Conditional code synchronization only for specific threads

Question

Assume that there are three groups of thread. lets say A,B, and C.

I want to create a code block in a method that blocking occurs between A and B type threads , C threads are allowed in all cases of the method invocation including the blocking portion.

In other words, if a A type of thread is in a blocked code portion, B is blocked but C is not blocked.

Do you have an idea if it is possible to do it? If so how this could be done?

Answer 1

You could have helper locking methods :

private final ReentrantLock mLock = new ReentrantLock();

void conditionalLock() {
    ThreadGroup group = Thread.currentThread().getThreadGroup();
    if (group.equals(groupA) || group.equals(groupB)) {
        mLock.lock();
    }
}

Edit changed/simplified condition as nicely suggested by erickson

void conditionalUnlock() {
    if (mLock.isHeldByCurrentThread()) {
        mLock.unlock();
    }
}

Then, in the method of the same class :

    conditionalLock();
    try {
        // block you want to synchronize between threads of group A & B
    } finally {
        conditionalUnlock();
    }