Re: [rules-users] Help with MatchesEvaluatorsDefinition that caches compiled regular expression patterns
Jared,
Your idea is actually interesting. Although, we would need to take care
of a few edge scenarios:
* The actual evaluator instance is supposed to be a "fly weight"
implementation, and as so, it might be used by multiple threads. So, first
thing, the cache map implementation must be thread safe.
* We had problems in the past when using static caches like that in
JEE/Spring/OSGi environments where you have multiple modules being loaded by
different classloaders etc. So, I think best would be to have a non-static
map for each: the StringMatchesEvaluator and the StringNotMatchesEvaluator
inner classes.
* We need a way to clean up the cache for no-longer used expressions.
Easiest way would probably be to use an LRU map as cache. The size of the
cache would probably have to be a configuration on the
KnowledgeBaseConfiguration, with a given default value. This would avoid
memory leaks.
Wanna try providing a patch for that?
Thanks,
Edson
2009/5/4 Jared Davis <sunray(a)davisprogramming.com>
I need some help placing a cache of compiled regular expressions
using the
MatchesEvaluatorsDefinition as a starting point.
Just for a test I placed a static map in the class:
static Map<String,Pattern> uglyHack = new HashMap<String,Pattern>();
Then in each of the evaluators I have different versions of:
Pattern p = uglyHack.get(value2);
if (p == null ) {
p = Pattern.compile(value2);
uglyHack.put(value2, p);
}
Matcher m = p.matcher(value1);
return m.matches();
instead of
return value1.matches( value2 );
The time elapsed to inserting objects into the workspace has been cut in
half.
.4 seconds -> .2
Has someone already done this "optimization?" Where should the cache be
stored?
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Edson Tirelli
JBoss Drools Core Development
JBoss, a division of Red Hat @ www.jboss.com
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