Your CFLOCK eliminates the difference between the two examples.
No it doesn't - the first example is *not* thread safe. I guarantee it. We know it from experience, trust me on this one!
This is the first reasonably compelling argument for putting createObject()
and init() together, so I want to make sure I understand right.
I'll explain the thread-safety problem...
. Two requests come in about the same time - and application.foo has not yet been created/initialized.
. Thread 1 gets as far as creating foo and setting application.foo but has not yet run init().
. Thread 2 gets to the test for application.foo existing and it passes.
. Thread 2 then goes off and uses application.foo (possibly while thread 1 is initializing it).
. Thread 2 bails because application.foo was not properly initialized before use.
There are of course several solutions to this (in addition to the method chaining approach). One is to lock *outside* the first <cfif> - the downside is that every single request has to lock (and single-thread that test) which is a performance bottleneck. Another is to change the outer (and inner) tests to include application.foo.isInitialized() - the downsides are (a) extra code needs to be executed on every request and (b) you now need an additional method on foo and requires the pseudo-constructor set a flag and the init() method set a flags (added complexity).
Regards, Sean
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