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lib/Bio/EnsEMBL/Utils/Cache.pm  view on Meta::CPAN

that key/value pair has an entry time associated with it, and 
as the cache fills up, those members of the cache that are
the oldest are removed to make room for new entries.

So, the cache only "remembers" the last written entries, up to the 
size of the cache.  This can be especially useful if you access 
great amounts of data, but only access a minority of the data a 
majority of the time. 

The implementation is a hash, for quick lookups, 
overlaying a doubly linked list for quick insertion and deletion.
On a WinNT PII 300, writes to the hash were done at a rate 
3100 per second, and reads from the hash at 6300 per second.   
Work has been done to optimize refreshing cache entries that are 
frequently read from, code like $cache{entry}, which moves the 
entry to the end of the linked list internally.

=cut

sub TIEHASH {
    my($class, $max_count, $options) = @_;