From 527df3c84bd71113cedc7f55089c02d1c099ecad Mon Sep 17 00:00:00 2001 From: =?utf8?q?Rami=20Ylim=C3=A4ki?= Date: Tue, 22 Mar 2011 14:33:23 +0200 Subject: [PATCH] Introduce a variant of xcb_poll_for_event for examining event queue. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit In some circumstances using xcb_poll_for_event is suboptimal because it checks the connection for new events. This may lead to a lot of failed nonblocking read system calls. Signed-off-by: Rami Ylimäki Signed-off-by: Jamey Sharp --- src/xcb.h | 16 ++++++++++++++++ src/xcb_in.c | 14 ++++++++++++-- 2 files changed, 28 insertions(+), 2 deletions(-) diff --git a/src/xcb.h b/src/xcb.h index 3e61ebd..8a81bb9 100644 --- a/src/xcb.h +++ b/src/xcb.h @@ -271,6 +271,22 @@ xcb_generic_event_t *xcb_wait_for_event(xcb_connection_t *c); */ xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c); +/** + * @brief Returns the next event without reading from the connection. + * @param c: The connection to the X server. + * @return The next already queued event from the server. + * + * This is a version of xcb_poll_for_event that only examines the + * event queue for new events. The function doesn't try to read new + * events from the connection if no queued events are found. + * + * This function is useful for callers that know in advance that all + * interesting events have already been read from the connection. For + * example, callers might use xcb_wait_for_reply and be interested + * only of events that preceded a specific reply. + */ +xcb_generic_event_t *xcb_poll_for_queued_event(xcb_connection_t *c); + /** * @brief Returns the next event or error that precedes the given request. * @param c: The connection to the X server. diff --git a/src/xcb_in.c b/src/xcb_in.c index 501e719..6107065 100644 --- a/src/xcb_in.c +++ b/src/xcb_in.c @@ -535,7 +535,7 @@ xcb_generic_event_t *xcb_wait_for_event(xcb_connection_t *c) return ret; } -xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c) +static xcb_generic_event_t *poll_for_next_event(xcb_connection_t *c, int queued) { xcb_generic_event_t *ret = 0; if(!c->has_error) @@ -543,13 +543,23 @@ xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c) pthread_mutex_lock(&c->iolock); /* FIXME: follow X meets Z architecture changes. */ ret = get_event(c); - if(!ret && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */ + if(!ret && !queued && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */ ret = get_event(c); pthread_mutex_unlock(&c->iolock); } return ret; } +xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c) +{ + return poll_for_next_event(c, 0); +} + +xcb_generic_event_t *xcb_poll_for_queued_event(xcb_connection_t *c) +{ + return poll_for_next_event(c, 1); +} + static xcb_generic_event_t *get_event_until(xcb_connection_t *c, uint64_t request) { if(c->in.events && XCB_SEQUENCE_COMPARE(c->in.events->sequence, <=, request)) -- 2.34.1