ceph/src/rocksdb/table/get_context.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under the BSD-style license found in the
   3 //  LICENSE file in the root directory of this source tree. An additional grant
   4 //  of patent rights can be found in the PATENTS file in the same directory.
   5
   6 #pragma once
   7 #include <string>
   8 #include "db/merge_context.h"
   9 #include "db/range_del_aggregator.h"
  10 #include "rocksdb/env.h"
  11 #include "rocksdb/types.h"
  12 #include "table/block.h"
  13
  14 namespace rocksdb {
  15 class MergeContext;
  16 class PinnedIteratorsManager;
  17
  18 class GetContext {
  19  public:
  20   enum GetState {
  21     kNotFound,
  22     kFound,
  23     kDeleted,
  24     kCorrupt,
  25     kMerge  // saver contains the current merge result (the operands)
  26   };
  27
  28   GetContext(const Comparator* ucmp, const MergeOperator* merge_operator,
  29              Logger* logger, Statistics* statistics, GetState init_state,
  30              const Slice& user_key, PinnableSlice* value, bool* value_found,
  31              MergeContext* merge_context, RangeDelAggregator* range_del_agg,
  32              Env* env, SequenceNumber* seq = nullptr,
  33              PinnedIteratorsManager* _pinned_iters_mgr = nullptr);
  34
  35   void MarkKeyMayExist();
  36
  37   // Records this key, value, and any meta-data (such as sequence number and
  38   // state) into this GetContext.
  39   //
  40   // Returns True if more keys need to be read (due to merges) or
  41   //         False if the complete value has been found.
  42   bool SaveValue(const ParsedInternalKey& parsed_key, const Slice& value,
  43                  Cleanable* value_pinner = nullptr);
  44
  45   // Simplified version of the previous function. Should only be used when we
  46   // know that the operation is a Put.
  47   void SaveValue(const Slice& value, SequenceNumber seq);
  48
  49   GetState State() const { return state_; }
  50
  51   RangeDelAggregator* range_del_agg() { return range_del_agg_; }
  52
  53   PinnedIteratorsManager* pinned_iters_mgr() { return pinned_iters_mgr_; }
  54
  55   // If a non-null string is passed, all the SaveValue calls will be
  56   // logged into the string. The operations can then be replayed on
  57   // another GetContext with replayGetContextLog.
  58   void SetReplayLog(std::string* replay_log) { replay_log_ = replay_log; }
  59
  60   // Do we need to fetch the SequenceNumber for this key?
  61   bool NeedToReadSequence() const { return (seq_ != nullptr); }
  62
  63  private:
  64   const Comparator* ucmp_;
  65   const MergeOperator* merge_operator_;
  66   // the merge operations encountered;
  67   Logger* logger_;
  68   Statistics* statistics_;
  69
  70   GetState state_;
  71   Slice user_key_;
  72   PinnableSlice* pinnable_val_;
  73   bool* value_found_;  // Is value set correctly? Used by KeyMayExist
  74   MergeContext* merge_context_;
  75   RangeDelAggregator* range_del_agg_;
  76   Env* env_;
  77   // If a key is found, seq_ will be set to the SequenceNumber of most recent
  78   // write to the key or kMaxSequenceNumber if unknown
  79   SequenceNumber* seq_;
  80   std::string* replay_log_;
  81   // Used to temporarily pin blocks when state_ == GetContext::kMerge
  82   PinnedIteratorsManager* pinned_iters_mgr_;
  83 };
  84
  85 void replayGetContextLog(const Slice& replay_log, const Slice& user_key,
  86                          GetContext* get_context);
  87
  88 }  // namespace rocksdb