src/EventLoop.cc

   1 /*
   2  * DEBUG: section 01    Main Loop
   3  * AUTHOR: Harvest Derived
   4  *
   5  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   6  * ----------------------------------------------------------
   7  *
   8  *  Squid is the result of efforts by numerous individuals from
   9  *  the Internet community; see the CONTRIBUTORS file for full
  10  *  details.   Many organizations have provided support for Squid's
  11  *  development; see the SPONSORS file for full details.  Squid is
  12  *  Copyrighted (C) 2001 by the Regents of the University of
  13  *  California; see the COPYRIGHT file for full details.  Squid
  14  *  incorporates software developed and/or copyrighted by other
  15  *  sources; see the CREDITS file for full details.
  16  *
  17  *  This program is free software; you can redistribute it and/or modify
  18  *  it under the terms of the GNU General Public License as published by
  19  *  the Free Software Foundation; either version 2 of the License, or
  20  *  (at your option) any later version.
  21  *
  22  *  This program is distributed in the hope that it will be useful,
  23  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25  *  GNU General Public License for more details.
  26  *
  27  *  You should have received a copy of the GNU General Public License
  28  *  along with this program; if not, write to the Free Software
  29  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  30  *
  31  */
  32
  33 #include "squid.h"
  34 #include "AsyncEngine.h"
  35 #include "Debug.h"
  36 #include "EventLoop.h"
  37 #include "base/AsyncCallQueue.h"
  38 #include "SquidTime.h"
  39
  40
  41 EventLoop::EventLoop() : errcount(0), last_loop(false), timeService(NULL),
  42         primaryEngine(NULL)
  43 {}
  44
  45 void
  46 EventLoop::checkEngine(AsyncEngine * engine, bool const primary)
  47 {
  48     int requested_delay;
  49
  50     if (!primary)
  51         requested_delay = engine->checkEvents(0);
  52     else
  53         requested_delay = engine->checkEvents(loop_delay);
  54
  55     if (requested_delay < 0)
  56         switch (requested_delay) {
  57
  58         case AsyncEngine::EVENT_IDLE:
  59             debugs(1, 9, "Engine " << engine << " is idle.");
  60             break;
  61
  62         case AsyncEngine::EVENT_ERROR:
  63             runOnceResult = false;
  64             error = true;
  65             break;
  66
  67         default:
  68             fatal_dump("unknown AsyncEngine result");
  69         }
  70     else {
  71         /* not idle or error */
  72         runOnceResult = false;
  73
  74         if (requested_delay < loop_delay)
  75             loop_delay = requested_delay;
  76     }
  77 }
  78
  79 void
  80 EventLoop::prepareToRun()
  81 {
  82     last_loop = false;
  83     errcount = 0;
  84 }
  85
  86 void
  87 EventLoop::registerEngine(AsyncEngine *engine)
  88 {
  89     engines.push_back(engine);
  90 }
  91
  92 void
  93 EventLoop::run()
  94 {
  95     prepareToRun();
  96
  97     while (!runOnce());
  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, DBG_CRITICAL, "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 }