An attempt at solving the redoubtable "subprocess busy" bug. I don't …

…think it works though.

dreampielib/gui/__init__.py

@@ -873,7 +873,7 @@ def call_subp_noblock(self, funcname, *args):
             return self.subp.recv_object()
         else:
             self._n_unclaimed_results += 1
-            raise TimeoutError
+            raise TimeoutError(while_receiving=True)
 
     def call_subp_catch(self, funcname, *args):
         """
@@ -888,6 +888,23 @@ def call_subp_catch(self, funcname, *args):
         except TimeoutError:
             return None
 
+    def _call_subp_catch_internal(self, funcname, *args):
+        """
+        We make a non-blocking call, but if a timeout is raised while waiting
+        for the result, we patch it up by decrementing _n_unclaimed_results.
+        This MIGHT fix a nasty bug whereby if the timeout is raised while
+        we wait for attribute completion, we get "stuck" thinking we have to
+        wait for a computation result that will never come.
+        """
+        if self.is_executing:
+            return None
+        try:
+            return self.call_subp_noblock(funcname, *args)
+        except TimeoutError as e:
+            if e.while_receiving:
+                self._n_unclaimed_results -= 1
+            return None
+
     def on_object_recv(self, obj):
         if self._n_unclaimed_results:
             self._n_unclaimed_results -= 1
@@ -1220,13 +1237,13 @@ def on_show_completions(self, _widget):
         self.autocomplete.show_completions(is_auto=False, complete=False)
 
     def complete_dict_keys(self, expr):
-        return self.call_subp_catch(u'complete_dict_keys', expr)
+        return self._call_subp_catch_internal(u'complete_dict_keys', expr)
 
     def complete_attributes(self, expr):
-        return self.call_subp_catch(u'complete_attributes', expr)
+        return self._call_subp_catch_internal(u'complete_attributes', expr)
 
     def complete_firstlevels(self):
-        return self.call_subp_catch(u'complete_firstlevels')
+        return self._call_subp_catch_internal(u'complete_firstlevels')
 
     def get_func_args(self, expr):
         return self.call_subp_catch(u'get_func_args', expr)

dreampielib/gui/common.py

@@ -30,4 +30,5 @@ def get_text(textbuffer, *args):
     return textbuffer.get_text(*args).decode('utf8')
 
 class TimeoutError(Exception):
-    pass
+    def __init__(self, while_receiving=False):
+    	self.while_receiving = while_receiving