Index: base/metrics/histogram_persistence.cc |
diff --git a/base/metrics/histogram_persistence.cc b/base/metrics/histogram_persistence.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..6b4cad472bb5793a97b91866095a1a21c192b494 |
--- /dev/null |
+++ b/base/metrics/histogram_persistence.cc |
@@ -0,0 +1,422 @@ |
+// Copyright (c) 2015 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#include "base/metrics/histogram_persistence.h" |
+ |
+#include "base/logging.h" |
+#include "base/memory/scoped_ptr.h" |
+#include "base/metrics/histogram.h" |
+#include "base/metrics/histogram_base.h" |
+#include "base/metrics/histogram_samples.h" |
+#include "base/metrics/statistics_recorder.h" |
+#include "base/synchronization/lock.h" |
+ |
+namespace base { |
+ |
+namespace { |
+ |
+// Enumerate possible creation results for reporting. |
+enum CreateHistogramResultType { |
+ // Everything was fine. |
+ CREATE_HISTOGRAM_SUCCESS = 0, |
+ |
+ // Pointer to metadata was not valid. |
+ CREATE_HISTOGRAM_INVALID_METADATA_POINTER, |
+ |
+ // Histogram metadata was not valid. |
+ CREATE_HISTOGRAM_INVALID_METADATA, |
+ |
+ // Ranges information was not valid. |
+ CREATE_HISTOGRAM_INVALID_RANGES_ARRAY, |
+ |
+ // Counts information was not valid. |
+ CREATE_HISTOGRAM_INVALID_COUNTS_ARRAY, |
+ |
+ // Could not allocate histogram memory due to corruption. |
+ CREATE_HISTOGRAM_ALLOCATOR_CORRUPT, |
+ |
+ // Could not allocate histogram memory due to lack of space. |
+ CREATE_HISTOGRAM_ALLOCATOR_FULL, |
+ |
+ // Could not allocate histogram memory due to unknown error. |
+ CREATE_HISTOGRAM_ALLOCATOR_ERROR, |
+ |
+ // Always keep this at the end. |
+ CREATE_HISTOGRAM_MAX |
+}; |
+ |
+// Type identifiers used when storing in persistent memory so they can be |
+// identified during extraction; the first 4 bytes of the SHA1 of the name |
+// is used as a unique integer. A "version number" is added to the base |
+// so that, if the structure of that object changes, stored older versions |
+// will be safely ignored. |
+enum : uint32_t { |
+ kTypeIdHistogram = 0xF1645910 + 1, // SHA1(Histogram) v1 |
+ kTypeIdRangesArray = 0xBCEA225A + 1, // SHA1(RangesArray) v1 |
+ kTypeIdCountsArray = 0x53215530 + 1, // SHA1(CountsArray) v1 |
+}; |
+ |
+// This data must be held in persistent memory in order for processes to |
+// locate and use histograms created elsewhere. |
+struct PersistentHistogramData { |
+ int histogram_type; |
+ int flags; |
+ int minimum; |
+ int maximum; |
+ size_t bucket_count; |
+ PersistentMemoryAllocator::Reference ranges_ref; |
+ uint32_t ranges_checksum; |
+ PersistentMemoryAllocator::Reference counts_ref; |
+ HistogramSamples::Metadata samples_metadata; |
+ |
+ // Space for the histogram name will be added during the actual allocation |
+ // request. This must be the last field of the structure. A zero-size array |
+ // or a "flexible" array would be preferred but is not (yet) valid C++. |
+ char name[1]; |
+}; |
+ |
+// The object held here will obviously not be destructed at process exit |
+// but that's okay since PersistentMemoryAllocator objects are explicitly |
+// forbidden from doing anything essential at exit anyway due to the fact |
+// that they depend on data managed elsewhere and which could be destructed |
+// first. |
+PersistentMemoryAllocator* g_allocator = nullptr; |
+ |
+// Take an array of range boundaries and create a proper BucketRanges object |
+// which is returned to the caller. A return of nullptr indicates that the |
+// passed boundaries are invalid. |
+BucketRanges* CreateRangesFromData(HistogramBase::Sample* ranges_data, |
+ uint32_t ranges_checksum, |
+ size_t count) { |
+ scoped_ptr<BucketRanges> ranges(new BucketRanges(count)); |
+ DCHECK_EQ(count, ranges->size()); |
+ for (size_t i = 0; i < count; ++i) { |
+ if (i > 0 && ranges_data[i] <= ranges_data[i - 1]) |
+ return nullptr; |
+ ranges->set_range(i, ranges_data[i]); |
+ } |
+ |
+ ranges->ResetChecksum(); |
+ if (ranges->checksum() != ranges_checksum) |
+ return nullptr; |
+ |
+ return ranges.release(); |
+} |
+ |
+} // namespace |
+ |
+const Feature kPersistentHistogramsFeature{ |
+ "PersistentHistograms", FEATURE_DISABLED_BY_DEFAULT |
+}; |
+ |
+// Get the histogram in which create results are stored. This is copied almost |
+// exactly from the STATIC_HISTOGRAM_POINTER_BLOCK macro but with added code |
+// to prevent recursion (a likely occurance because the creation of a new |
+// histogram can end up calling this.) |
+HistogramBase* GetCreateHistogramResultHistogram() { |
+ static base::subtle::AtomicWord atomic_histogram_pointer = 0; |
+ HistogramBase* histogram_pointer( |
+ reinterpret_cast<HistogramBase*>( |
+ base::subtle::Acquire_Load(&atomic_histogram_pointer))); |
+ if (!histogram_pointer) { |
+ // It's possible for multiple threads to make it here in parallel but |
+ // they'll always return the same result as there is a mutex in the Get. |
+ // The purpose of the "initialized" variable is just to ensure that |
+ // the same thread doesn't recurse which is also why it doesn't have |
+ // to be atomic. |
+ static bool initialized = false; |
+ if (!initialized) { |
+ initialized = true; |
+ histogram_pointer = LinearHistogram::FactoryGet( |
+ "UMA.CreatePersistentHistogram.Result", |
+ 1, CREATE_HISTOGRAM_MAX, CREATE_HISTOGRAM_MAX + 1, |
+ HistogramBase::kUmaTargetedHistogramFlag); |
+ base::subtle::Release_Store( |
+ &atomic_histogram_pointer, |
+ reinterpret_cast<base::subtle::AtomicWord>(histogram_pointer)); |
+ } |
+ } |
+ return histogram_pointer; |
+} |
+ |
+// Record the result of a histogram creation. |
+void RecordCreateHistogramResult(CreateHistogramResultType result) { |
+ HistogramBase* result_histogram = GetCreateHistogramResultHistogram(); |
+ if (result_histogram) |
+ result_histogram->Add(result); |
+} |
+ |
+void SetPersistentHistogramMemoryAllocator( |
+ PersistentMemoryAllocator* allocator) { |
+ // Releasing or changing an allocator is extremely dangerous because it |
+ // likely has histograms stored within it. If the backing memory is also |
+ // also released, future accesses to those histograms will seg-fault. |
+ // It's not a fatal CHECK() because tests do this knowing that all |
+ // such persistent histograms have already been forgotten. |
+ if (g_allocator) { |
+ LOG(WARNING) << "Active PersistentMemoryAllocator has been released." |
+ << " Some existing histogram pointers may be invalid."; |
+ delete g_allocator; |
+ } |
+ g_allocator = allocator; |
+} |
+ |
+PersistentMemoryAllocator* GetPersistentHistogramMemoryAllocator() { |
+ return g_allocator; |
+} |
+ |
+PersistentMemoryAllocator* ReleasePersistentHistogramMemoryAllocator() { |
+ PersistentMemoryAllocator* allocator = g_allocator; |
+ g_allocator = nullptr; |
+ return allocator; |
+}; |
+ |
+HistogramBase* CreatePersistentHistogram( |
+ PersistentMemoryAllocator* allocator, |
+ PersistentHistogramData* histogram_data_ptr) { |
+ if (!histogram_data_ptr) { |
+ RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_METADATA_POINTER); |
+ NOTREACHED(); |
+ return nullptr; |
+ } |
+ |
+ // Copy the histogram_data to local storage because anything in persistent |
+ // memory cannot be trusted as it could be changed at any moment by a |
+ // malicious actor that shares access. The contents of histogram_data are |
+ // validated below; the local copy is to ensure that the contents cannot |
+ // be externally changed between validation and use. |
+ PersistentHistogramData histogram_data = *histogram_data_ptr; |
+ |
+ HistogramBase::Sample* ranges_data = |
+ allocator->GetAsObject<HistogramBase::Sample>(histogram_data.ranges_ref, |
+ kTypeIdRangesArray); |
+ if (!ranges_data || histogram_data.bucket_count < 2 || |
+ histogram_data.bucket_count + 1 > |
+ std::numeric_limits<size_t>::max() / sizeof(HistogramBase::Sample) || |
+ allocator->GetAllocSize(histogram_data.ranges_ref) < |
+ (histogram_data.bucket_count + 1) * sizeof(HistogramBase::Sample)) { |
+ RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_RANGES_ARRAY); |
+ NOTREACHED(); |
+ return nullptr; |
+ } |
+ // To avoid racy destruction at shutdown, the following will be leaked. |
+ const BucketRanges* ranges = CreateRangesFromData( |
+ ranges_data, |
+ histogram_data.ranges_checksum, |
+ histogram_data.bucket_count + 1); |
+ if (!ranges) { |
+ RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_RANGES_ARRAY); |
+ NOTREACHED(); |
+ return nullptr; |
+ } |
+ ranges = StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges); |
+ |
+ HistogramBase::AtomicCount* counts_data = |
+ allocator->GetAsObject<HistogramBase::AtomicCount>( |
+ histogram_data.counts_ref, kTypeIdCountsArray); |
+ if (!counts_data || |
+ allocator->GetAllocSize(histogram_data.counts_ref) < |
+ histogram_data.bucket_count * sizeof(HistogramBase::AtomicCount)) { |
+ RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_COUNTS_ARRAY); |
+ NOTREACHED(); |
+ return nullptr; |
+ } |
+ |
+ std::string name(histogram_data_ptr->name); |
+ HistogramBase* histogram = nullptr; |
+ switch (histogram_data.histogram_type) { |
+ case HISTOGRAM: |
+ histogram = Histogram::PersistentGet( |
+ name, |
+ histogram_data.minimum, |
+ histogram_data.maximum, |
+ ranges, |
+ counts_data, |
+ histogram_data.bucket_count, |
+ &histogram_data_ptr->samples_metadata); |
+ break; |
+ case LINEAR_HISTOGRAM: |
+ histogram = LinearHistogram::PersistentGet( |
+ name, |
+ histogram_data.minimum, |
+ histogram_data.maximum, |
+ ranges, |
+ counts_data, |
+ histogram_data.bucket_count, |
+ &histogram_data_ptr->samples_metadata); |
+ break; |
+ case BOOLEAN_HISTOGRAM: |
+ histogram = BooleanHistogram::PersistentGet( |
+ name, |
+ ranges, |
+ counts_data, |
+ &histogram_data_ptr->samples_metadata); |
+ break; |
+ case CUSTOM_HISTOGRAM: |
+ histogram = CustomHistogram::PersistentGet( |
+ name, |
+ ranges, |
+ counts_data, |
+ histogram_data.bucket_count, |
+ &histogram_data_ptr->samples_metadata); |
+ break; |
+ } |
+ |
+ if (histogram) { |
+ DCHECK_EQ(histogram_data.histogram_type, histogram->GetHistogramType()); |
+ histogram->SetFlags(histogram_data.flags); |
+ } |
+ |
+ RecordCreateHistogramResult(CREATE_HISTOGRAM_SUCCESS); |
+ return histogram; |
+} |
+ |
+HistogramBase* GetPersistentHistogram( |
+ PersistentMemoryAllocator* allocator, |
+ int32_t ref) { |
+ // Unfortunately, the above "pickle" methods cannot be used as part of the |
+ // persistance because the deserialization methods always create local |
+ // count data (these must referenced the persistent counts) and always add |
+ // it to the local list of known histograms (these may be simple references |
+ // to histograms in other processes). |
+ PersistentHistogramData* histogram_data = |
+ allocator->GetAsObject<PersistentHistogramData>(ref, kTypeIdHistogram); |
+ size_t length = allocator->GetAllocSize(ref); |
+ if (!histogram_data || |
+ reinterpret_cast<char*>(histogram_data)[length - 1] != '\0') { |
+ RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_METADATA); |
+ NOTREACHED(); |
+ return nullptr; |
+ } |
+ return CreatePersistentHistogram(allocator, histogram_data); |
+} |
+ |
+HistogramBase* GetNextPersistentHistogram( |
+ PersistentMemoryAllocator* allocator, |
+ PersistentMemoryAllocator::Iterator* iter) { |
+ PersistentMemoryAllocator::Reference ref; |
+ uint32_t type_id; |
+ while ((ref = allocator->GetNextIterable(iter, &type_id)) != 0) { |
+ if (type_id == kTypeIdHistogram) |
+ return GetPersistentHistogram(allocator, ref); |
+ } |
+ return nullptr; |
+} |
+ |
+void FinalizePersistentHistogram(PersistentMemoryAllocator::Reference ref, |
+ bool registered) { |
+ // If the created persistent histogram was registered then it needs to |
+ // be marked as "iterable" in order to be found by other processes. |
+ if (registered) |
+ GetPersistentHistogramMemoryAllocator()->MakeIterable(ref); |
+ // If it wasn't registered then a race condition must have caused |
+ // two to be created. The allocator does not support releasing the |
+ // acquired memory so just change the type to be empty. |
+ else |
+ GetPersistentHistogramMemoryAllocator()->SetType(ref, 0); |
+} |
+ |
+HistogramBase* AllocatePersistentHistogram( |
+ PersistentMemoryAllocator* allocator, |
+ HistogramType histogram_type, |
+ const std::string& name, |
+ int minimum, |
+ int maximum, |
+ const BucketRanges* bucket_ranges, |
+ int32_t flags, |
+ PersistentMemoryAllocator::Reference* ref_ptr) { |
+ if (!allocator) |
+ return nullptr; |
+ |
+ size_t bucket_count = bucket_ranges->bucket_count(); |
+ // An overflow such as this, perhaps as the result of a milicious actor, |
+ // could lead to writing beyond the allocation boundary and into other |
+ // memory. Just fail the allocation and let the caller deal with it. |
+ if (bucket_count > std::numeric_limits<int32_t>::max() / |
+ sizeof(HistogramBase::AtomicCount)) { |
+ NOTREACHED(); |
+ return nullptr; |
+ } |
+ size_t counts_bytes = bucket_count * sizeof(HistogramBase::AtomicCount); |
+ size_t ranges_bytes = (bucket_count + 1) * sizeof(HistogramBase::Sample); |
+ PersistentMemoryAllocator::Reference ranges_ref = |
+ allocator->Allocate(ranges_bytes, kTypeIdRangesArray); |
+ PersistentMemoryAllocator::Reference counts_ref = |
+ allocator->Allocate(counts_bytes, kTypeIdCountsArray); |
+ PersistentMemoryAllocator::Reference histogram_ref = |
+ allocator->Allocate(offsetof(PersistentHistogramData, name) + |
+ name.length() + 1, kTypeIdHistogram); |
+ HistogramBase::Sample* ranges_data = |
+ allocator->GetAsObject<HistogramBase::Sample>(ranges_ref, |
+ kTypeIdRangesArray); |
+ PersistentHistogramData* histogram_data = |
+ allocator->GetAsObject<PersistentHistogramData>(histogram_ref, |
+ kTypeIdHistogram); |
+ |
+ // Only continue here if all allocations were successful. If they weren't |
+ // there is no way to free the space but that's not really a problem since |
+ // the allocations only fail because the space is full and so any future |
+ // attempts will also fail. |
+ if (counts_ref && ranges_data && histogram_data) { |
+ strcpy(histogram_data->name, name.c_str()); |
+ for (size_t i = 0; i < bucket_ranges->size(); ++i) |
+ ranges_data[i] = bucket_ranges->range(i); |
+ |
+ histogram_data->histogram_type = histogram_type; |
+ histogram_data->flags = flags; |
+ histogram_data->minimum = minimum; |
+ histogram_data->maximum = maximum; |
+ histogram_data->bucket_count = bucket_count; |
+ histogram_data->ranges_ref = ranges_ref; |
+ histogram_data->ranges_checksum = bucket_ranges->checksum(); |
+ histogram_data->counts_ref = counts_ref; |
+ |
+ // Create the histogram using resources in persistent memory. This ends up |
+ // resolving the "ref" values stored in histogram_data instad of just |
+ // using what is already known above but avoids duplicating the switch |
+ // statement here and serves as a double-check that everything is |
+ // correct before commiting the new histogram to persistent space. |
+ HistogramBase* histogram = |
+ CreatePersistentHistogram(allocator, histogram_data); |
+ DCHECK(histogram); |
+ if (ref_ptr != nullptr) |
+ *ref_ptr = histogram_ref; |
+ return histogram; |
+ } |
+ |
+ CreateHistogramResultType result; |
+ if (allocator->IsCorrupt()) { |
+ result = CREATE_HISTOGRAM_ALLOCATOR_CORRUPT; |
+ } else if (allocator->IsFull()) { |
+ result = CREATE_HISTOGRAM_ALLOCATOR_FULL; |
+ } else { |
+ result = CREATE_HISTOGRAM_ALLOCATOR_ERROR; |
+ } |
+ RecordCreateHistogramResult(result); |
+ |
+ return nullptr; |
+} |
+ |
+void ImportPersistentHistograms() { |
+ // Each call resumes from where it last left off so need persistant iterator. |
+ // The lock protects against concurrent access to the iterator and is created |
+ // dynamically so as to not require destruction during program exit. |
+ static PersistentMemoryAllocator::Iterator iter; |
+ static base::Lock* lock = new base::Lock(); |
+ |
+ if (g_allocator) { |
+ base::AutoLock auto_lock(*lock); |
+ if (iter.is_clear()) |
+ g_allocator->CreateIterator(&iter); |
+ |
+ for (;;) { |
+ HistogramBase* histogram = GetNextPersistentHistogram(g_allocator, &iter); |
+ if (!histogram) |
+ break; |
+ StatisticsRecorder::RegisterOrDeleteDuplicate(histogram); |
+ } |
+ } |
+} |
+ |
+} // namespace base |