[tracing] Switch to new heap dump format.

base/trace_event/heap_profiler_event_writer.h

+// Copyright 2015 The Chromium Authors. All rights reserved.

[ssid, 2017/03/13 03:38:00]

2017 all files

[DmitrySkiba, 2017/03/14 22:12:48]

Done.

+// 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_EVENT_WRITER_H_
+#define BASE_TRACE_EVENT_HEAP_PROFILER_EVENT_WRITER_H_
+
+#include <stddef.h>
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "base/base_export.h"
+
+/*
+  Heap profile event data format.
+
+  Input is:
+    1. Per allocator AllocationRegister
+    2. Per process deduplicators (for stack frames, types, strings)
+
+  Formatting event data has two steps:
+    1. Call ExportHeapDump() on allocation registers and accumulate results
+       in ExportedHeapDumpsMap. ExportHeapDump() exports allocation register
+       as "allocators/<allocator>" dictionary outlined below; deduplicators
+       contained in MemoryDumpSessionState are used in the process.
+    2. Call ExportHeapProfileEventData() with ExportedHeapDumpsMap and
+       MemoryDumpSessionState. This puts everything together:
+       a. Entries from ExportedHeapDumpsMap are formatted as
+          "allocators/<allocator>" nodes.
+       b. Deduplicators from MemoryDumpSessionState are formatted as
+          "maps/" nodes. Deduplicators are exported incrementally using
+          their ExportIncrementally() methods.
+
+  ExportHeapDump() aggregates allocation register entries first by backtrace,
+  then by type (i.e. creates map {(backtrace, type) -> AllocationMetrics}).
+  During aggregation backtraces and types are deduplicated.
+
+  Resulting event data format:
+  {
+    "version": 1,
+
+    "allocators": {
+      <allocator>: {
+        "nodes":  [<stack_frame_id1>, <stack_frame_id2>, ...],
+        "types":  [<type_id1>,        <type_id2>,        ...],
+        "counts": [<count1>,          <count2>,          ...],
+        "sizes":  [<size1>,           <size1>,           ...]
+      }
+    },
+
+    "maps": {
+      "nodes": [
+        {
+          "id": <stack_frame_id>,
+          "parent": <parent_id>,
+          "name_sid": <name_string_id>

[ssid, 2017/03/13 03:38:00]

Have you considered naming this just sid? name doesnt add much information here?

[DmitrySkiba, 2017/03/14 22:12:48]

I think it should be just 'name', but we can bikeshed once all other issues are
solved.

+        },
+        ...
+      ],
+      "types": [
+        {
+          "id": <type_id>,
+          "name_sid": <name_string_id>
+        }
+      ],
+      "strings": [
+        {
+          "id": <string_id>,
+          "string": <string>
+        }
+      ]
+    }
+  }
+*/
+
+namespace base {
+namespace trace_event {
+
+class AllocationRegister;
+class MemoryDumpSessionState;
+class TracedValue;
+
+// Exports heap allocations as "allocators/<allocator>" dictionary described
+// above. Return value is supposed to be added to ExportedHeapDumpsMap map
+// and later passed to ExportHeapProfileEventData().
+BASE_EXPORT std::unique_ptr<TracedValue> ExportHeapDump(
+    const AllocationRegister& allocation_register,
+    const MemoryDumpSessionState& session_state);
+
+// Maps allocator name to its heap dump.
+using ExportedHeapDumpsMap =
+    std::unordered_map<std::string, std::unique_ptr<TracedValue>>;
+
+// Exports event data according to the format described above.
+BASE_EXPORT std::unique_ptr<TracedValue> ExportHeapProfileEventData(
+    const ExportedHeapDumpsMap& heap_dumps,
+    const MemoryDumpSessionState& session_state);
+
+}  // namespace trace_event
+}  // namespace base
+
+#endif  // BASE_TRACE_EVENT_HEAP_PROFILER_EVENT_WRITER_H_