Implement a new flow event API that allows binding flow events and regular events.

base/trace_event/trace_event_impl.cc

Index: base/trace_event/trace_event_impl.cc
diff --git a/base/trace_event/trace_event_impl.cc b/base/trace_event/trace_event_impl.cc
index cd8cf4aa90c46e7167682715b3a8f91618dfbd97..39ca25d03c1e8f89d9e823d600c1c27a75bdbd8a 100644
--- a/base/trace_event/trace_event_impl.cc
+++ b/base/trace_event/trace_event_impl.cc
@@ -407,13 +407,11 @@ void InitializeMetadataEvent(TraceEvent* trace_event,
   unsigned char arg_type;
   unsigned long long arg_value;
   ::trace_event_internal::SetTraceValue(value, &arg_type, &arg_value);
-  trace_event->Initialize(thread_id,
-                          TraceTicks(), ThreadTicks(),
-                          TRACE_EVENT_PHASE_METADATA,
-                          &g_category_group_enabled[g_category_metadata],
-                          metadata_name, ::trace_event_internal::kNoEventId,
-                          num_args, &arg_name, &arg_type, &arg_value, NULL,
-                          TRACE_EVENT_FLAG_NONE);
+  trace_event->Initialize(
+      thread_id, TraceTicks(), ThreadTicks(), TRACE_EVENT_PHASE_METADATA,
+      &g_category_group_enabled[g_category_metadata], metadata_name,
+      ::trace_event_internal::kNoEventId, num_args, &arg_name, &arg_type,
+      &arg_value, NULL, TRACE_EVENT_FLAG_NONE, trace_event_internal::kNoBindId);
 }
 
 class AutoThreadLocalBoolean {
@@ -597,7 +595,8 @@ void TraceEvent::Initialize(
     const unsigned char* arg_types,
     const unsigned long long* arg_values,
     const scoped_refptr<ConvertableToTraceFormat>* convertable_values,
-    unsigned int flags) {
+    unsigned int flags,
+    unsigned long long bind_id) {

[dsinclair, 2015/07/17 13:39:41]

Move up below id.

   timestamp_ = timestamp;
   thread_timestamp_ = thread_timestamp;
   duration_ = TimeDelta::FromInternalValue(-1);
@@ -607,6 +606,7 @@ void TraceEvent::Initialize(
   thread_id_ = thread_id;
   phase_ = phase;
   flags_ = flags;
+  bind_id_ = bind_id;
 
   // Clamp num_args since it may have been set by a third_party library.
   num_args = (num_args > kTraceMaxNumArgs) ? kTraceMaxNumArgs : num_args;
@@ -848,6 +848,18 @@ void TraceEvent::AppendAsJSON(
   if (flags_ & TRACE_EVENT_FLAG_BIND_TO_ENCLOSING)
     StringAppendF(out, ",\"bp\":\"e\"");
 
+  if (flags_ & TRACE_EVENT_FLAG_FLOW_OUT) {

[dsinclair, 2015/07/17 13:39:40]

I think this needs to be a bit more complicated. What happens if I do flag ==
TRACE_EVENT_FLAG_FLOW_OUT | TRACE_EVENT_FLAG_FLOW_IN; (So, this is a step in the
flow).

if (flags_ & TRACE_EVENT_FLAG_FLOW_OUT || flags_ & TRACE_EVNET_FLAG_FLOW_IN)
  StringAppendF(out, ",\"bind_id\":\"0x%" PRIx64 "\"",
static_cast<uint64>(bind_id_));

if (flags & TRACE_EVENT_FLAG_FLOW_OUT)
  StringAppendF(out, ","bo:true");
if (flags & TRACE_EVENT_FLAG_FLOW_IN)
  StringAppendF(out, ","bi:true");


(Not sure of the bi,bo as the attributes, what do you think?)

+    StringAppendF(out, ",\"bind_id\":\"0x%" PRIx64 "\"",
+                  static_cast<uint64>(bind_id_));
+    StringAppendF(out, ",\"dir\":\"o\"");
+  }
+
+  if (flags_ & TRACE_EVENT_FLAG_FLOW_IN) {
+    StringAppendF(out, ",\"bind_id\":\"0x%" PRIx64 "\"",
+                  static_cast<uint64>(bind_id_));
+    StringAppendF(out, ",\"dir\":\"i\"");
+  }
+
   // Instant events also output their scope.
   if (phase_ == TRACE_EVENT_PHASE_INSTANT) {
     char scope = '?';
@@ -1208,11 +1220,10 @@ void TraceLog::ThreadLocalEventBuffer::ReportOverhead(
     TraceEvent* trace_event = AddTraceEvent(NULL);
     if (trace_event) {
       trace_event->Initialize(
-          static_cast<int>(PlatformThread::CurrentId()),
-          event_timestamp, event_thread_timestamp,
-          TRACE_EVENT_PHASE_COMPLETE,
+          static_cast<int>(PlatformThread::CurrentId()), event_timestamp,
+          event_thread_timestamp, TRACE_EVENT_PHASE_COMPLETE,
           &g_category_group_enabled[g_category_trace_event_overhead],
-          "overhead", 0, 0, NULL, NULL, NULL, NULL, 0);
+          "overhead", 0, 0, NULL, NULL, NULL, NULL, 0, 0);

[dsinclair, 2015/07/17 13:39:41]

If this 0 is id use the kNoId please.

       trace_event->UpdateDuration(now, thread_now);
     }
   }
@@ -2010,11 +2021,10 @@ TraceEventHandle TraceLog::AddTraceEvent(
     unsigned int flags) {
   int thread_id = static_cast<int>(base::PlatformThread::CurrentId());
   base::TraceTicks now = base::TraceTicks::Now();
-  return AddTraceEventWithThreadIdAndTimestamp(phase, category_group_enabled,
-                                               name, id, thread_id, now,
-                                               num_args, arg_names,
-                                               arg_types, arg_values,
-                                               convertable_values, flags);
+  return AddTraceEventWithThreadIdAndTimestamp(
+      phase, category_group_enabled, name, id, thread_id, now, num_args,
+      arg_names, arg_types, arg_values, convertable_values, flags,
+      trace_event_internal::kNoBindId);
 }
 
 TraceEventHandle TraceLog::AddTraceEventWithThreadIdAndTimestamp(
@@ -2029,7 +2039,8 @@ TraceEventHandle TraceLog::AddTraceEventWithThreadIdAndTimestamp(
     const unsigned char* arg_types,
     const unsigned long long* arg_values,
     const scoped_refptr<ConvertableToTraceFormat>* convertable_values,
-    unsigned int flags) {
+    unsigned int flags,
+    unsigned long long bind_id) {

[dsinclair, 2015/07/17 13:39:41]

Move up below thread_id

   TraceEventHandle handle = { 0, 0, 0 };
   if (!*category_group_enabled)
     return handle;
@@ -2121,9 +2132,9 @@ TraceEventHandle TraceLog::AddTraceEventWithThreadIdAndTimestamp(
 
     if (trace_event) {
       trace_event->Initialize(thread_id, offset_event_timestamp, thread_now,
-                              phase, category_group_enabled, name, id,
-                              num_args, arg_names, arg_types, arg_values,
-                              convertable_values, flags);
+                              phase, category_group_enabled, name, id, num_args,
+                              arg_names, arg_types, arg_values,
+                              convertable_values, flags, bind_id);
 
 #if defined(OS_ANDROID)
       trace_event->SendToATrace();
@@ -2515,7 +2526,7 @@ ScopedTraceBinaryEfficient::ScopedTraceBinaryEfficient(
             trace_event_internal::kNoEventId,
             static_cast<int>(base::PlatformThread::CurrentId()),
             base::TraceTicks::Now(), 0, NULL, NULL, NULL, NULL,
-            TRACE_EVENT_FLAG_NONE);
+            TRACE_EVENT_FLAG_NONE, 0);

[dsinclair, 2015/07/17 13:39:40]

Use kNoId.

   }
 }