CODEWITHSUNDEEP
javaconcurrencylocking
user3528733
user3528733

Reputation: 1299

Java concurrency, monitor for Lock

I am using Lock in my app and I wonder what is monitor in this case: 

public class BoundedBuffer {
    private final String[] buffer;
    private final int capacity;

    private int front;
    private int rear;
    private int count;

    private final Lock lock = new ReentrantLock();

    private final Condition notFull = lock.newCondition();
    private final Condition notEmpty = lock.newCondition();

    public BoundedBuffer(int capacity) {
        super();

        this.capacity = capacity;

        buffer = new String[capacity];
    }

    public void deposit(String data) throws InterruptedException {
        lock.lock();

        try {
            while (count == capacity) {
                notFull.await();
            }

            buffer[rear] = data;
            rear = (rear + 1) % capacity;
            count++;

            notEmpty.signal();
        } finally {
            lock.unlock();
        }
    }

In this example when invoking deposit method whole object is monitor or only lock ? This is like using synchronize(this) which lock whole instance ?

Upvotes: 2

Views: 182

Answers (1)

Zbynek Vyskovsky - kvr000
Zbynek Vyskovsky - kvr000

Reputation: 18825

Whole object doesn't have any special meaning here. Monitor means the combination of Lock and Condition so it's possible to atomically perform check and block until something happens, see wiki Monitor.

lock.lock ()is similar to synchronized keyword but Lock gives more flexibility. Among others it can create conditions which allow to notify about full/empty status and are connected to this Lock.

Upvotes: 2

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