On 20.02.2018 14:30, Raman Shishniou wrote:
On 02/20/2018 03:11 PM, Georg Chini wrote:
On 19.02.2018 16:01, Raman Shyshniou wrote:
Currently the pipe-source will remain running even if no
writer is connected and therefore no data is produced.
This patch adds the autosuspend=<bool> option to prevent this.
Source will stay suspended if no writer is connected.
This option is enabled by default.
---
src/modules/module-pipe-source.c | 279
++++++++++++++++++++++++++++++---------
1 file changed, 215 insertions(+), 64 deletions(-)
+
for (;;) {
int ret;
- struct pollfd *pollfd;
- pollfd = pa_rtpoll_item_get_pollfd(u->rtpoll_item, NULL);
+ if (chunk.length) {
+ /* We have a pending data, let's stop polling pipe.
+ * Setting up pollfd->events = 0 is not enough to stop
+ * POLLHUP spam if all writers are closed pipe.
+ * We need to stop polling pipe completely */
+ if (rtpoll_item) {
+ pa_rtpoll_item_free(rtpoll_item);
+ rtpoll_item = NULL;
+ }
+ } else {
+ /* We have no pending data, let's start polling pipe */
+ if (rtpoll_item == NULL) {
+ rtpoll_item = pa_rtpoll_item_new(u->rtpoll, PA_RTPOLL_NEVER,
1);
+ pollfd = pa_rtpoll_item_get_pollfd(rtpoll_item, NULL);
+ pollfd->events = POLLIN;
+ pollfd->fd = u->fd;
+ }
+ }
Why do you need to do that? As in your previous patches you
open the pipe for writing if all writers are disconnected, which
should stop POLLHUP's.
This patch tries to be platform-independent.
Unfortunately not all platforms set POLLHUP when a writer closed pipe.
Well, all platforms either set POLLIN or POLLHUP. If you have POLLHUP,
you know the pipe was closed. If you have POLLIN and l = 0 on your
read, you also know the pipe was closed.
Then you open your corkfd and stop the POLLHUP/POLLIN.
So why do you have to stop polling completely? When the next
POLLIN comes, you know that data has been written and POLLHUP
can no longer happen.
Moreover, when POLLHUP was set there may be data in pipe that must be read
before suspend. Linux sets POLLIN in that case. Freebsd and macos sets
POLLIN|POLLHUP even if no any data in pipe, but no writers left. Some platforms
do not set POLLHUP at all. So do read() and check it return 0 must be the only
condition to suspend source and open pipe for writing.
Yes, I agree, see above, but I still don't understand why you stop polling.
Also it cover cases when source suspended by user - we read data from pipe,
send resume, but source stays suspended. We must stop polling pipe, but
pollfd->events = 0 is not enough. If the writer make a open-write-close
while source stays suspended we will get endless POLLHUPs
I think this could be covered differently. You can set a flag "is_suspended"
when you have suspended the source because the writer disconnected.
Then you can do something like
if (SOURCE_IS_OPENED(source) || is_suspended) {
if (!is_suspended && u->corkfd >= 0)
close pipe for writing
...
} else if (u->corkfd < 0)
open pipe for writing
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