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rocksdb/table/block_based/partitioned_index_iterator.h

142 lines
4.6 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include "table/block_based/block_based_table_reader.h"
#include "table/block_based/block_based_table_reader_impl.h"
#include "table/block_based/block_prefetcher.h"
#include "table/block_based/reader_common.h"
namespace ROCKSDB_NAMESPACE {
// Iterator that iterates over partitioned index.
// Some upper and lower bound tricks played in block based table iterators
// could be played here, but it's too complicated to reason about index
// keys with upper or lower bound, so we skip it for simplicity.
class ParititionedIndexIterator : public InternalIteratorBase<IndexValue> {
// compaction_readahead_size: its value will only be used if for_compaction =
// true
public:
ParititionedIndexIterator(
const BlockBasedTable* table, const ReadOptions& read_options,
const InternalKeyComparator& icomp,
std::unique_ptr<InternalIteratorBase<IndexValue>>&& index_iter,
TableReaderCaller caller, size_t compaction_readahead_size = 0)
: table_(table),
read_options_(read_options),
#ifndef NDEBUG
icomp_(icomp),
#endif
user_comparator_(icomp.user_comparator()),
index_iter_(std::move(index_iter)),
block_iter_points_to_real_block_(false),
lookup_context_(caller),
block_prefetcher_(compaction_readahead_size) {}
~ParititionedIndexIterator() {}
void Seek(const Slice& target) override;
void SeekForPrev(const Slice&) override {
// Shouldn't be called.
assert(false);
}
void SeekToFirst() override;
void SeekToLast() override;
void Next() final override;
bool NextAndGetResult(IterateResult*) override {
assert(false);
return false;
}
void Prev() override;
bool Valid() const override {
return block_iter_points_to_real_block_ && block_iter_.Valid();
}
Slice key() const override {
assert(Valid());
return block_iter_.key();
}
Slice user_key() const override {
assert(Valid());
return block_iter_.user_key();
}
IndexValue value() const override {
assert(Valid());
return block_iter_.value();
}
Status status() const override {
// Prefix index set status to NotFound when the prefix does not exist
if (!index_iter_->status().ok() && !index_iter_->status().IsNotFound()) {
return index_iter_->status();
} else if (block_iter_points_to_real_block_) {
return block_iter_.status();
} else {
return Status::OK();
}
}
inline IterBoundCheck UpperBoundCheckResult() override {
// Shouldn't be called.
assert(false);
return IterBoundCheck::kUnknown;
}
void SetPinnedItersMgr(PinnedIteratorsManager*) override {
// Shouldn't be called.
assert(false);
}
bool IsKeyPinned() const override {
// Shouldn't be called.
assert(false);
return false;
}
bool IsValuePinned() const override {
// Shouldn't be called.
assert(false);
return false;
}
void ResetPartitionedIndexIter() {
if (block_iter_points_to_real_block_) {
block_iter_.Invalidate(Status::OK());
block_iter_points_to_real_block_ = false;
}
}
void SavePrevIndexValue() {
if (block_iter_points_to_real_block_) {
// Reseek. If they end up with the same data block, we shouldn't re-fetch
// the same data block.
prev_block_offset_ = index_iter_->value().handle.offset();
}
}
private:
friend class BlockBasedTableReaderTestVerifyChecksum_ChecksumMismatch_Test;
const BlockBasedTable* table_;
const ReadOptions read_options_;
#ifndef NDEBUG
const InternalKeyComparator& icomp_;
#endif
UserComparatorWrapper user_comparator_;
std::unique_ptr<InternalIteratorBase<IndexValue>> index_iter_;
IndexBlockIter block_iter_;
// True if block_iter_ is initialized and points to the same block
// as index iterator.
bool block_iter_points_to_real_block_;
uint64_t prev_block_offset_ = std::numeric_limits<uint64_t>::max();
BlockCacheLookupContext lookup_context_;
BlockPrefetcher block_prefetcher_;
// If `target` is null, seek to first.
void SeekImpl(const Slice* target);
void InitPartitionedIndexBlock();
void FindKeyForward();
void FindBlockForward();
void FindKeyBackward();
};
} // namespace ROCKSDB_NAMESPACE