This internally calls sd_bus_open(), which automatically selects the
system or session bus connection based on the presence and
content of a DBUS_STARTER_BUS_TYPE environment variable and
whether the calling process has root privileges.
This option is very helpful when creating services and clients that will use the system bus in production, but connect to a session
for testing.
Additional changes:
* Removed assertions null-checking make_unique() return values.
make_unique() calls new, and new is expected to throw or abort
on failure, making the assertions unhelpful.
* Corrected a typo in the ClosesAndUnrefsBusWhenDestructed
unit test for the system bus (tested the wrong function).
The underlying bus was thread_local, but the design assumption that Variants built on top of that instance won't outlive the thread was incorrect. In stress tests, Variants were moved (and this is completely legal) to a different thread.
Introduce mock of sdbus library through extracting its interface. Set up unit tests of Connection class through injection of sdbusMock to constructor. Clients of Connections class should use fabrics instead.
* Add preliminary changes for async server methods
* Refactor the Message concept and break it into distinctive types
* Continue working on async server methods (high-level API mainly)
* Continue developing support for async server
* Finishing async server methods
* Finishing async server methods (fixing tests & cleaning up)
* A little code cleaning
* Add unit tests for type traits of free functions
* Support for generating async server methods in stub headers
* Update ChangeLog for v0.3.0
* Update the tutorial with how to use async server-side methods
* Update the TOC in sdbus-c++ tutorial
* Update numbering in TOC
* Remove unnecessary code
* Final cleanups
