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# Copyright 2024 Helmut Grohne <helmut@subdivi.de>
# SPDX-License-Identifier: GPL-3
"""Communicate with a systemd instance via dbus using dbussy."""
import asyncio
import typing
import ravel
class SystemdJobWaiter:
"""Context manager for waiting for a systemd job to complete.
Typical usage:
with SystemdJobWaiter(bus) as wait:
job = create_a_job_on(bus)
result = await wait(job)
"""
systemd_path = "/org/freedesktop/systemd1"
systemd_iface = "org.freedesktop.systemd1.Manager"
def __init__(self, bus: ravel.Connection):
self.bus = bus
self.jobs_removed: dict[str, str] = {}
self.target_job: str | None = None
self.job_done = asyncio.get_running_loop().create_future()
@ravel.signal(name="JobRemoved", in_signature="uoss")
def _on_job_removed(
self, _id: int, path: str, _unit: str, result: str
) -> None:
if self.target_job is None:
self.jobs_removed[path] = result
elif self.target_job == path:
self.job_done.set_result(result)
def __enter__(self) -> "SystemdJobWaiter":
self.bus.listen_signal(
self.systemd_path,
False,
self.systemd_iface,
"JobRemoved",
self._on_job_removed,
)
return self
async def __call__(self, job: str, timeout: int | float = 60) -> str:
assert self.target_job is None
self.target_job = job
try:
return self.jobs_removed[job]
except KeyError:
return await asyncio.wait_for(self.job_done, timeout)
def __exit__(self, *exc_info: typing.Any) -> None:
self.bus.unlisten_signal(
self.systemd_path,
False,
self.systemd_iface,
"JobRemoved",
self._on_job_removed,
)
async def start_transient_unit(
unitname: str, properties: list[tuple[str, tuple[str, typing.Any]]]
) -> None:
"""Call the StartTransientUnit dbus method on the user manager. The given
properties are tuples of property names and dbus-typed values.
"""
bus = await ravel.session_bus_async()
with SystemdJobWaiter(bus) as wait:
result = await wait(
bus["org.freedesktop.systemd1"]["/org/freedesktop/systemd1"]
.get_interface("org.freedesktop.systemd1.Manager")
.StartTransientUnit(unitname, "fail", properties, [])[0],
)
if result != "done":
raise OSError("StartTransientUnit failed: " + result)
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