Enable programmatic access to Profile pause/resume

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1185 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -1970,6 +1970,23 @@ class EXPORT V8 {
    */
   static int AdjustAmountOfExternalAllocatedMemory(int change_in_bytes);
 
+  /**
+   * Suspends recording of tick samples in the profiler.
+   * When the V8 profiling mode is enabled (usually via command line
+   * switches) this function suspends recording of tick samples.
+   * Profiling ticks are discarded until ResumeProfiler() is called.
+   *
+   * See also the --prof and --prof_auto command line switches to
+   * enable V8 profiling.
+   */
+  static void PauseProfiler();
+
+  /**
+   * Resumes recording of tick samples in the profiler.
+   * See also PauseProfiler().
+   */
+  static void ResumeProfiler();
+
  private:
   V8();
 

src/api.cc

@@ -2652,6 +2652,18 @@ void V8::SetExternalSymbolCallback(ExternalSymbolCallback callback) {
   i::Heap::SetExternalSymbolCallback(callback);
 }
 
+void V8::PauseProfiler() {
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  i::Logger::PauseProfiler();
+#endif
+}
+
+void V8::ResumeProfiler() {
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  i::Logger::ResumeProfiler();
+#endif
+}
+
 
 String::Utf8Value::Utf8Value(v8::Handle<v8::Value> obj) {
   EnsureInitialized("v8::String::Utf8Value::Utf8Value()");

src/flag-definitions.h

@@ -324,6 +324,8 @@ DEFINE_bool(log_state_changes, false, "Log state changes.")
 DEFINE_bool(log_suspect, false, "Log suspect operations.")
 DEFINE_bool(prof, false,
             "Log statistical profiling information (implies --log-code).")
+DEFINE_bool(prof_auto, true,
+            "Used with --prof, starts profiling automatically")
 DEFINE_bool(log_regexp, false, "Log regular expression execution.")
 DEFINE_bool(sliding_state_window, false,
             "Update sliding state window counters.")

src/log.cc

@@ -81,6 +81,9 @@ class Profiler: public Thread {
 
   // Inserts collected profiling data into buffer.
   void Insert(TickSample* sample) {
+    if (paused_)
+      return;
+
     if (Succ(head_) == tail_) {
       overflow_ = true;
     } else {
@@ -102,6 +105,11 @@ class Profiler: public Thread {
 
   void Run();
 
+  // Pause and Resume TickSample data collection.
+  static bool paused() { return paused_; }
+  static void pause() { paused_ = true; }
+  static void resume() { paused_ = false; }
+
  private:
   // Returns the next index in the cyclic buffer.
   int Succ(int index) { return (index + 1) % kBufferSize; }
@@ -117,8 +125,13 @@ class Profiler: public Thread {
 
   // Tells whether worker thread should continue running.
   bool running_;
+
+  // Tells whether we are currently recording tick samples.
+  static bool paused_;
 };
 
+bool Profiler::paused_ = false;
+
 
 //
 // Ticker used to provide ticks to the profiler and the sliding state
@@ -744,6 +757,21 @@ void Logger::TickEvent(TickSample* sample, bool overflow) {
   if (overflow) fprintf(logfile_, ",overflow");
   fprintf(logfile_, "\n");
 }
+
+
+bool Logger::IsProfilerPaused() {
+  return profiler_->paused();
+}
+
+
+void Logger::PauseProfiler() {
+  profiler_->pause();
+}
+
+
+void Logger::ResumeProfiler() {
+  profiler_->resume();
+}
 #endif
 
 
@@ -822,6 +850,8 @@ bool Logger::Setup() {
 
   if (FLAG_prof) {
     profiler_ = new Profiler();
+    if (!FLAG_prof_auto)
+      profiler_->pause();
     profiler_->Engage();
   }
 

src/log.h

@@ -203,6 +203,13 @@ class Logger {
 
   static bool is_enabled() { return logfile_ != NULL; }
 
+  // Pause/Resume collection of profiling data.
+  // When data collection is paused, Tick events are discarded until
+  // data collection is Resumed.
+  static bool IsProfilerPaused();
+  static void PauseProfiler();
+  static void ResumeProfiler();
+
  private:
 
   // Emits the source code of a regexp. Used by regexp events.