Now that the necessary functions from log.h have been moved to macro.h,
we can stop including log.h in macro.h. This requires modifying source
files all over the tree to include log.h instead.
These operations might require slow I/O, and thus might block PID1's main
loop for an undeterminated amount of time. Instead of performing them
inline, fork a worker process and stash away the D-Bus message, and reply
once we get a SIGCHILD indicating they have completed. That way we don't
break compatibility and callers can continue to rely on the fact that when
they get the method reply the operation either succeeded or failed.
To keep backward compatibility, unlike reload control processes, these
are ran inside init.scope and not the target cgroup. Unlike ExecReload,
this is under our control and is not defined by the unit. This is necessary
because previously the operation also wasn't ran from the target cgroup,
so suddenly forking a copy-on-write copy of pid1 into the target cgroup
will make memory usage spike, and if there is a MemoryMax= or MemoryHigh=
set and the cgroup is already close to the limit, it will cause an OOM
kill, where previously it would have worked fine.
This is a generic implementation of a client-side logic of waiting until
a unit enters or leaves some state.
This is a more generic implementation of the WaitContext logic currently
in systemctl.c, and is supposed to replace it (a later commit does
this). It's similar to bus-wait-for-jobs.c and we probably should fold
that one into it later on.
This code is more powerful and cleaner than the WaitContext logic
however. In addition to waiting for a unit to exit this also allows us
to wait for a unit to leave the "maintainance" state.
This commit only implements the generic logic, and adds no users of it
yet.
Daan De Meyer
Mike Yuan
Luca Boccassi
David Tardon
Yu Watanabe
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Balint Reczey