Support WaitStrategy.randomExponentialWait() #28
Description
A combination between randomWait() and exponentialWait(), as described in http://en.wikipedia.org/wiki/Exponential_backoff , where the exponential wait time is used as the random range.
This is how I do it:
@Immutable
private static final class RandomExponentialWaitStrategy implements WaitStrategy {
private static final Random RANDOM = new Random();
private final long multiplier;
private final long maximumWait;
public RandomExponentialWaitStrategy(long multiplier,
long maximumWait) {
Preconditions.checkArgument(multiplier > 0L, "multiplier must be > 0 but is %d", multiplier);
Preconditions.checkArgument(maximumWait >= 0L, "maximumWait must be >= 0 but is %d", maximumWait);
Preconditions.checkArgument(multiplier < maximumWait, "multiplier must be < maximumWait but is %d", multiplier);
this.multiplier = multiplier;
this.maximumWait = maximumWait;
}
@Override
public long computeSleepTime(int previousAttemptNumber, long delaySinceFirstAttemptInMillis) {
long upperExp = Math.round(Math.pow(2, previousAttemptNumber));
long exp = Math.abs(RANDOM.nextLong()) % upperExp;
long result = Math.round(multiplier * exp);
if (result > maximumWait) {
result = maximumWait;
}
return result >= 0L ? result : 0L;
}
}