Type=idle is much like Type=simple, however between the fork() and the
exec() in the child we wait until PID 1 informs us that no jobs are
left.
This is mostly a cosmetic fix to make gettys appear only after all boot
output is finished and complete.
Note that this does not impact the normal job logic as we do not delay
the completion of any jobs. We just delay the invocation of the actual
binary, and only for services that otherwise would be of Type=simple.
Recursion is unnecessary, because we're deleting all transaction jobs
anyway. And the recursive deletion produces debug messages that are
pointless in transaction abort.
A transaction can be acyclic, but when it's added to installed jobs,
a cycle may result.
transaction_verify_order_one() attempts to detect these cases, but it
fails because the installed jobs often have the exact generation number
that makes them look as if they were walked already.
Fix it by resetting the generation numbers of all installed jobs before
detecting cycles.
An alternative fix could be to add the generation counter to the
Manager and use it instead of starting always from 1 in
transaction_activate(). But I prefer not having to worry about it
wrapping around.
The functions looked complicated with the nested loops with breaks,
continues, and "while (again)".
Here using goto actually makes them easier to understand.
Also correcting the comment about redundant jobs.
While having a Requires= dependency between units, the dependency is started
automatically on "systemctl start", but it's not started on "systemctl
restart".
JOB_RESTART jobs did not pull the dependencies for starting into the
transaction.
https://bugzilla.redhat.com/show_bug.cgi?id=802770
Note that the other bug noted in comment #2 has been fixed already by avoiding
the deletion of anchor jobs.
Previously transactions could reference installed jobs. It made some issues
difficult to fix.
This sets new rules for jobs:
A job cannot be both a member of a transaction and installed. When jobs are
created, they are linked to a transaction. The whole transaction is constructed
(with merging of jobs within, etc.). When it's complete, all the jobs are
unlinked from it one by one and let to install themselves. It is during the
installation when merging with previously installed jobs (from older
transactions) is contemplated.
Merging with installed jobs has different rules than merging within a
transaction:
- An installed conflicting job gets cancelled. It cannot be simply deleted,
because someone might be waiting for its completion on DBus.
- An installed, but still waiting, job can be safely merged into.
- An installed and running job can be tricky. For some job types it is safe to
just merge. For the other types we merge anyway, but put the job back into
JOB_WAITING to allow it to run again. This may be suboptimal, but it is not
currently possible to have more than one installed job for a unit.
Note this also fixes a bug where the anchor job could be deleted during merging
within the transaction.
Do not attempt to optimize away the job creation by refering to installed jobs.
We do not want to disturb installed jobs until commiting the transaction.
(A later patch to job merging will make the separation of transaction jobs and
installed jobs complete.)
manager.c takes care of the main loop, unit management, signal handling, ...
transaction.c computes transactions.
After split:
manager.c: 65 KB
transaction.c: 40 KB
