fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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440 lines
18 KiB
440 lines
18 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <stdint.h>
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#include <memory>
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#include <string>
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#include <utility>
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#include <vector>
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#include "rocksdb/options.h"
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#include "rocksdb/persistent_cache.h"
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#include "rocksdb/statistics.h"
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#include "rocksdb/status.h"
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#include "rocksdb/table.h"
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#include "table/filter_block.h"
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#include "table/format.h"
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#include "table/persistent_cache_helper.h"
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#include "table/table_properties_internal.h"
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#include "table/table_reader.h"
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#include "table/two_level_iterator.h"
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#include "util/cf_options.h"
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#include "util/coding.h"
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#include "util/file_reader_writer.h"
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namespace rocksdb {
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class Block;
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class BlockIter;
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class BlockHandle;
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class Cache;
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class FilterBlockReader;
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class BlockBasedFilterBlockReader;
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class FullFilterBlockReader;
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class Footer;
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class InternalKeyComparator;
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class Iterator;
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class RandomAccessFile;
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class TableCache;
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class TableReader;
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class WritableFile;
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struct BlockBasedTableOptions;
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struct EnvOptions;
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struct ReadOptions;
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class GetContext;
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class InternalIterator;
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using std::unique_ptr;
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typedef std::vector<std::pair<std::string, std::string>> KVPairBlock;
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// A Table is a sorted map from strings to strings. Tables are
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// immutable and persistent. A Table may be safely accessed from
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// multiple threads without external synchronization.
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class BlockBasedTable : public TableReader {
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public:
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static const std::string kFilterBlockPrefix;
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static const std::string kFullFilterBlockPrefix;
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// The longest prefix of the cache key used to identify blocks.
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// For Posix files the unique ID is three varints.
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static const size_t kMaxCacheKeyPrefixSize = kMaxVarint64Length * 3 + 1;
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// Attempt to open the table that is stored in bytes [0..file_size)
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// of "file", and read the metadata entries necessary to allow
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// retrieving data from the table.
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//
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// If successful, returns ok and sets "*table_reader" to the newly opened
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// table. The client should delete "*table_reader" when no longer needed.
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// If there was an error while initializing the table, sets "*table_reader"
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// to nullptr and returns a non-ok status.
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//
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// @param file must remain live while this Table is in use.
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// @param prefetch_index_and_filter_in_cache can be used to disable
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// prefetching of
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// index and filter blocks into block cache at startup
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// @param skip_filters Disables loading/accessing the filter block. Overrides
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// prefetch_index_and_filter_in_cache, so filter will be skipped if both
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// are set.
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static Status Open(const ImmutableCFOptions& ioptions,
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const EnvOptions& env_options,
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const BlockBasedTableOptions& table_options,
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const InternalKeyComparator& internal_key_comparator,
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unique_ptr<RandomAccessFileReader>&& file,
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uint64_t file_size, unique_ptr<TableReader>* table_reader,
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bool prefetch_index_and_filter_in_cache = true,
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bool skip_filters = false, int level = -1);
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bool PrefixMayMatch(const Slice& internal_key);
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// Returns a new iterator over the table contents.
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// The result of NewIterator() is initially invalid (caller must
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// call one of the Seek methods on the iterator before using it).
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// @param skip_filters Disables loading/accessing the filter block
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InternalIterator* NewIterator(const ReadOptions&, Arena* arena = nullptr,
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bool skip_filters = false) override;
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InternalIterator* NewRangeTombstoneIterator(
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const ReadOptions& read_options) override;
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// @param skip_filters Disables loading/accessing the filter block
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Status Get(const ReadOptions& readOptions, const Slice& key,
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GetContext* get_context, bool skip_filters = false) override;
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// Pre-fetch the disk blocks that correspond to the key range specified by
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// (kbegin, kend). The call will return error status in the event of
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// IO or iteration error.
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Status Prefetch(const Slice* begin, const Slice* end) override;
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// Given a key, return an approximate byte offset in the file where
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// the data for that key begins (or would begin if the key were
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// present in the file). The returned value is in terms of file
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// bytes, and so includes effects like compression of the underlying data.
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// E.g., the approximate offset of the last key in the table will
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// be close to the file length.
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uint64_t ApproximateOffsetOf(const Slice& key) override;
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// Returns true if the block for the specified key is in cache.
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// REQUIRES: key is in this table && block cache enabled
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bool TEST_KeyInCache(const ReadOptions& options, const Slice& key);
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// Set up the table for Compaction. Might change some parameters with
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// posix_fadvise
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void SetupForCompaction() override;
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std::shared_ptr<const TableProperties> GetTableProperties() const override;
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size_t ApproximateMemoryUsage() const override;
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// convert SST file to a human readable form
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Status DumpTable(WritableFile* out_file) override;
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void Close() override;
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~BlockBasedTable();
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bool TEST_filter_block_preloaded() const;
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bool TEST_index_reader_preloaded() const;
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// IndexReader is the interface that provide the functionality for index
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// access.
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class IndexReader {
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public:
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explicit IndexReader(const Comparator* comparator, Statistics* stats)
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: comparator_(comparator), statistics_(stats) {}
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virtual ~IndexReader() {}
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// Create an iterator for index access.
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// If iter is null then a new object is created on heap and the callee will
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// have the ownership. If a non-null iter is passed in it will be used, and
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// the returned value is either the same as iter or a new on-heap object
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// that
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// wrapps the passed iter. In the latter case the return value would point
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// to
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// a different object then iter and the callee has the ownership of the
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// returned object.
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virtual InternalIterator* NewIterator(BlockIter* iter = nullptr,
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bool total_order_seek = true) = 0;
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// The size of the index.
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virtual size_t size() const = 0;
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// Memory usage of the index block
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virtual size_t usable_size() const = 0;
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// return the statistics pointer
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virtual Statistics* statistics() const { return statistics_; }
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// Report an approximation of how much memory has been used other than
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// memory
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// that was allocated in block cache.
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virtual size_t ApproximateMemoryUsage() const = 0;
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protected:
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const Comparator* comparator_;
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private:
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Statistics* statistics_;
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};
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static Slice GetCacheKey(const char* cache_key_prefix,
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size_t cache_key_prefix_size,
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const BlockHandle& handle, char* cache_key);
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// Retrieve all key value pairs from data blocks in the table.
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// The key retrieved are internal keys.
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Status GetKVPairsFromDataBlocks(std::vector<KVPairBlock>* kv_pair_blocks);
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class BlockEntryIteratorState;
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private:
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template <class TValue>
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struct CachableEntry;
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struct Rep;
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Rep* rep_;
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bool compaction_optimized_;
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// input_iter: if it is not null, update this one and return it as Iterator
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static InternalIterator* NewDataBlockIterator(
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Rep* rep, const ReadOptions& ro, const Slice& index_value,
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BlockIter* input_iter = nullptr);
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// If block cache enabled (compressed or uncompressed), looks for the block
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// identified by handle in (1) uncompressed cache, (2) compressed cache, and
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// then (3) file. If found, inserts into the cache(s) that were searched
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// unsuccessfully (e.g., if found in file, will add to both uncompressed and
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// compressed caches if they're enabled).
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//
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// @param block_entry value is set to the uncompressed block if found. If
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// in uncompressed block cache, also sets cache_handle to reference that
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// block.
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static Status MaybeLoadDataBlockToCache(
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Rep* rep, const ReadOptions& ro, const BlockHandle& handle,
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Slice compression_dict, CachableEntry<Block>* block_entry);
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// For the following two functions:
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// if `no_io == true`, we will not try to read filter/index from sst file
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// were they not present in cache yet.
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CachableEntry<FilterBlockReader> GetFilter(bool no_io = false) const;
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// Get the iterator from the index reader.
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// If input_iter is not set, return new Iterator
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// If input_iter is set, update it and return it as Iterator
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//
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// Note: ErrorIterator with Status::Incomplete shall be returned if all the
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// following conditions are met:
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// 1. We enabled table_options.cache_index_and_filter_blocks.
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// 2. index is not present in block cache.
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// 3. We disallowed any io to be performed, that is, read_options ==
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// kBlockCacheTier
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InternalIterator* NewIndexIterator(
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const ReadOptions& read_options, BlockIter* input_iter = nullptr,
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CachableEntry<IndexReader>* index_entry = nullptr);
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// Read block cache from block caches (if set): block_cache and
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// block_cache_compressed.
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// On success, Status::OK with be returned and @block will be populated with
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// pointer to the block as well as its block handle.
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// @param compression_dict Data for presetting the compression library's
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// dictionary.
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static Status GetDataBlockFromCache(
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const Slice& block_cache_key, const Slice& compressed_block_cache_key,
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Cache* block_cache, Cache* block_cache_compressed,
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const ImmutableCFOptions& ioptions, const ReadOptions& read_options,
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BlockBasedTable::CachableEntry<Block>* block, uint32_t format_version,
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const Slice& compression_dict, size_t read_amp_bytes_per_bit);
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// Put a raw block (maybe compressed) to the corresponding block caches.
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// This method will perform decompression against raw_block if needed and then
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// populate the block caches.
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// On success, Status::OK will be returned; also @block will be populated with
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// uncompressed block and its cache handle.
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//
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// REQUIRES: raw_block is heap-allocated. PutDataBlockToCache() will be
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// responsible for releasing its memory if error occurs.
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// @param compression_dict Data for presetting the compression library's
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// dictionary.
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static Status PutDataBlockToCache(
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const Slice& block_cache_key, const Slice& compressed_block_cache_key,
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Cache* block_cache, Cache* block_cache_compressed,
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const ReadOptions& read_options, const ImmutableCFOptions& ioptions,
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CachableEntry<Block>* block, Block* raw_block, uint32_t format_version,
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const Slice& compression_dict, size_t read_amp_bytes_per_bit);
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// Calls (*handle_result)(arg, ...) repeatedly, starting with the entry found
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// after a call to Seek(key), until handle_result returns false.
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// May not make such a call if filter policy says that key is not present.
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friend class TableCache;
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friend class BlockBasedTableBuilder;
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void ReadMeta(const Footer& footer);
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// Create a index reader based on the index type stored in the table.
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// Optionally, user can pass a preloaded meta_index_iter for the index that
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// need to access extra meta blocks for index construction. This parameter
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// helps avoid re-reading meta index block if caller already created one.
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Status CreateIndexReader(
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IndexReader** index_reader,
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InternalIterator* preloaded_meta_index_iter = nullptr);
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bool FullFilterKeyMayMatch(const ReadOptions& read_options,
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FilterBlockReader* filter,
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const Slice& user_key) const;
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// Read the meta block from sst.
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static Status ReadMetaBlock(Rep* rep, std::unique_ptr<Block>* meta_block,
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std::unique_ptr<InternalIterator>* iter);
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// Create the filter from the filter block.
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FilterBlockReader* ReadFilter(Rep* rep) const;
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static void SetupCacheKeyPrefix(Rep* rep, uint64_t file_size);
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explicit BlockBasedTable(Rep* rep)
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: rep_(rep), compaction_optimized_(false) {}
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// Generate a cache key prefix from the file
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static void GenerateCachePrefix(Cache* cc,
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RandomAccessFile* file, char* buffer, size_t* size);
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static void GenerateCachePrefix(Cache* cc,
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WritableFile* file, char* buffer, size_t* size);
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// Helper functions for DumpTable()
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Status DumpIndexBlock(WritableFile* out_file);
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Status DumpDataBlocks(WritableFile* out_file);
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void DumpKeyValue(const Slice& key, const Slice& value,
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WritableFile* out_file);
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// No copying allowed
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explicit BlockBasedTable(const TableReader&) = delete;
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void operator=(const TableReader&) = delete;
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};
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// Maitaning state of a two-level iteration on a partitioned index structure
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class BlockBasedTable::BlockEntryIteratorState : public TwoLevelIteratorState {
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public:
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BlockEntryIteratorState(BlockBasedTable* table,
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const ReadOptions& read_options, bool skip_filters);
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InternalIterator* NewSecondaryIterator(const Slice& index_value) override;
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bool PrefixMayMatch(const Slice& internal_key) override;
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private:
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// Don't own table_
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BlockBasedTable* table_;
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const ReadOptions read_options_;
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bool skip_filters_;
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};
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// CachableEntry represents the entries that *may* be fetched from block cache.
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// field `value` is the item we want to get.
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// field `cache_handle` is the cache handle to the block cache. If the value
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// was not read from cache, `cache_handle` will be nullptr.
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template <class TValue>
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struct BlockBasedTable::CachableEntry {
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CachableEntry(TValue* _value, Cache::Handle* _cache_handle)
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: value(_value), cache_handle(_cache_handle) {}
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CachableEntry() : CachableEntry(nullptr, nullptr) {}
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void Release(Cache* cache) {
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if (cache_handle) {
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cache->Release(cache_handle);
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value = nullptr;
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cache_handle = nullptr;
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}
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}
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bool IsSet() const { return cache_handle != nullptr; }
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TValue* value = nullptr;
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// if the entry is from the cache, cache_handle will be populated.
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Cache::Handle* cache_handle = nullptr;
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};
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struct BlockBasedTable::Rep {
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Rep(const ImmutableCFOptions& _ioptions, const EnvOptions& _env_options,
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const BlockBasedTableOptions& _table_opt,
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const InternalKeyComparator& _internal_comparator, bool skip_filters)
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: ioptions(_ioptions),
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env_options(_env_options),
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table_options(_table_opt),
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filter_policy(skip_filters ? nullptr : _table_opt.filter_policy.get()),
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internal_comparator(_internal_comparator),
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filter_type(FilterType::kNoFilter),
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whole_key_filtering(_table_opt.whole_key_filtering),
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prefix_filtering(true),
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range_del_handle(BlockHandle::NullBlockHandle()),
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global_seqno(kDisableGlobalSequenceNumber) {}
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const ImmutableCFOptions& ioptions;
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const EnvOptions& env_options;
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const BlockBasedTableOptions& table_options;
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const FilterPolicy* const filter_policy;
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const InternalKeyComparator& internal_comparator;
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Status status;
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unique_ptr<RandomAccessFileReader> file;
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char cache_key_prefix[kMaxCacheKeyPrefixSize];
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size_t cache_key_prefix_size = 0;
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char persistent_cache_key_prefix[kMaxCacheKeyPrefixSize];
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size_t persistent_cache_key_prefix_size = 0;
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char compressed_cache_key_prefix[kMaxCacheKeyPrefixSize];
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size_t compressed_cache_key_prefix_size = 0;
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uint64_t dummy_index_reader_offset =
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0; // ID that is unique for the block cache.
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PersistentCacheOptions persistent_cache_options;
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// Footer contains the fixed table information
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Footer footer;
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// index_reader and filter will be populated and used only when
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// options.block_cache is nullptr; otherwise we will get the index block via
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// the block cache.
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unique_ptr<IndexReader> index_reader;
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unique_ptr<FilterBlockReader> filter;
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enum class FilterType {
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kNoFilter,
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kFullFilter,
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kBlockFilter,
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kPartitionedFilter,
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};
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FilterType filter_type;
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BlockHandle filter_handle;
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std::shared_ptr<const TableProperties> table_properties;
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// Block containing the data for the compression dictionary. We take ownership
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// for the entire block struct, even though we only use its Slice member. This
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// is easier because the Slice member depends on the continued existence of
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// another member ("allocation").
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std::unique_ptr<const BlockContents> compression_dict_block;
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BlockBasedTableOptions::IndexType index_type;
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bool hash_index_allow_collision;
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bool whole_key_filtering;
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bool prefix_filtering;
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// TODO(kailiu) It is very ugly to use internal key in table, since table
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// module should not be relying on db module. However to make things easier
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// and compatible with existing code, we introduce a wrapper that allows
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// block to extract prefix without knowing if a key is internal or not.
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unique_ptr<SliceTransform> internal_prefix_transform;
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// only used in level 0 files:
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// when pin_l0_filter_and_index_blocks_in_cache is true, we do use the
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// LRU cache, but we always keep the filter & idndex block's handle checked
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// out here (=we don't call Release()), plus the parsed out objects
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// the LRU cache will never push flush them out, hence they're pinned
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CachableEntry<FilterBlockReader> filter_entry;
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CachableEntry<IndexReader> index_entry;
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// range deletion meta-block is pinned through reader's lifetime when LRU
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// cache is enabled.
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CachableEntry<Block> range_del_entry;
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BlockHandle range_del_handle;
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// If global_seqno is used, all Keys in this file will have the same
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// seqno with value `global_seqno`.
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//
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// A value of kDisableGlobalSequenceNumber means that this feature is disabled
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// and every key have it's own seqno.
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SequenceNumber global_seqno;
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};
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} // namespace rocksdb
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