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Add a flag for blocking read

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Not all clients need nonblocking read, so add a flag to read
in blocking mode. In that mode, events are only read from the fd when
the queue is empty.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
This commit is contained in:
Peter Hutterer 2013-07-01 15:46:23 +10:00
parent a10fc33cd8
commit f3a6b0c685
3 changed files with 14 additions and 10 deletions
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19
libevdev/libevdev.c
View file

@ -556,18 +556,21 @@ int libevdev_next_event(struct libevdev *dev, unsigned int flags, struct input_e
update_state(dev, &e);
}
/* FIXME: check for O_NONBLOCK and if not set, skip if we have an
* event in the queue from the previous read.
*/
/* FIXME: if the first event after syncing is a SYN_DROPPED, log this */
/* Always read in some more events. Best case this smoothes over a potential SYN_DROPPED,
worst case we don't read fast enough and end up with SYN_DROPPED anyway */
worst case we don't read fast enough and end up with SYN_DROPPED anyway.
Except if the fd is in blocking mode and we still have events from the last read, don't
read in any more.
*/
do {
rc = read_more_events(dev);
if (rc < 0 && rc != -EAGAIN)
goto out;
if (!(flags & LIBEVDEV_READ_BLOCKING) ||
queue_num_elements(dev) == 0) {
rc = read_more_events(dev);
if (rc < 0 && rc != -EAGAIN)
goto out;
}
if (flags & LIBEVDEV_FORCE_SYNC) {
dev->need_sync = 1;

1
libevdev/libevdev.h
View file

@ -192,6 +192,7 @@ enum EvdevReadFlags {
LIBEVDEV_FORCE_SYNC = 4, /**< Pretend the next event is a SYN_DROPPED. There is
no reason to ever use this except for
automated tests, so don't. */
LIBEVDEV_READ_BLOCKING = 8, /**< The fd is not in O_NONBLOCK and a read may block */
};
/**

4
tools/libevdev-events.c
View file

@ -145,7 +145,7 @@ main(int argc, char **argv)
goto out;
file = argv[1];
fd = open(file, O_RDONLY | O_NONBLOCK);
fd = open(file, O_RDONLY);
if (fd < 0) {
perror("Failed to open device");
goto out;
@ -170,7 +170,7 @@ main(int argc, char **argv)
do {
struct input_event ev;
rc = libevdev_next_event(dev, LIBEVDEV_READ_NORMAL, &ev);
rc = libevdev_next_event(dev, LIBEVDEV_READ_NORMAL|LIBEVDEV_READ_BLOCKING, &ev);
if (rc == 1) {
printf("::::::::::::::::::::: dropped ::::::::::::::::::::::\n");
while (rc == 1) {