For providers that don't support dynamic probing, just fall back to doing
a static one on start() to make the UI developers life easier.
This also means that the monitor doesn't need to call _can_monitor() before
calling start.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/353>
Not posting DEVICE_ADDED messages while a device provider is being
started makes things awkward for applications, as they have to call
get_devices() after starting the monitor.
This requires redundant code on the application side, and as far as
I understand also could cause race conditions, when a device gets
added between the calls to gst_device_monitor_start() and
gst_device_monitor_get_devices(), causing the application to "see"
the same device twice.
By passing NULL to `g_signal_new` instead of a marshaller, GLib will
actually internally optimize the signal (if the marshaller is available
in GLib itself) by also setting the valist marshaller. This makes the
signal emission a bit more performant than the regular marshalling,
which still needs to box into `GValue` and call libffi in case of a
generic marshaller.
Note that for custom marshallers, one would use
`g_signal_set_va_marshaller()` with the valist marshaller instead.
Thi introduces new APIs to post a `DEVICE_CHANGED` message on the
bus so the application is notifies when a device is modified. For
example, if the "defaultness" of a device was changed or any property
that can be changed at any time. Atomically changing the device
object notifying that way allow us to abtract away the internal threads.
New APIS:
- gst_message_new_device_changed
- gst_message_parse_device_changed
- gst_device_provider_device_changed
GstDeviceProvider has a started_count private variable counter,
and the gst_device_provider_start() documentation emphasizes the
importance of balancing the start and stop calls.
However, when starting a provider that is already started, the
current code will never increment the counter more than once.
So you start it twice, but it will have start_count 1, which is the
maximum value it will ever see.
Then when you stop it twice, on the 2nd stop, after decrementing the
counter in gst_device_provider_stop():
else if (provider->priv->started_count < 1) {
g_critical
("Trying to stop a GstDeviceProvider %s which is already stopped",
GST_OBJECT_NAME (provider));
and the program is killed.
Fix this by incrementing the counter when starting a device provider that
was already started.
Add methods to add/remove the providers that should be hidden by this
provider. Also make a method to get a list of hidden providers.
This makes it possible to have multiple systems monitor the same devices
and remove duplicates.
Add a property to see all devices, even duplicate ones from hidden
providers.
* GstGlobalDeviceMonitor was renamed to GstDeviceMonitor
* Expand GST_MESSAGE_DEVICE to the full enum value names
* Correct the incorrect references to the GstDeviceProvider interfaces
* Describe caps arguments for gstcheck interface
* Add missing docs for GstNetAddressMeta and its add function
* Add docs for toc helper macros
* Avoid refering to GstValueList type as done elsewhere
Fixes https://bugzilla.gnome.org/show_bug.cgi?id=732786
