src/EventLoop.cc

   1
   2 /*
   3  * $Id: EventLoop.cc,v 1.6 2008/02/12 23:49:44 rousskov Exp $
   4  *
   5  * DEBUG: section 1     Main Loop
   6  * AUTHOR: Harvest Derived
   7  *
   8  * SQUID Web Proxy Cache          http://www.squid-cache.org/
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  10  *
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  14  *  development; see the SPONSORS file for full details.  Squid is
  15  *  Copyrighted (C) 2001 by the Regents of the University of
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  17  *  incorporates software developed and/or copyrighted by other
  18  *  sources; see the CREDITS file for full details.
  19  *
  20  *  This program is free software; you can redistribute it and/or modify
  21  *  it under the terms of the GNU General Public License as published by
  22  *  the Free Software Foundation; either version 2 of the License, or
  23  *  (at your option) any later version.
  24  *
  25  *  This program is distributed in the hope that it will be useful,
  26  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  27  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28  *  GNU General Public License for more details.
  29  *
  30  *  You should have received a copy of the GNU General Public License
  31  *  along with this program; if not, write to the Free Software
  32  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  33  *
  34  */
  35
  36 #include "EventLoop.h"
  37 #include "AsyncCallQueue.h"
  38
  39 EventLoop::EventLoop() : errcount(0), last_loop(false), timeService(NULL),
  40         primaryEngine(NULL)
  41 {}
  42
  43 void
  44 EventLoop::checkEngine(AsyncEngine * engine, bool const primary)
  45 {
  46     int requested_delay;
  47
  48     if (!primary)
  49         requested_delay = engine->checkEvents(0);
  50     else
  51         requested_delay = engine->checkEvents(loop_delay);
  52
  53     if (requested_delay < 0)
  54         switch (requested_delay) {
  55
  56         case AsyncEngine::EVENT_IDLE:
  57             debugs(1, 9, "Engine " << engine << " is idle.");
  58             break;
  59
  60         case AsyncEngine::EVENT_ERROR:
  61             runOnceResult = false;
  62             error = true;
  63             break;
  64
  65         default:
  66             fatal_dump("unknown AsyncEngine result");
  67         }
  68     else {
  69         /* not idle or error */
  70         runOnceResult = false;
  71
  72         if (requested_delay < loop_delay)
  73             loop_delay = requested_delay;
  74     }
  75 }
  76
  77 void
  78 EventLoop::prepareToRun()
  79 {
  80     last_loop = false;
  81     errcount = 0;
  82 }
  83
  84 void
  85 EventLoop::registerEngine(AsyncEngine *engine)
  86 {
  87     engines.push_back(engine);
  88 }
  89
  90 void
  91 EventLoop::run()
  92 {
  93     prepareToRun();
  94
  95     while (!runOnce())
  96
  97         ;
  98 }
  99
 100 bool
 101 EventLoop::runOnce()
 102 {
 103     bool sawActivity = false;
 104     runOnceResult = true;
 105     error = false;
 106     loop_delay = EVENT_LOOP_TIMEOUT;
 107
 108     AsyncEngine *waitingEngine = primaryEngine;
 109     if (!waitingEngine && !engines.empty())
 110         waitingEngine = engines.back();
 111
 112     do {
 113         // generate calls and events
 114         typedef engine_vector::iterator EVI;
 115         for (EVI i = engines.begin(); i != engines.end(); ++i) {
 116             if (*i != waitingEngine)
 117                 checkEngine(*i, false);
 118         }
 119
 120         // dispatch calls accumulated so far
 121         sawActivity = dispatchCalls();
 122         if (sawActivity)
 123             runOnceResult = false;
 124         } while (sawActivity);
 125
 126     if (waitingEngine != NULL)
 127         checkEngine(waitingEngine, true);
 128
 129     if (timeService != NULL)
 130         timeService->tick();
 131
 132     // dispatch calls scheduled by waitingEngine and timeService
 133     sawActivity = dispatchCalls();
 134     if (sawActivity)
 135         runOnceResult = false;
 136
 137     if (error) {
 138         ++errcount;
 139         debugs(1, 0, "Select loop Error. Retry " << errcount);
 140     } else
 141         errcount = 0;
 142
 143     if (errcount == 10)
 144         return true;
 145
 146     if (last_loop)
 147         return true;
 148
 149     return runOnceResult;
 150 }
 151
 152 // dispatches calls accumulated during checkEngine()
 153 bool
 154 EventLoop::dispatchCalls()
 155 {
 156     bool dispatchedSome = AsyncCallQueue::Instance().fire();
 157     return dispatchedSome;
 158 }
 159
 160 void
 161 EventLoop::setPrimaryEngine(AsyncEngine * engine)
 162 {
 163     for (engine_vector::iterator i = engines.begin();
 164             i != engines.end(); ++i)
 165         if (*i == engine) {
 166             primaryEngine = engine;
 167             return;
 168         }
 169
 170     fatal("EventLoop::setPrimaryEngine: No such engine!.");
 171 }
 172
 173 void
 174 EventLoop::setTimeService(TimeEngine *engine)
 175 {
 176     timeService = engine;
 177 }
 178
 179 void
 180 EventLoop::stop()
 181 {
 182     last_loop = true;
 183 }