Re: Synchronization in java.util.Collections

[Eric Blake]

Dalibor Topic wrote:
> Hi,
>
> I've looked over Classpath's implementation of
> synchronized* methods in java.util.Collections, and I
> don't understand why the synchronized wrapper classes
> sync on their own specific mutex field instead of
> syncing on themselves?
>
> i.e. why not have all the wrapper methods synchronized
> and drop the mutex field? That's how kaffe does it.

They sync on the specified mutex so iterators (which are different 
instances) can sync on the same mutex.  It is also essential for 
correctly implementing things like Map.subMap(), where the sub-map must 
synchronize on the original map.

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Eric Blake             address@hidden
  BYU student, free software programmer