ceph/src/rocksdb/util/duplicate_detector.h

   1 // Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #pragma once
   7
   8 #ifndef __STDC_FORMAT_MACROS
   9 #define __STDC_FORMAT_MACROS
  10 #endif
  11
  12 #include <inttypes.h>
  13
  14 #include "util/set_comparator.h"
  15
  16 namespace rocksdb {
  17 // During recovery if the memtable is flushed we cannot rely on its help on
  18 // duplicate key detection and as key insert will not be attempted. This class
  19 // will be used as a emulator of memtable to tell if insertion of a key/seq
  20 // would have resulted in duplication.
  21 class DuplicateDetector {
  22  public:
  23   explicit DuplicateDetector(DBImpl* db) : db_(db) {}
  24   bool IsDuplicateKeySeq(uint32_t cf, const Slice& key, SequenceNumber seq) {
  25     assert(seq >= batch_seq_);
  26     if (batch_seq_ != seq) {  // it is a new batch
  27       keys_.clear();
  28     }
  29     batch_seq_ = seq;
  30     CFKeys& cf_keys = keys_[cf];
  31     if (cf_keys.size() == 0) {  // just inserted
  32       InitWithComp(cf);
  33     }
  34     auto it = cf_keys.insert(key);
  35     if (it.second == false) {  // second is false if a element already existed.
  36       keys_.clear();
  37       InitWithComp(cf);
  38       keys_[cf].insert(key);
  39       return true;
  40     }
  41     return false;
  42   }
  43
  44  private:
  45   SequenceNumber batch_seq_ = 0;
  46   DBImpl* db_;
  47   using CFKeys = std::set<Slice, SetComparator>;
  48   std::map<uint32_t, CFKeys> keys_;
  49   void InitWithComp(const uint32_t cf) {
  50     auto h = db_->GetColumnFamilyHandle(cf);
  51     if (!h) {
  52       // TODO(myabandeh): This is not a concern in MyRocks as drop cf is not
  53       // implemented yet. When it does, we should return proper error instead
  54       // of throwing exception.
  55       ROCKS_LOG_FATAL(
  56           db_->immutable_db_options().info_log,
  57           "Recovering an entry from the dropped column family %" PRIu32
  58           ". WAL must must have been emptied before dropping the column "
  59           "family", cf);
  60 #ifndef ROCKSDB_LITE
  61       throw std::runtime_error(
  62           "Recovering an entry from a dropped column family. "
  63           "WAL must must have been flushed before dropping the column "
  64           "family");
  65 #endif
  66       return;
  67     }
  68     auto cmp = h->GetComparator();
  69     keys_[cf] = CFKeys(SetComparator(cmp));
  70   }
  71 };
  72 }  // namespace rocksdb