Ask event_base_loop to finish when we add a pending stream

Fixes bug 19969; bugfix on b1d56fc58. We can fix this some more in
later Tors, but for now, this is probably the right fix for us.

changes/bug19969

@@ -0,0 +1,10 @@
+  o Major bugfixes (client performance);
+    - Clients now respond to new application stream requests when
+      they arrive, rather than waiting up to one second before starting
+      to handle them. Fixes part of bug 19969; bugfix on 0.2.8.1-alpha.
+
+  o Major bugfixes (clients on flaky network connections);
+    - When Tor leaves standby because of a new application request, open
+      circuits as needed to serve that request. Previously, we would
+      potentially wait a very long time. Fixes part of bug 19969; bugfix
+      on 0.2.8.1-alpha.

src/or/connection_edge.c

@@ -892,6 +892,15 @@ connection_ap_mark_as_pending_circuit_(entry_connection_t *entry_conn,
 
   untried_pending_connections = 1;
   smartlist_add(pending_entry_connections, entry_conn);
+
+  /* Work-around for bug 19969: we handle pending_entry_connections at
+   * the end of run_main_loop_once(), but in many cases that function will
+   * take a very long time, if ever, to finish its call to event_base_loop().
+   *
+   * So the fix is to tell it right now that it ought to finish its loop at
+   * its next available opportunity.
+   */
+  tell_event_loop_to_finish();
 }
 
 /** Mark <b>entry_conn</b> as no longer waiting for a circuit. */