[Tracing] V8 Tracing Controller

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index 611b3b570b1a4448cf5feae7dd13174e3934e289..4b1103a1905049b7ef2b344e0f7238f8a75bf860 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -35,6 +35,7 @@
 #include "src/ostreams.h"
 
 #include "include/libplatform/libplatform.h"
+#include "include/libplatform/v8-tracing.h"
 #ifndef V8_SHARED
 #include "src/api.h"
 #include "src/base/cpu.h"
@@ -1996,6 +1997,12 @@ bool Shell::SetOptions(int argc, char* argv[]) {
         return false;
       }
       argv[i] = NULL;
+    } else if (strcmp(argv[i], "--enable-tracing") == 0) {
+      options.trace_enabled = true;
+      argv[i] = NULL;
+    } else if (strncmp(argv[i], "--trace-config=", 15) == 0) {
+      options.trace_config = argv[i] + 15;
+      argv[i] = NULL;
     }
   }
 
@@ -2412,6 +2419,7 @@ static void DumpHeapConstants(i::Isolate* isolate) {
 
 
 int Shell::Main(int argc, char* argv[]) {
+  std::ofstream trace_file;
 #if (defined(_WIN32) || defined(_WIN64))
   UINT new_flags =
       SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX | SEM_NOOPENFILEERRORBOX;
@@ -2479,6 +2487,38 @@ int Shell::Main(int argc, char* argv[]) {
     Initialize(isolate);
     PerIsolateData data(isolate);
 
+    if (options.trace_enabled) {

[Yang, 2016/07/21 11:26:55]

Can we factor out all of this into a new function? Possibly integrate Jochen's
suggestion of doing JSON.parse from there rather than inside
CreateTraceConfigFromJSON.

[fmeawad, 2016/07/26 09:08:09]

It is now much simpler as we removed the trace_config check.

+      trace_file.open("v8_trace.json");
+      platform::tracing::TracingController* tracing_controller =
+          new platform::tracing::TracingController();
+      platform::tracing::TraceBuffer* trace_buffer =
+          platform::tracing::TraceBuffer::CreateTraceBufferRingBuffer(
+              platform::tracing::TraceBuffer::kRingBufferChunks,
+              platform::tracing::TraceWriter::CreateJSONTraceWriter(
+                  trace_file));
+      platform::tracing::TraceConfig* trace_config;
+      if (options.trace_config) {
+        int size = 0;
+        char* trace_config_str =

[Yang, 2016/07/21 11:26:55]

Is this string going to be deleted anywhere? It looks like it would leak.

[fmeawad, 2016/07/26 09:08:09]

Removed with the removal of the JSON config for now.

+            ReadChars(nullptr, options.trace_config, &size);
+        trace_config =
+            platform::tracing::TraceConfig::CreateTraceConfigFromJSON(
+                isolate, trace_config_str);
+      } else {
+        trace_config =
+            platform::tracing::TraceConfig::CreateDefaultTraceConfig();
+      }
+      tracing_controller->Initialize(trace_buffer);
+      tracing_controller->StartTracing(trace_config);
+#ifndef V8_SHARED
+      if (!i::FLAG_verify_predictable) {
+        platform::SetTracingController(g_platform, tracing_controller);
+      }
+#else
+      platform::SetTracingController(g_platform, tracing_controller);
+#endif
+    }
+
 #ifndef V8_SHARED
     if (options.dump_heap_constants) {
       DumpHeapConstants(reinterpret_cast<i::Isolate*>(isolate));