[glib] gdbus-peer test: let GDBusServer start before notifying main thread

[Simon McVittie <smcv src gnome org>]

commit 6f859fe21a1955ab60ba4aa7e22841c7dbffdea3
Author: Simon McVittie <simon mcvittie collabora co uk>
Date:   Thu May 7 16:45:48 2015 +0100

    gdbus-peer test: let GDBusServer start before notifying main thread
    
    When running the nonce-tcp and tcp-anonymous tests in one run
    of gdbus-peer, or running one of them twice via command-line options
    "-p /gdbus/tcp-anonymous -p /gdbus/tcp-anonymous", the one run second
    would sometimes fail to connect with ECONNRESET.
    
    Adding more debug messages revealed that in the successful case,
    g_main_loop_run() was executed in the server thread first:
    
     # tcp-anonymous: server thread: listening on tcp:host=localhost,port=53517
     # tcp-anonymous: server thread: starting server...
     # tcp-anonymous: server thread: creating main loop...
     # tcp-anonymous: server thread: running main loop...
     # tcp-anonymous: main thread: trying tcp:host=localhost,port=53517...
     # tcp-anonymous: main thread: waiting for server thread...
    
    but in the failing case, the main thread attempted to connect
    before the call to g_main_loop_run() in the server thread:
    
     # tcp-anonymous: server thread: listening on tcp:host=localhost,port=40659
     # tcp-anonymous: server thread: starting server...
     # tcp-anonymous: server thread: creating main loop...
     # tcp-anonymous: main thread: trying tcp:host=localhost,port=40659...
     # tcp-anonymous: server thread: running main loop...
    
    (The log message "creating main loop" was immediately before
    create_service_loop(), and "running main loop" was immediately
    before g_main_loop_run().)
    
    To ensure that the GDBusServer has a chance to start accepting
    connections before the main thread tries to connect to it, do not
    tell the main thread about the service_loop immediately, but instead
    defer it to an idle.
    
    Bug: https://bugzilla.gnome.org/show_bug.cgi?id=749079
    Signed-off-by: Simon McVittie <simon mcvittie collabora co uk>
    Reviewed-by: Philip Withnall <philip withnall collabora co uk>

 gio/tests/gdbus-peer.c |   41 ++++++++++++++++++++++++++++-------------
 1 files changed, 28 insertions(+), 13 deletions(-)
---
diff --git a/gio/tests/gdbus-peer.c b/gio/tests/gdbus-peer.c
index 6c6f3b0..2c702ab 100644
--- a/gio/tests/gdbus-peer.c
+++ b/gio/tests/gdbus-peer.c
@@ -335,14 +335,34 @@ on_new_connection (GDBusServer *server,
   return TRUE;
 }
 
-static void
-create_service_loop (GMainContext *service_context)
+/* We don't tell the main thread about the new GDBusServer until it has
+ * had a chance to start listening. */
+static gboolean
+idle_in_service_loop (gpointer loop)
 {
   g_assert (service_loop == NULL);
   g_mutex_lock (&service_loop_lock);
-  service_loop = g_main_loop_new (service_context, FALSE);
+  service_loop = loop;
   g_cond_broadcast (&service_loop_cond);
   g_mutex_unlock (&service_loop_lock);
+
+  return G_SOURCE_REMOVE;
+}
+
+static void
+run_service_loop (GMainContext *service_context)
+{
+  GMainLoop *loop;
+  GSource *source;
+
+  g_assert (service_loop == NULL);
+
+  loop = g_main_loop_new (service_context, FALSE);
+  source = g_idle_source_new ();
+  g_source_set_callback (source, idle_in_service_loop, loop, NULL);
+  g_source_attach (source, service_context);
+  g_source_unref (source);
+  g_main_loop_run (loop);
 }
 
 static void
@@ -417,8 +437,7 @@ service_thread_func (gpointer user_data)
 
   g_dbus_server_start (server);
 
-  create_service_loop (service_context);
-  g_main_loop_run (service_loop);
+  run_service_loop (service_context);
 
   g_main_context_pop_thread_default (service_context);
 
@@ -512,8 +531,7 @@ service_thread_func (gpointer data)
                     data);
   g_socket_service_start (service);
 
-  create_service_loop (service_context);
-  g_main_loop_run (service_loop);
+  run_service_loop (service_context);
 
   g_main_context_pop_thread_default (service_context);
 
@@ -1212,8 +1230,7 @@ nonce_tcp_service_thread_func (gpointer user_data)
 
   g_dbus_server_start (server);
 
-  create_service_loop (service_context);
-  g_main_loop_run (service_loop);
+  run_service_loop (service_context);
 
   g_main_context_pop_thread_default (service_context);
 
@@ -1405,8 +1422,7 @@ tcp_anonymous_service_thread_func (gpointer user_data)
 
   g_dbus_server_start (server);
 
-  create_service_loop (service_context);
-  g_main_loop_run (service_loop);
+  run_service_loop (service_context);
 
   g_main_context_pop_thread_default (service_context);
 
@@ -1561,8 +1577,7 @@ codegen_service_thread_func (gpointer user_data)
                     G_CALLBACK (codegen_on_new_connection),
                     animal);
 
-  create_service_loop (service_context);
-  g_main_loop_run (service_loop);
+  run_service_loop (service_context);
 
   g_object_unref (animal);