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/byteorder.h>
  43 #include <sys/time.h>
  44
  45 #include <signal.h>
  46 #include <syslog.h>
  47
  48 #include <climits>
  49 #include <list>
  50 #include <map>
  51 #include <string>
  52
  53 #include <devdctl/guid.h>
  54 #include <devdctl/event.h>
  55 #include <devdctl/event_factory.h>
  56 #include <devdctl/consumer.h>
  57 #include <devdctl/exception.h>
  58
  59 #include "callout.h"
  60 #include "vdev_iterator.h"
  61 #include "zfsd.h"
  62 #include "zfsd_exception.h"
  63
  64 std::list<Callout *> Callout::s_activeCallouts;
  65 bool                 Callout::s_alarmFired(false);
  66
  67 void
  68 Callout::Init()
  69 {
  70         signal(SIGALRM,  Callout::AlarmSignalHandler);
  71 }
  72
  73 bool
  74 Callout::Stop()
  75 {
  76         if (!IsPending())
  77                 return (false);
  78
  79         for (std::list<Callout *>::iterator it(s_activeCallouts.begin());
  80              it != s_activeCallouts.end(); it++) {
  81                 if (*it != this)
  82                         continue;
  83
  84                 it = s_activeCallouts.erase(it);
  85                 if (it != s_activeCallouts.end()) {
  86
  87                         /*
  88                          * Maintain correct interval for the
  89                          * callouts that follow the just removed
  90                          * entry.
  91                          */
  92                         timeradd(&(*it)->m_interval, &m_interval,
  93                                  &(*it)->m_interval);
  94                 }
  95                 break;
  96         }
  97         m_pending = false;
  98         return (true);
  99 }
 100
 101 bool
 102 Callout::Reset(const timeval &interval, CalloutFunc_t *func, void *arg)
 103 {
 104         bool cancelled(false);
 105
 106         if (!timerisset(&interval))
 107                 throw ZfsdException("Callout::Reset: interval of 0");
 108
 109         cancelled = Stop();
 110
 111         m_interval = interval;
 112         m_func     = func;
 113         m_arg      = arg;
 114         m_pending  = true;
 115
 116         std::list<Callout *>::iterator it(s_activeCallouts.begin());
 117         for (; it != s_activeCallouts.end(); it++) {
 118
 119                 if (timercmp(&(*it)->m_interval, &m_interval, <=)) {
 120                         /*
 121                          * Decrease our interval by those that come
 122                          * before us.
 123                          */
 124                         timersub(&m_interval, &(*it)->m_interval, &m_interval);
 125                 } else {
 126                         /*
 127                          * Account for the time between the newly
 128                          * inserted event and those that follow.
 129                          */
 130                         timersub(&(*it)->m_interval, &m_interval,
 131                                  &(*it)->m_interval);
 132                         break;
 133                 }
 134         }
 135         s_activeCallouts.insert(it, this);
 136
 137
 138         if (s_activeCallouts.front() == this) {
 139                 itimerval timerval = { {0, 0}, m_interval };
 140
 141                 setitimer(ITIMER_REAL, &timerval, NULL);
 142         }
 143
 144         return (cancelled);
 145 }
 146
 147 void
 148 Callout::AlarmSignalHandler(int)
 149 {
 150         s_alarmFired = true;
 151         ZfsDaemon::WakeEventLoop();
 152 }
 153
 154 void
 155 Callout::ExpireCallouts()
 156 {
 157         if (!s_alarmFired)
 158                 return;
 159
 160         s_alarmFired = false;
 161         if (s_activeCallouts.empty()) {
 162                 /* Callout removal/SIGALRM race was lost. */
 163                 return;
 164         }
 165
 166         /*
 167          * Expire the first callout (the one we used to set the
 168          * interval timer) as well as any callouts following that
 169          * expire at the same time (have a zero interval from
 170          * the callout before it).
 171          */
 172         do {
 173                 Callout *cur(s_activeCallouts.front());
 174                 s_activeCallouts.pop_front();
 175                 cur->m_pending = false;
 176                 cur->m_func(cur->m_arg);
 177         } while (!s_activeCallouts.empty()
 178               && timerisset(&s_activeCallouts.front()->m_interval) == 0);
 179
 180         if (!s_activeCallouts.empty()) {
 181                 Callout *next(s_activeCallouts.front());
 182                 itimerval timerval = { { 0, 0 }, next->m_interval };
 183
 184                 setitimer(ITIMER_REAL, &timerval, NULL);
 185         }
 186 }
 187
 188 timeval
 189 Callout::TimeRemaining() const
 190 {
 191         /*
 192          * Outline: Add the m_interval for each callout in s_activeCallouts
 193          * ahead of this, except for the first callout.  Add to that the result
 194          * of getitimer (That's because the first callout stores its original
 195          * interval setting while the timer is ticking).
 196          */
 197         itimerval timervalToAlarm;
 198         timeval timeToExpiry;
 199         std::list<Callout *>::iterator it;
 200
 201         if (!IsPending()) {
 202                 timeToExpiry.tv_sec = INT_MAX;
 203                 timeToExpiry.tv_usec = 999999;  /*maximum normalized value*/
 204                 return (timeToExpiry);
 205         }
 206
 207         timerclear(&timeToExpiry);
 208         getitimer(ITIMER_REAL, &timervalToAlarm);
 209         timeval& timeToAlarm = timervalToAlarm.it_value;
 210         timeradd(&timeToExpiry, &timeToAlarm, &timeToExpiry);
 211
 212         it =s_activeCallouts.begin();
 213         it++;   /*skip the first callout in the list*/
 214         for (; it != s_activeCallouts.end(); it++) {
 215                 timeradd(&timeToExpiry, &(*it)->m_interval, &timeToExpiry);
 216                 if ((*it) == this)
 217                         break;
 218         }
 219         return (timeToExpiry);
 220 }