src/DiskIO/DiskFile.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_DISKFILE_H
  34 #define SQUID_DISKFILE_H
  35
  36 #include "squid.h"
  37
  38 #include "RefCount.h"
  39
  40 class IORequestor;
  41
  42 class ReadRequest;
  43
  44 class WriteRequest;
  45
  46 class DiskFile : public RefCountable
  47 {
  48
  49 public:
  50
  51     /// generally useful configuration options supported by some children
  52     class Config
  53     {
  54     public:
  55         Config(): ioTimeout(0), ioRate(-1) {}
  56
  57         /// canRead/Write should return false if expected I/O delay exceeds it
  58         time_msec_t ioTimeout; // not enforced if zero, which is the default
  59
  60         /// shape I/O request stream to approach that many per second
  61         int ioRate; // not enforced if negative, which is the default
  62     };
  63
  64     typedef RefCount<DiskFile> Pointer;
  65
  66     /// notes supported configuration options; kids must call this first
  67     virtual void configure(const Config &cfg) {}
  68
  69     virtual void open(int flags, mode_t mode, RefCount<IORequestor> callback) = 0;
  70     virtual void create(int flags, mode_t mode, RefCount<IORequestor> callback) = 0;
  71     virtual void read(ReadRequest *) = 0;
  72     virtual void write(WriteRequest *) = 0;
  73     virtual void close() = 0;
  74     virtual bool canRead() const = 0;
  75     virtual bool canWrite() const {return true;}
  76
  77     /** During migration only */
  78     virtual int getFD() const {return -1;}
  79
  80     virtual bool error() const = 0;
  81
  82     /** Inform callers if there is IO in progress */
  83     virtual bool ioInProgress() const = 0;
  84 };
  85
  86 #endif /* SQUID_DISKFILE_H */