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From Perrin Harkins <>
Subject Re: Persisting data across authenticate <-> authorize ?
Date Mon, 13 Dec 2004 07:07:28 GMT
On Mon, 2004-12-13 at 00:38 -0600, David Nicol wrote:
> i may be mistaken, but i have been under the impression that berkeley and
> others get corrupted if two processes write to the same open db at the
> same time.

BerkeleyDB can use page-level or database-level locking, coordinated
through IPC.  (Not sure exactly what it uses -- semaphores?)  If you
were to disable this locking, or use DB_File instead of BerkeleyDB, you
would have problems.

> DirDB maps a tied hash to a directory, with one entry per file. 
> Hashrefs turn into
> subdirectories.  It is designed to be safe accross NFS, using directory locking
> instead of flock() when it has to.

Being safe across NFS is an interesting feature which the other file-
based ones do not have.  That means the comparisons would be to a simple
MySQL table or to Cache::Memcached.

- Perrin

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