[jbosscache-dev] Fqns and immutability

Related to the "Fqns-as-strings" discussion, we assume that all Fqns are immutable. I.e., they have no mutators and when we peek() at their elements, we get an immutable collection. But this does not mean that Fqns which are equal point to the same object though. For example, assertSame(Fqn.fromString("/stuff"), Fqn.fromString("/stuff")) fails even though assertEquals(Fqn.fromString("/stuff"), Fqn.fromString("/stuff")) passes. The question to ask is, should the Fqn constructors be made private (or protected), forcing users to use factory methods like Fqn.fromString(String s) and Fqn.fromObjects(Object... objects) and Fqn.fromObjects(Fqn base, Object... objects) so that these factory methods can maintain references to existing Fqns (perhaps in a weak map so they can be gc'd when no longer referenced) and reuse these if possible rather than construction all the time? This was prompted by my running some profiling tests on 2.0.0.BETA1 and found that almost 6% of the time spent (only on a particular test - so not a generic comment) was spent on Fqn construction. And quite often this was the same Fqn. Thoughts? -- Manik Surtani Lead, JBoss Cache JBoss, a division of Red Hat Email: manik(a)jboss.org Telephone: +44 7786 702 706 MSN: manik(a)surtani.org Yahoo/AIM/Skype: maniksurtani