[Yanel-dev] Concurrent Read Write Locks

[Michael Wechner]

Hi Balz

I remember that you once suggested how we should improve concurrent 
read/write operations, but
unfortunately I cannot find your email anymore.

I think the behaviour should be as follows:

- Concurrent read operations do not block each other
- If a thread wants to write, then it first needs to wait until all 
current read operations have finished
- A write operation blocks new read requests until the writing has finished

It seems to me the following articles describe the solution quite nicely

http://www.javalobby.org/java/forums/t45090.html
http://tutorials.jenkov.com/java-concurrency/read-write-locks.html

WDYT?

As an alternative we could also implement the functionality, that if a 
repository has revisions enabled and
if revisions are actually being created, that the read process always 
accesses the most recent revision, which
would normally be the same as accessing the actuall node. Of course the 
creation of the revision would also have to be locked.

Thanks

Michael