Record Chrome trace events in tcmalloc heap profiles

base/debug/trace_event_memory.h

+// Copyright 2013 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_DEBUG_TRACE_EVENT_MEMORY_H_
+#define BASE_DEBUG_TRACE_EVENT_MEMORY_H_
+
+#include "base/base_export.h"
+#include "base/debug/trace_event_impl.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/timer/timer.h"
+
+namespace base {
+
+class MessageLoopProxy;
+
+namespace debug {
+
+// Watches for chrome://tracing to be enabled or disabled. When tracing is
+// enabled, also enables tcmalloc heap profiling. This class is the preferred
+// way to turn trace-base heap memory profiling on and off.
+class BASE_EXPORT TraceMemoryController
+    : public TraceLog::EnabledStateObserver {
+ public:
+  // |message_loop_proxy| must be a proxy to the primary thread for the client
+  // process, e.g. the UI thread in a browser.
+  TraceMemoryController(

[jar (doing other things), 2013/07/04 02:18:30]

nit: explicit?

[James Cook, 2013/07/08 23:21:34]

Done.

+      scoped_refptr<MessageLoopProxy> message_loop_proxy);
+  virtual ~TraceMemoryController();
+
+  // base::debug::TraceLog::EnabledStateChangedObserver overrides:
+  virtual void OnTraceLogEnabled() OVERRIDE;
+  virtual void OnTraceLogDisabled() OVERRIDE;
+
+  // Starts heap memory profiling.
+  void StartProfiling();
+
+  // Ends heap memory profiling.
+  void StopProfiling();
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(TraceMemoryTest, TraceMemoryController);
+
+  bool IsTimerRunningForTest() const;
+
+  // Ensures the observer starts and stops tracing on the primary thread.
+  scoped_refptr<MessageLoopProxy> message_loop_proxy_;
+
+  // Timer to schedule memory profile dumps.
+  RepeatingTimer<TraceMemoryController> dump_timer_;
+
+  WeakPtrFactory<TraceMemoryController> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(TraceMemoryController);
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+// A scoped context for memory tracing. Pushes the name onto a stack for
+// recording by tcmalloc heap profiling.
+class BASE_EXPORT ScopedTraceMemory {
+ public:
+  // Memory for |name| must be static, for example, a literal string in
+  // a TRACE_EVENT macro.
+  ScopedTraceMemory(const char* name);

[jar (doing other things), 2013/07/04 02:18:30]

nit: explicit

[James Cook, 2013/07/08 23:21:34]

Done.

+  ~ScopedTraceMemory();
+
+  // Testing interface:
+  static int GetStackIndexForTest();
+  static const char* GetItemForTest(int index);
+};

[jar (doing other things), 2013/07/04 02:18:30]

nit: DISALLOW_COPY_AND_ASSIGN  (despite the fact that we don't manipulate
'em.... it is just a style rule).

[James Cook, 2013/07/08 23:21:34]

Done.

+
+//////////////////////////////////////////////////////////////////////////////
+
+// Converts tcmalloc's heap profiler data with psuedo-stacks in |input| to
+// trace event compatible JSON and appends to |output|. Visible for testing.
+BASE_EXPORT void AppendHeapProfileAsTraceFormat(const char* input,
+                                                std::string* output);
+
+// Converts the first |line| of heap profiler data, which contains totals for
+// all allocations in a special format, into trace event compatible JSON and
+// appends to |output|. Visible for testing.
+BASE_EXPORT void AppendHeapProfileTotalsAsTraceFormat(const std::string& line,
+                                                      std::string* output);
+
+// Converts a single |line| of heap profiler data into trace event compatible
+// JSON and appends to |output|. Returns true if the line was valid and has a
+// non-zero number of current allocations. Visible for testing.
+BASE_EXPORT bool AppendHeapProfileLineAsTraceFormat(const std::string& line,
+                                                    std::string* output);
+
+}  // namespace debug
+}  // namespace base
+
+// Make local variables with unique names based on the line number. Note that
+// the extra level of redirection is needed.
+#define INTERNAL_TRACE_MEMORY_ID3(line) trace_memory_unique_##line
+#define INTERNAL_TRACE_MEMORY_ID2(line) INTERNAL_TRACE_MEMORY_ID3(line)
+#define INTERNAL_TRACE_MEMORY_ID INTERNAL_TRACE_MEMORY_ID2(__LINE__)
+
+// Generates a unique local variable name.
+// TODO(jamescook): Make it record both category and name.
+#define INTERNAL_TRACE_MEMORY(category, name) \
+  base::debug::ScopedTraceMemory INTERNAL_TRACE_MEMORY_ID(name);
+
+// A special trace name that allows us to ignore memory allocations inside
+// the memory dump system itself. The allocations are recorded, but the
+// visualizer skips them. Must match the value in heap.js.
+#define TRACE_MEMORY_IGNORE "trace-memory-ignore"
+
+#endif  // BASE_DEBUG_TRACE_EVENT_MEMORY_H_