1// Copyright 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_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_
6#define BASE_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_
7
8#include <stddef.h>
9
10#include <memory>
11#include <set>
12
13#include "base/base_export.h"
14#include "base/containers/hash_tables.h"
15#include "base/macros.h"
16#include "base/trace_event/heap_profiler_allocation_context.h"
17
18namespace base {
19namespace trace_event {
20
21class MemoryDumpSessionState;
22class StackFrameDeduplicator;
23class TracedValue;
24class TypeNameDeduplicator;
25
26// Aggregates |metrics_by_context|, recursively breaks down the heap, and
27// returns a traced value with an "entries" array that can be dumped in the
28// trace log, following the format described in https://goo.gl/KY7zVE. The
29// number of entries is kept reasonable because long tails are not included.
30BASE_EXPORT std::unique_ptr<TracedValue> ExportHeapDump(
31    const hash_map<AllocationContext, AllocationMetrics>& metrics_by_context,
32    const MemoryDumpSessionState& session_state);
33
34namespace internal {
35
36namespace {
37struct Bucket;
38}
39
40// An entry in the "entries" array as described in https://goo.gl/KY7zVE.
41struct BASE_EXPORT Entry {
42  size_t size;
43  size_t count;
44
45  // References a backtrace in the stack frame deduplicator. -1 means empty
46  // backtrace (the root of the tree).
47  int stack_frame_id;
48
49  // References a type name in the type name deduplicator. -1 indicates that
50  // the size is the cumulative size for all types (the root of the tree).
51  int type_id;
52};
53
54// Comparison operator to enable putting |Entry| in a |std::set|.
55BASE_EXPORT bool operator<(Entry lhs, Entry rhs);
56
57// Serializes entries to an "entries" array in a traced value.
58BASE_EXPORT std::unique_ptr<TracedValue> Serialize(const std::set<Entry>& dump);
59
60// Helper class to dump a snapshot of an |AllocationRegister| or other heap
61// bookkeeping structure into a |TracedValue|. This class is intended to be
62// used as a one-shot local instance on the stack.
63class BASE_EXPORT HeapDumpWriter {
64 public:
65  // The |stack_frame_deduplicator| and |type_name_deduplicator| are not owned.
66  // The heap dump writer assumes exclusive access to them during the lifetime
67  // of the dump writer. The heap dumps are broken down for allocations bigger
68  // than |breakdown_threshold_bytes|.
69  HeapDumpWriter(StackFrameDeduplicator* stack_frame_deduplicator,
70                 TypeNameDeduplicator* type_name_deduplicator,
71                 uint32_t breakdown_threshold_bytes);
72
73  ~HeapDumpWriter();
74
75  // Aggregates allocations to compute the total size of the heap, then breaks
76  // down the heap recursively. This produces the values that should be dumped
77  // in the "entries" array. The number of entries is kept reasonable because
78  // long tails are not included. Use |Serialize| to convert to a traced value.
79  const std::set<Entry>& Summarize(
80      const hash_map<AllocationContext, AllocationMetrics>& metrics_by_context);
81
82 private:
83  // Inserts an |Entry| for |Bucket| into |entries_|. Returns false if the
84  // entry was present before, true if it was not.
85  bool AddEntryForBucket(const Bucket& bucket);
86
87  // Recursively breaks down a bucket into smaller buckets and adds entries for
88  // the buckets worth dumping to |entries_|.
89  void BreakDown(const Bucket& bucket);
90
91  // The collection of entries that is filled by |Summarize|.
92  std::set<Entry> entries_;
93
94  // Helper for generating the |stackFrames| dictionary. Not owned, must outlive
95  // this heap dump writer instance.
96  StackFrameDeduplicator* const stack_frame_deduplicator_;
97
98  // Helper for converting type names to IDs. Not owned, must outlive this heap
99  // dump writer instance.
100  TypeNameDeduplicator* const type_name_deduplicator_;
101
102  // Minimum size of an allocation for which an allocation bucket will be
103  // broken down with children.
104  uint32_t breakdown_threshold_bytes_;
105
106  DISALLOW_COPY_AND_ASSIGN(HeapDumpWriter);
107};
108
109}  // namespace internal
110}  // namespace trace_event
111}  // namespace base
112
113#endif  // BASE_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_
114