[tracing] Switch to new heap dump format.

base/trace_event/heap_profiler_heap_dump_writer.h

-// Copyright 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_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_
-#define BASE_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_
-
-#include <stddef.h>
-
-#include <memory>
-#include <set>
-#include <unordered_map>
-
-#include "base/base_export.h"
-#include "base/macros.h"
-#include "base/trace_event/heap_profiler_allocation_context.h"
-
-namespace base {
-namespace trace_event {
-
-class HeapProfilerSerializationState;
-class StackFrameDeduplicator;
-class TracedValue;
-class TypeNameDeduplicator;
-
-// Aggregates |metrics_by_context|, recursively breaks down the heap, and
-// returns a traced value with an "entries" array that can be dumped in the
-// trace log, following the format described in https://goo.gl/KY7zVE. The
-// number of entries is kept reasonable because long tails are not included.
-BASE_EXPORT std::unique_ptr<TracedValue> ExportHeapDump(
-    const std::unordered_map<AllocationContext, AllocationMetrics>&
-        metrics_by_context,
-    const HeapProfilerSerializationState& heap_profiler_serialization_state);
-
-namespace internal {
-
-namespace {
-struct Bucket;
-}
-
-// An entry in the "entries" array as described in https://goo.gl/KY7zVE.
-struct BASE_EXPORT Entry {
-  size_t size;
-  size_t count;
-
-  // References a backtrace in the stack frame deduplicator. -1 means empty
-  // backtrace (the root of the tree).
-  int stack_frame_id;
-
-  // References a type name in the type name deduplicator. -1 indicates that
-  // the size is the cumulative size for all types (the root of the tree).
-  int type_id;
-};
-
-// Comparison operator to enable putting |Entry| in a |std::set|.
-BASE_EXPORT bool operator<(Entry lhs, Entry rhs);
-
-// Serializes entries to an "entries" array in a traced value.
-BASE_EXPORT std::unique_ptr<TracedValue> Serialize(const std::set<Entry>& dump);
-
-// Helper class to dump a snapshot of an |AllocationRegister| or other heap
-// bookkeeping structure into a |TracedValue|. This class is intended to be
-// used as a one-shot local instance on the stack.
-class BASE_EXPORT HeapDumpWriter {
- public:
-  // The |stack_frame_deduplicator| and |type_name_deduplicator| are not owned.
-  // The heap dump writer assumes exclusive access to them during the lifetime
-  // of the dump writer. The heap dumps are broken down for allocations bigger
-  // than |breakdown_threshold_bytes|.
-  HeapDumpWriter(StackFrameDeduplicator* stack_frame_deduplicator,
-                 TypeNameDeduplicator* type_name_deduplicator,
-                 uint32_t breakdown_threshold_bytes);
-
-  ~HeapDumpWriter();
-
-  // Aggregates allocations to compute the total size of the heap, then breaks
-  // down the heap recursively. This produces the values that should be dumped
-  // in the "entries" array. The number of entries is kept reasonable because
-  // long tails are not included. Use |Serialize| to convert to a traced value.
-  const std::set<Entry>& Summarize(
-      const std::unordered_map<AllocationContext, AllocationMetrics>&
-          metrics_by_context);
-
- private:
-  // Inserts an |Entry| for |Bucket| into |entries_|. Returns false if the
-  // entry was present before, true if it was not.
-  bool AddEntryForBucket(const Bucket& bucket);
-
-  // Recursively breaks down a bucket into smaller buckets and adds entries for
-  // the buckets worth dumping to |entries_|.
-  void BreakDown(const Bucket& bucket);
-
-  // The collection of entries that is filled by |Summarize|.
-  std::set<Entry> entries_;
-
-  // Helper for generating the |stackFrames| dictionary. Not owned, must outlive
-  // this heap dump writer instance.
-  StackFrameDeduplicator* const stack_frame_deduplicator_;
-
-  // Helper for converting type names to IDs. Not owned, must outlive this heap
-  // dump writer instance.
-  TypeNameDeduplicator* const type_name_deduplicator_;
-
-  // Minimum size of an allocation for which an allocation bucket will be
-  // broken down with children.
-  uint32_t breakdown_threshold_bytes_;
-
-  DISALLOW_COPY_AND_ASSIGN(HeapDumpWriter);
-};
-
-}  // namespace internal
-}  // namespace trace_event
-}  // namespace base
-
-#endif  // BASE_TRACE_EVENT_HEAP_PROFILER_HEAP_DUMP_WRITER_H_