Bio::DB::FileCache(3)

NAME
Bio::DB::FileCache - In file cache for BioSeq objects

SYNOPSIS
  $cachedb = Bio::DB::FileCache->new($real_db);

  #
  # $real_db is a Bio::DB::RandomAccessI database
  #

  $seq = $cachedb->get_Seq_by_id('ROA1_HUMAN');

  #
  # $seq is a Bio::Seq object
  #

  # more control provided with named-parameter form

  $cachedb = Bio::DB::FileCache->new( -seqdb => $real_db,
                                      -file  => $path,
                                      -keep  => $flag,
                                    );
=head1 DESCRIPTION

This is a disk cache system which saves the objects returned by Bio::DB::RandomAccessI on disk. The disk cache grows without limit, while the process is running, but is automatically unlinked at process termination unless the -keep flag is set.

This module requires DB_File and Storable.

CONTACT
Lincoln Stein <lstein@cshl.org>

  Support
Please direct usage questions or support issues to the mailing list:

bioperl-l@bioperl.org

rather than to the module maintainer directly. Many experienced and reponsive experts will be able look at the problem and quickly address it. Please include a thorough description of the problem with code and data examples if at all possible.

  Reporting Bugs
Report bugs to the Bioperl bug tracking system to help us keep track the bugs and their resolution. Bug reports can be submitted via the web:

  http://bugzilla.open-bio.org/

APPENDIX
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _

  new
 Title   : new
 Usage   : $db = Bio::DB::FileCache->new(
                 -seqdb => $db,   # Bio::DB::RandomAccessI database
                 -file  => $path, # path to index file
                 -keep  => $flag, # don't unlink index file
          )
 Function: creates a new on-disk cache
 Returns : a Bio::DB::RandomAccessI database
 Args    : as above
 Throws  : "Must be a randomaccess database" exception
           "Could not open primary index file" exception

If no index file is specified, will create a temporary file in your system's temporary file directory. The name of this temporary file can be retrieved using file_name().

  get_Seq_by_id
 Title   : get_Seq_by_id
 Usage   : $seq = $db->get_Seq_by_id('ROA1_HUMAN')
 Function: Gets a Bio::Seq object by its name
 Returns : a Bio::Seq object
 Args    : the id (as a string) of a sequence
 Throws  : "id does not exist" exception

  get_Seq_by_acc
 Title   : get_Seq_by_acc
 Usage   : $seq = $db->get_Seq_by_acc('X77802');
 Function: Gets a Bio::Seq object by accession number
 Returns : A Bio::Seq object
 Args    : accession number (as a string)
 Throws  : "acc does not exist" exception

  seqdb
 Title   : seqdb
 Usage   : $seqdb = $db->seqdb([$seqdb])
 Function: gets/sets the Bio::DB::RandomAccessI database
 Returns : a Bio::DB::RandomAccessI database
 Args    : new sequence database (optional)
 Throws  : nothing

  file_name
 Title   : file_name
 Usage   : $path = $db->file_name([$file_name])
 Function: gets/sets the name of the cache file
 Returns : a path
 Args    : new cache file name (optional)
 Throws  : nothing

It probably isn't useful to set the cache file name after you've opened it.

  keep
 Title   : keep
 Usage   : $keep = $db->keep([$flag])
 Function: gets/sets the value of the "keep" flag
 Returns : current value
 Args    : new value (optional)
 Throws  : nothing

The keep flag will cause the index file to be unlinked when the process exits. Since on some operating systems (Unix, OS/2) the unlinking occurs during the new() call immediately after opening the file, it probably isn't safe to change this value.

  db
 Title   : db
 Usage   : $db->db
 Function: returns tied hash to index database
 Returns : a Berkeley DB tied hashref
 Args    : none
 Throws  : nothing

  flush
 Title   : flush
 Usage   : $db->flush
 Function: flushes the cache
 Returns : nothing
 Args    : none
 Throws  : nothing

  get_Seq_by_version
 Title   : get_Seq_by_version
 Usage   : $seq = $db->get_Seq_by_version('X77802.1');
 Function: Gets a Bio::Seq object by sequence version
 Returns : A Bio::Seq object
 Args    : accession.version (as a string)
 Throws  : "acc.version does not exist" exception