vespajlib/src/main/java/com/yahoo/concurrent/classlock/ClassLocking.java


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package com.yahoo.concurrent.classlock;

import java.util.HashMap;
import java.util.Map;
import java.util.function.BooleanSupplier;

/**
 * @author valerijf
 */
public class ClassLocking {
    private final Map<Class<?>, ClassLock> classLocks = new HashMap<>();

    public synchronized ClassLock lock(Class<?> clazz) {
        return lockWhile(clazz, () -> true);
    }

    public synchronized ClassLock lockWhile(Class<?> clazz, BooleanSupplier interruptCondition) {
        while(classLocks.containsKey(clazz)) {
            try {
                wait();
            } catch (InterruptedException ignored) { }
        }

        if (! interruptCondition.getAsBoolean()) {
            throw new LockInterruptException();
        }

        ClassLock classLock = new ClassLock(this, clazz);
        classLocks.put(clazz, classLock);
        return classLock;
    }

    synchronized void unlock(Class<?> clazz, ClassLock classLock) {
        if (classLock.equals(classLocks.get(clazz))) {
            classLocks.remove(clazz);
            notifyAll();
        } else {
            throw new IllegalArgumentException("Lock has already been released");
        }
    }
}