src/DiskIO/DiskFile.h

   1 /*
   2  * Copyright (C) 1996-2017 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_DISKFILE_H
  10 #define SQUID_DISKFILE_H
  11
  12 #include "base/RefCount.h"
  13 #include "SquidTime.h"
  14
  15 class IORequestor;
  16
  17 class ReadRequest;
  18
  19 class WriteRequest;
  20
  21 class DiskFile : public RefCountable
  22 {
  23
  24 public:
  25
  26     /// generally useful configuration options supported by some children
  27     class Config
  28     {
  29     public:
  30         Config(): ioTimeout(0), ioRate(-1) {}
  31
  32         /// canRead/Write should return false if expected I/O delay exceeds it
  33         time_msec_t ioTimeout; // not enforced if zero, which is the default
  34
  35         /// shape I/O request stream to approach that many per second
  36         int ioRate; // not enforced if negative, which is the default
  37     };
  38
  39     typedef RefCount<DiskFile> Pointer;
  40
  41     /// notes supported configuration options; kids must call this first
  42     virtual void configure(const Config &) {}
  43
  44     virtual void open(int flags, mode_t mode, RefCount<IORequestor> callback) = 0;
  45     virtual void create(int flags, mode_t mode, RefCount<IORequestor> callback) = 0;
  46     virtual void read(ReadRequest *) = 0;
  47     virtual void write(WriteRequest *) = 0;
  48     virtual void close() = 0;
  49     virtual bool canRead() const = 0;
  50     virtual bool canWrite() const {return true;}
  51
  52     /** During migration only */
  53     virtual int getFD() const {return -1;}
  54
  55     virtual bool error() const = 0;
  56
  57     /** Inform callers if there is IO in progress */
  58     virtual bool ioInProgress() const = 0;
  59 };
  60
  61 #endif /* SQUID_DISKFILE_H */
  62