event-loop: Add an optional post-dispatch source callout

This lets a source mark itself as ready to dispatch even though the fd
didn't trigger.   What can happen is that for the X11 socket, some other
source callback (the drm fd or a wayland client socket) can cause somebody
to do an X roundtrip (DRI2 get buffers, for example) and queue up events
in the xcb buffer.  When we get back to epoll, the X fd no longer polls
readable and we don't process those events until we get another X event.

The check callback is called after a round of dispatching and lets a source
check if it has data to dispatch and mark itself ready.  Next round of
dispatching will then process it immediately instead of blocking in
epoll_wait().

diff --git a/wayland/event-loop.c b/wayland/event-loop.c
index 8166356..4ca9111 100644 (file)
--- a/wayland/event-loop.c
+++ b/wayland/event-loop.c
@@ -38,6 +38,8 @@
 struct wl_event_loop {
        int epoll_fd;
        struct wl_list idle_list;
+       struct wl_list ready_list;
+       struct wl_list check_list;
 };
 
 struct wl_event_source_interface {
@@ -49,13 +51,15 @@ struct wl_event_source_interface {
 struct wl_event_source {
        struct wl_event_source_interface *interface;
        struct wl_event_loop *loop;
+       wl_event_source_check_func_t check;
+       struct wl_list link;
+       void *data;
 };
 
 struct wl_event_source_fd {
        struct wl_event_source base;
        int fd;
        wl_event_loop_fd_func_t func;
-       void *data;
 };
 
 static void
@@ -71,7 +75,7 @@ wl_event_source_fd_dispatch(struct wl_event_source *source,
        if (ep->events & EPOLLOUT)
                mask |= WL_EVENT_WRITEABLE;
 
-       fd_source->func(fd_source->fd, mask, fd_source->data);
+       fd_source->func(fd_source->fd, mask, fd_source->base.data);
 }
 
 static int
@@ -110,7 +114,7 @@ wl_event_loop_add_fd(struct wl_event_loop *loop,
        source->base.loop = loop;
        source->fd = fd;
        source->func = func;
-       source->data = data;
+       source->base.data = data;
 
        memset(&ep, 0, sizeof ep);
        if (mask & WL_EVENT_READABLE)
@@ -150,7 +154,6 @@ struct wl_event_source_timer {
        struct wl_event_source base;
        int fd;
        wl_event_loop_timer_func_t func;
-       void *data;
 };
 
 static void
@@ -163,7 +166,7 @@ wl_event_source_timer_dispatch(struct wl_event_source *source,
 
        read(timer_source->fd, &expires, sizeof expires);
 
-       timer_source->func(timer_source->data);
+       timer_source->func(timer_source->base.data);
 }
 
 static int
@@ -205,7 +208,7 @@ wl_event_loop_add_timer(struct wl_event_loop *loop,
        }
 
        source->func = func;
-       source->data = data;
+       source->base.data = data;
 
        memset(&ep, 0, sizeof ep);
        ep.events = EPOLLIN;
@@ -244,7 +247,6 @@ struct wl_event_source_signal {
        int fd;
        int signal_number;
        wl_event_loop_signal_func_t func;
-       void *data;
 };
 
 static void
@@ -257,7 +259,8 @@ wl_event_source_signal_dispatch(struct wl_event_source *source,
 
        read(signal_source->fd, &signal_info, sizeof signal_info);
 
-       signal_source->func(signal_source->signal_number, signal_source->data);
+       signal_source->func(signal_source->signal_number,
+                           signal_source->base.data);
 }
 
 static int
@@ -305,7 +308,7 @@ wl_event_loop_add_signal(struct wl_event_loop *loop,
        sigprocmask(SIG_BLOCK, &mask, NULL);
 
        source->func = func;
-       source->data = data;
+       source->base.data = data;
 
        memset(&ep, 0, sizeof ep);
        ep.events = EPOLLIN;
@@ -322,7 +325,6 @@ wl_event_loop_add_signal(struct wl_event_loop *loop,
 
 struct wl_event_source_idle {
        struct wl_event_source base;
-       struct wl_list link;
        wl_event_loop_idle_func_t func;
        void *data;
 };
@@ -340,7 +342,7 @@ wl_event_source_idle_remove(struct wl_event_source *source)
        struct wl_event_source_idle *idle_source =
                (struct wl_event_source_idle *) source;
 
-       wl_list_remove(&idle_source->link);
+       wl_list_remove(&idle_source->base.link);
        free(source);
 
        return 0;
@@ -366,15 +368,29 @@ wl_event_loop_add_idle(struct wl_event_loop *loop,
        source->base.loop = loop;
 
        source->func = func;
-       source->data = data;
-       wl_list_insert(loop->idle_list.prev, &source->link);
+       source->base.data = data;
+       wl_list_insert(loop->idle_list.prev, &source->base.link);
 
        return &source->base;
 }
 
+WL_EXPORT void
+wl_event_source_check(struct wl_event_source *source,
+                     wl_event_source_check_func_t check)
+{
+       source->check = check;
+       if (check)
+               wl_list_insert(source->loop->check_list.prev, &source->link);
+       else
+               wl_list_remove(&source->link);
+}
+
 WL_EXPORT int
 wl_event_source_remove(struct wl_event_source *source)
 {
+       if (source->check)
+               wl_list_remove(&source->link);
+
        source->interface->remove(source);
 
        return 0;
@@ -395,6 +411,8 @@ wl_event_loop_create(void)
                return NULL;
        }
        wl_list_init(&loop->idle_list);
+       wl_list_init(&loop->ready_list);
+       wl_list_init(&loop->check_list);
 
        return loop;
 }
@@ -410,14 +428,22 @@ WL_EXPORT int
 wl_event_loop_dispatch(struct wl_event_loop *loop, int timeout)
 {
        struct epoll_event ep[32];
-       struct wl_event_source *source;
+       struct wl_event_source *source, *next;
        struct wl_event_source_idle *idle;
        int i, count;
 
+       ep[0].events = 0;
+       while (!wl_list_empty(&loop->ready_list)) {
+               source = container_of(loop->ready_list.next,
+                                     struct wl_event_source, link);
+               wl_list_remove(&source->link);
+               wl_list_insert(loop->check_list.prev, &source->link);
+               source->interface->dispatch(source, &ep[0]);
+       }
+
        count = epoll_wait(loop->epoll_fd, ep, ARRAY_LENGTH(ep), timeout);
        if (count < 0)
                return -1;
-
        for (i = 0; i < count; i++) {
                source = ep[i].data.ptr;
                source->interface->dispatch(source, &ep[i]);
@@ -425,12 +451,19 @@ wl_event_loop_dispatch(struct wl_event_loop *loop, int timeout)
 
        while (!wl_list_empty(&loop->idle_list)) {
                idle = container_of(loop->idle_list.next,
-                                     struct wl_event_source_idle, link);
-               wl_list_remove(&idle->link);
+                                   struct wl_event_source_idle, base.link);
+               wl_list_remove(&idle->base.link);
                idle->func(idle->data);
                free(idle);
        }
 
+       wl_list_for_each_safe(source, next, &loop->check_list, link) {
+               if (source->check(source, source->data)) {
+                       wl_list_remove(&source->link);
+                       wl_list_insert(loop->ready_list.prev, &source->link);
+               }
+       }
+               
        return 0;
 }
 

diff --git a/wayland/wayland-server.h b/wayland/wayland-server.h
index d80ca32..09ffcd1 100644 (file)
--- a/wayland/wayland-server.h
+++ b/wayland/wayland-server.h
@@ -38,6 +38,8 @@ enum {
 
 struct wl_event_loop;
 struct wl_event_source;
+typedef int (*wl_event_source_check_func_t)(struct wl_event_source *source,
+                                           void *data);
 typedef void (*wl_event_loop_fd_func_t)(int fd, uint32_t mask, void *data);
 typedef void (*wl_event_loop_timer_func_t)(void *data);
 typedef void (*wl_event_loop_signal_func_t)(int signal_number, void *data);
@@ -62,6 +64,8 @@ wl_event_loop_add_signal(struct wl_event_loop *loop,
 int wl_event_source_timer_update(struct wl_event_source *source,
                                 int ms_delay);
 int wl_event_source_remove(struct wl_event_source *source);
+void wl_event_source_check(struct wl_event_source *source,
+                          wl_event_source_check_func_t check);
 
 
 int wl_event_loop_dispatch(struct wl_event_loop *loop, int timeout);