ceph/src/rocksdb/utilities/blob_db/blob_db_iterator.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 #ifndef ROCKSDB_LITE
   8
   9 #include "db/arena_wrapped_db_iter.h"
  10 #include "rocksdb/iterator.h"
  11 #include "util/stop_watch.h"
  12 #include "utilities/blob_db/blob_db_impl.h"
  13
  14 namespace ROCKSDB_NAMESPACE {
  15 class Statistics;
  16 class SystemClock;
  17
  18 namespace blob_db {
  19
  20 using ROCKSDB_NAMESPACE::ManagedSnapshot;
  21
  22 class BlobDBIterator : public Iterator {
  23  public:
  24   BlobDBIterator(ManagedSnapshot* snapshot, ArenaWrappedDBIter* iter,
  25                  BlobDBImpl* blob_db, SystemClock* clock,
  26                  Statistics* statistics)
  27       : snapshot_(snapshot),
  28         iter_(iter),
  29         blob_db_(blob_db),
  30         clock_(clock),
  31         statistics_(statistics) {}
  32
  33   virtual ~BlobDBIterator() = default;
  34
  35   bool Valid() const override {
  36     if (!iter_->Valid()) {
  37       return false;
  38     }
  39     return status_.ok();
  40   }
  41
  42   Status status() const override {
  43     if (!iter_->status().ok()) {
  44       return iter_->status();
  45     }
  46     return status_;
  47   }
  48
  49   void SeekToFirst() override {
  50     StopWatch seek_sw(clock_, statistics_, BLOB_DB_SEEK_MICROS);
  51     RecordTick(statistics_, BLOB_DB_NUM_SEEK);
  52     iter_->SeekToFirst();
  53     while (UpdateBlobValue()) {
  54       iter_->Next();
  55     }
  56   }
  57
  58   void SeekToLast() override {
  59     StopWatch seek_sw(clock_, statistics_, BLOB_DB_SEEK_MICROS);
  60     RecordTick(statistics_, BLOB_DB_NUM_SEEK);
  61     iter_->SeekToLast();
  62     while (UpdateBlobValue()) {
  63       iter_->Prev();
  64     }
  65   }
  66
  67   void Seek(const Slice& target) override {
  68     StopWatch seek_sw(clock_, statistics_, BLOB_DB_SEEK_MICROS);
  69     RecordTick(statistics_, BLOB_DB_NUM_SEEK);
  70     iter_->Seek(target);
  71     while (UpdateBlobValue()) {
  72       iter_->Next();
  73     }
  74   }
  75
  76   void SeekForPrev(const Slice& target) override {
  77     StopWatch seek_sw(clock_, statistics_, BLOB_DB_SEEK_MICROS);
  78     RecordTick(statistics_, BLOB_DB_NUM_SEEK);
  79     iter_->SeekForPrev(target);
  80     while (UpdateBlobValue()) {
  81       iter_->Prev();
  82     }
  83   }
  84
  85   void Next() override {
  86     assert(Valid());
  87     StopWatch next_sw(clock_, statistics_, BLOB_DB_NEXT_MICROS);
  88     RecordTick(statistics_, BLOB_DB_NUM_NEXT);
  89     iter_->Next();
  90     while (UpdateBlobValue()) {
  91       iter_->Next();
  92     }
  93   }
  94
  95   void Prev() override {
  96     assert(Valid());
  97     StopWatch prev_sw(clock_, statistics_, BLOB_DB_PREV_MICROS);
  98     RecordTick(statistics_, BLOB_DB_NUM_PREV);
  99     iter_->Prev();
 100     while (UpdateBlobValue()) {
 101       iter_->Prev();
 102     }
 103   }
 104
 105   Slice key() const override {
 106     assert(Valid());
 107     return iter_->key();
 108   }
 109
 110   Slice value() const override {
 111     assert(Valid());
 112     if (!iter_->IsBlob()) {
 113       return iter_->value();
 114     }
 115     return value_;
 116   }
 117
 118   // Iterator::Refresh() not supported.
 119
 120  private:
 121   // Return true if caller should continue to next value.
 122   bool UpdateBlobValue() {
 123     value_.Reset();
 124     status_ = Status::OK();
 125     if (iter_->Valid() && iter_->status().ok() && iter_->IsBlob()) {
 126       Status s = blob_db_->GetBlobValue(iter_->key(), iter_->value(), &value_);
 127       if (s.IsNotFound()) {
 128         return true;
 129       } else {
 130         if (!s.ok()) {
 131           status_ = s;
 132         }
 133         return false;
 134       }
 135     } else {
 136       return false;
 137     }
 138   }
 139
 140   std::unique_ptr<ManagedSnapshot> snapshot_;
 141   std::unique_ptr<ArenaWrappedDBIter> iter_;
 142   BlobDBImpl* blob_db_;
 143   SystemClock* clock_;
 144   Statistics* statistics_;
 145   Status status_;
 146   PinnableSlice value_;
 147 };
 148 }  // namespace blob_db
 149 }  // namespace ROCKSDB_NAMESPACE
 150 #endif  // !ROCKSDB_LITE