src/core/common/uptime.hpp

/*
 *  Copyright (c) 2021, The OpenThread Authors.
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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
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 */

/**
 * @file
 *   This file includes definitions for tracking device's uptime.
 */

#ifndef UPTIME_HPP_
#define UPTIME_HPP_

#include "openthread-core-config.h"

#if !OPENTHREAD_CONFIG_UPTIME_ENABLE && OPENTHREAD_FTD
#error "OPENTHREAD_CONFIG_UPTIME_ENABLE is required for FTD"
#endif

#if OPENTHREAD_CONFIG_UPTIME_ENABLE

#include "common/locator.hpp"
#include "common/non_copyable.hpp"
#include "common/string.hpp"
#include "common/time.hpp"
#include "common/timer.hpp"

namespace ot {

/**
 * Implements tracking of device uptime (in msec).
 *
 */
class Uptime : public InstanceLocator, private NonCopyable
{
public:
    static constexpr uint16_t kStringSize = OT_UPTIME_STRING_SIZE; ///< Recommended string size to represent uptime.

    /**
     * Initializes an `Uptime` instance.
     *
     * @param[in] aInstance   The OpenThread instance.
     *
     */
    explicit Uptime(Instance &aInstance);

    /**
     * Returns the current device uptime (in msec).
     *
     * The uptime is maintained as number of milliseconds since OpenThread instance was initialized.
     *
     * @returns The uptime (number of milliseconds).
     *
     */
    uint64_t GetUptime(void) const;

    /**
     * Gets the current uptime as a human-readable string.
     *
     * The string follows the format "<hh>:<mm>:<ss>.<mmmm>" for hours, minutes, seconds and millisecond (if uptime is
     * shorter than one day) or "<dd>d.<hh>:<mm>:<ss>.<mmmm>" (if longer than a day).
     *
     * If the resulting string does not fit in @p aBuffer (within its @p aSize characters), the string will be
     * truncated but the outputted string is always null-terminated.
     *
     * @param[out] aBuffer   A pointer to a char array to output the string.
     * @param[in]  aSize     The size of @p aBuffer (in bytes). Recommended to use `OT_UPTIME_STRING_SIZE`.
     *
     */
    void GetUptime(char *aBuffer, uint16_t aSize) const;

    /**
     * Converts an uptime value (number of milliseconds) to a human-readable string.
     *
     * The string follows the format "<hh>:<mm>:<ss>.<mmmm>" for hours, minutes, seconds and millisecond (if uptime is
     * shorter than one day) or "<dd>d.<hh>:<mm>:<ss>.<mmmm>" (if longer than a day). @p aIncludeMsec can be used
     * to determine whether `.<mmm>` milliseconds is included or omitted in the resulting string.
     *
     * @param[in]     aUptime        The uptime to convert.
     * @param[in,out] aWriter        A `StringWriter` to append the converted string to.
     * @param[in]     aIncludeMsec   Whether to include `.<mmm>` milliseconds in the string.
     *
     */
    static void UptimeToString(uint64_t aUptime, StringWriter &aWriter, bool aIncludeMsec);

    /**
     * Converts a given uptime as number of milliseconds to number of seconds.
     *
     * @param[in] aUptimeInMilliseconds    Uptime in milliseconds (as `uint64_t`).
     *
     * @returns The converted @p aUptimeInMilliseconds to seconds (as `uint32_t`).
     *
     */
    static uint32_t MsecToSec(uint64_t aUptimeInMilliseconds)
    {
        return static_cast<uint32_t>(aUptimeInMilliseconds / 1000u);
    }

    /**
     * Converts a given uptime as number of seconds to number of milliseconds.
     *
     * @param[in] aUptimeInSeconds    Uptime in seconds (as `uint32_t`).
     *
     * @returns The converted @p aUptimeInSeconds to milliseconds (as `uint64_t`).
     *
     */
    static uint64_t SecToMsec(uint32_t aUptimeInSeconds) { return static_cast<uint64_t>(aUptimeInSeconds) * 1000u; }

private:
    static constexpr uint32_t kTimerInterval = (1 << 30);

    static_assert(static_cast<uint32_t>(4 * kTimerInterval) == 0, "kTimerInterval is not correct");

    void HandleTimer(void);

    using UptimeTimer = TimerMilliIn<Uptime, &Uptime::HandleTimer>;

    TimeMilli   mStartTime;
    uint32_t    mOverflowCount;
    UptimeTimer mTimer;
};

} // namespace ot

#endif // OPENTHREAD_CONFIG_UPTIME_ENABLE

#endif // UPTIME_HPP_