/*-
 * Copyright (c) 2011, 2012, 2013 Spectra Logic Corporation
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * 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,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 *
 * NO WARRANTY
 * 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 MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
 *
 * Authors: Justin T. Gibbs     (Spectra Logic Corporation)
 */

/**
 * \file callout.cc
 *
 * \brief Implementation of the Callout class - multi-client
 *        timer services built on top of the POSIX interval timer.
 */

#include <sys/byteorder.h>
#include <sys/time.h>

#include <signal.h>
#include <syslog.h>

#include <climits>
#include <list>
#include <map>
#include <string>

#include <devdctl/guid.h>
#include <devdctl/event.h>
#include <devdctl/event_factory.h>
#include <devdctl/consumer.h>
#include <devdctl/exception.h>

#include "callout.h"
#include "vdev_iterator.h"
#include "zfsd.h"
#include "zfsd_exception.h"

std::list<Callout *> Callout::s_activeCallouts;
bool                 Callout::s_alarmFired(false);

void
Callout::Init()
{
        signal(SIGALRM,  Callout::AlarmSignalHandler);
}

bool
Callout::Stop()
{
        if (!IsPending())
                return (false);

        for (std::list<Callout *>::iterator it(s_activeCallouts.begin());
             it != s_activeCallouts.end(); it++) {
                if (*it != this)
                        continue;

                it = s_activeCallouts.erase(it);
                if (it != s_activeCallouts.end()) {

                        /*
                         * Maintain correct interval for the
                         * callouts that follow the just removed
                         * entry.
                         */
                        timeradd(&(*it)->m_interval, &m_interval,
                                 &(*it)->m_interval);
                }
                break;
        }
        m_pending = false;
        return (true);
}

bool
Callout::Reset(const timeval &interval, CalloutFunc_t *func, void *arg)
{
        bool cancelled(false);

        if (!timerisset(&interval))
                throw ZfsdException("Callout::Reset: interval of 0");

        cancelled = Stop();

        m_interval = interval;
        m_func     = func;
        m_arg      = arg;
        m_pending  = true;

        std::list<Callout *>::iterator it(s_activeCallouts.begin());
        for (; it != s_activeCallouts.end(); it++) {

                if (timercmp(&(*it)->m_interval, &m_interval, <=)) {
                        /*
                         * Decrease our interval by those that come
                         * before us.
                         */
                        timersub(&m_interval, &(*it)->m_interval, &m_interval);
                } else {
                        /*
                         * Account for the time between the newly
                         * inserted event and those that follow.
                         */
                        timersub(&(*it)->m_interval, &m_interval,
                                 &(*it)->m_interval);
                        break;
                }
        }
        s_activeCallouts.insert(it, this);


        if (s_activeCallouts.front() == this) {
                itimerval timerval = { {0, 0}, m_interval };

                setitimer(ITIMER_REAL, &timerval, NULL);
        }

        return (cancelled);
}

void
Callout::AlarmSignalHandler(int)
{
        s_alarmFired = true;
        ZfsDaemon::WakeEventLoop();
}

void
Callout::ExpireCallouts()
{
        if (!s_alarmFired)
                return;

        s_alarmFired = false;
        if (s_activeCallouts.empty()) {
                /* Callout removal/SIGALRM race was lost. */
                return;
        }

        /*
         * Expire the first callout (the one we used to set the
         * interval timer) as well as any callouts following that
         * expire at the same time (have a zero interval from
         * the callout before it).
         */
        do {
                Callout *cur(s_activeCallouts.front());
                s_activeCallouts.pop_front();
                cur->m_pending = false;
                cur->m_func(cur->m_arg);
        } while (!s_activeCallouts.empty()
              && timerisset(&s_activeCallouts.front()->m_interval) == 0);

        if (!s_activeCallouts.empty()) {
                Callout *next(s_activeCallouts.front());
                itimerval timerval = { { 0, 0 }, next->m_interval };

                setitimer(ITIMER_REAL, &timerval, NULL);
        }
}

timeval
Callout::TimeRemaining() const
{
        /*
         * Outline: Add the m_interval for each callout in s_activeCallouts
         * ahead of this, except for the first callout.  Add to that the result
         * of getitimer (That's because the first callout stores its original
         * interval setting while the timer is ticking).
         */
        itimerval timervalToAlarm;
        timeval timeToExpiry;
        std::list<Callout *>::iterator it;

        if (!IsPending()) {
                timeToExpiry.tv_sec = INT_MAX;
                timeToExpiry.tv_usec = 999999;  /*maximum normalized value*/
                return (timeToExpiry);
        }

        timerclear(&timeToExpiry);
        getitimer(ITIMER_REAL, &timervalToAlarm);
        timeval& timeToAlarm = timervalToAlarm.it_value;
        timeradd(&timeToExpiry, &timeToAlarm, &timeToExpiry);

        it =s_activeCallouts.begin();
        it++;   /*skip the first callout in the list*/
        for (; it != s_activeCallouts.end(); it++) {
                timeradd(&timeToExpiry, &(*it)->m_interval, &timeToExpiry);
                if ((*it) == this)
                        break;
        }
        return (timeToExpiry);
}