src/StoreIOState.h

   1 /*
   2  * Copyright (C) 1996-2021 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_STOREIOSTATE_H
  10 #define SQUID_STOREIOSTATE_H
  11
  12 #include "base/RefCount.h"
  13 #include "cbdata.h"
  14 #include "mem/forward.h"
  15 #include "store/forward.h"
  16
  17 class StoreIOState : public RefCountable
  18 {
  19
  20 public:
  21     typedef RefCount<StoreIOState> Pointer;
  22
  23     /*
  24      * STRCB is the "store read callback".  STRCB functions are
  25      * passed to storeRead().  Examples of STRCB callbacks are:
  26      * storeClientReadBody
  27      * storeClientReadHeader
  28      */
  29     typedef void STRCB(void *their_data, const char *buf, ssize_t len, StoreIOState::Pointer self);
  30
  31     /*
  32      * STFNCB is the "store file number callback."  It is called
  33      * when an underlying storage module has allocated the swap
  34      * file number and also indicates that the swap file has been
  35      * opened for reading or writing.  STFNCB functions are passed
  36      * to storeCreate() and storeOpen().  Examples of STFNCB callbacks
  37      * are:
  38      * storeSwapInFileNotify
  39      * storeSwapOutFileNotify
  40      */
  41     typedef void STFNCB(void *their_data, int errflag, StoreIOState::Pointer self);
  42
  43     /*
  44      * STIOCB is the "store close callback" for store files.  It
  45      * is called when the store file is closed.  STIOCB functions
  46      * are passed to storeCreate() and storeOpen(). Examples of
  47      * STIOCB callbacks are:
  48      * storeSwapOutFileClosed
  49      * storeSwapInFileClosed
  50      */
  51     typedef void STIOCB(void *their_data, int errflag, StoreIOState::Pointer self);
  52
  53     /* StoreIOState does not get mempooled - it's children do */
  54     void *operator new (size_t amount);
  55     void operator delete (void *address);
  56
  57     StoreIOState(StoreIOState::STFNCB *cbFile, StoreIOState::STIOCB *cbIo, void *data);
  58     virtual ~StoreIOState();
  59
  60     off_t offset() const {return offset_;}
  61
  62     virtual void read_(char *buf, size_t size, off_t offset, STRCB * callback, void *callback_data) = 0;
  63     /** write the given buffer and free it when it is no longer needed
  64      *  \param offset zero for the very first write and -1 for all other writes
  65      *  \retval false if write failed (callback has been or will be called)
  66      */
  67     virtual bool write(char const *buf, size_t size, off_t offset, FREE * free_func) = 0;
  68
  69     typedef enum {
  70         wroteAll, ///< success: caller supplied all data it wanted to swap out
  71         writerGone, ///< failure: caller left before swapping out everything
  72         readerDone ///< success or failure: either way, stop swapping in
  73     } CloseHow;
  74     virtual void close(int how) = 0; ///< finish or abort swapping per CloseHow
  75
  76     // Tests whether we are working with the primary/public StoreEntry chain.
  77     // Reads start reading the primary chain, but it may become secondary.
  78     // There are two store write kinds:
  79     // * regular writes that change (usually append) the entry visible to all and
  80     // * header updates that create a fresh chain (while keeping the stale one usable).
  81     bool touchingStoreEntry() const;
  82
  83     sdirno swap_dirn;
  84     sfileno swap_filen;
  85     StoreEntry *e;      /* Need this so the FS layers can play god */
  86     mode_t mode;
  87     off_t offset_; ///< number of bytes written or read for this entry so far
  88     STFNCB *file_callback;  // XXX: Unused. TODO: Remove.
  89     STIOCB *callback;
  90     void *callback_data;
  91
  92     struct {
  93         STRCB *callback;
  94         void *callback_data;
  95     } read;
  96
  97     struct {
  98         bool closing;   /* debugging aid */
  99     } flags;
 100 };
 101
 102 StoreIOState::Pointer storeCreate(StoreEntry *, StoreIOState::STFNCB *, StoreIOState::STIOCB *, void *);
 103 StoreIOState::Pointer storeOpen(StoreEntry *, StoreIOState::STFNCB *, StoreIOState::STIOCB *, void *);
 104 void storeClose(StoreIOState::Pointer, int how);
 105 void storeRead(StoreIOState::Pointer, char *, size_t, off_t, StoreIOState::STRCB *, void *);
 106 void storeIOWrite(StoreIOState::Pointer, char const *, size_t, off_t, FREE *);
 107
 108 #endif /* SQUID_STOREIOSTATE_H */
 109