Initial GetSample implementation.

src/log.cc

Index: src/log.cc
diff --git a/src/log.cc b/src/log.cc
index 0c6c4355aad9cff1577b8d262c119c1f593cdeeb..5aa16f51defd0e36b1a3e4f23c7f4252490ba859 100644
--- a/src/log.cc
+++ b/src/log.cc
@@ -1535,7 +1535,7 @@ void Logger::TickEvent(TickSample* sample, bool overflow) {
   }
   for (unsigned i = 0; i < sample->frames_count; ++i) {
     msg.Append(',');
-    msg.AppendAddress(sample->stack[i]);
+    msg.AppendAddress(static_cast<Address>(sample->stack[i]));
   }
   msg.WriteToLogFile();
 }
@@ -1869,6 +1869,13 @@ bool Logger::SetUp(Isolate* isolate) {
     profiler_->Engage();
   }
 
+  // TODO(gholap): This one's for the new sampler API. (include/v8-sampler.h)

[yurys, 2014/09/09 14:35:20]

There is no include/v8-sampler.h

[gholap, 2014/09/17 02:35:06]

Done.

+  //               Call to IncreaseProfilingDepth causes the
+  //               SIGPROF signal handler to be installed on the VM thread.
+  //               Figure out whether there's a way to only optionally
+  //               do this based on a runtime flag.
+  ticker_->IncreaseProfilingDepth();

[yurys, 2014/09/09 14:35:20]

This breaks the invariant as now Sampler::IsProfiling will always return true.
Doing this unconditionally is weird. We shouldn't need SIGPROF handler unless
profiler is on. Having thread state passed into v8::Isolate::GetSample as
described in the document would help to avoid such issues.

[gholap, 2014/09/17 02:35:06]

Done.

+
   if (FLAG_log_internal_timer_events || FLAG_prof) timer_.Start();
 
   return true;