1 /* 2 * Copyright (c) 2016, The OpenThread Authors. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. Neither the name of the copyright holder nor the 13 * names of its contributors may be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /** 30 * @file 31 * This file includes definitions for the trickle timer logic. 32 */ 33 34 #ifndef TRICKLE_TIMER_HPP_ 35 #define TRICKLE_TIMER_HPP_ 36 37 #include "openthread-core-config.h" 38 39 #include "common/numeric_limits.hpp" 40 #include "common/timer.hpp" 41 42 namespace ot { 43 44 /** 45 * @addtogroup core-timer-trickle 46 * 47 * @brief 48 * This module includes definitions for the trickle timer logic. 49 * 50 * @{ 51 * 52 */ 53 54 /** 55 * This class implements a trickle timer. 56 * 57 */ 58 class TrickleTimer : public TimerMilli 59 { 60 public: 61 /** 62 * This enumeration defines the modes of operation for the `TrickleTimer`. 63 * 64 */ 65 enum Mode : uint8_t 66 { 67 kModeTrickle, ///< Operate as the normal trickle logic (as per RFC 6206). 68 kModePlainTimer, ///< Operate as a plain periodic timer with random interval selected within min/max intervals. 69 }; 70 71 /** 72 * Special value for redundancy constant (aka `k`) to indicate infinity (when used, it disables trickle timer's 73 * suppression behavior, invoking the handler callback independent of number of "consistent" events). 74 * 75 */ 76 static constexpr uint16_t kInfiniteRedundancyConstant = NumericLimits<uint16_t>::kMax; 77 78 /** 79 * This function pointer is called when the timer expires (i.e., transmission should happen). 80 * 81 * @param[in] aTimer A reference to the trickle timer. 82 * 83 */ 84 typedef void (&Handler)(TrickleTimer &aTimer); 85 86 /** 87 * This constructor initializes a `TrickleTimer` instance. 88 * 89 * @param[in] aInstance A reference to the OpenThread instance. 90 * @param[in] aHandler A handler which is called when transmission should occur. 91 * 92 */ 93 TrickleTimer(Instance &aInstance, Handler aHandler); 94 95 /** 96 * This method indicates whether or not the trickle timer instance is running. 97 * 98 * @retval TRUE If the trickle timer is running. 99 * @retval FALSE If the trickle timer is not running. 100 * 101 */ IsRunning(void) const102 bool IsRunning(void) const { return TimerMilli::IsRunning(); } 103 104 /** 105 * This method gets the current operation mode of the trickle timer. 106 * 107 * @returns The current operation mode of the timer. 108 * 109 */ GetMode(void) const110 Mode GetMode(void) const { return mMode; } 111 112 /** 113 * This method starts the trickle timer. 114 * 115 * @param[in] aMode The operation mode of timer (trickle or plain periodic mode). 116 * @param[in] aIntervalMin The minimum interval for the timer in milliseconds. 117 * @param[in] aIntervalMax The maximum interval for the timer in milliseconds. 118 * @param[in] aRedundancyConstant The redundancy constant for the timer, also known as `k`. The default value 119 * is set to `kInfiniteRedundancyConstant` which disables the suppression behavior 120 * (i.e., handler is always invoked independent of number of "consistent" events). 121 * 122 */ 123 void Start(Mode aMode, 124 uint32_t aIntervalMin, 125 uint32_t aIntervalMax, 126 uint16_t aRedundancyConstant = kInfiniteRedundancyConstant); 127 128 /** 129 * This method stops the trickle timer. 130 * 131 */ Stop(void)132 void Stop(void) { TimerMilli::Stop(); } 133 134 /** 135 * This method indicates to the trickle timer a 'consistent' event. 136 * 137 * The 'consistent' events are used to control suppression behavior. The trickle timer keeps track of the number of 138 * 'consistent' events in each interval. The timer handler is invoked only if the number of `consistent` events 139 * received in the interval is less than the redundancy constant. 140 * 141 */ 142 void IndicateConsistent(void); 143 144 /** 145 * This method indicates to the trickle timer an 'inconsistent' event. 146 * 147 * Receiving an 'inconsistent' event causes the trickle timer to reset (i.e., start with interval set to the min 148 * value) unless the current interval being used is already equal to the min interval. 149 * 150 */ 151 void IndicateInconsistent(void); 152 153 private: 154 enum Phase : uint8_t 155 { 156 kBeforeRandomTime, // Trickle timer is before random time `t` in the current interval. 157 kAfterRandomTime, // Trickle timer is after random time `t` in the current interval. 158 }; 159 160 void StartNewInterval(void); 161 static void HandleTimer(Timer &aTimer); 162 void HandleTimer(void); 163 void HandleEndOfTimeInInterval(void); 164 void HandleEndOfInterval(void); 165 166 // Shadow base class `TimerMilli` methods to ensure they are hidden. StartAt(void)167 void StartAt(void) {} FireAt(void)168 void FireAt(void) {} FireAtIfEarlier(void)169 void FireAtIfEarlier(void) {} GetFireTime(void)170 void GetFireTime(void) {} 171 172 uint32_t mIntervalMin; // Minimum interval (aka `Imin`). 173 uint32_t mIntervalMax; // Maximum interval (aka `Imax`). 174 uint32_t mInterval; // Current interval (aka `I`). 175 uint32_t mTimeInInterval; // Time in interval (aka `t`). 176 uint16_t mRedundancyConstant; // Redundancy constant (aka 'k'). 177 uint16_t mCounter; // A counter for number of "consistent" transmissions (aka 'c'). 178 Handler mHandler; // Handler callback. 179 Mode mMode; // Trickle timer operation mode. 180 Phase mPhase; // Trickle timer phase (before or after time `t` in the current interval). 181 }; 182 183 /** 184 * @} 185 * 186 */ 187 188 } // namespace ot 189 190 #endif // TRICKLE_TIMER_HPP_ 191