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Re: [Nmh-workers] Locking (specifically, sequences)
From: |
Ken Hornstein |
Subject: |
Re: [Nmh-workers] Locking (specifically, sequences) |
Date: |
Sun, 10 Mar 2013 13:04:26 -0400 |
>> - The "complex" case, where the sequence file could
>> potentially be changed from the time that it's first
>> read until the sequence file needs to be manipulated.
>> "inc" is an example; "pick" is another.
>
>Is sortm in the same category as folder -pack?
Yeah, I think so.
>I'm worried about something else: concurrent read/write of
>the sequences file. If two or more processes read it and
>write it concurrently, the last one to write will destroy
>everything that the other processes wrote. Locked-read-
>write will detect that, but I'm not sure we can always
>correct it. I don't have a concrete example of where we
>can't, but it feels analogous to a merge conflict.
AFAICT, if you reread the sequences file, that will solve that
problem. I cannot think of a scenario when it does not; can
you think of one that doing that will fail?
>How so? It depends what "adding" means, but I would limit
>that to just nmh commands that can add a new message. I
>think that's inc, refile, rcvstore, burst, and thing that
>fcc's (comp, dist, forw, repl, mhmail). And I don't think
>they'll overwrite a message that any other, even non-nmh,
>program had created.
Programs that use folder_addmsg() are safe to run concurrently.
inc does not.
--Ken
- Re: [Nmh-workers] Locking (specifically, sequences), (continued)
- Re: [Nmh-workers] Locking (specifically, sequences), Valdis . Kletnieks, 2013/03/12
- Re: [Nmh-workers] Locking (specifically, sequences), Ken Hornstein, 2013/03/12
- Re: [Nmh-workers] Locking (specifically, sequences), Valdis . Kletnieks, 2013/03/12
- Re: [Nmh-workers] Locking (specifically, sequences), Lyndon Nerenberg, 2013/03/12
- Re: [Nmh-workers] Locking (specifically, sequences), Lyndon Nerenberg, 2013/03/11
- Re: [Nmh-workers] Locking (specifically, sequences), Ken Hornstein, 2013/03/11
- Re: [Nmh-workers] Locking (specifically, sequences), Lyndon Nerenberg, 2013/03/11
- Re: [Nmh-workers] Locking (specifically, sequences), Ralph Corderoy, 2013/03/10
- Re: [Nmh-workers] Locking (specifically, sequences), Ken Hornstein, 2013/03/10
Re: [Nmh-workers] Locking (specifically, sequences), David Levine, 2013/03/10
- Re: [Nmh-workers] Locking (specifically, sequences),
Ken Hornstein <=
Re: [Nmh-workers] Locking (specifically, sequences), David Levine, 2013/03/10
Re: [Nmh-workers] Locking (specifically, sequences), David Levine, 2013/03/10