diff options
Diffstat (limited to 'base/metrics/sparse_histogram.h')
-rw-r--r-- | base/metrics/sparse_histogram.h | 34 |
1 files changed, 3 insertions, 31 deletions
diff --git a/base/metrics/sparse_histogram.h b/base/metrics/sparse_histogram.h index 3b302d6f22..97709ba18f 100644 --- a/base/metrics/sparse_histogram.h +++ b/base/metrics/sparse_histogram.h @@ -13,45 +13,17 @@ #include <string> #include "base/base_export.h" -#include "base/compiler_specific.h" -#include "base/logging.h" #include "base/macros.h" #include "base/metrics/histogram_base.h" -#include "base/metrics/sample_map.h" +#include "base/metrics/histogram_samples.h" #include "base/synchronization/lock.h" namespace base { -// Sparse histograms are well suited for recording counts of exact sample values -// that are sparsely distributed over a large range. -// -// The implementation uses a lock and a map, whereas other histogram types use a -// vector and no lock. It is thus more costly to add values to, and each value -// stored has more overhead, compared to the other histogram types. However it -// may be more efficient in memory if the total number of sample values is small -// compared to the range of their values. -// -// UMA_HISTOGRAM_ENUMERATION would be better suited for a smaller range of -// enumerations that are (nearly) contiguous. Also for code that is expected to -// run often or in a tight loop. -// -// UMA_HISTOGRAM_SPARSE_SLOWLY is good for sparsely distributed and or -// infrequently recorded values. -// -// For instance, Sqlite.Version.* are SPARSE because for any given database, -// there's going to be exactly one version logged, meaning no gain to having a -// pre-allocated vector of slots once the fleet gets to version 4 or 5 or 10. -// Likewise Sqlite.Error.* are SPARSE, because most databases generate few or no -// errors and there are large gaps in the set of possible errors. -#define UMA_HISTOGRAM_SPARSE_SLOWLY(name, sample) \ - do { \ - base::HistogramBase* histogram = base::SparseHistogram::FactoryGet( \ - name, base::HistogramBase::kUmaTargetedHistogramFlag); \ - histogram->Add(sample); \ - } while (0) - class HistogramSamples; class PersistentHistogramAllocator; +class Pickle; +class PickleIterator; class BASE_EXPORT SparseHistogram : public HistogramBase { public: |