l0co created COLLECTIONS-469:
--------------------------------
Summary: PassiveExpiringMap performance improvemend and refreshing
policy
Key: COLLECTIONS-469
URL: https://issues.apache.org/jira/browse/COLLECTIONS-469
Project: Commons Collections
Issue Type: New Feature
Components: Map
Affects Versions: 4.0-beta-1
Reporter: l0co
Priority: Minor
A copy from COLLECTIONS-467.
Two remarks about current trunk implementation of PassiveExpiringMap.
You should additionally keep the value of the next element timeout (the
youngest timeout) in object field, so that you don't need to iterate through
whole map to find elements for expiration on each call. It improves performance
by calculating only simple if for most cases:
{code}
public class PassiveExpiringMap {
long youngestTimeoutMs = 0; // assert to have next timeout time for youngest
element here always, or 0 if map is empty
private void removeAllExpired(final long now) {
if (youngestTimeoutMs>0 && youngestTimeoutMs<=now) {
// do the cleanup
}
}
}
{code}
The second remark concerns the refreshing policy. As I can see there's no
refreshing policy in current implementation, there should be at last two
policies: NoRefresh (working as the current) and RefreshOnHit - which updates
element expiration time when the element is "hit" (eg. by get()), so that the
map always removes the least used resources.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
