src/fs/rock/RockIoState.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_FS_ROCK_IO_STATE_H
  10 #define SQUID_FS_ROCK_IO_STATE_H
  11
  12 #include "fs/rock/RockSwapDir.h"
  13 #include "sbuf/MemBlob.h"
  14
  15 class DiskFile;
  16
  17 namespace Rock
  18 {
  19
  20 class DbCellHeader;
  21 class SwapDir;
  22
  23 /// \ingroup Rock
  24 class IoState: public ::StoreIOState
  25 {
  26     MEMPROXY_CLASS(IoState);
  27
  28 public:
  29     typedef RefCount<IoState> Pointer;
  30
  31     IoState(Rock::SwapDir::Pointer &aDir, StoreEntry *e, StoreIOState::STFNCB *cbFile, StoreIOState::STIOCB *cbIo, void *data);
  32     virtual ~IoState();
  33
  34     void file(const RefCount<DiskFile> &aFile);
  35
  36     // ::StoreIOState API
  37     virtual void read_(char *buf, size_t size, off_t offset, STRCB * callback, void *callback_data);
  38     virtual bool write(char const *buf, size_t size, off_t offset, FREE * free_func);
  39     virtual void close(int how);
  40
  41     /// whether we are still waiting for the I/O results (i.e., not closed)
  42     bool stillWaiting() const { return theFile != NULL; }
  43
  44     /// forwards read data to the reader that initiated this I/O
  45     void callReaderBack(const char *buf, int rlen);
  46
  47     /// called by SwapDir::writeCompleted() after the last write and on error
  48     void finishedWriting(const int errFlag);
  49
  50     /* one and only one of these will be set and locked; access via *Anchor() */
  51     const Ipc::StoreMapAnchor *readableAnchor_; ///< starting point for reading
  52     Ipc::StoreMapAnchor *writeableAnchor_; ///< starting point for writing
  53
  54     /// the last db slot successfully read or written
  55     SlotId splicingPoint;
  56     /// when reading, this is the next slot we are going to read (if asked)
  57     /// when writing, this is the next slot to use after the last fresh slot
  58     SlotId staleSplicingPointNext;
  59
  60 private:
  61     const Ipc::StoreMapAnchor &readAnchor() const;
  62     Ipc::StoreMapAnchor &writeAnchor();
  63     const Ipc::StoreMapSlice &currentReadableSlice() const;
  64
  65     void tryWrite(char const *buf, size_t size, off_t offset);
  66     size_t writeToBuffer(char const *buf, size_t size);
  67     void writeToDisk(const SlotId nextSlot);
  68     void writeBufToDisk(const SlotId nextSlot, const bool eof, const bool lastWrite);
  69     SlotId reserveSlotForWriting();
  70
  71     void callBack(int errflag);
  72
  73     Rock::SwapDir::Pointer dir; ///< swap dir that initiated I/O
  74     const size_t slotSize; ///< db cell size
  75     int64_t objOffset; ///< object offset for current db slot
  76     SlotId sidCurrent; ///< ID of the db slot currently being read or written
  77
  78     RefCount<DiskFile> theFile; // "file" responsible for this I/O
  79     MemBlob theBuf; // use for write content accumulation only
  80 };
  81
  82 } // namespace Rock
  83
  84 #endif /* SQUID_FS_ROCK_IO_STATE_H */
  85