Index: base/metrics/histogram_persistence.h |
diff --git a/base/metrics/histogram_persistence.h b/base/metrics/histogram_persistence.h |
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+// 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. |
+ |
+#ifndef BASE_METRICS_HISTOGRAM_PERSISTENCE_H_ |
+#define BASE_METRICS_HISTOGRAM_PERSISTENCE_H_ |
+ |
+#include "base/base_export.h" |
+#include "base/feature_list.h" |
+#include "base/memory/scoped_ptr.h" |
+#include "base/metrics/histogram_base.h" |
+#include "base/metrics/persistent_memory_allocator.h" |
+ |
+namespace base { |
+ |
+// Feature definition for enabling histogram persistence. |
+BASE_EXPORT extern const Feature kPersistentHistogramsFeature; |
+ |
+// Histogram containing creation results. Visible for testing. |
+BASE_EXPORT HistogramBase* GetCreateHistogramResultHistogram(); |
+ |
+// Access a PersistentMemoryAllocator for storing histograms in space that |
+// can be persisted or shared between processes. There is only ever one |
+// allocator for all such histograms created by a single process though one |
+// process may access the histograms created by other processes if it has a |
+// handle on its memory segment. This takes ownership of the object and |
+// should not be changed without great care as it is likely that there will |
+// be pointers to data held in that space. |
+BASE_EXPORT void SetPersistentHistogramMemoryAllocator( |
+ PersistentMemoryAllocator* allocator); |
+BASE_EXPORT PersistentMemoryAllocator* GetPersistentHistogramMemoryAllocator(); |
+ |
+// This access to the persistent allocator is only for testing; it extracts |
+// the current allocator completely. This allows easy creation of histograms |
+// within persistent memory segments which can then be extracted and used |
+// in other ways. |
+BASE_EXPORT PersistentMemoryAllocator* |
+ReleasePersistentHistogramMemoryAllocator(); |
+ |
+// Recreate a Histogram from data held in persistent memory. Though this |
+// object will be local to the current process, the sample data will be |
+// shared with all other threads referencing it. This method takes a |ref| |
+// to the top- level histogram data and the |allocator| on which it is found. |
+// This method will return nullptr if any problem is detected with the data. |
+// The |allocator| may or may not be the same as the PersistentMemoryAllocator |
+// set for general use so that this method can be used to extract Histograms |
+// from persistent memory segments other than the default place that this |
+// process is creating its own histograms. The caller must take ownership of |
+// the returned object and destroy it when no longer needed. |
+BASE_EXPORT HistogramBase* GetPersistentHistogram( |
+ PersistentMemoryAllocator* allocator, |
+ int32_t ref); |
+ |
+// Get the next histogram in persistent data based on iterator. The caller |
+// must take ownership of the returned object and destroy it when no longer |
+// needed. |
+BASE_EXPORT HistogramBase* GetNextPersistentHistogram( |
+ PersistentMemoryAllocator* allocator, |
+ PersistentMemoryAllocator::Iterator* iter); |
+ |
+// Finalize the creation of the histogram, making it available to other |
+// processes if it is the registered instance. |
+void FinalizePersistentHistogram(PersistentMemoryAllocator::Reference ref, |
+ bool register); |
+ |
+// Allocate a new persistent histogram. This does *not* make the object |
+// iterable in the allocator; call MakeIterable(ref) directly if that is |
+// desired. |
+BASE_EXPORT 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); |
+ |
+// Import new histograms from attached PersistentMemoryAllocator. It's |
+// possible for other processes to create histograms in the attached memory |
+// segment; this adds those to the internal list of known histograms to |
+// avoid creating duplicates that would have to merged during reporting. |
+// Every call to this method resumes from the last entry it saw so it costs |
+// nothing if nothing new has been added. |
+void ImportPersistentHistograms(); |
+ |
+} // namespace base |
+ |
+#endif // BASE_METRICS_HISTOGRAM_PERSISTENCE_H_ |