 allocator->GetAsObject<HistogramBase::AtomicCount>( | |
| 275 histogram_data.counts_ref, kTypeIdCountsArray); | |
| 276 size_t counts_bytes = | |
| 277 CalculateRequiredCountsBytes(histogram_data.bucket_count); | |
| 278 if (!counts_data || !counts_bytes || | |
| 279 allocator->GetAllocSize(histogram_data.counts_ref) < counts_bytes) { | |
| 280 RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_COUNTS_ARRAY); | |
| 281 NOTREACHED(); | |
| 282 return nullptr; | |
| 283 } | |
| 284 | |
| 285 // After the main "counts" array is a second array using for storing what | |
| 286 // was previously logged. This is used to calculate the "delta" during | |
| 287 // snapshot operations. | |
| 288 HistogramBase::AtomicCount* logged_data = | |
| 289 counts_data + histogram_data.bucket_count; | |
| 290 | |
| 291 std::string name(histogram_data_ptr->name); | |
| 292 HistogramBase* histogram = nullptr; | |
| 293 switch (histogram_data.histogram_type) { | |
| 294 case HISTOGRAM: | |
| 295 histogram = Histogram::PersistentGet( | |
| 296 name, | |
| 297 histogram_data.minimum, | |
| 298 histogram_data.maximum, | |
| 299 ranges, | |
| 300 counts_data, | |
| 301 logged_data, | |
| 302 histogram_data.bucket_count, | |
| 303 &histogram_data_ptr->samples_metadata, | |
| 304 &histogram_data_ptr->logged_metadata); | |
| 305 DCHECK(histogram); | |
| 306 break; | |
| 307 case LINEAR_HISTOGRAM: | |
| 308 histogram = LinearHistogram::PersistentGet( | |
| 309 name, | |
| 310 histogram_data.minimum, | |
| 311 histogram_data.maximum, | |
| 312 ranges, | |
| 313 counts_data, | |
| 314 logged_data, | |
| 315 histogram_data.bucket_count, | |
| 316 &histogram_data_ptr->samples_metadata, | |
| 317 &histogram_data_ptr->logged_metadata); | |
| 318 DCHECK(histogram); | |
| 319 break; | |
| 320 case BOOLEAN_HISTOGRAM: | |
| 321 histogram = BooleanHistogram::PersistentGet( | |
| 322 name, | |
| 323 ranges, | |
| 324 counts_data, | |
| 325 logged_data, | |
| 326 &histogram_data_ptr->samples_metadata, | |
| 327 &histogram_data_ptr->logged_metadata); | |
| 328 DCHECK(histogram); | |
| 329 break; | |
| 330 case CUSTOM_HISTOGRAM: | |
| 331 histogram = CustomHistogram::PersistentGet( | |
| 332 name, | |
| 333 ranges, | |
| 334 counts_data, | |
| 335 logged_data, | |
| 336 histogram_data.bucket_count, | |
| 337 &histogram_data_ptr->samples_metadata, | |
| 338 &histogram_data_ptr->logged_metadata); | |
| 339 DCHECK(histogram); | |
| 340 break; | |
| 341 default: | |
| 342 NOTREACHED(); | |
| 343 } | |
| 344 | |
| 345 if (histogram) { | |
| 346 DCHECK_EQ(histogram_data.histogram_type, histogram->GetHistogramType()); | |
| 347 histogram->SetFlags(histogram_data.flags); | |
| 348 RecordCreateHistogramResult(CREATE_HISTOGRAM_SUCCESS); | |
| 349 } else { | |
| 350 RecordCreateHistogramResult(CREATE_HISTOGRAM_UNKNOWN_TYPE); | |
| 351 } | |
| 352 | |
| 353 return histogram; | |
| 354 } | |
| 355 | |
| 356 HistogramBase* GetPersistentHistogram( | |
| 357 PersistentMemoryAllocator* allocator, | |
| 358 int32_t ref) { | |
| 359 // Unfortunately, the above "pickle" methods cannot be used as part of the | |
| 360 // persistance because the deserialization methods always create local | |
| 361 // count data (these must referenced the persistent counts) and always add | |
| 362 // it to the local list of known histograms (these may be simple references | |
| 363 // to histograms in other processes). | |
| 364 PersistentHistogramData* histogram_data = | |
| 365 allocator->GetAsObject<PersistentHistogramData>(ref, kTypeIdHistogram); | |
| 366 size_t length = allocator->GetAllocSize(ref); | |
| 367 if (!histogram_data || | |
| 368 reinterpret_cast<char*>(histogram_data)[length - 1] != '\0') { | |
| 369 RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_METADATA); | |
| 370 NOTREACHED(); | |
| 371 return nullptr; | |
| 372 } | |
| 373 return CreatePersistentHistogram(allocator, histogram_data); | |
| 374 } | |
| 375 | |
| 376 HistogramBase* GetNextPersistentHistogram( | |
| 377 PersistentMemoryAllocator* allocator, | |
| 378 PersistentMemoryAllocator::Iterator* iter) { | |
| 379 PersistentMemoryAllocator::Reference ref; | |
| 380 uint32_t type_id; | |
| 381 while ((ref = allocator->GetNextIterable(iter, &type_id)) != 0) { | |
| 382 if (type_id == kTypeIdHistogram) | |
| 383 return GetPersistentHistogram(allocator, ref); | |
| 384 } | |
| 385 return nullptr; | |
| 386 } | |
| 387 | |
| 388 void FinalizePersistentHistogram(PersistentMemoryAllocator::Reference ref, | |
| 389 bool registered) { | |
| 390 // If the created persistent histogram was registered then it needs to | |
| 391 // be marked as "iterable" in order to be found by other processes. | |
| 392 if (registered) | |
| 393 GetPersistentHistogramMemoryAllocator()->MakeIterable(ref); | |
| 394 // If it wasn't registered then a race condition must have caused | |
| 395 // two to be created. The allocator does not support releasing the | |
| 396 // acquired memory so just change the type to be empty. | |
| 397 else | |
| 398 GetPersistentHistogramMemoryAllocator()->SetType(ref, 0); | |
| 399 } | |
| 400 | |
| 401 HistogramBase* AllocatePersistentHistogram( | |
| 402 PersistentMemoryAllocator* allocator, | |
| 403 HistogramType histogram_type, | |
| 404 const std::string& name, | |
| 405 int minimum, | |
| 406 int maximum, | |
| 407 const BucketRanges* bucket_ranges, | |
| 408 int32_t flags, | |
| 409 PersistentMemoryAllocator::Reference* ref_ptr) { | |
| 410 if (!allocator) | |
| 411 return nullptr; | |
| 412 | |
| 413 // If the allocator is corrupt, don't waste time trying anything else. | |
| 414 // This also allows differentiating on the dashboard between allocations | |
| 415 // failed due to a corrupt allocator and the number of process instances | |
| 416 // with one, the latter being idicated by "newly corrupt", below. | |
| 417 if (allocator->IsCorrupt()) { | |
| 418 RecordCreateHistogramResult(CREATE_HISTOGRAM_ALLOCATOR_CORRUPT); | |
| 419 return nullptr; | |
| 420 } | |
| 421 | |
| 422 // If CalculateRequiredCountsBytes() returns zero then the bucket_count | |
| 423 // was not valid. | |
| 424 size_t bucket_count = bucket_ranges->bucket_count(); | |
| 425 size_t counts_bytes = CalculateRequiredCountsBytes(bucket_count); | |
| 426 if (!counts_bytes) { | |
| 427 NOTREACHED(); | |
| 428 return nullptr; | |
| 429 } | |
| 430 | |
| 431 size_t ranges_bytes = (bucket_count + 1) * sizeof(HistogramBase::Sample); | |
| 432 PersistentMemoryAllocator::Reference ranges_ref = | |
| 433 allocator->Allocate(ranges_bytes, kTypeIdRangesArray); | |
| 434 PersistentMemoryAllocator::Reference counts_ref = | |
| 435 allocator->Allocate(counts_bytes, kTypeIdCountsArray); | |
| 436 PersistentMemoryAllocator::Reference histogram_ref = | |
| 437 allocator->Allocate(offsetof(PersistentHistogramData, name) + | |
| 438 name.length() + 1, kTypeIdHistogram); | |
| 439 HistogramBase::Sample* ranges_data = | |
| 440 allocator->GetAsObject<HistogramBase::Sample>(ranges_ref, | |
| 441 kTypeIdRangesArray); | |
| 442 PersistentHistogramData* histogram_data = | |
| 443 allocator->GetAsObject<PersistentHistogramData>(histogram_ref, | |
| 444 kTypeIdHistogram); | |
| 445 | |
| 446 // Only continue here if all allocations were successful. If they weren't | |
| 447 // there is no way to free the space but that's not really a problem since | |
| 448 // the allocations only fail because the space is full and so any future | |
| 449 // attempts will also fail. | |
| 450 if (counts_ref && ranges_data && histogram_data) { | |
| 451 strcpy(histogram_data->name, name.c_str()); | |
| 452 for (size_t i = 0; i < bucket_ranges->size(); ++i) | |
| 453 ranges_data[i] = bucket_ranges->range(i); | |
| 454 | |
| 455 histogram_data->histogram_type = histogram_type; | |
| 456 histogram_data->flags = flags; | |
| 457 histogram_data->minimum = minimum; | |
| 458 histogram_data->maximum = maximum; | |
| 459 histogram_data->bucket_count = static_cast<uint32_t>(bucket_count); | |
| 460 histogram_data->ranges_ref = ranges_ref; | |
| 461 histogram_data->ranges_checksum = bucket_ranges->checksum(); | |
| 462 histogram_data->counts_ref = counts_ref; | |
| 463 | |
| 464 // Create the histogram using resources in persistent memory. This ends up | |
| 465 // resolving the "ref" values stored in histogram_data instad of just | |
| 466 // using what is already known above but avoids duplicating the switch | |
| 467 // statement here and serves as a double-check that everything is | |
| 468 // correct before commiting the new histogram to persistent space. | |
| 469 HistogramBase* histogram = | |
| 470 CreatePersistentHistogram(allocator, histogram_data); | |
| 471 DCHECK(histogram); | |
| 472 if (ref_ptr != nullptr) | |
| 473 *ref_ptr = histogram_ref; | |
| 474 return histogram; | |
| 475 } | |
| 476 | |
| 477 CreateHistogramResultType result; | |
| 478 if (allocator->IsCorrupt()) { | |
| 479 RecordCreateHistogramResult(CREATE_HISTOGRAM_ALLOCATOR_NEWLY_CORRUPT); | |
| 480 result = CREATE_HISTOGRAM_ALLOCATOR_CORRUPT; | |
| 481 } else if (allocator->IsFull()) { | |
| 482 result = CREATE_HISTOGRAM_ALLOCATOR_FULL; | |
| 483 } else { | |
| 484 result = CREATE_HISTOGRAM_ALLOCATOR_ERROR; | |
| 485 } | |
| 486 RecordCreateHistogramResult(result); | |
| 487 NOTREACHED() << "error=" << result; | |
| 488 | |
| 489 return nullptr; | |
| 490 } | |
| 491 | |
| 492 void ImportPersistentHistograms() { | |
| 493 // The lock protects against concurrent access to the iterator and is created | |
| 494 // in a thread-safe manner when needed. | |
| 495 static base::LazyInstance<base::Lock>::Leaky lock = LAZY_INSTANCE_INITIALIZER; | |
| 496 | |
| 497 if (g_allocator) { | |
| 498 base::AutoLock auto_lock(lock.Get()); | |
| 499 | |
| 500 // Each call resumes from where it last left off so need persistant | |
| 501 // iterator. This class has a constructor so even the definition has | |
| 502 // to be protected by the lock in order to be thread-safe. | |
| 503 static PersistentMemoryAllocator::Iterator iter; | |
| 504 if (iter.is_clear()) | |
| 505 g_allocator->CreateIterator(&iter); | |
| 506 | |
| 507 while (true) { | |
| 508 HistogramBase* histogram = GetNextPersistentHistogram(g_allocator, &iter); | |
| 509 if (!histogram) | |
| 510 break; | |
| 511 StatisticsRecorder::RegisterOrDeleteDuplicate(histogram); | |
| 512 } | |
| 513 } | |
| 514 } | |
| 515 | |
| 516 } // namespace base | |
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Chromium Code Reviews
Issue 1738063002:
Refactor histogram_persistence to be a class. (Closed)
Base URL: https://chromium.googlesource.com/chromium/src.git@master