Re: Non-blocking lock requests during the grace period

From: Trond Myklebust (trond.myklebust@fys.uio.no)
Date: Fri Nov 15 2002 - 15:01:21 EST

>>>>> " " == Juan Gomez <juang@us.ibm.com> writes:

> (note that F_GETLK man page does not provide EAGAIN as a
> possible error code).

Hmm....

In the Single UNIX spec, there appears to be a rather unexpected
difference between expected behaviour for lockf and fcntl here:

http://www.db.opengroup.org/cgi-bin/dbcgi?CALLER=sud2/indx.tpl&TOKEN=FIYR&TPL=sd_fileframe&dir=xsh&file=lockf

[EACCES] or [EAGAIN]
       The function argument is F_TLOCK or F_TEST and the section is already
       locked by another process.

OTOH

http://www.db.opengroup.org/cgi-bin/dbcgi?CALLER=sud2/indx.tpl&TOKEN=FIYR&TPL=sd_fileframe&dir=xsh&file=fcntl

[EACCES] or [EAGAIN]
    The cmd argument is F_SETLK, and one of the following conditions
    is true:

        * The type of lock (l_type) is shared ( F_RDLCK) or exclusive
          ( F_WRLCK), and the segment of a file to be locked is
          already exclusive locked by another process.
        * The type of lock is exclusive, and some portion of the file
          segment to be locked is already shared locked or exclusive
          locked by another process.

Cheers,
  Trond
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