Handle filling up of memory buffer to make log processing in DevTools Profiler easier.

src/log.cc

Index: src/log.cc
diff --git a/src/log.cc b/src/log.cc
index e149fdb17a89ba80071bf76ee238df3e1159a7fc..14d1f00993d1af986760e8eab217154eb9543cae 100644
--- a/src/log.cc
+++ b/src/log.cc
@@ -813,12 +813,14 @@ void Logger::PauseProfiler() {
   if (FLAG_prof_lazy) {
     if (!FLAG_sliding_state_window) ticker_->Stop();
     FLAG_log_code = false;
+    // Must be the same message as Log::kDynamicBufferSeal.
     LOG(UncheckedStringEvent("profiler", "pause"));
   }
 }
 
 
 void Logger::ResumeProfiler() {
+  if (!Log::IsEnabled()) return;
   if (FLAG_prof_lazy) {
     LOG(UncheckedStringEvent("profiler", "resume"));
     FLAG_log_code = true;
@@ -829,6 +831,14 @@ void Logger::ResumeProfiler() {
 }
 
 
+// This function can be called when Log's mutex is acquired,
+// either from main or Profiler's thread.
+void Logger::StopLoggingAndProfiling() {
+  Log::stop();
+  PauseProfiler();
+}
+
+
 bool Logger::IsProfilerSamplerActive() {
   return ticker_->IsActive();
 }
@@ -995,6 +1005,8 @@ bool Logger::Setup() {
     profiler_->Engage();
   }
 
+  LogMessageBuilder::write_failure_handler = StopLoggingAndProfiling;
+
   return true;
 
 #else
@@ -1005,6 +1017,8 @@ bool Logger::Setup() {
 
 void Logger::TearDown() {
 #ifdef ENABLE_LOGGING_AND_PROFILING
+  LogMessageBuilder::write_failure_handler = NULL;
+
   // Stop the profiler before closing the file.
   if (profiler_ != NULL) {
     profiler_->Disengage();