Copyright 1996-2003 John D. Polstra.
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* This product includes software developed by John D. Polstra.
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* $Id: BackoffTimer.i3.html,v 1.3 2010-04-29 17:17:57 wagner Exp $
INTERFACE BackoffTimer;
IMPORT Thread, Time;
TYPE
T <: ROOT;
A BackoffTimer.T, or backoff timer, supports timed retries through
exponential backoff with random jitter.
PROCEDURE New(min, max: Time.T;
backoff: REAL;
jitter: REAL): T;
Creates a new backoff timer with the given parameters.
Disregarding jitter for a moment, the first retry interval will be
min. Subsequent retry intervals will increase by the factor
backoff each time, until max is reached.
jitter is applied after the above calculation. It specifies the
magnitude of the random component relative to the number calculated
above. For example, a jitter of 0.1 will cause the interval to be
perturbed randomly each time by plus or minus 10 percent.
PROCEDURE Pause(bt: T);
Pause until it is time for the next retry.
PROCEDURE AlertPause(bt: T) RAISES {Thread.Alerted};
Like Pause, but alertable.
PROCEDURE Get(bt: T): Time.T;
Returns the retry interval that will be used the next time Pause or
AlertPause is called.
END BackoffTimer.