Work in progress

This work extends AIStateMachine to run multiplex() in the thread
that calls run(), cont() or set_state(). Note that all three
eventually call locked_cont(), so thats where multiplex() is called
from. Calling multiplex() means "running the state machine", as in
"calling multiplex_impl".

Currently only LLURLRequest uses this feature, and then only
for the HTTPGetResponder, and well only for the initializing,
start up and normal finish states.

A current/remaining problem is that we run into a situation where
the curl thread runs a statemachine to it's finish and kills it,
while the main thread is also 'running' it and tries to call
multiplex while the statemachine isn't running anymore.

indra/llmessage/llurlrequest.cpp

@@ -83,6 +83,24 @@ LLURLRequest::LLURLRequest(LLURLRequest::ERequestAction action, std::string cons
 {
 }
 
+bool LLURLRequest::thread_safe_impl(void) const
+{
+  if (base_state() == bs_run &&
+	  (mRunState == AICurlEasyRequestStateMachine_removed_after_finished ||
+	   mRunState == AICurlEasyRequestStateMachine_addRequest) &&
+	  mResponder->thread_safe_complete())
+  {
+	return true;
+  }
+
+  // AICurlEasyRequestStateMachine::initialize_impl is thread safe because the statemachine
+  // will only just have been created and no other thread can know of this instance.
+  if (base_state() == bs_initialize)
+	return true;
+
+  return false;
+}
+
 void LLURLRequest::initialize_impl(void)
 {
 	// If the header is "Pragma" with no value, the caller intends to