How to acquire a lock by a key

Question

What is the best way to prevent concurrent update of one record in a key-value set without locking the entire set? Semantically, I\'m looking for some kind of locking by a k

Answer 1

If the "record" you mention is a mutable object and "update" means that the object's internal state is modified without disturbing the structure of the container, then you can accomplish what you want just by locking the record object.

If however "update" means removing the record object from the container and replacing it, then you must lock then entire container to prevent other threads from seeing it in an inconsistent state.

In either case, you should be looking at the classes in the java.util.concurrent package.