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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 #ifndef BASE_METRICS_HISTOGRAM_PERSISTENCE_H_ | |
6 #define BASE_METRICS_HISTOGRAM_PERSISTENCE_H_ | |
7 | |
8 #include "base/base_export.h" | |
9 #include "base/feature_list.h" | |
10 #include "base/memory/scoped_ptr.h" | |
11 #include "base/metrics/histogram_base.h" | |
12 #include "base/metrics/persistent_memory_allocator.h" | |
13 | |
14 namespace base { | |
15 | |
16 BASE_EXPORT extern const Feature kPersistentHistogramsFeature; | |
17 | |
18 // Access a PersistentMemoryAllocator for storing histograms in space that | |
19 // can be persisted or shared between processes. There is only ever one | |
20 // allocator for all such histograms created by a single process though one | |
21 // process may access the histograms created by other processes if it has a | |
22 // handle on its memory segment. This takes ownership of the object and | |
23 // should not be changed without great care as it is likely that there will | |
24 // be pointers to data held in that space. | |
25 BASE_EXPORT void SetPersistentHistogramMemoryAllocator( | |
26 PersistentMemoryAllocator* a); | |
Alexei Svitkine (slow)
2016/01/12 21:54:45
Nit: longer param name.
bcwhite
2016/01/13 13:38:29
Done.
| |
27 BASE_EXPORT PersistentMemoryAllocator* GetPersistentHistogramMemoryAllocator(); | |
28 | |
29 // This access to the persistent allocator is only for testing; it extracts | |
30 // the current allocator completely. This allows easy creation of histograms | |
31 // within persistent memory segments which can then be extracted and used | |
32 // in other ways. | |
33 BASE_EXPORT PersistentMemoryAllocator* | |
34 ReleasePersistentHistogramMemoryAllocator(); | |
35 | |
36 // Recreate a Histogram from data held in persistent memory. Though this | |
37 // object will be local to the current process, the sample data will be | |
38 // shared with all other threads referencing it. This method takes a |ref| | |
39 // to the top- level histogram data and the |allocator| on which it is found. | |
40 // This method will return nullptr if any problem is detected with the data. | |
41 // The |allocator| may or may not be the same as the PersistentMemoryAllocator | |
42 // set for general use so that this method can be used to extract Histograms | |
43 // from persistent memory segments other than the default place that this | |
44 // process is creating its own histograms. The caller must take ownership of | |
45 // the returned object and destroy it when no longer needed. | |
46 BASE_EXPORT HistogramBase* GetPersistentHistogram( | |
47 PersistentMemoryAllocator* allocator, | |
48 int32_t ref); | |
49 | |
50 // Get the next histogram in persistent data based on iterator. The caller | |
51 // must take ownership of the returned object and destroy it when no longer | |
52 // needed. | |
53 BASE_EXPORT HistogramBase* GetNextPersistentHistogram( | |
54 PersistentMemoryAllocator* allocator, | |
55 PersistentMemoryAllocator::Iterator* iter); | |
56 | |
57 // Finalize the creation of the histogram, making it available to other | |
58 // processes if it is the registered instance. | |
59 void FinalizePersistentHistogram(PersistentMemoryAllocator::Reference ref, | |
60 bool register); | |
61 | |
62 // Allocate a new persistent histogram. This does *not* make the object | |
63 // iterable in the allocator; call MakeIterable(ref) directly if that is | |
64 // desired. | |
65 BASE_EXPORT HistogramBase* AllocatePersistentHistogram( | |
66 PersistentMemoryAllocator* allocator, | |
67 HistogramType histogram_type, | |
68 const std::string& name, | |
69 int minimum, | |
70 int maximum, | |
71 const BucketRanges* bucket_ranges, | |
72 int32_t flags, | |
73 PersistentMemoryAllocator::Reference* ref_ptr); | |
74 | |
75 // Import new histograms from attached PersistentMemoryAllocator. It's | |
76 // possible for other processes to create histograms in the attached memory | |
77 // segment; this adds those to the internal list of known histograms to | |
78 // avoid creating duplicates that would have to merged during reporting. | |
79 // Every call to this method resumes from the last entry it saw so it costs | |
80 // nothing if nothing new has been added. | |
81 void ImportPersistentHistograms(); | |
82 | |
83 } // namespace base | |
84 | |
85 #endif // BASE_METRICS_HISTOGRAM_PERSISTENCE_H_ | |
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