src/DiskIO/DiskFile.h

   1 /*
   2  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   3  * ----------------------------------------------------------
   4  *
   5  *  Squid is the result of efforts by numerous individuals from
   6  *  the Internet community; see the CONTRIBUTORS file for full
   7  *  details.   Many organizations have provided support for Squid's
   8  *  development; see the SPONSORS file for full details.  Squid is
   9  *  Copyrighted (C) 2001 by the Regents of the University of
  10  *  California; see the COPYRIGHT file for full details.  Squid
  11  *  incorporates software developed and/or copyrighted by other
  12  *  sources; see the CREDITS file for full details.
  13  *
  14  *  This program is free software; you can redistribute it and/or modify
  15  *  it under the terms of the GNU General Public License as published by
  16  *  the Free Software Foundation; either version 2 of the License, or
  17  *  (at your option) any later version.
  18  *
  19  *  This program is distributed in the hope that it will be useful,
  20  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  *  GNU General Public License for more details.
  23  *
  24  *  You should have received a copy of the GNU General Public License
  25  *  along with this program; if not, write to the Free Software
  26  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  27  *
  28  * Copyright (c) 2003 Robert Collins <robertc@squid-cache.org>
  29  */
  30
  31 #ifndef SQUID_DISKFILE_H
  32 #define SQUID_DISKFILE_H
  33
  34 #include "typedefs.h"
  35
  36 #include "RefCount.h"
  37
  38 class IORequestor;
  39
  40 class ReadRequest;
  41
  42 class WriteRequest;
  43
  44 class DiskFile : public RefCountable
  45 {
  46
  47 public:
  48
  49     /// generally useful configuration options supported by some children
  50     class Config
  51     {
  52     public:
  53         Config(): ioTimeout(0), ioRate(-1) {}
  54
  55         /// canRead/Write should return false if expected I/O delay exceeds it
  56         time_msec_t ioTimeout; // not enforced if zero, which is the default
  57
  58         /// shape I/O request stream to approach that many per second
  59         int ioRate; // not enforced if negative, which is the default
  60     };
  61
  62     typedef RefCount<DiskFile> Pointer;
  63
  64     /// notes supported configuration options; kids must call this first
  65     virtual void configure(const Config &cfg) {}
  66
  67     virtual void open(int flags, mode_t mode, RefCount<IORequestor> callback) = 0;
  68     virtual void create(int flags, mode_t mode, RefCount<IORequestor> callback) = 0;
  69     virtual void read(ReadRequest *) = 0;
  70     virtual void write(WriteRequest *) = 0;
  71     virtual void close() = 0;
  72     virtual bool canRead() const = 0;
  73     virtual bool canWrite() const {return true;}
  74
  75     /** During migration only */
  76     virtual int getFD() const {return -1;}
  77
  78     virtual bool error() const = 0;
  79
  80     /** Inform callers if there is IO in progress */
  81     virtual bool ioInProgress() const = 0;
  82 };
  83
  84 #endif /* SQUID_DISKFILE_H */