[PATCH] event-loop: Use two-step destruction of event loop sources.

[Jonas Ådahl]

Instead of directly destroying an event source upon removal only destroy
it in case its event loop is not dispatching. If dispatching the event
source is marked for destruction and added to the check list and
destroyed in post_dispatch_check(); if not it is destroyed immediately.

Signed-off-by: Jonas Ådahl <jadahl at gmail.com>
---
 src/event-loop.c |   73 ++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/src/event-loop.c b/src/event-loop.c
index 2dfe0ae..7f2ef80 100644
--- a/src/event-loop.c
+++ b/src/event-loop.c
@@ -39,12 +39,15 @@ struct wl_event_loop {
 	int epoll_fd;
 	struct wl_list check_list;
 	struct wl_list idle_list;
+
+	int dispatching;
 };
 
 struct wl_event_source_interface {
 	int (*dispatch)(struct wl_event_source *source,
 			struct epoll_event *ep);
 	int (*remove)(struct wl_event_source *source);
+	int (*destroy)(struct wl_event_source *source);
 };
 
 struct wl_event_source {
@@ -52,6 +55,7 @@ struct wl_event_source {
 	struct wl_event_loop *loop;
 	struct wl_list link;
 	void *data;
+	int destroy;
 };
 
 struct wl_event_source_fd {
@@ -61,6 +65,13 @@ struct wl_event_source_fd {
 };
 
 static int
+wl_event_source_generic_destroy(struct wl_event_source *source)
+{
+	free(source);
+	return 0;
+}
+
+static int
 wl_event_source_fd_dispatch(struct wl_event_source *source,
 			    struct epoll_event *ep)
 {
@@ -82,17 +93,14 @@ wl_event_source_fd_remove(struct wl_event_source *source)
 	struct wl_event_source_fd *fd_source =
 		(struct wl_event_source_fd *) source;
 	struct wl_event_loop *loop = source->loop;
-	int fd;
-
-	fd = fd_source->fd;
-	free(source);
 
-	return epoll_ctl(loop->epoll_fd, EPOLL_CTL_DEL, fd, NULL);
+	return epoll_ctl(loop->epoll_fd, EPOLL_CTL_DEL, fd_source->fd, NULL);
 }
 
 struct wl_event_source_interface fd_source_interface = {
 	wl_event_source_fd_dispatch,
-	wl_event_source_fd_remove
+	wl_event_source_fd_remove,
+	wl_event_source_generic_destroy
 };
 
 WL_EXPORT struct wl_event_source *
@@ -104,7 +112,7 @@ wl_event_loop_add_fd(struct wl_event_loop *loop,
 	struct wl_event_source_fd *source;
 	struct epoll_event ep;
 
-	source = malloc(sizeof *source);
+	source = calloc(1, sizeof *source);
 	if (source == NULL)
 		return NULL;
 
@@ -179,13 +187,13 @@ wl_event_source_timer_remove(struct wl_event_source *source)
 		(struct wl_event_source_timer *) source;
 
 	close(timer_source->fd);
-	free(source);
 	return 0;
 }
 
 struct wl_event_source_interface timer_source_interface = {
 	wl_event_source_timer_dispatch,
-	wl_event_source_timer_remove
+	wl_event_source_timer_remove,
+	wl_event_source_generic_destroy
 };
 
 WL_EXPORT struct wl_event_source *
@@ -196,7 +204,7 @@ wl_event_loop_add_timer(struct wl_event_loop *loop,
 	struct wl_event_source_timer *source;
 	struct epoll_event ep;
 
-	source = malloc(sizeof *source);
+	source = calloc(1, sizeof *source);
 	if (source == NULL)
 		return NULL;
 
@@ -278,13 +286,13 @@ wl_event_source_signal_remove(struct wl_event_source *source)
 		(struct wl_event_source_signal *) source;
 
 	close(signal_source->fd);
-	free(source);
 	return 0;
 }
 
 struct wl_event_source_interface signal_source_interface = {
 	wl_event_source_signal_dispatch,
-	wl_event_source_signal_remove
+	wl_event_source_signal_remove,
+	wl_event_source_generic_destroy
 };
 
 WL_EXPORT struct wl_event_source *
@@ -297,7 +305,7 @@ wl_event_loop_add_signal(struct wl_event_loop *loop,
 	struct epoll_event ep;
 	sigset_t mask;
 
-	source = malloc(sizeof *source);
+	source = calloc(1, sizeof *source);
 	if (source == NULL)
 		return NULL;
 
@@ -337,17 +345,10 @@ struct wl_event_source_idle {
 	wl_event_loop_idle_func_t func;
 };
 
-static int
-wl_event_source_idle_remove(struct wl_event_source *source)
-{
-	free(source);
-
-	return 0;
-}
-
 struct wl_event_source_interface idle_source_interface = {
 	NULL,
-	wl_event_source_idle_remove
+	NULL,
+	wl_event_source_generic_destroy
 };
 
 WL_EXPORT struct wl_event_source *
@@ -357,7 +358,7 @@ wl_event_loop_add_idle(struct wl_event_loop *loop,
 {
 	struct wl_event_source_idle *source;
 
-	source = malloc(sizeof *source);
+	source = calloc(1, sizeof *source);
 	if (source == NULL)
 		return NULL;
 
@@ -381,11 +382,22 @@ wl_event_source_check(struct wl_event_source *source)
 WL_EXPORT int
 wl_event_source_remove(struct wl_event_source *source)
 {
+	struct wl_event_loop *loop = source->loop;
+
 	if (!wl_list_empty(&source->link))
 		wl_list_remove(&source->link);
 
 	source->interface->remove(source);
 
+	if (loop->dispatching) {
+		source->destroy = 1;
+
+		if (!wl_list_empty(&source->link))
+			wl_list_remove(&source->link);
+		wl_event_source_check(source);
+	} else
+		source->interface->destroy(source);
+
 	return 0;
 }
 
@@ -425,8 +437,13 @@ post_dispatch_check(struct wl_event_loop *loop)
 
 	ep.events = 0;
 	n = 0;
-	wl_list_for_each_safe(source, next, &loop->check_list, link)
-		n += source->interface->dispatch(source, &ep);
+	wl_list_for_each_safe(source, next, &loop->check_list, link) {
+		if (source->destroy) {
+			wl_list_remove(&source->link);
+			source->interface->destroy(source);
+		} else
+			n += source->interface->dispatch(source, &ep);
+	}
 
 	return n;
 }
@@ -456,11 +473,15 @@ wl_event_loop_dispatch(struct wl_event_loop *loop, int timeout)
 	count = epoll_wait(loop->epoll_fd, ep, ARRAY_LENGTH(ep), timeout);
 	if (count < 0)
 		return -1;
+
+	loop->dispatching = 1;
 	n = 0;
 	for (i = 0; i < count; i++) {
 		source = ep[i].data.ptr;
-		n += source->interface->dispatch(source, &ep[i]);
+		if (!source->destroy)
+			n += source->interface->dispatch(source, &ep[i]);
 	}
+	loop->dispatching = 0;
 
 	while (n > 0)
 		n = post_dispatch_check(loop);
-- 
1.7.5.4