Sean Whitton writes ("Bug#1125487: tag2upload service needs to be able to retry
against ftpmaster API"):
> Ian Jackson [16/Jan 12:43pm GMT] wrote:
> > I thought of a number of options for such an arrangement:
> >
> > 1. dgit-repos-server uses the self-pipe trick turning (a) into an
> > fd, so that it can be selected on. What a palaver, unless
> > there's a covnenient library we could use.
> >
> > 2. dgit rpush notifies dgit-repos-server by sending a signal to its
> > parent (!), and dgit-repos-server uses sigwait. Does perl
> > even have a convenient way to sigwait?
> >
> > 3. dgit-repos-server forks again, for littel child whose job it is to
> > proxy the commit-to-public-upload dance. That way if *that* child
> > doesn't crash, dgit-repos-server knows what the o2m protocol state
> > is.
> >
> > 4. dgit rpush writes the o2m protocol state to a file.
> > Before it starts the commit-to-public-upload dance it writes
> > UNKNOWN file. After dgit rpush exits, dgit-repos-server can read
> > this file to see if it can reuse the o2m connection. (dgit rpush
> > is very unlikely to crash during the commit-to-public-upload dance
> > unless it's because the o2m connection is in any case broken.)
> >
> > 5. Instead of modifying dgit rpush, provide a stunt wrapper for gpg.
> > This is *actually* the commitment point. But the last thing we
> > want to do is get more entangled with the gnupg CLI interface.
>
> (3) seems preferable to me.
I thought of another option:
6. dgit rpush raises SIGTTIN when it reaches the commitment point.
d-r-s sends it SIGCONT, and provides it confirmation via a
non-synchronising channel too (so that some administrator's
SIGCONT isn't taken as success). This allows d-r-s to use
waitpid WSTOPPED to collect either possible next event.
Something would need to take some extra measures to avoid leaking
stopped dgit rpush processes, because a stopped process won't die
from usually-fatal signals. For example, maybe a child process,
or timer_create(2), to send a SIGCONT after a timeout. (Doing
this in d-r-s itself is bad because what if it crashes due
to a problem talking to the manager.)
Ian.
--
Ian Jackson <[email protected]> These opinions are my own.
Pronouns: they/he. If I emailed you from @fyvzl.net or @evade.org.uk,
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