eloop: allow enabling/disabling fd sources

We sometimes want to be able to enable/disable an fd-source without
allocating memory (for a short period, for instance). Therefore, introduce
two new functions to enable and disable an fd source.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

diff --git a/src/eloop.c b/src/eloop.c
index 6764d32..3bfc4d0 100644 (file)
--- a/src/eloop.c
+++ b/src/eloop.c
@@ -71,6 +71,7 @@ struct ev_fd {
        ev_fd_cb cb;
        void *data;
 
+       bool enabled;
        struct ev_eloop *loop;
 };
 
@@ -346,7 +347,7 @@ int ev_eloop_dispatch(struct ev_eloop *loop, int timeout)
 
        for (i = 0; i < count; ++i) {
                fd = ep[i].data.ptr;
-               if (!fd || !fd->cb)
+               if (!fd || !fd->cb || !fd->enabled)
                        continue;
 
                mask = 0;
@@ -358,7 +359,7 @@ int ev_eloop_dispatch(struct ev_eloop *loop, int timeout)
                        mask |= EV_ERR;
                if (ep[i].events & EPOLLHUP) {
                        mask |= EV_HUP;
-                       epoll_ctl(loop->efd, EPOLL_CTL_DEL, fd->fd, NULL);
+                       ev_fd_disable(fd);
                }
 
                fd->cb(fd, mask, fd->data);
@@ -506,6 +507,7 @@ int ev_fd_new(struct ev_fd **out, int rfd, int mask, ev_fd_cb cb, void *data)
        fd->mask = mask;
        fd->cb = cb;
        fd->data = data;
+       fd->enabled = true;
 
        *out = fd;
        return 0;
@@ -527,28 +529,44 @@ void ev_fd_unref(struct ev_fd *fd)
        free(fd);
 }
 
-bool ev_fd_is_bound(struct ev_fd *fd)
+static void fd_epoll_add(struct ev_fd *fd)
 {
-       return fd && fd->loop;
-}
+       struct epoll_event ep;
+       int ret;
 
-void ev_fd_set_cb_data(struct ev_fd *fd, ev_fd_cb cb, void *data)
-{
-       if (!fd)
+       if (!fd->loop)
                return;
 
-       fd->cb = cb;
-       fd->data = data;
+       memset(&ep, 0, sizeof(ep));
+       if (fd->mask & EV_READABLE)
+               ep.events |= EPOLLIN;
+       if (fd->mask & EV_WRITEABLE)
+               ep.events |= EPOLLOUT;
+       ep.data.ptr = fd;
+
+       ret = epoll_ctl(fd->loop->efd, EPOLL_CTL_ADD, fd->fd, &ep);
+       if (ret)
+               log_warning("cannot add fd %d to epoll set (%d): %m",
+                           fd->fd, errno);
 }
 
-void ev_fd_update(struct ev_fd *fd, int mask)
+static void fd_epoll_remove(struct ev_fd *fd)
 {
-       struct epoll_event ep;
+       int ret;
 
-       if (!fd)
+       if (!fd->loop)
                return;
 
-       fd->mask = mask;
+       ret = epoll_ctl(fd->loop->efd, EPOLL_CTL_DEL, fd->fd, NULL);
+       if (ret)
+               log_warning("cannto remote fd %d from epoll set (%d): %m",
+                           fd->fd, errno);
+}
+
+static void fd_epoll_update(struct ev_fd *fd)
+{
+       struct epoll_event ep;
+       int ret;
 
        if (!fd->loop)
                return;
@@ -560,8 +578,58 @@ void ev_fd_update(struct ev_fd *fd, int mask)
                ep.events |= EPOLLOUT;
        ep.data.ptr = fd;
 
-       if (epoll_ctl(fd->loop->efd,  EPOLL_CTL_MOD, fd->fd, &ep))
-               log_warning("cannot update epoll fd (%d): %m", errno);
+       ret = epoll_ctl(fd->loop->efd,  EPOLL_CTL_MOD, fd->fd, &ep);
+       if (ret)
+               log_warning("cannot update epoll fd %d (%d): %m",
+                           fd->fd, errno);
+}
+
+void ev_fd_enable(struct ev_fd *fd)
+{
+       if (!fd || fd->enabled)
+               return;
+
+       fd->enabled = true;
+       fd_epoll_add(fd);
+}
+
+void ev_fd_disable(struct ev_fd *fd)
+{
+       if (!fd || !fd->enabled)
+               return;
+
+       fd->enabled = false;
+       fd_epoll_remove(fd);
+}
+
+bool ev_fd_is_enabled(struct ev_fd *fd)
+{
+       return fd && fd->enabled;
+}
+
+bool ev_fd_is_bound(struct ev_fd *fd)
+{
+       return fd && fd->loop;
+}
+
+void ev_fd_set_cb_data(struct ev_fd *fd, ev_fd_cb cb, void *data)
+{
+       if (!fd)
+               return;
+
+       fd->cb = cb;
+       fd->data = data;
+}
+
+void ev_fd_update(struct ev_fd *fd, int mask)
+{
+       if (!fd)
+               return;
+
+       fd->mask = mask;
+       if (!fd->enabled)
+               return;
+       fd_epoll_update(fd);
 }
 
 int ev_eloop_new_fd(struct ev_eloop *loop, struct ev_fd **out, int rfd,
@@ -577,42 +645,25 @@ int ev_eloop_new_fd(struct ev_eloop *loop, struct ev_fd **out, int rfd,
        if (ret)
                return ret;
 
-       ret = ev_eloop_add_fd(loop, fd);
-       if (ret) {
-               ev_fd_unref(fd);
-               return ret;
-       }
-
+       ev_eloop_add_fd(loop, fd);
        ev_fd_unref(fd);
+
        *out = fd;
        return 0;
 }
 
 int ev_eloop_add_fd(struct ev_eloop *loop, struct ev_fd *fd)
 {
-       struct epoll_event ep;
-
-       if (!loop || !fd)
+       if (!loop || !fd || fd->loop)
                return -EINVAL;
 
-       if (fd->loop)
-               return -EALREADY;
-
-       memset(&ep, 0, sizeof(ep));
-       if (fd->mask & EV_READABLE)
-               ep.events |= EPOLLIN;
-       if (fd->mask & EV_WRITEABLE)
-               ep.events |= EPOLLOUT;
-       ep.data.ptr = fd;
-
-       if (epoll_ctl(loop->efd, EPOLL_CTL_ADD, fd->fd, &ep) < 0)
-               return -errno;
-
        fd->loop = loop;
-
        ev_fd_ref(fd);
        ev_eloop_ref(loop);
 
+       if (fd->enabled)
+               fd_epoll_add(fd);
+
        return 0;
 }
 
@@ -625,8 +676,8 @@ void ev_eloop_rm_fd(struct ev_fd *fd)
                return;
 
        loop = fd->loop;
-
-       epoll_ctl(loop->efd, EPOLL_CTL_DEL, fd->fd, NULL);
+       if (fd->enabled)
+               fd_epoll_remove(fd);
 
        /*
         * If we are currently dispatching events, we need to remove ourself

diff --git a/src/eloop.h b/src/eloop.h
index 776ec0c..221761b 100644 (file)
--- a/src/eloop.h
+++ b/src/eloop.h
@@ -82,6 +82,9 @@ int ev_fd_new(struct ev_fd **out, int fd, int mask, ev_fd_cb cb, void *data);
 void ev_fd_ref(struct ev_fd *fd);
 void ev_fd_unref(struct ev_fd *fd);
 
+void ev_fd_enable(struct ev_fd *fd);
+void ev_fd_disable(struct ev_fd *fd);
+bool ev_fd_is_enabled(struct ev_fd *fd);
 bool ev_fd_is_bound(struct ev_fd *fd);
 void ev_fd_set_cb_data(struct ev_fd *fd, ev_fd_cb cb, void *data);
 void ev_fd_update(struct ev_fd *fd, int mask);