import java.util.Random;

import org.junit.Test;

public class Bar {

	private static final long rate = 10L; // ten exceptions allowed
	private static final long per = 60000L; // per minute (= 12.000
											// milliseconds)
	private static long allowance = rate;
	private static long last = System.currentTimeMillis();

	@Test
	public void testThresholding() {
		// Algorithm adapted from:
		// http://stackoverflow.com/questions/667508/whats-a-good-rate-limiting-algorithm
		for (int i = 0; i < 120; i++) {
			try {
				businessMethod();
			}
			catch (RuntimeException e) {
				long time = System.currentTimeMillis();
				long passedMs = Math.max(time - last, 1);
				last = time;

				double coeff = (double) rate / (double) per;
				long increment = Math.round(passedMs * coeff);

				allowance += increment;

				System.out.printf("-----------------------------\n");
				System.out.printf("time\t\t:%d\n", time);
				System.out.printf("passed (ms)\t:%d\n", passedMs);
				System.out.printf("increment\t:%d\n", increment);
				System.out.printf("allowance\t:%d\n", allowance);

				// Uncomment this block to enable throttling to the
				// defined rate.
				// if (allowance > rate) {
				// allowance = rate; // throttle
				// }
				// System.out.printf("throttled\t:%d\n", allowance);

				if (allowance < 1) {
					System.out.println("==> too many exceptions!");
				}
				else {
					System.out.println("==> still inside the limit.");
					allowance--;
				}

			}
		}
	}

	private void businessMethod() {
		// How many percent of business calls result in an exception
		final int exceptionPercent = 10;

		System.out.println("Business method");

		int val = new Random().nextInt(101);
		int delay = new Random().nextInt(1001);
		try {
			Thread.sleep(delay);
			if (val <= exceptionPercent) {
				throw new RuntimeException("BusinessException");
			}
		}
		catch (InterruptedException e) {
			// ignore
		}
	}
}

<VirtualHost *:80>
    ServerName m.example.com

    ProxyRequests Off
    ProxyPreserveHost On

    <Proxy *>
       Order deny,allow
       Allow from all
    </Proxy>

    ProxyPass /m http://localhost:8080/example
    ProxyPassReverse /m http://localhost:8080/example

    <Location /mpo>
        Order allow,deny
        Allow from all
    </Location>

</VirtualHost>
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