Record Chrome trace events in tcmalloc heap profiles

base/debug/trace_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_MEMORY_H_
+#define BASE_DEBUG_TRACE_MEMORY_H_
+
+#include "base/base_export.h"
+#include "base/debug/trace_event_impl.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/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 TraceMemoryTraceLogObserver
+    : 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.
+  TraceMemoryTraceLogObserver(
+      scoped_refptr<MessageLoopProxy> message_loop_proxy);
+  virtual ~TraceMemoryTraceLogObserver();
+
+  // 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();
+
+  bool IsTimerRunningForTest() const;

[dsinclair, 2013/06/18 15:30:15]

If this is only for test, can we make it private and friend the test class?

[James Cook, 2013/06/29 00:02:42]

Done.

+
+ private:
+  // Ensures the observer starts and stops tracing on the primary thread.
+  scoped_refptr<MessageLoopProxy> message_loop_proxy_;
+
+  // Timer to schedule memory profile dumps.
+  RepeatingTimer<TraceMemoryTraceLogObserver> dump_timer_;
+
+  WeakPtrFactory<TraceMemoryTraceLogObserver> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(TraceMemoryTraceLogObserver);
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+// A scoped context for memory tracing. Pushes the category onto a stack for
+// recording by tcmalloc heap profiling.
+class BASE_EXPORT ScopedTraceMemory {
+ public:
+  ScopedTraceMemory(const char* category);

[dsinclair, 2013/06/18 15:30:15]

The memory for category, does that need to be static or, who owns it?

[James Cook, 2013/06/29 00:02:42]

Added clarifying comment and changed to |name|, since that's what it actually
records right now.

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

[dsinclair, 2013/06/18 15:30:15]

You'll need to be careful when you add category in here as they can be a comma
separated list.

TRACE_MEMORY("foo,bar,baz", "boop");

[James Cook, 2013/06/29 00:02:42]

OK.  For now I'm only recording the name, but we'll have to decide how category
works (should it be recorded as-is, or split, and if split which fragment wins).

+#define 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_MEMORY_H_