Howdy,
I've been loooking carefully at what's new in wicket 1.5 and how its
concepts map to the earlier versions.
I've been particularly interested in how resource managment had been
given much care in 1.5.
One great feature is consistent resource id suffix generation. I have
however found an issue that may lead to a performace hit.
It is advised to use MessageDigestResourceVersion rather than the
default LastModifiedResourceVersion in production environments,
especially clustered ones. Thus the following code present in
application init() method:
getResourceSettings().setCachingStrategy(
new FilenameWithVersionResourceCachingStrategy(
new
MessageDigestResourceVersion()));
This however is highly ineficient as each and every access to any
resource (resource link generation, in fact) results in message digest
computation, regardless whether it is going to be sent back to the
browser or not. Lets wrap the MessageDigestResourceVersion with
CachingResourceVersion then:
getResourceSettings().setCachingStrategy(
new FilenameWithVersionResourceCachingStrategy(
new CachingResourceVersion(new
MessageDigestResourceVersion())));
Aha! Much better? Not exactly. Now the message digest will be computed
just once, and will stay in a cache for the lifetime of the
application. Whenever resource changes, the browser might be confused
to use stale cached version rather than request a new resource (Yes,
we do substitute context resources during runtime).
It'd be nice to have some IResourceVersion implementation that caches
the computed resource version for some preconfigured period of time or
recalculates it on every n-th access. Or is triggeerd by some more
complex rule.
getResourceSettings().setCachingStrategy(
new FilenameWithVersionResourceCachingStrategy(
new
UpdateableCachingResourceVersion(new
MessageDigestResourceVersion(), new Or(new AccessedMoreThan(5), new
OlderThan(30000)))));
If you find it worth putting into core, I can file a jira issue and
provide an appropriate patch.
regz,
/dd
--
/* Spelin donut mader if iz ina coment */
