src/fs/rock/RockHeaderUpdater.h

   1 /*
   2  * Copyright (C) 1996-2022 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     class IoCbParams {
  32     public:
  33         IoCbParams(const char *aBuf, ssize_t aSize) : buf(aBuf), size(aSize) {}
  34         const char *buf;
  35         ssize_t size;
  36     };
  37     HeaderUpdater(const Rock::SwapDir::Pointer &aStore, const Ipc::StoreMapUpdate &update);
  38     ~HeaderUpdater() override = default;
  39
  40 protected:
  41     /* AsyncJob API */
  42     void start() override;
  43     bool doneAll() const override;
  44     void swanSong() override;
  45
  46 private:
  47     static StoreIOState::STRCB NoteRead;
  48     static StoreIOState::STIOCB NoteDoneReading;
  49     static StoreIOState::STIOCB NoteDoneWriting;
  50
  51     void startReading();
  52     void stopReading(const char *why);
  53     void readMore(const char *why);
  54     void noteRead(const IoCbParams result);
  55     void noteDoneReading(int errflag);
  56     void parseReadBytes();
  57
  58     void startWriting();
  59     void noteDoneWriting(int errflag);
  60
  61     Rock::SwapDir::Pointer store; ///< cache_dir where the entry is stored
  62     Ipc::StoreMapUpdate update; ///< Ipc::StoreMap update reservation
  63
  64     StoreIOState::Pointer reader; ///< reads old headers and old data
  65     StoreIOState::Pointer writer; ///< writes new headers and old data
  66
  67     SBuf readerBuffer; ///< I/O buffer for a single read operation
  68     SBuf exchangeBuffer; ///< bytes read but not yet discarded or written
  69     uint64_t bytesRead; ///< total entry bytes read from Store so far
  70
  71     size_t staleSwapHeaderSize; ///< stored size of the stale entry metadata
  72
  73     SlotId staleSplicingPointNext; ///< non-updatable old HTTP body suffix start
  74 };
  75
  76 inline
  77 std::ostream &operator <<(std::ostream &os, const HeaderUpdater::IoCbParams &params)
  78 {
  79     os << static_cast<const void *>(params.buf) << "," << params.size;
  80     return os;
  81 }
  82
  83 } // namespace Rock
  84
  85 #endif /* SQUID_FS_ROCK_HEADER_UPDATER_H */
  86