.ig
 Copyright (C) 1993,1994 by the author(s).
 
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 WITHOUT ANY WARRANTY for any part of this software to work correctly
 or as described in the manuals. See the ShapeTools Public License
 for details.

 Permission is granted to use, copy, modify, or distribute any part of
 this software but only under the conditions described in the ShapeTools 
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 preserved on all copies.


Author: Andreas Lampen (Andreas.Lampen@cs.tu-berlin.de)

$Header: af_transact.3[7.0] Fri Jun 25 14:33:21 1993 andy@cs.tu-berlin.de frozen $
..
.TH af_transact 3 "Fri Jun 25 14:33:21 1993" "AtFS-1.71" "Attribute Filesystem (AtFS)"
.SH NAME
af_transaction, af_commit, af_abort \- a simple transaction mechanism for AtFS
.SH SYNOPSIS
#include <atfs.h>
.sp
int af_transaction (void)
.sp
int af_commit (void)
.sp
int af_abort (void)
.sp
.SH DESCRIPTION
These functions implement a simple transaction mechanism for AtFS.
A transaction starts with calling \fIaf_transaction\fP. All changes to
existing ASOs performed hereafter have no immediate permanent effect.
They rather get into effect, when the transaction is ended.
Calling \fIaf_commit\fP ends the transactions and causes all changes to
be saved to disk. \fIaf_abort\fP aborts the transaction without saving
the changes. These will then be discarded.
.LP
Only modification of the state of existing source ASOs will be
deferred. Creation or deletion of ASOs have immediate effect,
regardless if a transaction is in effect or not. Additionally, all
operations on derived ASOs (all operations on the derived object
cache) are not affected by the transaction.
.LP
All archive files that are to be changed when the transaction is
finished are locked until the end of the transaction.
The lock prevents all other applications to perform any modifications
on the archive file. You should make sure, that ending a transaction
should never be dependent on the successful termination of another
application (deadlock danger).
.SH DIAGNOSTICS
Upon error, \-1 is returned
and \fIaf_errno\fP is set to the corresponding error number.
.SH BUGS
Changes to the contents of busy versions have immediate effect.