Index: base/metrics/sample_vector.h |
diff --git a/base/metrics/sample_vector.h b/base/metrics/sample_vector.h |
index ee26c52101912df69856d107ebc330390269b0cf..84cdbc9fad2469dbf71079e3f306789918856b75 100644 |
--- a/base/metrics/sample_vector.h |
+++ b/base/metrics/sample_vector.h |
@@ -14,28 +14,27 @@ |
#include <memory> |
#include <vector> |
+#include "base/atomicops.h" |
#include "base/compiler_specific.h" |
#include "base/gtest_prod_util.h" |
#include "base/macros.h" |
#include "base/metrics/histogram_base.h" |
#include "base/metrics/histogram_samples.h" |
+#include "base/metrics/persistent_memory_allocator.h" |
namespace base { |
class BucketRanges; |
-class BASE_EXPORT SampleVector : public HistogramSamples { |
+class BASE_EXPORT SampleVectorBase : public HistogramSamples { |
public: |
- explicit SampleVector(const BucketRanges* bucket_ranges); |
- SampleVector(uint64_t id, const BucketRanges* bucket_ranges); |
- SampleVector(uint64_t id, |
- HistogramBase::AtomicCount* counts, |
- size_t counts_size, |
- Metadata* meta, |
- const BucketRanges* bucket_ranges); |
- ~SampleVector() override; |
+ SampleVectorBase(uint64_t id, const BucketRanges* bucket_ranges); |
+ SampleVectorBase(uint64_t id, |
+ Metadata* meta, |
+ const BucketRanges* bucket_ranges); |
+ ~SampleVectorBase() override; |
- // HistogramSamples implementation: |
+ // HistogramSamples: |
void Accumulate(HistogramBase::Sample value, |
HistogramBase::Count count) override; |
HistogramBase::Count GetCount(HistogramBase::Sample value) const override; |
@@ -52,25 +51,93 @@ class BASE_EXPORT SampleVector : public HistogramSamples { |
virtual size_t GetBucketIndex(HistogramBase::Sample value) const; |
+ void MoveSingleSampleToCounts(); |
+ |
+ void MountCountsStorage(); |
+ virtual bool MountExistingCountsStorage() const = 0; |
+ virtual HistogramBase::Count* CreateCountsStorageWhileLocked() = 0; |
+ |
+ HistogramBase::AtomicCount* counts() { |
+ return reinterpret_cast<HistogramBase::AtomicCount*>( |
+ subtle::NoBarrier_Load(&counts_)); |
+ } |
+ |
+ const HistogramBase::AtomicCount* counts() const { |
+ return reinterpret_cast<HistogramBase::AtomicCount*>( |
+ subtle::NoBarrier_Load(&counts_)); |
+ } |
+ |
+ void set_counts(HistogramBase::AtomicCount* counts) const { |
+ subtle::NoBarrier_Store(&counts_, reinterpret_cast<uintptr_t>(counts)); |
+ } |
+ |
+ size_t counts_size() const { return counts_size_; } |
+ |
private: |
+ friend class SampleVectorTest; |
FRIEND_TEST_ALL_PREFIXES(HistogramTest, CorruptSampleCounts); |
FRIEND_TEST_ALL_PREFIXES(SharedHistogramTest, CorruptSampleCounts); |
- // In the case where this class manages the memory, here it is. |
- std::vector<HistogramBase::AtomicCount> local_counts_; |
- |
- // These are raw pointers rather than objects for flexibility. The actual |
- // memory is either managed by local_counts_ above or by an external object |
- // and passed in directly. |
- HistogramBase::AtomicCount* counts_; |
- size_t counts_size_; |
+ // |counts_| is actually a pointer to a HistogramBase::AtomicCount array but |
+ // is held as an AtomicWord for concurrency reasons. When combined with the |
+ // single_sample held in the metadata, there are four possible states: |
+ // 1) single_sample == zero, counts_ == null |
+ // 2) single_sample != zero, counts_ == null |
+ // 3) single_sample != zero, counts_ != null BUT IS EMPTY |
+ // 4) single_sample == zero, counts_ != null and may have data |
+ // Once |counts_| is set, it can never revert and any existing single-sample |
+ // must be moved to this storage. It is mutable because changing it doesn't |
+ // change the (const) data but must adapt if a non-const object causes the |
+ // storage to be allocated and updated. |
+ mutable subtle::AtomicWord counts_ = 0; |
+ const size_t counts_size_; |
// Shares the same BucketRanges with Histogram object. |
const BucketRanges* const bucket_ranges_; |
+ DISALLOW_COPY_AND_ASSIGN(SampleVectorBase); |
+}; |
+ |
+// A sample vector that uses local memory for the counts array. |
+class BASE_EXPORT SampleVector : public SampleVectorBase { |
+ public: |
+ explicit SampleVector(const BucketRanges* bucket_ranges); |
+ SampleVector(uint64_t id, const BucketRanges* bucket_ranges); |
+ ~SampleVector() override; |
+ |
+ private: |
+ // SampleVectorBase: |
+ bool MountExistingCountsStorage() const override; |
+ HistogramBase::Count* CreateCountsStorageWhileLocked() override; |
+ |
+ // Simple local storage for counts. |
+ mutable std::vector<HistogramBase::AtomicCount> local_counts_; |
+ |
DISALLOW_COPY_AND_ASSIGN(SampleVector); |
}; |
+// A sample vector that uses persistent memory for the counts array. |
+class BASE_EXPORT PersistentSampleVector : public SampleVectorBase { |
+ public: |
+ PersistentSampleVector(uint64_t id, |
+ const BucketRanges* bucket_ranges, |
+ Metadata* meta, |
+ const DelayedPersistentAllocation& counts); |
+ ~PersistentSampleVector() override; |
+ |
+ private: |
+ // SampleVectorBase: |
+ bool MountExistingCountsStorage() const override; |
+ HistogramBase::Count* CreateCountsStorageWhileLocked() override; |
+ |
+ // Persistent storage for counts. |
+ DelayedPersistentAllocation persistent_counts_; |
+ |
+ DISALLOW_COPY_AND_ASSIGN(PersistentSampleVector); |
+}; |
+ |
+// An iterator for sample vectors. This could be defined privately in the .cc |
+// file but is here for easy testing. |
class BASE_EXPORT SampleVectorIterator : public SampleCountIterator { |
public: |
SampleVectorIterator(const std::vector<HistogramBase::AtomicCount>* counts, |