Adding flow traces for blink scheduler events

Source/platform/TraceEvent.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 433 matching lines @@
 #define TRACE_EVENT_COPY_ASYNC_END1(category, name, id, arg1_name, arg1_val) \
     INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
         category, name, id, TRACE_EVENT_FLAG_COPY, \
         arg1_name, arg1_val)
 #define TRACE_EVENT_COPY_ASYNC_END2(category, name, id, arg1_name, arg1_val, \
         arg2_name, arg2_val) \
     INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
         category, name, id, TRACE_EVENT_FLAG_COPY, \
         arg1_name, arg1_val, arg2_name, arg2_val)
 
+
+// Records a single FLOW_BEGIN event called "name" immediately, with 0, 1 or 2
+// associated arguments. If the category is not enabled, then this
+// does nothing.
+// - category and name strings must have application lifetime (statics or

[alexclarke, 2014/09/01 11:24:20]

|category|? and |name|?

[picksi1, 2014/09/01 13:33:47]

You are correct, but as this code is cut-and-pasted from
src/base/debug/TraceEvent.h in chromium it is probably best to keep both
in-sync. As discussed I believe this file will be removed once Blink and
Chromium repo's are merged.

+//   literals). They may not include " chars.

[alexclarke, 2014/09/01 11:24:20]

inverted commas?

[picksi1, 2014/09/01 13:33:47]

As above

+// - |id| is used to match the FLOW_BEGIN event with the FLOW_END event. FLOW
+//   events are considered to match if their category_group, name and id values
+//   all match. |id| must either be a pointer or an integer value up to 64 bits.
+//   If it's a pointer, the bits will be xored with a hash of the process ID so
+//   that the same pointer on two different processes will not collide.
+// FLOW events are different from ASYNC events in how they are drawn by the
+// tracing UI. A FLOW defines asynchronous data flow, such as posting a task
+// (FLOW_BEGIN) and later executing that task (FLOW_END). Expect FLOWs to be
+// drawn as lines or arrows from FLOW_BEGIN scopes to FLOW_END scopes. Similar
+// to ASYNC, a FLOW can consist of multiple phases. The first phase is defined
+// by the FLOW_BEGIN calls. Additional phases can be defined using the FLOW_STEP
+// macros. When the operation completes, call FLOW_END. An async operation can
+// span threads and processes, but all events in that operation must use the
+// same |name| and |id|. Each event can have its own args.
+#define TRACE_EVENT_FLOW_BEGIN0(category_group, name, id) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_FLOW_BEGIN1(category_group, name, id, arg1_name, arg1_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_FLOW_BEGIN2(category_group, name, id, arg1_name, arg1_val, \
+        arg2_name, arg2_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE, \
+        arg1_name, arg1_val, arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_FLOW_BEGIN0(category_group, name, id) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_FLOW_BEGIN1(category_group, name, id, arg1_name, \
+        arg1_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY, \
+        arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_FLOW_BEGIN2(category_group, name, id, arg1_name, \
+        arg1_val, arg2_name, arg2_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY, \
+        arg1_name, arg1_val, arg2_name, arg2_val)
+
+// Records a single FLOW_STEP event for |step| immediately. If the category
+// is not enabled, then this does nothing. The |name| and |id| must match the
+// FLOW_BEGIN event above. The |step| param identifies this step within the
+// async event. This should be called at the beginning of the next phase of an
+// asynchronous operation.
+#define TRACE_EVENT_FLOW_STEP0(category_group, name, id, step) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_STEP, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE, "step", step)
+#define TRACE_EVENT_FLOW_STEP1(category_group, name, id, step, \
+        arg1_name, arg1_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_STEP, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE, "step", step, \
+        arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_FLOW_STEP0(category_group, name, id, step) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_STEP, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY, "step", step)
+#define TRACE_EVENT_COPY_FLOW_STEP1(category_group, name, id, step, \
+        arg1_name, arg1_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_STEP, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY, "step", step, \
+        arg1_name, arg1_val)
+
+// Records a single FLOW_END event for "name" immediately. If the category
+// is not enabled, then this does nothing.
+#define TRACE_EVENT_FLOW_END0(category_group, name, id) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_FLOW_END1(category_group, name, id, arg1_name, arg1_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_FLOW_END2(category_group, name, id, arg1_name, arg1_val, \
+        arg2_name, arg2_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, \
+        category_group, name, id, TRACE_EVENT_FLAG_NONE, \
+        arg1_name, arg1_val, arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_FLOW_END0(category_group, name, id) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_FLOW_END1(category_group, name, id, arg1_name, \
+        arg1_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY, \
+        arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_FLOW_END2(category_group, name, id, arg1_name, \
+        arg1_val, arg2_name, arg2_val) \
+    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, \
+        category_group, name, id, TRACE_EVENT_FLAG_COPY, \
+        arg1_name, arg1_val, arg2_name, arg2_val)
+
+
 // Creates a scope of a sampling state with the given category and name (both must
 // be constant strings). These states are intended for a sampling profiler.
 // Implementation note: we store category and name together because we don't
 // want the inconsistency/expense of storing two pointers.
 // |thread_bucket| is [0..2] and is used to statically isolate samples in one
 // thread from others.
 //
 // {  // The sampling state is set within this scope.
 //    TRACE_EVENT_SAMPLING_STATE_SCOPE_FOR_BUCKET(0, "category", "name");
 //    ...;
@@ skipping 177 matching lines @@
 #define TRACE_EVENT_PHASE_ASYNC_BEGIN ('S')
 #define TRACE_EVENT_PHASE_ASYNC_STEP_INTO  ('T')
 #define TRACE_EVENT_PHASE_ASYNC_STEP_PAST  ('p')
 #define TRACE_EVENT_PHASE_ASYNC_END   ('F')
 #define TRACE_EVENT_PHASE_METADATA ('M')
 #define TRACE_EVENT_PHASE_COUNTER  ('C')
 #define TRACE_EVENT_PHASE_SAMPLE  ('P')
 #define TRACE_EVENT_PHASE_CREATE_OBJECT ('N')
 #define TRACE_EVENT_PHASE_SNAPSHOT_OBJECT ('O')
 #define TRACE_EVENT_PHASE_DELETE_OBJECT ('D')
+#define TRACE_EVENT_PHASE_FLOW_BEGIN ('s')
+#define TRACE_EVENT_PHASE_FLOW_STEP  ('t')
+#define TRACE_EVENT_PHASE_FLOW_END   ('f')
 
 // Flags for changing the behavior of TRACE_EVENT_API_ADD_TRACE_EVENT.
 #define TRACE_EVENT_FLAG_NONE        (static_cast<unsigned char>(0))
 #define TRACE_EVENT_FLAG_COPY        (static_cast<unsigned char>(1 << 0))
 #define TRACE_EVENT_FLAG_HAS_ID      (static_cast<unsigned char>(1 << 1))
 #define TRACE_EVENT_FLAG_MANGLE_ID   (static_cast<unsigned char>(1 << 2))
 
 // Type values for identifying types in the TraceValue union.
 #define TRACE_VALUE_TYPE_BOOL         (static_cast<unsigned char>(1))
 #define TRACE_VALUE_TYPE_UINT         (static_cast<unsigned char>(2))
@@ skipping 344 matching lines @@
     const char* m_categoryGroup;
     const char* m_name;
     IDType m_id;
 };
 
 } // namespace TraceEvent
 
 } // namespace blink
 
 #endif