GroupHost::running() would sometimes cause plugins to get terminated
prematurely when connecting to another plugin's group host process since
the plugin's own group host process has exited.
This is a pretty huge change that will be important for being able to
handle nested or mutually recursive `dispatch()` and `audioMaster()`
calls. This sadly all had to be done in a single commit, so here's a
summary:
- `src/common/sockets.h:Sockets` contains all sockets on both the plugin
and the Wine host side, and is used to both listen on and connect to
the sockets.
- Sockets and other temporary files respect `$XDG_RUNTIME_DIR` instead
of being dumped in `/tmp`.
- All sockets now have a unique endpoint in
`/run/user/<uid>/yabridge-<plugin_name>-<random_id>/`. This is
important for when we want to have multiple socket connections for
handling `dispatch()` and `audioMaster()`.
- Because of the above, we no longer clean up the socket endpoint files
after the connection gets established during initialization. Instead
we'll remove the socket base directory when shutting down.
As per Boost.Asio's manual, an explicit `socket.shutdown()` is needed
before calling `close()`. For some reason this worked fine in almost
every situation, but when hosting both a plugin hosted within a group
host process and a normal individually hosted plugin within a single
process, and then removing those two plugins in order, the
`host_vst_dispatch` socket of the first plugin never got closed. This
would hang the entire shutdown sequence to hang on the
`dispatch_handler` jthread.
First discovered in #45
Boost.Process's `boost::process::environment::at` throws when the
environment variable does not exist, as opposed to `operator[]` which
falls back to an empty value.
This cleans up the PluginBridge significantly by getting rid of all
fields and handling that was only needed for connecting to plugin
groups. This was also the last thing I wanted to refactor before
releasing the plugin groups feature with yabridge 1.2.
Robbert van der Helm