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 #include <list>
  11 #include <map>
  12 #include <ostream>
  13
  14 /**
  15  * SloppyCRCMap
  16  *
  17  * Opportunistically track CRCs on any reads or writes that cover full
  18  * blocks.  Verify read results when we have CRC data available for
  19  * the given extent.
  20  */
  21 class SloppyCRCMap {
  22   static const int crc_iv = 0xffffffff;
  23
  24   std::map<uint64_t, uint32_t> crc_map;  // offset -> crc(-1)
  25   uint32_t block_size;
  26   uint32_t zero_crc;
  27
  28 public:
  29   SloppyCRCMap(uint32_t b=0) {
  30     set_block_size(b);
  31   }
  32
  33   void set_block_size(uint32_t b) {
  34     block_size = b;
  35     //zero_crc = ceph_crc32c(0xffffffff, NULL, block_size);
  36     if (b) {
  37       bufferlist bl;
  38       bl.append_zero(block_size);
  39       zero_crc = bl.crc32c(crc_iv);
  40     } else {
  41       zero_crc = crc_iv;
  42     }
  43   }
  44
  45   /// update based on a write
  46   void write(uint64_t offset, uint64_t len, const bufferlist& bl,
  47              std::ostream *out = NULL);
  48
  49   /// update based on a truncate
  50   void truncate(uint64_t offset);
  51
  52   /// update based on a zero/punch_hole
  53   void zero(uint64_t offset, uint64_t len);
  54
  55   /// update based on a zero/punch_hole
  56   void clone_range(uint64_t offset, uint64_t len, uint64_t srcoff, const SloppyCRCMap& src,
  57                    std::ostream *out = NULL);
  58
  59   /**
  60    * validate a read result
  61    *
  62    * @param offset offset
  63    * @param length length
  64    * @param bl data read
  65    * @param err option ostream to describe errors in detail
  66    * @returns error count, 0 for success
  67    */
  68   int read(uint64_t offset, uint64_t len, const bufferlist& bl, std::ostream *err);
  69
  70   void encode(bufferlist& bl) const;
  71   void decode(bufferlist::iterator& bl);
  72   void dump(Formatter *f) const;
  73   static void generate_test_instances(std::list<SloppyCRCMap*>& ls);
  74 };
  75 WRITE_CLASS_ENCODER(SloppyCRCMap)
  76
  77 #endif