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// $Id: TrickleTimer.nc,v 1.5 2010-06-29 22:07:47 scipio Exp $
/*
* Copyright (c) 2006 Stanford University. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
* - Neither the name of the copyright holder nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* A network trickle timer. A trickle timer has a period in the range
* [L, H]. After firing, the period is doubled, up to H. If the period
* is P, then the timer is scheduled to fire in the interval [0.5P, P]
* (the second half of a period). The period can be reset to L (the
* smallest period, and therefore the highest frequency).
*
* The timer may be suppressed. If a user of the interface has heard
* enough packets from other nodes that indicate its transmitting a
* packet would be unncessarily redundant, then the timer does not
* fire. The timer has a constant K and a counter C. If C >e; K, then
* the timer does not fire. When an interval ends, C is reset to 0.
* Calling <tt>incrementCounter</tt> increments C by one.
*
* For details, refer to Levis et al., "A Self-Regulating Algorithm
* for Code Maintenance and Propagation in Wireless Sensor Networks,"
* NSDI 2004. The component providing this interface defines the
* constants L, H, and K.
*
* @author Philip Levis
* @date Jan 7 2006
*/
interface TrickleTimer {
/**
* Start the trickle timer. At boot, the timer period is its maximum
* value (H). If a protocol requires starting at the minimum value
* (e.g., fast start), then it should call <tt>reset</tt> before
* <tt>start</tt>.
*
* @return error_t SUCCESS if the timer was started, EBUSY if it is already
* running, and FAIL otherwise.
*/
command error_t start();
/**
* Stop the trickle timer. This call sets the timer period to H and
* C to 0.
*/
command void stop();
/**
* Reset the timer period to L. If called while the timer is running,
* then a new interval (of length L) begins immediately.
*/
command void reset();
/**
* Increment the counter C. When an interval ends, C is set to 0.
*/
command void incrementCounter();
/**
* The trickle timer has fired. Signaled if C > K.
*/
event void fired();
}
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