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rocksdb/db/compaction_iterator.h

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4.4 KiB

// 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.
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#include <algorithm>
#include <deque>
#include <string>
#include <vector>
#include "db/compaction.h"
#include "db/merge_helper.h"
#include "rocksdb/compaction_filter.h"
#include "util/log_buffer.h"
namespace rocksdb {
struct CompactionIteratorStats {
// Compaction statistics
int64_t num_record_drop_user = 0;
int64_t num_record_drop_hidden = 0;
int64_t num_record_drop_obsolete = 0;
uint64_t total_filter_time = 0;
// Input statistics
// TODO(noetzli): The stats are incomplete. They are lacking everything
// consumed by MergeHelper.
uint64_t num_input_records = 0;
uint64_t num_input_deletion_records = 0;
uint64_t num_input_corrupt_records = 0;
uint64_t total_input_raw_key_bytes = 0;
uint64_t total_input_raw_value_bytes = 0;
};
class CompactionIterator {
public:
CompactionIterator(Iterator* input, const Comparator* cmp,
MergeHelper* merge_helper, SequenceNumber last_sequence,
std::vector<SequenceNumber>* snapshots, Env* env,
bool expect_valid_internal_key,
Statistics* stats = nullptr,
Compaction* compaction = nullptr,
const CompactionFilter* compaction_filter = nullptr,
LogBuffer* log_buffer = nullptr);
void ResetRecordCounts();
// Seek to the beginning of the compaction iterator output.
//
// REQUIRED: Call only once.
void SeekToFirst();
// Produces the next record in the compaction.
//
// REQUIRED: SeekToFirst() has been called.
void Next();
// Getters
const Slice& key() const { return key_; }
const Slice& value() const { return value_; }
const Status& status() const { return status_; }
const ParsedInternalKey& ikey() const { return ikey_; }
bool Valid() const { return valid_; }
Slice user_key() const { return current_user_key_.GetKey(); }
const CompactionIteratorStats& iter_stats() const { return iter_stats_; }
private:
// Processes the input stream to find the next output
void NextFromInput();
// Do last preparations before presenting the output to the callee. At this
// point this only zeroes out the sequence number if possible for better
// compression.
void PrepareOutput();
// Given a sequence number, return the sequence number of the
// earliest snapshot that this sequence number is visible in.
// The snapshots themselves are arranged in ascending order of
// sequence numbers.
// Employ a sequential search because the total number of
// snapshots are typically small.
inline SequenceNumber findEarliestVisibleSnapshot(
SequenceNumber in, SequenceNumber* prev_snapshot);
Iterator* input_;
const Comparator* cmp_;
MergeHelper* merge_helper_;
const std::vector<SequenceNumber>* snapshots_;
Env* env_;
bool expect_valid_internal_key_;
Statistics* stats_;
Compaction* compaction_;
const CompactionFilter* compaction_filter_;
LogBuffer* log_buffer_;
bool bottommost_level_;
bool valid_ = false;
SequenceNumber visible_at_tip_;
SequenceNumber earliest_snapshot_;
SequenceNumber latest_snapshot_;
// State
Slice key_;
Slice value_;
Status status_;
ParsedInternalKey ikey_;
bool has_current_user_key_ = false;
IterKey current_user_key_;
SequenceNumber current_user_key_sequence_;
SequenceNumber current_user_key_snapshot_;
MergeOutputIterator merge_out_iter_;
std::string updated_key_;
std::string compaction_filter_value_;
IterKey delete_key_;
// "level_ptrs" holds indices that remember which file of an associated
// level we were last checking during the last call to compaction->
// KeyNotExistsBeyondOutputLevel(). This allows future calls to the function
// to pick off where it left off since each subcompaction's key range is
// increasing so a later call to the function must be looking for a key that
// is in or beyond the last file checked during the previous call
std::vector<size_t> level_ptrs_;
CompactionIteratorStats iter_stats_;
};
} // namespace rocksdb