LoopBufferTest.java

interface LoopBuffer {
	int push(int insert);
}

class ArrayLoopBuffer implements LoopBuffer {

	private int[] buf;
	private int index = 0;

	public ArrayLoopBuffer(int size) {
		buf = new int[size];
	}

	@Override
	public int push(int insert) {
		int out = buf[index];
		buf[index] = insert;
		index = (index + 1) % buf.length;
		return out;
	}

}

class LinkedLoopBuffer implements LoopBuffer {

	private Node current;

	public LinkedLoopBuffer(int size) {
		current = new Node(null);
		Node last = current;
		for (int i=1; i < size; i++) {
			last = new Node(last);
		}
		current.next = last;
	}

	@Override
	public int push(int insert) {
		int out = current.value;
		current.value = insert;
		current = current.next;
		return out;
	}

	private class Node {
		
		private int value;
		private Node next;

		private Node(Node next) {
			this.next = next;
		}

	}

}


public class LoopBufferTest {

	public static final int INSERTION_TEST_LENGTH = 1000;
	public static final int INSERTION_TEST_CYCLES = 100000000;
	public static final int CREATION_TEST_CYCLES = 1000000;
	public static final int CREATION_TEST_LENGTH = 1000;

	public static void main(String[] args) {
		long start;

		start = System.currentTimeMillis();
		for (int i=0; i < CREATION_TEST_CYCLES; i++) {
			new ArrayLoopBuffer(CREATION_TEST_LENGTH);
		}
		System.out.println("ALB creation time: " + (System.currentTimeMillis() - start));

		start = System.currentTimeMillis();
		for (int i=0; i < CREATION_TEST_CYCLES; i++) {
			new LinkedLoopBuffer(CREATION_TEST_LENGTH);
		}
		System.out.println("LLB creation time: " + (System.currentTimeMillis() - start));

		LoopBuffer alb = new ArrayLoopBuffer(INSERTION_TEST_LENGTH);
		start = System.currentTimeMillis();
		for (int i=0; i < INSERTION_TEST_CYCLES; i++) {
			alb.push(i);
		}
		System.out.println("ALB insertion time: " + (System.currentTimeMillis() - start));
		
		LoopBuffer llb = new LinkedLoopBuffer(INSERTION_TEST_LENGTH);
		start = System.currentTimeMillis();
		for (int i=0; i < INSERTION_TEST_CYCLES; i++) {
			llb.push(i);
		}
		System.out.println("LLB insertion time: " + (System.currentTimeMillis() - start));
	}
	
}