Better thread locking

[Paul Tomblin]

Does java have a "built-in" class to do thread locking like a database
does? I want to maintain data consistency, so if a reader is working, no
writer can start but other readers can, and if a writer is working no
readers or writers can start. Is there something like that in the class
library already? Or should I write my own?

 

[Piotr Kobzda]

Does java have a "built-in" class to do thread locking like a database
does? I want to maintain data consistency, so if a reader is working, no
writer can start but other readers can, and if a writer is working no
readers or writers can start. Is there something like that in the class
library already? Or should I write my own?

Look at java.util.concurrent.locks classes. In particular ReadWriteLock
may appear useful for you.


piotr

 

[Paul Tomblin]

Look at java.util.concurrent.locks classes. In particular ReadWriteLock
may appear useful for you.

Is that in Java 1.5? I can't find it in the 1.4.2 documentation. Darn,
that means I can't use it yet (we've got one more release with the 1.5 jvm
but not using 1.5 features before we're allowed to use 1.5 for real - it's
a long story why).

Thanks for pointing that out.

 

[Daniel Dyer]

Is that in Java 1.5? I can't find it in the 1.4.2 documentation. Darn,
that means I can't use it yet (we've got one more release with the 1.5
jvm
but not using 1.5 features before we're allowed to use 1.5 for real -
it's
a long story why).

Yes it is in 5.0 and not in 1.4.2. However, it is based on Doug Lea's
util.concurrent library
(http://g.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html),
which you should be able to download and use with 1.4.2.

This link (http://dcl.mathcs.emory.edu/util/backport-util-concurrent/)
might be useful too.

Dan.