src/core/common/timer.hpp

/*
 *  Copyright (c) 2016, The OpenThread Authors.
 *  All rights reserved.
 *
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 *  modification, are permitted provided that the following conditions are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. 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.
 *  3. 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
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 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 */

/**
 * @file
 *   This file includes definitions for the multiplexed timer service.
 */

#ifndef TIMER_HPP_
#define TIMER_HPP_

#include "openthread-core-config.h"

#include <stddef.h>
#include <stdint.h>

#include <openthread/platform/alarm-micro.h>
#include <openthread/platform/alarm-milli.h>

#include "common/debug.hpp"
#include "common/linked_list.hpp"
#include "common/locator.hpp"
#include "common/tasklet.hpp"
#include "common/time.hpp"

namespace ot {

class TimerMilliScheduler;

/**
 * @addtogroup core-timer
 *
 * @brief
 *   This module includes definitions for the multiplexed timer service.
 *
 * @{
 *
 */

/**
 * This class implements a timer.
 *
 */
class Timer : public InstanceLocator, public OwnerLocator, public LinkedListEntry<Timer>
{
    friend class TimerScheduler;
    friend class LinkedListEntry<Timer>;

public:
    /**
     * This constant defines maximum delay allowed when starting a timer.
     *
     */
    static const uint32_t kMaxDelay = (Time::kMaxDuration >> 1);

    /**
     * This function pointer is called when the timer expires.
     *
     * @param[in]  aTimer    A reference to the expired timer instance.
     *
     */
    typedef void (*Handler)(Timer &aTimer);

    /**
     * This constructor creates a timer instance.
     *
     * @param[in]  aInstance   A reference to the OpenThread instance.
     * @param[in]  aHandler    A pointer to a function that is called when the timer expires.
     * @param[in]  aOwner      A pointer to owner of the `Timer` object.
     *
     */
    Timer(Instance &aInstance, Handler aHandler, void *aOwner)
        : InstanceLocator(aInstance)
        , OwnerLocator(aOwner)
        , mHandler(aHandler)
        , mFireTime()
        , mNext(this)
    {
    }

    /**
     * This method returns the fire time of the timer.
     *
     * @returns The fire time.
     *
     */
    Time GetFireTime(void) const { return mFireTime; }

    /**
     * This method indicates whether or not the timer instance is running.
     *
     * @retval TRUE   If the timer is running.
     * @retval FALSE  If the timer is not running.
     *
     */
    bool IsRunning(void) const { return (mNext != this); }

protected:
    /**
     * This method indicates if the fire time of this timer is strictly before the fire time of a second given timer.
     *
     * @param[in]  aSecondTimer   A reference to the second timer object.
     * @param[in]  aNow           The current time (milliseconds or microsecond, depending on timer type).
     *
     * @retval TRUE  If the fire time of this timer object is strictly before aTimer's fire time
     * @retval FALSE If the fire time of this timer object is the same or after aTimer's fire time.
     *
     */
    bool DoesFireBefore(const Timer &aSecondTimer, Time aNow);

    void Fired(void) { mHandler(*this); }

    Handler mHandler;
    Time    mFireTime;
    Timer * mNext;
};

/**
 * This class implements the millisecond timer.
 *
 */
class TimerMilli : public Timer
{
public:
    /**
     * This constructor creates a millisecond timer instance.
     *
     * @param[in]  aInstance   A reference to the OpenThread instance.
     * @param[in]  aHandler    A pointer to a function that is called when the timer expires.
     * @param[in]  aOwner      A pointer to the owner of the `TimerMilli` object.
     *
     */
    TimerMilli(Instance &aInstance, Handler aHandler, void *aOwner)
        : Timer(aInstance, aHandler, aOwner)
    {
    }

    /**
     * This method schedules the timer to fire after a given delay (in milliseconds) from now.
     *
     * @param[in]  aDelay   The delay in milliseconds. It must not be longer than `kMaxDelay`.
     *
     */
    void Start(uint32_t aDelay);

    /**
     * This method schedules the timer to fire after a given delay (in milliseconds) from a given start time.
     *
     * @param[in]  aStartTime  The start time.
     * @param[in]  aDelay      The delay in milliseconds. It must not be longer than `kMaxDelay`.
     *
     */
    void StartAt(TimeMilli sStartTime, uint32_t aDelay);

    /**
     * This method schedules the timer to fire at a given fire time.
     *
     * @param[in]  aFireTime  The fire time.
     *
     */
    void FireAt(TimeMilli aFireTime);

    /**
     * This method (re-)schedules the timer with a given a fire time only if the timer is not running or the new given
     * fire time is earlier than the current fire time.
     *
     * @param[in]  aFireTime  The fire time.
     *
     */
    void FireAtIfEarlier(TimeMilli aFireTime);

    /**
     * This method stops the timer.
     *
     */
    void Stop(void);

    /**
     * This static method returns the current time in milliseconds.
     *
     * @returns The current time in milliseconds.
     *
     */
    static TimeMilli GetNow(void) { return TimeMilli(otPlatAlarmMilliGetNow()); }
};

/**
 * This class implements a millisecond timer that also maintains a user context pointer.
 *
 * In typical `TimerMilli`/`TimerMicro` use, in the timer callback handler, the owner of the timer is determined using
 * `GetOwner<Type>` method. This method works if there is a single instance of `Type` within OpenThread instance
 * hierarchy. The `TimerMilliContext` is intended for cases where there may be multiple instances of the same class/type
 * using a timer object. `TimerMilliContext` will store a context `void *` information.
 *
 */
class TimerMilliContext : public TimerMilli
{
public:
    /**
     * This constructor creates a millisecond timer that also maintains a user context pointer.
     *
     * @param[in]  aInstance   A reference to the OpenThread instance.
     * @param[in]  aHandler    A pointer to a function that is called when the timer expires.
     * @param[in]  aContext    A pointer to an arbitrary context information.
     *
     */
    TimerMilliContext(Instance &aInstance, Handler aHandler, void *aContext)
        : TimerMilli(aInstance, aHandler, aContext)
        , mContext(aContext)
    {
    }

    /**
     * This method returns the pointer to the arbitrary context information.
     *
     * @returns Pointer to the arbitrary context information.
     *
     */
    void *GetContext(void) { return mContext; }

private:
    void *mContext;
};

/**
 * This class implements the base timer scheduler.
 *
 */
class TimerScheduler : public InstanceLocator
{
    friend class Timer;

protected:
    /**
     * The Alarm APIs definition
     *
     */
    struct AlarmApi
    {
        void (*AlarmStartAt)(otInstance *aInstance, uint32_t aT0, uint32_t aDt);
        void (*AlarmStop)(otInstance *aInstance);
        uint32_t (*AlarmGetNow)(void);
    };

    /**
     * This constructor initializes the object.
     *
     * @param[in]  aInstance  A reference to the instance object.
     *
     */
    explicit TimerScheduler(Instance &aInstance)
        : InstanceLocator(aInstance)
        , mTimerList()
    {
    }

    /**
     * This method adds a timer instance to the timer scheduler.
     *
     * @param[in]  aTimer     A reference to the timer instance.
     * @param[in]  aAlarmApi  A reference to the Alarm APIs.
     *
     */
    void Add(Timer &aTimer, const AlarmApi &aAlarmApi);

    /**
     * This method removes a timer instance to the timer scheduler.
     *
     * @param[in]  aTimer     A reference to the timer instance.
     * @param[in]  aAlarmApi  A reference to the Alarm APIs.
     *
     */
    void Remove(Timer &aTimer, const AlarmApi &aAlarmApi);

    /**
     * This method processes the running timers.
     *
     * @param[in]  aAlarmApi  A reference to the Alarm APIs.
     *
     */
    void ProcessTimers(const AlarmApi &aAlarmApi);

    /**
     * This method sets the platform alarm based on timer at front of the list.
     *
     * @param[in]  aAlarmApi  A reference to the Alarm APIs.
     *
     */
    void SetAlarm(const AlarmApi &aAlarmApi);

    LinkedList<Timer> mTimerList;
};

/**
 * This class implements the millisecond timer scheduler.
 *
 */
class TimerMilliScheduler : public TimerScheduler
{
public:
    /**
     * This constructor initializes the object.
     *
     * @param[in]  aInstance  A reference to the instance object.
     *
     */
    explicit TimerMilliScheduler(Instance &aInstance)
        : TimerScheduler(aInstance)
    {
    }

    /**
     * This method adds a timer instance to the timer scheduler.
     *
     * @param[in]  aTimer  A reference to the timer instance.
     *
     */
    void Add(TimerMilli &aTimer) { TimerScheduler::Add(aTimer, sAlarmMilliApi); }

    /**
     * This method removes a timer instance to the timer scheduler.
     *
     * @param[in]  aTimer  A reference to the timer instance.
     *
     */
    void Remove(TimerMilli &aTimer) { TimerScheduler::Remove(aTimer, sAlarmMilliApi); }

    /**
     * This method processes the running timers.
     *
     */
    void ProcessTimers(void) { TimerScheduler::ProcessTimers(sAlarmMilliApi); }

private:
    static const AlarmApi sAlarmMilliApi;
};

#if OPENTHREAD_CONFIG_PLATFORM_USEC_TIMER_ENABLE
class TimerMicroScheduler;

/**
 * This class implements the microsecond timer.
 *
 */
class TimerMicro : public Timer
{
public:
    /**
     * This constructor creates a timer instance.
     *
     * @param[in]  aInstance   A reference to the OpenThread instance.
     * @param[in]  aHandler    A pointer to a function that is called when the timer expires.
     * @param[in]  aOwner      A pointer to owner of the `TimerMicro` object.
     *
     */
    TimerMicro(Instance &aInstance, Handler aHandler, void *aOwner)
        : Timer(aInstance, aHandler, aOwner)
    {
    }

    /**
     * This method schedules the timer to fire after a given delay (in microseconds) from now.
     *
     * @param[in]  aDelay   The delay in microseconds. It must not be be longer than `kMaxDelay`.
     *
     */
    void Start(uint32_t aDelay);

    /**
     * This method schedules the timer to fire after a given delay (in microseconds) from a given start time.
     *
     * @param[in]  aStartTime  The start time.
     * @param[in]  aDelay      The delay in microseconds. It must not be longer than `kMaxDelay`.
     *
     */
    void StartAt(TimeMicro aStartTime, uint32_t aDelay);

    /**
     * This method schedules the timer to fire at a given fire time.
     *
     * @param[in]  aFireTime  The fire time.
     *
     */
    void FireAt(TimeMicro aFireTime);

    /**
     * This method stops the timer.
     *
     */
    void Stop(void);

    /**
     * This static method returns the current time in microseconds.
     *
     * @returns The current time in microseconds.
     *
     */
    static TimeMicro GetNow(void) { return Time(otPlatAlarmMicroGetNow()); }
};

/**
 * This class implements the microsecond timer scheduler.
 *
 */
class TimerMicroScheduler : public TimerScheduler
{
public:
    /**
     * This constructor initializes the object.
     *
     * @param[in]  aInstance  A reference to the instance object.
     *
     */
    TimerMicroScheduler(Instance &aInstance)
        : TimerScheduler(aInstance)
    {
    }

    /**
     * This method adds a timer instance to the timer scheduler.
     *
     * @param[in]  aTimer  A reference to the timer instance.
     *
     */
    void Add(TimerMicro &aTimer) { TimerScheduler::Add(aTimer, sAlarmMicroApi); }

    /**
     * This method removes a timer instance to the timer scheduler.
     *
     * @param[in]  aTimer  A reference to the timer instance.
     *
     */
    void Remove(TimerMicro &aTimer) { TimerScheduler::Remove(aTimer, sAlarmMicroApi); }

    /**
     * This method processes the running timers.
     *
     */
    void ProcessTimers(void) { TimerScheduler::ProcessTimers(sAlarmMicroApi); }

private:
    static const AlarmApi sAlarmMicroApi;
};
#endif // OPENTHREAD_CONFIG_PLATFORM_USEC_TIMER_ENABLE

/**
 * @}
 *
 */

} // namespace ot

#endif // TIMER_HPP_