.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_cache.3[7.0] Mon Jul 19 18:19:37 1993 andy@cs.tu-berlin.de frozen $
..
.TH af_cache 3 "Mon Jul 19 18:19:37 1993" "AtFS-1.71" "Attribute Filesystem (AtFS)"
.SH NAME
af_savecache, af_cachesize \- AtFS derived object cache handling
.SH SYNOPSIS
#include <atfs.h>
.sp
int af_savecache (Af_key *busyAso, Af_key* cachedAso, char *attr, int mode)
.sp
int af_cachesize (char path, int totalMax, int maxPerName, int maxPerGivenAttr);
.sp
.SH DESCRIPTION
\fIaf_savecache\fP copies a busy attributed software object
(\fIbusyAso\fP) to a derived object cache. A key for the resulting
cached ASO is returned in the buffer \fIcachedAso\fP.
Derived object caches are intended to hold derived 
objects that can be reproduced at any time. Reproducibility is
important, because cached ASOs may be deleted automatically due to
storage limitations for derived object caches.
A cache allows a certain number of versions per name (see function
af_cachesize described below) to be stored. When this number is
reached, each time a new version arrives, the oldest version (access
date) gets cleaned out.
.LP
The strategy of cleaning out old versions when space is needed for new
ones is influenced by the \fIattr\fP argument. When this is given
af_savecache searches for cached versions (with the same name as
the new one) carrying the given attribute. If it finds one or more
such versions, the oldest (access date) of them will be eliminated.
.LP
The \fImode\fP argument may have one of the following values
.TP 3c
AF_STORE_COMPLETE
(default) The cached file is stored unmodified.
.TP
AF_STORE_COMPRESSED
The cached file will be stored in a compressed format.
.LP
ASOs that are saved in derived object caches do not
automatically get a version number. By means of \fIaf_svnum\fP (manual
page af_version(3)) you can attach any version number to an ASO stored
in a derived object cache.
.LP
\fIaf_cachesize\fP defines the size strategy of the cache in directory
\fIpath\fP. It sets the maximum cache size for the whole directory
(\fItotalMax\fP), the maximum number of versions per name
(\fImaxPerName\fP), and the number of versions allowed simultaneously
carrying the elimination attribute (see before). A value less or equal
zero given for any of the arguments of af_cachesize will cause this
argument to be ignored.
.SH DIAGNOSTICS
Upon error, \-1 is returned and \fIaf_errno\fP is set to the
corresponding error number.
.SH BUGS
Compression of cached files (mode AF_STORE_COMPRESSED) is not yet
supported.
.LP
af_cachesize cannot shrink derived object caches yet. Values given
must be greater or equal the prevoius size.