Java bounded non-blocking buffer for high concurrent situation

Question

Basically I need a data structure to store the temporary chatting messages on the server side. It should be:

• bounded: because I don\'t need store too many messa

Answer 1

You can use LinkedBlockingQueue with the non-blocking methods offer (or add) and poll to access it. You can create it with a fixed capacity to make it bounded.

LinkedBlockingQueue<String> myStrings = new LinkedBlockingQueue<String>(100);
myStrings.offer("Hi!"); // returns false if limit is reached
myStrings.add("Hi, again!"); // throws exception if limit is reached
String s = myStrings.poll(); // returns null if queue is empty

Answer 2

LinkedTransferQueue is a blocking, unbounded queue that doesn't enforce strict FIFO ordering. It will only block when taking from an empty queue, but never on adding to one. You could add a soft cap to evict elements by adding either a size or read & write counters.

Depending on your requirements, you may be able to write a custom lock-free ring buffer.

Answer 3

Did you take a look at ConcurrentLinkedQueue? The page says

This implementation employs an efficient "wait-free" algorithm...

Wait-freedom is one of the strongest guarantee you can obtain....

Answer 4

You could utilize the Apache Commons CircularFifoBuffer. It meets your first and last criteria. To support concurrency, you can wrap the base buffer in it's synchronized version like so:

Buffer fifo = BufferUtils.synchronizedBuffer(new CircularFifoBuffer());

Good luck on the project.

Answer 5

You can add non-blocking behaviour to an ArrayBlockingQueue by surrounding it with a conditional offer() statement, where failure of the queue to accept the offer results in the head being dropped and the offer being re-made:

    public class LearnToQueue {


    public static void main(String[] args){
        Queue<Integer> FIFO = new ArrayBlockingQueue<Integer>(4);

        int i = 0;

        while ( i < 10 ){

            if (!FIFO.offer(i)){
            // You can pipe the head of the queue anywhere you want to
                FIFO.remove();
                FIFO.offer(i);
            }
            System.out.println(FIFO.toString());
            i++;

        }
    }

    }