Make "stop" do nothing but set the stopped flag, as in

2001-09-15  Jon Trowbridge  <trow@ximian.com>

	* backend/ebook/e-book-listener.c (e_book_listener_stop): Make
	"stop" do nothing but set the stopped flag, as in
	e-book-view-listener.c.
	(e_book_listener_destroy): Clean up our queue here, rather than in
	e_book_listener_stop.
	(response_free): Added.  Move the rather lengthy bit of code
	needed to free a EBookListenerResponse into one place.
	(e_book_listener_check_queue): Properly deal with the stopped
	flag.
	(e_book_listener_queue_response): If the stopped flag is set, just
	drop the incoming response.

	* backend/ebook/e-book-view-listener.c
	(e_book_view_listener_stop): Make "stop" do nothing but set the
	stopped flag.
	(e_book_view_listener_destroy): Move all of the clean-up that used
	to be in e_book_view_listener_stop here.  This considerably simplifies
	the logic required to avoid various race conditions.
	(e_book_view_listener_check_queue): Properly deal with the stopped flag.
	(e_book_view_listener_queue_response): Drop all incoming responses if
	we are stopped.

2001-09-14  Jon Trowbridge  <trow@ximian.com>

	* backend/pas/pas-book.c (pas_book_queue_request): Hold a
	reference to the book on behalf of our idle function.
	(pas_book_check_queue): When we are finished, drop the reference
	we've been holding on behalf of the idle function.

	* backend/pas/pas-backend-file.c
	(pas_backend_file_process_create_card): Hold a reference to the
	book_view while sending our notifications.
	(pas_backend_file_process_remove_card): Hold a reference to the
	book_view while sending our notifications.

	* gui/contact-editor/e-contact-quick-add.c (quick_add_unref): Remove
	debugging spew.

	* backend/ebook/e-book-util.c: Remove a lot of unused code that
	worked around bugs that have long since been fixed.
	(simple_query_disconnect): Added.  Breaks out the part of
	simple_query_free that disconnect signals.
	(simple_query_free): Replace code w/ a call to
	simple_query_disconnect.
	(simple_query_sequence_complete_cb): Call simple_query_disconnect
	before executing the callback, so that our callbacks don't get
	triggered by any book changes that might occur during that
	callback.

	* backend/ebook/e-book-view-listener.c
	(e_book_view_listener_check_queue): Changed to be consistent with
	e_book_listener_check_queue.
	(e_book_view_listener_queue_response): Also changed to use a
	high-frequency timeout.

	* backend/ebook/e-book-listener.c (e_book_listener_check_queue):
	OK, I've agonized over this stupid little function, and it should
	now be race-free.
	(e_book_listener_queue_response): We process our response queue in
	a high-frequency timeout rather than an idle.  Using an idle
	function leads to some tricky race conditions and bad interactions
	with bonobo's semi-broken attempts to take over event processing.
	(e_book_view_listener_stop): Manually disable our timeout and
	clean up.

svn path=/trunk/; revision=12851

5 files changed, 178 insertions, 208 deletions

diff --git a/addressbook/backend/ebook/e-book-listener.c b/addressbook/backend/ebook/e-book-listener.c
index 86b2e5cb9d..a66701847d 100644
--- a/addressbook/backend/ebook/e-book-listener.c
+++ b/addressbook/backend/ebook/e-book-listener.c
@@ -27,43 +27,92 @@ POA_GNOME_Evolution_Addressbook_BookListener__vepv  e_book_listener_vepv;
 
 struct _EBookListenerPrivate {
 	GList   *response_queue;
-	gint     idle_id;
-	gboolean idle_lock;
+	gint     timeout_id;
 
-	guint stopped : 1;
+	guint timeout_lock : 1;
+	guint stopped      : 1;
 };
 
-static gboolean
-e_book_listener_check_queue (EBookListener *listener)
+static void
+response_free (EBookListenerResponse *resp)
 {
-	if (listener->priv->idle_lock)
-		return TRUE;
-
-	listener->priv->idle_lock = TRUE;
+	if (resp == NULL)
+		return;
 
-	if (listener->priv->stopped) {
-		listener->priv->idle_id = 0;
-		goto exit_gracefully;
+	g_free (resp->msg);
+	g_free (resp->id);
+
+	if (resp->book != CORBA_OBJECT_NIL) {
+		CORBA_Environment ev;
+		
+		CORBA_exception_init (&ev);
+		
+		bonobo_object_release_unref (resp->book, &ev);
+		
+		if (ev._major != CORBA_NO_EXCEPTION) {
+			g_warning ("e_book_listener_destroy: "
+				   "Exception destroying book "
+				   "in response queue!\n");
+		}
+		
+		CORBA_exception_free (&ev);
 	}
 
-	if (listener->priv->response_queue != NULL) {
-		gtk_signal_emit (GTK_OBJECT (listener), e_book_listener_signals [RESPONSES_QUEUED]);
+	if (resp->cursor != CORBA_OBJECT_NIL) {
+		CORBA_Environment ev;
+
+		CORBA_exception_init (&ev);
+		
+		bonobo_object_release_unref (resp->cursor, &ev);
+
+		if (ev._major != CORBA_NO_EXCEPTION) {
+			g_warning ("e_book_listener_destroy: "
+				   "Exception destroying cursor "
+				   "in response queue!\n");
+		}
+		
+		CORBA_exception_free (&ev);
 	}
 
-	if (listener->priv->response_queue == NULL) {
-		listener->priv->idle_id = 0;
+	if (resp->book_view != CORBA_OBJECT_NIL) {
+		CORBA_Environment ev;
+		
+		CORBA_exception_init (&ev);
+		
+		bonobo_object_release_unref (resp->book_view, &ev);
+		
+		if (ev._major != CORBA_NO_EXCEPTION) {
+			g_warning ("e_book_listener_destroy: "
+				   "Exception destroying book_view "
+				   "in response queue!\n");
+		}
+		
+		CORBA_exception_free (&ev);
 	}
+	
+	g_free (resp);
+}
 
- exit_gracefully:
+static gboolean
+e_book_listener_check_queue (EBookListener *listener)
+{
+	if (listener->priv->timeout_lock)
+		return TRUE;
 
-	listener->priv->idle_lock = FALSE;
-	
-	/* Only drop the reference when we exit for the last time. */
-	if (listener->priv->idle_id == 0) {
-		gtk_object_unref (GTK_OBJECT (listener));
+	listener->priv->timeout_lock = TRUE;
+
+	if (listener->priv->response_queue != NULL && !listener->priv->stopped) {
+		gtk_signal_emit (GTK_OBJECT (listener), e_book_listener_signals [RESPONSES_QUEUED]);
+	}
+
+	if (listener->priv->response_queue == NULL || listener->priv->stopped) {
+		listener->priv->timeout_id = 0;
+		listener->priv->timeout_lock = FALSE;
+		bonobo_object_unref (BONOBO_OBJECT (listener)); /* release the timeout's reference */
 		return FALSE;
 	}
 
+	listener->priv->timeout_lock = FALSE;
 	return TRUE;
 }
 
@@ -71,16 +120,24 @@ static void
 e_book_listener_queue_response (EBookListener         *listener,
 				EBookListenerResponse *response)
 {
-	listener->priv->response_queue =
-		g_list_append (listener->priv->response_queue,
-			       response);
+	if (response == NULL)
+		return;
+
+	if (listener->priv->stopped) {
+		response_free (response);
+		return;
+	}
+
+	listener->priv->response_queue = g_list_append (listener->priv->response_queue, response);
 
-	if (listener->priv->idle_id == 0) {
+	if (listener->priv->timeout_id == 0) {
 
-		/* Hold a reference to the listener until the idle function is finished. */
-		gtk_object_ref (GTK_OBJECT (listener));
+		/* 20 == an arbitrary small integer */
+		listener->priv->timeout_id = g_timeout_add (20, (GSourceFunc) e_book_listener_check_queue, listener);
 
-		listener->priv->idle_id = g_idle_add ((GSourceFunc) e_book_listener_check_queue, listener);
+		/* Hold a reference on behalf of the timeout */
+		bonobo_object_ref (BONOBO_OBJECT (listener));
+		
 	}
 }
 
@@ -655,79 +712,31 @@ e_book_listener_init (EBookListener *listener)
 void
 e_book_listener_stop (EBookListener *listener)
 {
+	g_return_if_fail (E_IS_BOOK_LISTENER (listener));
+
+	listener->priv->stopped = TRUE;
+}
+
+static void
+e_book_listener_destroy (GtkObject *object)
+{
+	EBookListener *listener = E_BOOK_LISTENER (object);
 	GList *l;
 
-	if (listener->priv->stopped)
-		return;
+	/* Remove our response queue handler: In theory, this can never happen since we
+	 always hold a reference to the listener while the timeout is running. */
+	if (listener->priv->timeout_id) {
+		g_source_remove (listener->priv->timeout_id);
+	}
 
+	/* Clean up anything still sitting in response_queue */
 	for (l = listener->priv->response_queue; l != NULL; l = l->next) {
 		EBookListenerResponse *resp = l->data;
 
-		g_free (resp->msg);
-		g_free (resp->id);
-
-		if (resp->book != CORBA_OBJECT_NIL) {
-			CORBA_Environment ev;
-
-			CORBA_exception_init (&ev);
-
-			bonobo_object_release_unref (resp->book, &ev);
-
-			if (ev._major != CORBA_NO_EXCEPTION) {
-				g_warning ("e_book_listener_destroy: "
-					   "Exception destroying book "
-					   "in response queue!\n");
-			}
-			
-			CORBA_exception_free (&ev);
-		}
-
-		if (resp->cursor != CORBA_OBJECT_NIL) {
-			CORBA_Environment ev;
-
-			CORBA_exception_init (&ev);
-
-			bonobo_object_release_unref (resp->cursor, &ev);
-
-			if (ev._major != CORBA_NO_EXCEPTION) {
-				g_warning ("e_book_listener_destroy: "
-					   "Exception destroying cursor "
-					   "in response queue!\n");
-			}
-			
-			CORBA_exception_free (&ev);
-		}
-
-		if (resp->book_view != CORBA_OBJECT_NIL) {
-			CORBA_Environment ev;
-
-			CORBA_exception_init (&ev);
-
-			bonobo_object_release_unref (resp->book_view, &ev);
-
-			if (ev._major != CORBA_NO_EXCEPTION) {
-				g_warning ("e_book_listener_destroy: "
-					   "Exception destroying book_view "
-					   "in response queue!\n");
-			}
-			
-			CORBA_exception_free (&ev);
-		}
-
-		g_free (resp);
+		response_free (resp);
 	}
 	g_list_free (listener->priv->response_queue);
-	listener->priv->response_queue = NULL;
-
-	listener->priv->stopped = TRUE;
-}
-
-static void
-e_book_listener_destroy (GtkObject *object)
-{
-	EBookListener     *listener = E_BOOK_LISTENER (object);
 
-	e_book_listener_stop (listener);
 	g_free (listener->priv);
 	
 	GTK_OBJECT_CLASS (e_book_listener_parent_class)->destroy (object);
diff --git a/addressbook/backend/ebook/e-book-util.c b/addressbook/backend/ebook/e-book-util.c
index c65c70dfde..3943117ce0 100644
--- a/addressbook/backend/ebook/e-book-util.c
+++ b/addressbook/backend/ebook/e-book-util.c
@@ -186,11 +186,6 @@ book_issue_tag (EBook *book)
 	return tag;
 }
 
-#ifdef USE_WORKAROUND
-static GList *WORKAROUND_sq_queue = NULL;
-static gboolean WORKAROUND_running_query = FALSE;
-#endif
-
 static SimpleQueryInfo *
 simple_query_new (EBook *book, const char *query, EBookSimpleQueryCallback cb, gpointer closure)
 {
@@ -206,47 +201,37 @@ simple_query_new (EBook *book, const char *query, EBookSimpleQueryCallback cb, g
 	/* Automatically add ourselves to the EBook's pending list. */
 	book_add_simple_query (book, sq);
 
-#ifdef USE_WORKAROUND
-	/* Add ourselves to the queue. */
-	WORKAROUND_sq_queue = g_list_append (WORKAROUND_sq_queue, sq);
-#endif
-
 	return sq;
 }
 
 static void
+simple_query_disconnect (SimpleQueryInfo *sq)
+{
+	if (sq->add_tag) {
+		gtk_signal_disconnect (GTK_OBJECT (sq->view), sq->add_tag);
+		sq->add_tag = 0;
+	}
+
+	if (sq->seq_complete_tag) {
+		gtk_signal_disconnect (GTK_OBJECT (sq->view), sq->seq_complete_tag);
+		sq->seq_complete_tag = 0;
+	}
+
+	if (sq->view) {
+		gtk_object_unref (GTK_OBJECT (sq->view));
+		sq->view = NULL;
+	}
+}
+
+static void
 simple_query_free (SimpleQueryInfo *sq)
 {
 	/* Remove ourselves from the EBook's pending list. */
 	book_remove_simple_query (sq->book, sq);
 
-#ifdef USE_WORKAROUND
-	Glist *i;
-	
-	/* If we are still in the queue, remove ourselves. */
-	for (i = WORKAROUND_sq_queue; i != NULL; i = g_list_next (i)) {
-		if (i->data == sq) {
-			WORKAROUND_sq_queue = g_list_remove_link (WORKAROUND_sq_queue, i);
-			g_list_free_1 (i);
-			break;
-		} 
-	}
-#endif
-	
 	g_free (sq->query);
 
-	if (sq->add_tag)
-		gtk_signal_disconnect (GTK_OBJECT (sq->view), sq->add_tag);
-	if (sq->seq_complete_tag)
-		gtk_signal_disconnect (GTK_OBJECT (sq->view), sq->seq_complete_tag);
-
-#ifdef USE_WORKAROUND
-	if (sq->view)
-		WORKAROUND_running_query = FALSE;
-#endif
-
-	if (sq->view)
-		gtk_object_unref (GTK_OBJECT (sq->view));
+	simple_query_disconnect (sq);
 
 	if (sq->book)
 		gtk_object_unref (GTK_OBJECT (sq->book));
@@ -271,6 +256,9 @@ simple_query_sequence_complete_cb (EBookView *view, gpointer closure)
 {
 	SimpleQueryInfo *sq = closure;
 
+	/* Disconnect signals, so that we don't pick up any changes to the book that occur
+	   in our callback */
+	simple_query_disconnect (sq);
 	sq->cb (sq->book, E_BOOK_SIMPLE_QUERY_STATUS_SUCCESS, sq->cards, sq->closure);
 	simple_query_free (sq);
 }
@@ -299,31 +287,6 @@ simple_query_book_view_cb (EBook *book, EBookStatus status, EBookView *book_view
 						   sq);
 }
 
-#ifdef USE_WORKAROUND
-static gint
-WORKAROUND_try_queue (gpointer foo)
-{
-	if (WORKAROUND_sq_queue) {
-		SimpleQueryInfo *sq;
-		GList *i;
-
-		if (WORKAROUND_running_query) 
-			return TRUE;
-
-		WORKAROUND_running_query = TRUE;
-		sq = WORKAROUND_sq_queue->data;
-
-		i = WORKAROUND_sq_queue;
-		WORKAROUND_sq_queue = g_list_remove_link (WORKAROUND_sq_queue, WORKAROUND_sq_queue);
-		g_list_free_1 (i);
-
-		e_book_get_book_view (sq->book, sq->query, simple_query_book_view_cb, sq);
-	}
-
-	return FALSE;
-}
-#endif
-
 guint
 e_book_simple_query (EBook *book, const char *query, EBookSimpleQueryCallback cb, gpointer closure)
 {
@@ -334,11 +297,7 @@ e_book_simple_query (EBook *book, const char *query, EBookSimpleQueryCallback cb
 	g_return_val_if_fail (cb, 0);
 
 	sq = simple_query_new (book, query, cb, closure);
-#ifdef USE_WORKAROUND
-	gtk_timeout_add (50, WORKAROUND_try_queue, NULL);
-#else
 	e_book_get_book_view (book, (gchar *) query, simple_query_book_view_cb, sq);
-#endif
 
 	return sq->tag;
 }
diff --git a/addressbook/backend/ebook/e-book-view-listener.c b/addressbook/backend/ebook/e-book-view-listener.c
index 0b862fc61b..40e467ef93 100644
--- a/addressbook/backend/ebook/e-book-view-listener.c
+++ b/addressbook/backend/ebook/e-book-view-listener.c
@@ -27,44 +27,32 @@ POA_GNOME_Evolution_Addressbook_BookViewListener__vepv  e_book_view_listener_vep
 
 struct _EBookViewListenerPrivate {
 	GList   *response_queue;
-	gint     idle_id;
-	gboolean idle_lock;
+	gint     timeout_id;
 
-	guint stopped : 1;
+	guint timeout_lock : 1;
+	guint stopped      : 1;
 };
 
-/* Only release our listener reference when the idle is finished. */
 static gboolean
 e_book_view_listener_check_queue (EBookViewListener *listener)
 {
-	if (listener->priv->idle_lock)
+	if (listener->priv->timeout_lock)
 		return TRUE;
 
-	listener->priv->idle_lock = TRUE;
+	listener->priv->timeout_lock = TRUE;
 
-	if (listener->priv->stopped) {
-		listener->priv->idle_id = 0;
-		goto exit_gracefully;
-	}
-
-	if (listener->priv->response_queue != NULL) {
+	if (listener->priv->response_queue != NULL && !listener->priv->stopped) {
 		gtk_signal_emit (GTK_OBJECT (listener), e_book_view_listener_signals [RESPONSES_QUEUED]);
 	}
 
-	if (listener->priv->response_queue == NULL) {
-		listener->priv->idle_id = 0;
-	}
-
- exit_gracefully:
-
-	listener->priv->idle_lock = FALSE;
-	
-	/* Only drop the reference when we exit for the last time. */
-	if (listener->priv->idle_id == 0) {
-		gtk_object_unref (GTK_OBJECT (listener));
+	if (listener->priv->response_queue == NULL || listener->priv->stopped) {
+		listener->priv->timeout_id = 0;
+		listener->priv->timeout_lock = FALSE;
+		bonobo_object_unref (BONOBO_OBJECT (listener));
 		return FALSE;
 	}
 
+	listener->priv->timeout_lock = FALSE;
 	return TRUE;
 }
 
@@ -72,14 +60,28 @@ static void
 e_book_view_listener_queue_response (EBookViewListener         *listener,
 				     EBookViewListenerResponse *response)
 {
+	if (response == NULL)
+		return;
+
+	if (listener->priv->stopped) {
+		/* Free response and return */
+		g_free (response->id);
+		g_list_foreach (response->cards, (GFunc) gtk_object_unref, NULL);
+		g_list_free (response->cards);
+		g_free (response->message);
+		g_free (response);
+		return;
+	}
+	
 	listener->priv->response_queue = g_list_append (listener->priv->response_queue, response);
 
-	if (listener->priv->idle_id == 0) {
+	if (listener->priv->timeout_id == 0) {
 
-		/* Hold a reference to the listener while the idle is active. */
-		gtk_object_ref (GTK_OBJECT (listener));
+		/* Here, 20 == an arbitrary small number */		
+		listener->priv->timeout_id = g_timeout_add (20, (GSourceFunc) e_book_view_listener_check_queue, listener);
 
-		listener->priv->idle_id = g_idle_add ((GSourceFunc) e_book_view_listener_check_queue, listener);
+		/* Hold a reference to the listener on behalf of the timeout */
+		bonobo_object_ref (BONOBO_OBJECT (listener));
 	}
 }
 
@@ -340,24 +342,31 @@ e_book_view_listener_init (EBookViewListener *listener)
 {
 	listener->priv                 = g_new0 (EBookViewListenerPrivate, 1);
 	listener->priv->response_queue = NULL;
-	listener->priv->idle_id        = 0;
+	listener->priv->timeout_id     = 0;
+	listener->priv->timeout_lock   = FALSE;
 	listener->priv->stopped        = FALSE;
 }
 
 void
 e_book_view_listener_stop (EBookViewListener *listener)
 {
-	GList *l;
-
-	if (listener->priv->stopped)
-		return;
+	g_return_if_fail (E_IS_BOOK_VIEW_LISTENER (listener));
+	listener->priv->stopped = TRUE;
+}
 
-	if (listener->priv->idle_id) {
-		g_source_remove(listener->priv->idle_id);
-		listener->priv->idle_id = 0;
-		bonobo_object_unref (BONOBO_OBJECT (listener));
+static void
+e_book_view_listener_destroy (GtkObject *object)
+{
+	EBookViewListener *listener = E_BOOK_VIEW_LISTENER (object);
+	GList *l;
+	
+	/* Remove our response queue handler: In theory, this can never happen since we
+	 always hold a reference to the listener while the timeout is running. */
+	if (listener->priv->timeout_id) {
+		g_source_remove (listener->priv->timeout_id);
 	}
 
+	/* Clear out the queue */
 	for (l = listener->priv->response_queue; l != NULL; l = l->next) {
 		EBookViewListenerResponse *resp = l->data;
 
@@ -365,24 +374,17 @@ e_book_view_listener_stop (EBookViewListener *listener)
 
 		g_list_foreach(resp->cards, (GFunc) gtk_object_unref, NULL);
 		g_list_free(resp->cards);
+		resp->cards = NULL;
 
 		g_free (resp->message);
+		resp->message = NULL;
 
 		g_free (resp);
 	}
 	g_list_free (listener->priv->response_queue);
-	listener->priv->response_queue = NULL;
-
-	listener->priv->stopped = TRUE;
-}
-
-static void
-e_book_view_listener_destroy (GtkObject *object)
-{
-	EBookViewListener     *listener = E_BOOK_VIEW_LISTENER (object);
-
-	e_book_view_listener_stop (listener);
+	
 	g_free (listener->priv);
+	listener->priv = NULL;
 	
 	GTK_OBJECT_CLASS (e_book_view_listener_parent_class)->destroy (object);
 }
diff --git a/addressbook/backend/ebook/e-book-view.c b/addressbook/backend/ebook/e-book-view.c
index 39aab8623f..e56c7e90bc 100644
--- a/addressbook/backend/ebook/e-book-view.c
+++ b/addressbook/backend/ebook/e-book-view.c
@@ -114,7 +114,7 @@ e_book_view_check_listener_queue (EBookViewListener *listener, EBookView *book_v
 	EBookViewListenerResponse *resp;
 
 	resp = e_book_view_listener_pop_response (listener);
-
+	
 	if (resp == NULL)
 		return;
 
@@ -170,11 +170,11 @@ e_book_view_construct (EBookView *book_view, GNOME_Evolution_Addressbook_BookVie
 	 * Create our local BookListener interface.
 	 */
 	book_view->priv->listener = listener;
-
-	bonobo_object_ref(BONOBO_OBJECT(book_view->priv->listener));
 	book_view->priv->responses_queued_id = gtk_signal_connect (GTK_OBJECT (book_view->priv->listener), "responses_queued",
 								   e_book_view_check_listener_queue, book_view);
 
+	bonobo_object_ref(BONOBO_OBJECT(book_view->priv->listener));
+
 	return TRUE;
 }
 
diff --git a/addressbook/backend/ebook/e-book.c b/addressbook/backend/ebook/e-book.c
index 856b1d92b5..7c7738835c 100644
--- a/addressbook/backend/ebook/e-book.c
+++ b/addressbook/backend/ebook/e-book.c
@@ -305,7 +305,7 @@ e_book_do_response_get_view (EBook                 *book,
 		return;
 	}
 	
-	book_view = e_book_view_new(resp->book_view, op->listener);
+	book_view = e_book_view_new (resp->book_view, op->listener);
 
 	if (book_view != NULL) {
 		e_book_view_set_book (book_view, book);