src/fs/rock/RockIoState.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_FS_ROCK_IO_STATE_H
  10 #define SQUID_FS_ROCK_IO_STATE_H
  11
  12 #include "fs/rock/forward.h"
  13 #include "fs/rock/RockSwapDir.h"
  14 #include "sbuf/MemBlob.h"
  15
  16 class DiskFile;
  17
  18 namespace Rock
  19 {
  20
  21 class DbCellHeader;
  22 class SwapDir;
  23
  24 /// \ingroup Rock
  25 class IoState: public ::StoreIOState
  26 {
  27     MEMPROXY_CLASS(IoState);
  28
  29 public:
  30     typedef RefCount<IoState> Pointer;
  31
  32     IoState(Rock::SwapDir::Pointer &aDir, StoreEntry *e, StoreIOState::STFNCB *cbFile, StoreIOState::STIOCB *cbIo, void *data);
  33     virtual ~IoState();
  34
  35     void file(const RefCount<DiskFile> &aFile);
  36
  37     // ::StoreIOState API
  38     virtual void read_(char *buf, size_t size, off_t offset, STRCB * callback, void *callback_data);
  39     virtual bool write(char const *buf, size_t size, off_t offset, FREE * free_func);
  40     virtual void close(int how);
  41
  42     /// whether we are still waiting for the I/O results (i.e., not closed)
  43     bool stillWaiting() const { return theFile != NULL; }
  44
  45     /// forwards read data (or an error) to the reader that initiated this I/O
  46     void handleReadCompletion(Rock::ReadRequest &request, const int rlen, const int errFlag);
  47
  48     /// called by SwapDir::writeCompleted() after the last write and on error
  49     void finishedWriting(const int errFlag);
  50
  51     /// notes that the disker has satisfied the given I/O request
  52     /// \returns whether all earlier I/O requests have been satisfied already
  53     bool expectedReply(const IoXactionId receivedId);
  54
  55     /* one and only one of these will be set and locked; access via *Anchor() */
  56     const Ipc::StoreMapAnchor *readableAnchor_; ///< starting point for reading
  57     Ipc::StoreMapAnchor *writeableAnchor_; ///< starting point for writing
  58
  59     /// the last db slot successfully read or written
  60     SlotId splicingPoint;
  61     /// when reading, this is the next slot we are going to read (if asked)
  62     /// when writing, this is the next slot to use after the last fresh slot
  63     SlotId staleSplicingPointNext;
  64
  65 private:
  66     const Ipc::StoreMapAnchor &readAnchor() const;
  67     Ipc::StoreMapAnchor &writeAnchor();
  68     const Ipc::StoreMapSlice &currentReadableSlice() const;
  69
  70     void tryWrite(char const *buf, size_t size, off_t offset);
  71     size_t writeToBuffer(char const *buf, size_t size);
  72     void writeToDisk();
  73
  74     void callReaderBack(const char *buf, int rlen);
  75     void callBack(int errflag);
  76
  77     Rock::SwapDir::Pointer dir; ///< swap dir that initiated I/O
  78     const size_t slotSize; ///< db cell size
  79     int64_t objOffset; ///< object offset for current db slot
  80
  81     /// The very first entry slot. Usually the same as anchor.first,
  82     /// but writers set anchor.first only after the first write is done.
  83     SlotId sidFirst;
  84
  85     /// Unused by readers.
  86     /// For writers, the slot pointing (via .next) to sidCurrent.
  87     SlotId sidPrevious;
  88
  89     /// For readers, the db slot currently being read from disk.
  90     /// For writers, the reserved db slot currently being filled (to be written).
  91     SlotId sidCurrent;
  92
  93     /// Unused by readers.
  94     /// For writers, the reserved db slot that sidCurrent.next will point to.
  95     SlotId sidNext;
  96
  97     /// the number of read or write requests we sent to theFile
  98     uint64_t requestsSent;
  99
 100     /// the number of successful responses we received from theFile
 101     uint64_t repliesReceived;
 102
 103     RefCount<DiskFile> theFile; // "file" responsible for this I/O
 104     MemBlob theBuf; // use for write content accumulation only
 105 };
 106
 107 } // namespace Rock
 108
 109 #endif /* SQUID_FS_ROCK_IO_STATE_H */
 110