src/DiskIO/DiskIOStrategy.h

   1 /*
   2  * $Id$
   3  *
   4  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   5  * ----------------------------------------------------------
   6  *
   7  *  Squid is the result of efforts by numerous individuals from
   8  *  the Internet community; see the CONTRIBUTORS file for full
   9  *  details.   Many organizations have provided support for Squid's
  10  *  development; see the SPONSORS file for full details.  Squid is
  11  *  Copyrighted (C) 2001 by the Regents of the University of
  12  *  California; see the COPYRIGHT file for full details.  Squid
  13  *  incorporates software developed and/or copyrighted by other
  14  *  sources; see the CREDITS file for full details.
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License as published by
  18  *  the Free Software Foundation; either version 2 of the License, or
  19  *  (at your option) any later version.
  20  *
  21  *  This program is distributed in the hope that it will be useful,
  22  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  23  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24  *  GNU General Public License for more details.
  25  *
  26  *  You should have received a copy of the GNU General Public License
  27  *  along with this program; if not, write to the Free Software
  28  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  29  *
  30  * Copyright (c) 2003 Robert Collins <robertc@squid-cache.org>
  31  */
  32
  33 #ifndef SQUID_DISKIOSTRATEGY_H
  34 #define SQUID_DISKIOSTRATEGY_H
  35
  36 #include "squid.h"
  37
  38 #include "RefCount.h"
  39
  40 class DiskFile;
  41
  42 class ConfigOption;
  43
  44 class DiskIOStrategy
  45 {
  46
  47 public:
  48     virtual ~DiskIOStrategy() {}
  49
  50     /** Can the IO Strategy handle more requests ? */
  51     virtual bool shedLoad() = 0;
  52
  53     /** What is the current load? 999 = 99.9% */
  54     virtual int load() = 0;
  55
  56     /** Return a handle for performing IO operations */
  57     virtual RefCount<DiskFile> newFile(char const *path) = 0;
  58
  59     /** flush all IO operations  */
  60     virtual void sync() {}
  61
  62     /** unlink a file by path */
  63     virtual void unlinkFile(char const *) = 0;
  64
  65     /** perform any pending callbacks */
  66     virtual int callback() { return 0; }
  67
  68     /** Init per-instance logic */
  69     virtual void init() {}
  70
  71     /** cachemgr output on the IO instance stats */
  72     virtual void statfs(StoreEntry & sentry)const {}
  73
  74     /** module specific options */
  75     virtual ConfigOption *getOptionTree() const { return NULL;}
  76 };
  77
  78 /* Because we need the DiskFile definition for newFile. */
  79 #include "DiskFile.h"
  80
  81 class SingletonIOStrategy : public DiskIOStrategy
  82 {
  83
  84 public:
  85     SingletonIOStrategy(DiskIOStrategy *anIO) : io(anIO) {}
  86
  87     virtual bool shedLoad() { return io->shedLoad(); }
  88
  89     virtual int load() { return io->load(); }
  90
  91     virtual RefCount<DiskFile> newFile (char const *path) {return io->newFile(path); }
  92
  93     virtual void sync() { io->sync(); }
  94
  95     virtual void unlinkFile (char const *path) { io->unlinkFile(path); }
  96
  97     virtual int callback() { return io->callback(); }
  98
  99     virtual void init() { io->init(); }
 100
 101     virtual void statfs(StoreEntry & sentry)const { io->statfs(sentry); }
 102
 103     virtual ConfigOption *getOptionTree() const { return io->getOptionTree(); }
 104
 105 private:
 106     DiskIOStrategy *io;
 107 };
 108
 109 #endif /* SQUID_DISKIOSTRATEGY_H */