ruby: add magic "nolock " prefix to run ruby without Suspending main df

plugins/ruby/ruby.cpp

@@ -118,18 +118,8 @@ DFhackCExport command_result plugin_shutdown ( color_ostream &out )
     return CR_OK;
 }
 
-// send a single ruby line to be evaluated by the ruby thread
-DFhackCExport command_result plugin_eval_ruby( color_ostream &out, const char *command)
+static command_result do_plugin_eval_ruby(color_ostream &out, const char *command)
 {
-    // if dlopen failed
-    if (!r_thread)
-        return CR_FAILURE;
-
-    // wrap all ruby code inside a suspend block
-    // if we dont do that and rely on ruby code doing it, we'll deadlock in
-    // onupdate
-    CoreSuspender suspend;
-
     command_result ret;
 
     // ensure ruby thread is idle
@@ -159,6 +149,27 @@ DFhackCExport command_result plugin_eval_ruby( color_ostream &out, const char *c
     return ret;
 }
 
+// send a single ruby line to be evaluated by the ruby thread
+DFhackCExport command_result plugin_eval_ruby( color_ostream &out, const char *command)
+{
+    // if dlopen failed
+    if (!r_thread)
+        return CR_FAILURE;
+
+    if (!strncmp(command, "nolock ", 7)) {
+        // debug only!
+        // run ruby commands without locking the main thread
+        // useful when the game is frozen after a segfault
+        return do_plugin_eval_ruby(out, command+7);
+    } else {
+        // wrap all ruby code inside a suspend block
+        // if we dont do that and rely on ruby code doing it, we'll deadlock in
+        // onupdate
+        CoreSuspender suspend;
+        return do_plugin_eval_ruby(out, command);
+    }
+}
+
 DFhackCExport command_result plugin_onupdate ( color_ostream &out )
 {
     if (!r_thread)