cddl/usr.sbin/zfsd/callout.cc

   1 /*-
   2  * Copyright (c) 2011, 2012, 2013 Spectra Logic Corporation
   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
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions, and the following disclaimer,
  10  *    without modification.
  11  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  12  *    substantially similar to the "NO WARRANTY" disclaimer below
  13  *    ("Disclaimer") and any redistribution must be conditioned upon
  14  *    including a substantially similar Disclaimer requirement for further
  15  *    binary redistribution.
  16  *
  17  * NO WARRANTY
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  26  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  27  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  28  * POSSIBILITY OF SUCH DAMAGES.
  29  *
  30  * Authors: Justin T. Gibbs     (Spectra Logic Corporation)
  31  *
  32  * $FreeBSD$
  33  */
  34
  35 /**
  36  * \file callout.cc
  37  *
  38  * \brief Implementation of the Callout class - multi-client
  39  *        timer services built on top of the POSIX interval timer.
  40  */
  41
  42 #include <sys/time.h>
  43
  44 #include <signal.h>
  45 #include <syslog.h>
  46
  47 #include <climits>
  48 #include <list>
  49 #include <map>
  50 #include <string>
  51
  52 #include <devdctl/guid.h>
  53 #include <devdctl/event.h>
  54 #include <devdctl/event_factory.h>
  55 #include <devdctl/consumer.h>
  56 #include <devdctl/exception.h>
  57
  58 #include "callout.h"
  59 #include "vdev_iterator.h"
  60 #include "zfsd.h"
  61 #include "zfsd_exception.h"
  62
  63 std::list<Callout *> Callout::s_activeCallouts;
  64 bool                 Callout::s_alarmFired(false);
  65
  66 void
  67 Callout::Init()
  68 {
  69         signal(SIGALRM,  Callout::AlarmSignalHandler);
  70 }
  71
  72 bool
  73 Callout::Stop()
  74 {
  75         if (!IsPending())
  76                 return (false);
  77
  78         for (std::list<Callout *>::iterator it(s_activeCallouts.begin());
  79              it != s_activeCallouts.end(); it++) {
  80                 if (*it != this)
  81                         continue;
  82
  83                 it = s_activeCallouts.erase(it);
  84                 if (it != s_activeCallouts.end()) {
  85
  86                         /*
  87                          * Maintain correct interval for the
  88                          * callouts that follow the just removed
  89                          * entry.
  90                          */
  91                         timeradd(&(*it)->m_interval, &m_interval,
  92                                  &(*it)->m_interval);
  93                 }
  94                 break;
  95         }
  96         m_pending = false;
  97         return (true);
  98 }
  99
 100 bool
 101 Callout::Reset(const timeval &interval, CalloutFunc_t *func, void *arg)
 102 {
 103         bool cancelled(false);
 104
 105         if (!timerisset(&interval))
 106                 throw ZfsdException("Callout::Reset: interval of 0");
 107
 108         cancelled = Stop();
 109
 110         m_interval = interval;
 111         m_func     = func;
 112         m_arg      = arg;
 113         m_pending  = true;
 114
 115         std::list<Callout *>::iterator it(s_activeCallouts.begin());
 116         for (; it != s_activeCallouts.end(); it++) {
 117
 118                 if (timercmp(&(*it)->m_interval, &m_interval, <=)) {
 119                         /*
 120                          * Decrease our interval by those that come
 121                          * before us.
 122                          */
 123                         timersub(&m_interval, &(*it)->m_interval, &m_interval);
 124                 } else {
 125                         /*
 126                          * Account for the time between the newly
 127                          * inserted event and those that follow.
 128                          */
 129                         timersub(&(*it)->m_interval, &m_interval,
 130                                  &(*it)->m_interval);
 131                         break;
 132                 }
 133         }
 134         s_activeCallouts.insert(it, this);
 135
 136
 137         if (s_activeCallouts.front() == this) {
 138                 itimerval timerval = { {0, 0}, m_interval };
 139
 140                 setitimer(ITIMER_REAL, &timerval, NULL);
 141         }
 142
 143         return (cancelled);
 144 }
 145
 146 void
 147 Callout::AlarmSignalHandler(int)
 148 {
 149         s_alarmFired = true;
 150         ZfsDaemon::WakeEventLoop();
 151 }
 152
 153 void
 154 Callout::ExpireCallouts()
 155 {
 156         if (!s_alarmFired)
 157                 return;
 158
 159         s_alarmFired = false;
 160         if (s_activeCallouts.empty()) {
 161                 /* Callout removal/SIGALRM race was lost. */
 162                 return;
 163         }
 164
 165         /*
 166          * Expire the first callout (the one we used to set the
 167          * interval timer) as well as any callouts following that
 168          * expire at the same time (have a zero interval from
 169          * the callout before it).
 170          */
 171         do {
 172                 Callout *cur(s_activeCallouts.front());
 173                 s_activeCallouts.pop_front();
 174                 cur->m_pending = false;
 175                 cur->m_func(cur->m_arg);
 176         } while (!s_activeCallouts.empty()
 177               && timerisset(&s_activeCallouts.front()->m_interval) == 0);
 178
 179         if (!s_activeCallouts.empty()) {
 180                 Callout *next(s_activeCallouts.front());
 181                 itimerval timerval = { { 0, 0 }, next->m_interval };
 182
 183                 setitimer(ITIMER_REAL, &timerval, NULL);
 184         }
 185 }
 186
 187 timeval
 188 Callout::TimeRemaining() const
 189 {
 190         /*
 191          * Outline: Add the m_interval for each callout in s_activeCallouts
 192          * ahead of this, except for the first callout.  Add to that the result
 193          * of getitimer (That's because the first callout stores its original
 194          * interval setting while the timer is ticking).
 195          */
 196         itimerval timervalToAlarm;
 197         timeval timeToExpiry;
 198         std::list<Callout *>::iterator it;
 199
 200         if (!IsPending()) {
 201                 timeToExpiry.tv_sec = INT_MAX;
 202                 timeToExpiry.tv_usec = 999999;  /*maximum normalized value*/
 203                 return (timeToExpiry);
 204         }
 205
 206         timerclear(&timeToExpiry);
 207         getitimer(ITIMER_REAL, &timervalToAlarm);
 208         timeval& timeToAlarm = timervalToAlarm.it_value;
 209         timeradd(&timeToExpiry, &timeToAlarm, &timeToExpiry);
 210
 211         it =s_activeCallouts.begin();
 212         it++;   /*skip the first callout in the list*/
 213         for (; it != s_activeCallouts.end(); it++) {
 214                 timeradd(&timeToExpiry, &(*it)->m_interval, &timeToExpiry);
 215                 if ((*it) == this)
 216                         break;
 217         }
 218         return (timeToExpiry);
 219 }