ceph/src/common/SloppyCRCMap.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3
   4 #ifndef CEPH_COMMON_SLOPPYCRCMAP_H
   5 #define CEPH_COMMON_SLOPPYCRCMAP_H
   6
   7 #include "include/encoding.h"
   8 #include "common/Formatter.h"
   9
  10 /**
  11  * SloppyCRCMap
  12  *
  13  * Opportunistically track CRCs on any reads or writes that cover full
  14  * blocks.  Verify read results when we have CRC data available for
  15  * the given extent.
  16  */
  17 class SloppyCRCMap {
  18   static const int crc_iv = 0xffffffff;
  19
  20   std::map<uint64_t, uint32_t> crc_map;  // offset -> crc(-1)
  21   uint32_t block_size;
  22   uint32_t zero_crc;
  23
  24 public:
  25   SloppyCRCMap(uint32_t b=0) {
  26     set_block_size(b);
  27   }
  28
  29   void set_block_size(uint32_t b) {
  30     block_size = b;
  31     //zero_crc = ceph_crc32c(0xffffffff, NULL, block_size);
  32     if (b) {
  33       bufferlist bl;
  34       bl.append_zero(block_size);
  35       zero_crc = bl.crc32c(crc_iv);
  36     } else {
  37       zero_crc = crc_iv;
  38     }
  39   }
  40
  41   /// update based on a write
  42   void write(uint64_t offset, uint64_t len, const bufferlist& bl,
  43              std::ostream *out = NULL);
  44
  45   /// update based on a truncate
  46   void truncate(uint64_t offset);
  47
  48   /// update based on a zero/punch_hole
  49   void zero(uint64_t offset, uint64_t len);
  50
  51   /// update based on a zero/punch_hole
  52   void clone_range(uint64_t offset, uint64_t len, uint64_t srcoff, const SloppyCRCMap& src,
  53                    std::ostream *out = NULL);
  54
  55   /**
  56    * validate a read result
  57    *
  58    * @param offset offset
  59    * @param length length
  60    * @param bl data read
  61    * @param err option ostream to describe errors in detail
  62    * @returns error count, 0 for success
  63    */
  64   int read(uint64_t offset, uint64_t len, const bufferlist& bl, std::ostream *err);
  65
  66   void encode(bufferlist& bl) const;
  67   void decode(bufferlist::iterator& bl);
  68   void dump(Formatter *f) const;
  69   static void generate_test_instances(std::list<SloppyCRCMap*>& ls);
  70 };
  71 WRITE_CLASS_ENCODER(SloppyCRCMap)
  72
  73 #endif