Until now, the solution to ensure that even large messages are fully sent out has been to flush the connection queues after each sending of a message, which is likely an unnecessary call (with unnecessary cost) in vast majority of cases, and which may block the connection from doing other work until the large message is fully sent out. This was a rather quick, hacky workaround.
Now, after the sending the message we check whether it has been sent out fully or not. If not (outbound queues are non-empty), then we send a wake-up signal to the connection event loop. The event loop thread then fetches new sd-bus timeouts and events and will see that there are pending outbound messages to process, and will process them together with any other prospective pending events, until there is nothing to process (i.e., the outbound message has been fully dispatched).
This reorganizes the layers of abstraction in the sense how `Message` depends on `Connection` and vice versa. Now, `Message` has a link to the `Connection`. This replaces the shortcut link to the low-level `SdBus` interface that the `Message` kept. The interactions from `Message` now go through `Connection` which forwards them to `SdBus`. `Connection` is now a sole owner of the low-level `SdBus` interface. This allows for future changes around `SdBus` (e.g. a change from virtual functions back to non-virtual functions) without affecting the rest of the library. `Proxy`s and `Object`s can now send messages directly without having to go through `Connection`. The `Connection` no more depends on `Message` business-logic methods; it serves only as a factory for messages.
The flow for creating messages: `Proxy`/`Object` -> `Connection` -> `SdBus`
The flow for sending messages: (`Proxy`/`Object` ->) `Message` -> `Connection` -> `SdBus`
This also better reflects how dependencies are managed in the underlying sd-bus library.
Additionally, `getSdBusInterface()` methods are removed which was anyway planned, and improves the design by "Tell, don't ask" principle.
This refactoring is the necessary enabler for other upcoming improvements (regarding sending long messages, or creds refactoring, for example).
Make all the API consistent by using return_slot_t-based overloads for returning the slots to clients, and overloads without that tag for "floating" slots. floating_slot_t tag was previously added for API backwards compatibility reasons, but now is a (counter-)duplicate to the return_slot_t.
This introduces strong types for `std::string`-based D-Bus types. This facilitates safer, less error-prone and more expressive API.
What previously was `auto proxy = createProxy("org.sdbuscpp.concatenator", "/org/sdbuscpp/concatenator");` is now written like `auto proxy = createProxy(ServiceName{"org.sdbuscpp.concatenator"}, ObjectPath{"/org/sdbuscpp/concatenator"});`.
These types are:
* `ObjectPath` type for the object path (the type has been around already but now is also used consistently in sdbus-c++ API for object path strings),
* `InterfaceName` type for D-Bus interface names,
* `BusName` (and its aliases `ServiceName` and `ConnectionName`) type for bus/service/connection names,
* `MemberName` (and its aliases `MethodName`, `SignalName` and `PropertyName`) type for D-Bus method, signal and property names,
* `Signature` type for the D-Bus signature (the type has been around already but now is also used consistently in sdbus-c++ API for signature strings),
* `Error::Name` type for D-Bus error names.
This PR makes things around connection factories a little more consistent and more intuitive:
* createConnection() has been removed. One shall call more expressive createSystemConnection() instead to get a connection to the system bus.
* createDefaultBusConnection() has been renamed to createBusConnection(), so as not to be confused with libsystemd's default_bus, which is a different thing (a reusable thread-local bus).
Proxies still by default call createBusConnection() to get a connection when the connection is not provided explicitly by the caller, but now createBusConnection() does a different thing, so now the proxies connect to either session bus or system bus depending on the context (as opposed to always to system bus like before).
The integration tests were modified to use createBusConnection().
This makes D-Bus proxy signal registration more flexible, more dynamic, and less error-prone since no `finishRegistration()` call is needed. A proxy can register to a signal at any time during its lifetime, and can unregister freely by simply destroying the associated slot.
This improves the D-Bus object API registration/unregistration by making it more flexible, more dynamic, closer to sd-bus API design but still on high abstraction level, and -- most importantly -- less error-prone since no `finishRegistration()` call is needed anymore.
sd_bus_match_signal() is more convenient than more general sd_bus_add_match() for signal registration, and requires less code on our side. Plus, systemd of at least v238 is required for sdbus-c++ v2, and this version already ships with sd_bus_match_signal().
Signatures of callbacks async_reply_handler, signal_handler, message_handler and property_set_callback were modified to take input message objects by value, as opposed to non-const ref.
The callee assumes ownership of the message. This API is more idiomatic, more expressive, cleaner and safer. Move semantics is used to pass messages to the callback handlers. In some cases, this also improves performance.
In case a signal arrives during the `RequestName` or `ReleaseName` D-Bus call (which is a synchronous call), the signal may not be processed immediately, which is a bug. This is solved now by waking up the event loop.
* feat: add support for direct connections
* refactor: simplify a bit, change comments, extend tests
* fix: compiler warning about unused variable
* docs: add section on direct connections to the tutorial
---------
Co-authored-by: Maksim Fedyarov <m.fedyarov@omp.ru>
Co-authored-by: Stanislav Angelovič <stanislav.angelovic@protonmail.com>
* chore: don't use systemd headers with elogind
In file included from src/VTableUtils.c:27:
src/VTableUtils.h:30:10: fatal error: 'systemd/sd-bus.h' file not found
#include <systemd/sd-bus.h>
^~~~~~~~~~~~~~~~~~
* chore: add basu support
Similar to elogind but also supported on non-Linux.
* chore(tests): permit /var/lib/machine-id on non-systemd
https://github.com/elogind/elogind/commit/84fdc0fc61c1https://git.sr.ht/~emersion/basu/commit/8324e6729231
* chore(ci): add simple freebsd job
Mainly to cover libc++ and basu.
* chore(ci): explicitly pass CMAKE_INSTALL_PREFIX
Some sdbus-cpp tests require configuring system bus. However, Linux
testing relies on writing outside of prefix in order to affect current
system bus instance instead of launching a dedicated one.
* chore(tests): respect CMAKE_INSTALL_PREFIX for system bus config
DBus isn't part of base system on BSDs, so may not use /etc for configs.
Also, testing installation failed as non-root:
$ cmake -DBUILD_TESTS=1 -DCMAKE_INSTALL_PREFIX=/tmp/sdbus-cpp_prefix -DTESTS_INSTALL_PATH=/tmp/sdbus-cpp_prefix/tests
$ cmake --build .
$ cmake --install .
[...]
CMake Error at tests/cmake_install.cmake:105 (file):
file cannot create directory: /etc/dbus-1/system.d. Maybe need
administrative privileges.
* chore(tests): temporarily skip 1 test on FreeBSD to keep CI happy
* chore(ci): run tests in freebsd job
* Add methods to initiate custom session bus connection
The new function helper `createSessionBusConnectionWithAddress` allows to create connection to session bus with custom address.
Signed-off-by: Alexander Livenets <a.livenets@gmail.com>
* feat: add support for session bus connection at custom address
Co-authored-by: Stanislav Angelovic <stanislav.angelovic@siemens.com>
fix timeout handling
* Despite what is documented in sd_bus_get_timeout(3), the timeout
returned is actually an absolute time point of Linux's CLOCK_MONOTONIC
clock. Hence, we first have to subtract the current time from the
timeout in order to get a relative time that can be passed to poll.
* For async call timeouts to reliably work, we need a way to notify the
event loop of a connection that is currently blocked waiting in poll.
I.e. assume the event loop thread entered poll with a timeout set to
T1. Afterwards, the main thread starts an async call C with a timeout
T2 < T1. In order for C to be canceled after its timeout T1 has
elapsed, we have to be able to notify the event loop so that it can
update its poll data.
Co-authored-by: Urs Ritzmann <ursritzmann@protonmail.ch>
Co-authored-by: Lukasz Marcul <lukasz.marcul@onemeter.com>
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.
Stanislav Angelovič
Stanislav Angelovic
Stanislav Angelovic
Marcel Hellwig
Jan Beich
alivenetsandStanislav Angelovic
Michal Hučko
Stanislav Angelovič
David Leeds
riuriuriu
Bruno Marchand
Jay