NAME

       af_savecache, af_cachesize - AtFS derived object cache handling

SYNOPSIS

       #include <atfs.h>

       int af_savecache (Af_key *busyAso, Af_key* cachedAso, char *attr, int mode)

       int af_cachesize (char path, int totalMax, int maxPerName, int maxPerGivenAttr);

DESCRIPTION

       af_savecache copies a busy attributed software object (busyAso) to a derived object cache.
       A key for the resulting cached ASO is returned in the buffer  cachedAso.   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.

       The strategy of cleaning out old versions when space is needed for new ones is  influenced
       by  the  attr 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.

       The mode argument may have one of the following values

       AF_STORE_COMPLETE
                   (default) The cached file is stored unmodified.

       AF_STORE_COMPRESSED
                   The cached file will be stored in a compressed format.

       ASOs that are saved in derived object caches do not automatically get a version number. By
       means of af_svnum (manual page af_version(3)) you can attach any version number to an  ASO
       stored in a derived object cache.

       af_cachesize defines the size strategy of the cache in directory path. It sets the maximum
       cache size for the whole directory (totalMax), the maximum number  of  versions  per  name
       (maxPerName),  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.

DIAGNOSTICS

       Upon error, -1 is returned and af_errno is set to the corresponding error number.

BUGS

       Compression of cached files (mode AF_STORE_COMPRESSED) is not yet supported.

       af_cachesize  cannot  shrink  derived  object  caches yet. Values given must be greater or
       equal the prevoius size.