Merge TinyOS 2.1.1 into master.

[tinyos-2.x.git] / tos / lib / net / dhv / interfaces / DhvTrickleTimer.nc

diff --git a/tos/lib/net/dhv/interfaces/DhvTrickleTimer.nc b/tos/lib/net/dhv/interfaces/DhvTrickleTimer.nc
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+// $Id$
+/*
+ * "Copyright (c) 2006 Stanford University. All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation for any purpose, without fee, and without written
+ * agreement is hereby granted, provided that the above copyright
+ * notice, the following two paragraphs and the author appear in all
+ * copies of this software.
+ * 
+ * IN NO EVENT SHALL STANFORD UNIVERSITY BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF STANFORD UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ * 
+ * STANFORD UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE
+ * PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND STANFORD UNIVERSITY
+ * HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
+ * ENHANCEMENTS, OR MODIFICATIONS."
+ */
+
+/*
+ * 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 &gte; 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
+ * @author Thanh Dang
+ * @date   Aug 5 2009
+ */ 
+
+
+interface DhvTrickleTimer {
+
+  /**
+   * 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();
+
+  /**
+   * The trickle timer has fired. Signaled if C &gt; K.
+   */  
+  event void fired();
+
+  /**
+   * Compute the window size based on Dip's estimates
+   */
+  event uint32_t requestWindowSize();
+
+  /**
+   * Resets the timer period to H.
+   */
+  command void maxInterval();
+}