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module-rtp: Replace state_changed callbacks

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The state_changed callbacks fulfill multiple roles, which is both a problem
regarding separation of concerns and regarding code clarity. De facto,
these callbacks cover error reporting, opening connections, and closing
connection, all in one, depending on a state that is arguably an internal
stream detail. The code in these callbacks tie these internal states to
assumptions that opening/closing callbacks is directly tied to specific
state changes in a common way, which is not always true. For example,
stopping the stream may not _actually_ stop it if a background send timer
is still running.

The notion of a "state_changed" callback is also problematic because the
pw_streams that are used in rtp-sink and rtp-source also have a callback
for state changes, causing confusion.

Solve this by replacing state_changed with three new callbacks:

1. report_error : Used for reporting nonrecoverable errors to the caller.
   Note that currently, no one does such error reporting, but the feature
   does exist, so this callback is introduced to preserve said feature.
2. open_connection : Used for opening a connection. Its optional return
   value informs about success or failure.
3. close_connection : Used for opening a connection. Its optional return
   value informs about success or failure.

Importantly, these callbacks do not export any internal stream state. This
improves encapsulation, and also makes it possible to invoke these
callbacks in situations that may not neatly map to a state change. One
example could be to close the connection as part of a stream_start call
to close any connection(s) left over from a previous run. (Followup commits
will in fact introduce such measures.)
This commit is contained in:
Carlos Rafael Giani 2025-08-21 13:30:11 +02:00 • committed by Wim Taymans
parent 2f22c1d595
commit 3476e77714
6 changed files with 156 additions and 78 deletions
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74
src/modules/module-rtp-source.c
View file

@ -385,13 +385,13 @@ error:
return res;
}
static int stream_start(struct impl *impl);
static void stream_open_connection(void *data, int *result);
static void on_stream_start_retry_timer_event(void *data, uint64_t expirations)
static void on_open_connection_retry_timer_event(void *data, uint64_t expirations)
{
struct impl *impl = data;
pw_log_debug("trying again to start RTP listener after previous attempt failed with ENODEV");
stream_start(impl);
pw_log_debug("trying again to open connection after previous attempt failed with ENODEV");
stream_open_connection(impl, NULL);
}
static void destroy_stream_start_retry_timer(struct impl *impl)
@ -402,12 +402,23 @@ static void destroy_stream_start_retry_timer(struct impl *impl)
}
}
static int stream_start(struct impl *impl)
static void stream_report_error(void *data, const char *error)
{
struct impl *impl = data;
if (error) {
pw_log_error("stream error: %s", error);
pw_impl_module_schedule_destroy(impl->module);
}
}
static void stream_open_connection(void *data, int *result)
{
int res = 0;
int fd;
struct impl *impl = data;
if (impl->source != NULL)
return 0;
goto finish;
pw_log_info("starting RTP listener");
@ -431,7 +442,7 @@ static int stream_start(struct impl *impl)
struct timespec value, interval;
impl->stream_start_retry_timer = pw_loop_add_timer(impl->main_loop,
on_stream_start_retry_timer_event, impl);
on_open_connection_retry_timer_event, impl);
/* Use a 1-second retry interval. The network interfaces
* are likely to be up and running then. */
value.tv_sec = 1;
@ -445,14 +456,16 @@ static int stream_start(struct impl *impl)
/* It is important to return 0 in this case. Otherwise, the nonzero return
* value will later be propagated through the core as an error. */
return 0;
res = 0;
goto finish;
} else {
pw_log_error("failed to create socket: %m");
/* If ENODEV was returned earlier, and the stream_start_retry_timer
* was consequently created, but then a non-ENODEV error occurred,
* the timer must be stopped and removed. */
destroy_stream_start_retry_timer(impl);
return -errno;
res = -errno;
goto finish;
}
}
@ -465,13 +478,27 @@ static int stream_start(struct impl *impl)
if (impl->source == NULL) {
pw_log_error("can't create io source: %m");
close(fd);
return -errno;
res = -errno;
goto finish;
}
return 0;
finish:
if (res != 0) {
pw_log_error("failed to start RTP stream: %s", spa_strerror(res));
rtp_stream_set_error(impl->stream, res, "Can't start RTP stream");
}
if (result)
*result = res;
}
static void stream_stop(struct impl *impl)
static void stream_close_connection(void *data, int *result)
{
struct impl *impl = data;
if (result)
*result = 0;
if (!impl->source)
return;
@ -489,25 +516,6 @@ static void stream_destroy(void *d)
impl->stream = NULL;
}
static void stream_state_changed(void *data, bool started, const char *error)
{
struct impl *impl = data;
int res;
if (error) {
pw_log_error("stream error: %s", error);
pw_impl_module_schedule_destroy(impl->module);
} else if (started) {
if ((res = stream_start(impl)) < 0) {
pw_log_error("failed to start RTP stream: %s", spa_strerror(res));
rtp_stream_set_error(impl->stream, res, "Can't start RTP stream");
}
} else {
if (!impl->always_process && !impl->standby)
stream_stop(impl);
}
}
static void stream_props_changed(struct impl *impl, uint32_t id, const struct spa_pod *param)
{
struct spa_pod_object *obj = (struct spa_pod_object *)param;
@ -572,7 +580,9 @@ static void stream_param_changed(void *data, uint32_t id, const struct spa_pod *
static const struct rtp_stream_events stream_events = {
RTP_VERSION_STREAM_EVENTS,
.destroy = stream_destroy,
.state_changed = stream_state_changed,
.report_error = stream_report_error,
.open_connection = stream_open_connection,
.close_connection = stream_close_connection,
.param_changed = stream_param_changed,
};