src/DiskIO/DiskIOStrategy.h

   1 /*
   2  * Copyright (C) 1996-2018 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_DISKIOSTRATEGY_H
  10 #define SQUID_DISKIOSTRATEGY_H
  11
  12 #include "base/RefCount.h"
  13 #include "Store.h"
  14
  15 class DiskFile;
  16
  17 class ConfigOption;
  18
  19 class DiskIOStrategy
  20 {
  21
  22 public:
  23     virtual ~DiskIOStrategy() {}
  24
  25     /** Can the IO Strategy handle more requests ? */
  26     virtual bool shedLoad() = 0;
  27
  28     /** What is the current load? 999 = 99.9% */
  29     virtual int load() = 0;
  30
  31     /** Return a handle for performing IO operations */
  32     virtual RefCount<DiskFile> newFile(char const *path) = 0;
  33
  34     /** flush all IO operations  */
  35     virtual void sync() {}
  36
  37     /** whether the IO Strategy can use unlinkd */
  38     virtual bool unlinkdUseful() const = 0;
  39
  40     /** unlink a file by path */
  41     virtual void unlinkFile(char const *) = 0;
  42
  43     /** perform any pending callbacks */
  44     virtual int callback() { return 0; }
  45
  46     /** Init per-instance logic */
  47     virtual void init() {}
  48
  49     /** cachemgr output on the IO instance stats */
  50     virtual void statfs(StoreEntry &) const {}
  51
  52     /** module specific options */
  53     virtual ConfigOption *getOptionTree() const {return NULL;}
  54 };
  55
  56 /* Because we need the DiskFile definition for newFile. */
  57 #include "DiskFile.h"
  58
  59 class SingletonIOStrategy : public DiskIOStrategy
  60 {
  61
  62 public:
  63     SingletonIOStrategy(DiskIOStrategy *anIO) : io(anIO) {}
  64
  65     virtual bool shedLoad() { return io->shedLoad(); }
  66
  67     virtual int load() { return io->load(); }
  68
  69     virtual RefCount<DiskFile> newFile (char const *path) {return io->newFile(path); }
  70
  71     virtual void sync() { io->sync(); }
  72
  73     virtual bool unlinkdUseful() const { return io->unlinkdUseful(); }
  74
  75     virtual void unlinkFile(char const *path) { io->unlinkFile(path); }
  76
  77     virtual int callback() { return io->callback(); }
  78
  79     virtual void init() { io->init(); }
  80
  81     virtual void statfs(StoreEntry & sentry) const { io->statfs(sentry); }
  82
  83     virtual ConfigOption *getOptionTree() const { return io->getOptionTree(); }
  84
  85 private:
  86     DiskIOStrategy *io;
  87 };
  88
  89 #endif /* SQUID_DISKIOSTRATEGY_H */
  90