src/fs/rock/RockHeaderUpdater.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_FS_ROCK_HEADER_UPDATER_H
  10 #define SQUID_FS_ROCK_HEADER_UPDATER_H
  11
  12 #include "base/AsyncJob.h"
  13 #include "cbdata.h"
  14 #include "fs/rock/forward.h"
  15 #include "fs/rock/RockSwapDir.h"
  16 #include "ipc/StoreMap.h"
  17
  18 namespace Rock
  19 {
  20
  21 /// Updates HTTP headers of a single Rock store entry:
  22 /// * reads old body data in the same slot as the last old headers slot, if any
  23 /// * writes new headers (1+ slots)
  24 /// * writes old data (0-2 slots)
  25 /// * chains the new entry prefix (1+ slots) to the old entry suffix (0+ slots)
  26 class HeaderUpdater: public AsyncJob
  27 {
  28     CBDATA_CHILD(HeaderUpdater);
  29
  30 public:
  31     HeaderUpdater(const Rock::SwapDir::Pointer &aStore, const Ipc::StoreMapUpdate &update);
  32     virtual ~HeaderUpdater() override = default;
  33
  34 protected:
  35     /* AsyncJob API */
  36     virtual void start() override;
  37     virtual bool doneAll() const override;
  38     virtual void swanSong() override;
  39
  40 private:
  41     static StoreIOState::STRCB NoteRead;
  42     static StoreIOState::STIOCB NoteDoneReading;
  43     static StoreIOState::STIOCB NoteDoneWriting;
  44
  45     void startReading();
  46     void stopReading(const char *why);
  47     void readMore(const char *why);
  48     void noteRead(ssize_t result);
  49     void noteDoneReading(int errflag);
  50     void parseReadBytes();
  51
  52     void startWriting();
  53     void noteDoneWriting(int errflag);
  54
  55     Rock::SwapDir::Pointer store; ///< cache_dir where the entry is stored
  56     Ipc::StoreMapUpdate update; ///< Ipc::StoreMap update reservation
  57
  58     StoreIOState::Pointer reader; ///< reads old headers and old data
  59     StoreIOState::Pointer writer; ///< writes new headers and old data
  60
  61     SBuf readerBuffer; ///< I/O buffer for a single read operation
  62     SBuf exchangeBuffer; ///< bytes read but not yet discarded or written
  63     uint64_t bytesRead; ///< total entry bytes read from Store so far
  64
  65     int staleSwapHeaderSize; ///< stored size of the stale entry metadata
  66
  67     SlotId staleSplicingPointNext; ///< non-updatable old HTTP body suffix start
  68 };
  69
  70 } // namespace Rock
  71
  72 #endif /* SQUID_FS_ROCK_HEADER_UPDATER_H */
  73