Java: Synchronizing on primitives?

Question

In our system, we have a method that will do some work when it\'s called with a certain ID:

public void doWork(long id) { /* ... */ }

Now, this

Answer 1

I might be late to the game, but this solution isn't leaking any memory and you don't have to remember to do any lock releases:

Synchronizer synchronizer = new Synchronizer();

...

// first thread - acquires "lock" for accountId accAAA

synchronizer.synchronizeOn(accountId("accAAA"), () -> {
    long balance = loadBalance("accAAA")
    if (balance > 10_000) {
        decrementBalance("accAAA", 10_000)
    }
})

...

// second thread - is blocked while first thread runs (as it uses the same "lock" for accountId accAAA)

synchronizer.synchronizeOn(accountId("accAAA"), () -> {
    long balance = loadBalance("accAAA")
    if (balance > 2_000) {
        decrementBalance("accAAA", 2_000)
    }
})

...

// third thread - won't be blocked by previous threads (as it is for a different accountId)

synchronizer.synchronizeOn(accountId("accXYZ"), () -> {
    long balance = loadBalance("accXYZ")
    if (balance > 3_500) {
        decrementBalance("accXYZ", 3_500)
    }
})

to use it you just add a dependency:

compile 'com.github.matejtymes:javafixes:1.3.0'