[evolution-data-server] CamelIMAPXServer: Work around refcounting issue in IDLE thread.

[Matthew Barnes <mbarnes src gnome org>]

commit 5c73cfabebfeae75aa0f1faa944efd7771e6b261
Author: Matthew Barnes <mbarnes redhat com>
Date:   Fri Jan 17 11:02:02 2014 -0500

    CamelIMAPXServer: Work around refcounting issue in IDLE thread.
    
    Use the ol' weak-reference-as-callback-closure trick to avoid IDLE
    command callbacks holding the last CamelIMAPXServer reference.

 camel/providers/imapx/camel-imapx-server.c |   46 +++++++++++++++++++++++----
 1 files changed, 39 insertions(+), 7 deletions(-)
---
diff --git a/camel/providers/imapx/camel-imapx-server.c b/camel/providers/imapx/camel-imapx-server.c
index 6d8a186..ae6b010 100644
--- a/camel/providers/imapx/camel-imapx-server.c
+++ b/camel/providers/imapx/camel-imapx-server.c
@@ -515,6 +515,32 @@ static void        imapx_maybe_select              (CamelIMAPXServer *is,
 
 G_DEFINE_TYPE (CamelIMAPXServer, camel_imapx_server, G_TYPE_OBJECT)
 
+static GWeakRef *
+imapx_weak_ref_new (gpointer object)
+{
+       GWeakRef *weak_ref;
+
+       /* XXX Might want to expose this in Camel's public API if it
+        *     proves useful elsewhere.  Based on e_weak_ref_new(). */
+
+       weak_ref = g_slice_new0 (GWeakRef);
+       g_weak_ref_set (weak_ref, object);
+
+       return weak_ref;
+}
+
+static void
+imapx_weak_ref_free (GWeakRef *weak_ref)
+{
+       g_return_if_fail (weak_ref != NULL);
+
+       /* XXX Might want to expose this in Camel's public API if it
+        *     proves useful elsewhere.  Based on e_weak_ref_free(). */
+
+       g_weak_ref_set (weak_ref, NULL);
+       g_slice_free (GWeakRef, weak_ref);
+}
+
 static const CamelIMAPXUntaggedRespHandlerDesc *
 replace_untagged_descriptor (GHashTable *untagged_handlers,
                              const gchar *key,
@@ -3583,7 +3609,10 @@ imapx_call_idle (gpointer data)
        GCancellable *cancellable;
        GError *local_error = NULL;
 
-       is = CAMEL_IMAPX_SERVER (data);
+       is = g_weak_ref_get (data);
+
+       if (is == NULL)
+               goto exit;
 
        /* XXX Rename to 'pending_lock'? */
        g_mutex_lock (&is->priv->idle_lock);
@@ -3592,11 +3621,11 @@ imapx_call_idle (gpointer data)
        g_mutex_unlock (&is->priv->idle_lock);
 
        if (is->priv->idle_state != IMAPX_IDLE_PENDING)
-               return G_SOURCE_REMOVE;
+               goto exit;
 
        mailbox = g_weak_ref_get (&is->priv->select_mailbox);
        if (mailbox == NULL)
-               return G_SOURCE_REMOVE;
+               goto exit;
 
        folder = imapx_server_ref_folder (is, mailbox);
        cancellable = g_weak_ref_get (&is->priv->parser_cancellable);
@@ -3636,6 +3665,9 @@ imapx_call_idle (gpointer data)
        g_clear_object (&folder);
        g_clear_object (&cancellable);
 
+exit:
+       g_clear_object (&is);
+
        return G_SOURCE_REMOVE;
 }
 
@@ -3662,8 +3694,8 @@ imapx_idle_thread (gpointer data)
        g_source_set_name (pending, "imapx_call_idle");
        g_source_set_callback (
                pending, imapx_call_idle,
-               g_object_ref (is),
-               (GDestroyNotify) g_object_unref);
+               imapx_weak_ref_new (is),
+               (GDestroyNotify) imapx_weak_ref_free);
        g_source_attach (pending, is->priv->idle_main_context);
        is->priv->idle_pending = g_source_ref (pending);
        g_source_unref (pending);
@@ -3765,8 +3797,8 @@ imapx_start_idle (CamelIMAPXServer *is)
                g_source_set_name (pending, "imapx_call_idle");
                g_source_set_callback (
                        pending, imapx_call_idle,
-                       g_object_ref (is),
-                       (GDestroyNotify) g_object_unref);
+                       imapx_weak_ref_new (is),
+                       (GDestroyNotify) imapx_weak_ref_free);
                g_source_attach (pending, is->priv->idle_main_context);
                is->priv->idle_pending = g_source_ref (pending);
                g_source_unref (pending);