fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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249 lines
12 KiB
249 lines
12 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root 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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//
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// Thread-safe (provides internal synchronization)
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#pragma once
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#include <cstdint>
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#include <string>
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#include <vector>
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#include "db/dbformat.h"
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#include "db/range_del_aggregator.h"
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#include "options/cf_options.h"
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#include "port/port.h"
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#include "rocksdb/cache.h"
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#include "rocksdb/env.h"
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#include "rocksdb/options.h"
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#include "rocksdb/table.h"
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#include "table/table_reader.h"
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#include "trace_replay/block_cache_tracer.h"
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#include "util/coro_utils.h"
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namespace ROCKSDB_NAMESPACE {
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class Env;
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class Arena;
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struct FileDescriptor;
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class GetContext;
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class HistogramImpl;
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// Manages caching for TableReader objects for a column family. The actual
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// cache is allocated separately and passed to the constructor. TableCache
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// wraps around the underlying SST file readers by providing Get(),
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// MultiGet() and NewIterator() methods that hide the instantiation,
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// caching and access to the TableReader. The main purpose of this is
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// performance - by caching the TableReader, it avoids unnecessary file opens
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// and object allocation and instantiation. One exception is compaction, where
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// a new TableReader may be instantiated - see NewIterator() comments
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//
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// Another service provided by TableCache is managing the row cache - if the
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// DB is configured with a row cache, and the lookup key is present in the row
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// cache, lookup is very fast. The row cache is obtained from
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// ioptions.row_cache
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class TableCache {
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public:
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TableCache(const ImmutableOptions& ioptions,
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const FileOptions* storage_options, Cache* cache,
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BlockCacheTracer* const block_cache_tracer,
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const std::shared_ptr<IOTracer>& io_tracer,
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const std::string& db_session_id);
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~TableCache();
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// Return an iterator for the specified file number (the corresponding
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// file length must be exactly "file_size" bytes). If "table_reader_ptr"
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// is non-nullptr, also sets "*table_reader_ptr" to point to the Table object
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// underlying the returned iterator, or nullptr if no Table object underlies
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// the returned iterator. The returned "*table_reader_ptr" object is owned
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// by the cache and should not be deleted, and is valid for as long as the
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// returned iterator is live.
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// @param options Must outlive the returned iterator.
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// @param range_del_agg If non-nullptr, adds range deletions to the
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// aggregator. If an error occurs, returns it in a NewErrorInternalIterator
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// @param for_compaction If true, a new TableReader may be allocated (but
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// not cached), depending on the CF options
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// @param skip_filters Disables loading/accessing the filter block
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// @param level The level this table is at, -1 for "not set / don't know"
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InternalIterator* NewIterator(
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const ReadOptions& options, const FileOptions& toptions,
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const InternalKeyComparator& internal_comparator,
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const FileMetaData& file_meta, RangeDelAggregator* range_del_agg,
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const std::shared_ptr<const SliceTransform>& prefix_extractor,
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TableReader** table_reader_ptr, HistogramImpl* file_read_hist,
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TableReaderCaller caller, Arena* arena, bool skip_filters, int level,
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size_t max_file_size_for_l0_meta_pin,
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const InternalKey* smallest_compaction_key,
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const InternalKey* largest_compaction_key, bool allow_unprepared_value);
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// If a seek to internal key "k" in specified file finds an entry,
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// call get_context->SaveValue() repeatedly until
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// it returns false. As a side effect, it will insert the TableReader
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// into the cache and potentially evict another entry
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// @param get_context Context for get operation. The result of the lookup
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// can be retrieved by calling get_context->State()
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// @param file_read_hist If non-nullptr, the file reader statistics are
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// recorded
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// @param skip_filters Disables loading/accessing the filter block
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// @param level The level this table is at, -1 for "not set / don't know"
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Status Get(
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const ReadOptions& options,
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const InternalKeyComparator& internal_comparator,
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const FileMetaData& file_meta, const Slice& k, GetContext* get_context,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr,
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HistogramImpl* file_read_hist = nullptr, bool skip_filters = false,
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int level = -1, size_t max_file_size_for_l0_meta_pin = 0);
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// Return the range delete tombstone iterator of the file specified by
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// `file_meta`.
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Status GetRangeTombstoneIterator(
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const ReadOptions& options,
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const InternalKeyComparator& internal_comparator,
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const FileMetaData& file_meta,
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std::unique_ptr<FragmentedRangeTombstoneIterator>* out_iter);
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// If a seek to internal key "k" in specified file finds an entry,
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// call get_context->SaveValue() repeatedly until
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// it returns false. As a side effect, it will insert the TableReader
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// into the cache and potentially evict another entry
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// @param mget_range Pointer to the structure describing a batch of keys to
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// be looked up in this table file. The result is stored
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// in the embedded GetContext
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// @param skip_filters Disables loading/accessing the filter block
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// @param level The level this table is at, -1 for "not set / don't know"
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DECLARE_SYNC_AND_ASYNC(
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Status, MultiGet, const ReadOptions& options,
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const InternalKeyComparator& internal_comparator,
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const FileMetaData& file_meta, const MultiGetContext::Range* mget_range,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr,
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HistogramImpl* file_read_hist = nullptr, bool skip_filters = false,
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int level = -1);
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// Evict any entry for the specified file number
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static void Evict(Cache* cache, uint64_t file_number);
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// Query whether specified file number is currently in cache
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static bool HasEntry(Cache* cache, uint64_t file_number);
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// Clean table handle and erase it from the table cache
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// Used in DB close, or the file is not live anymore.
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void EraseHandle(const FileDescriptor& fd, Cache::Handle* handle);
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// Find table reader
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// @param skip_filters Disables loading/accessing the filter block
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// @param level == -1 means not specified
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Status FindTable(
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const ReadOptions& ro, const FileOptions& toptions,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& file_fd, Cache::Handle**,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr,
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const bool no_io = false, bool record_read_stats = true,
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HistogramImpl* file_read_hist = nullptr, bool skip_filters = false,
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int level = -1, bool prefetch_index_and_filter_in_cache = true,
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size_t max_file_size_for_l0_meta_pin = 0,
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Temperature file_temperature = Temperature::kUnknown);
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// Get TableReader from a cache handle.
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TableReader* GetTableReaderFromHandle(Cache::Handle* handle);
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// Get the table properties of a given table.
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// @no_io: indicates if we should load table to the cache if it is not present
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// in table cache yet.
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// @returns: `properties` will be reset on success. Please note that we will
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// return Status::Incomplete() if table is not present in cache and
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// we set `no_io` to be true.
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Status GetTableProperties(
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const FileOptions& toptions,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& file_meta,
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std::shared_ptr<const TableProperties>* properties,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr,
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bool no_io = false);
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Status ApproximateKeyAnchors(const ReadOptions& ro,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& file_meta,
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std::vector<TableReader::Anchor>& anchors);
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// Return total memory usage of the table reader of the file.
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// 0 if table reader of the file is not loaded.
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size_t GetMemoryUsageByTableReader(
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const FileOptions& toptions,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& fd,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr);
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// Returns approximated offset of a key in a file represented by fd.
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uint64_t ApproximateOffsetOf(
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const Slice& key, const FileDescriptor& fd, TableReaderCaller caller,
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const InternalKeyComparator& internal_comparator,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr);
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// Returns approximated data size between start and end keys in a file
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// represented by fd (the start key must not be greater than the end key).
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uint64_t ApproximateSize(
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const Slice& start, const Slice& end, const FileDescriptor& fd,
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TableReaderCaller caller,
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const InternalKeyComparator& internal_comparator,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr);
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// Release the handle from a cache
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void ReleaseHandle(Cache::Handle* handle);
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Cache* get_cache() const { return cache_; }
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// Capacity of the backing Cache that indicates infinite TableCache capacity.
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// For example when max_open_files is -1 we set the backing Cache to this.
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static const int kInfiniteCapacity = 0x400000;
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// The tables opened with this TableCache will be immortal, i.e., their
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// lifetime is as long as that of the DB.
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void SetTablesAreImmortal() {
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if (cache_->GetCapacity() >= kInfiniteCapacity) {
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immortal_tables_ = true;
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}
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}
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private:
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// Build a table reader
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Status GetTableReader(
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const ReadOptions& ro, const FileOptions& file_options,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& fd, bool sequential_mode, bool record_read_stats,
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HistogramImpl* file_read_hist, std::unique_ptr<TableReader>* table_reader,
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const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr,
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bool skip_filters = false, int level = -1,
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bool prefetch_index_and_filter_in_cache = true,
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size_t max_file_size_for_l0_meta_pin = 0,
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Temperature file_temperature = Temperature::kUnknown);
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// Create a key prefix for looking up the row cache. The prefix is of the
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// format row_cache_id + fd_number + seq_no. Later, the user key can be
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// appended to form the full key
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void CreateRowCacheKeyPrefix(const ReadOptions& options,
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const FileDescriptor& fd,
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const Slice& internal_key,
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GetContext* get_context, IterKey& row_cache_key);
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// Helper function to lookup the row cache for a key. It appends the
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// user key to row_cache_key at offset prefix_size
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bool GetFromRowCache(const Slice& user_key, IterKey& row_cache_key,
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size_t prefix_size, GetContext* get_context);
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const ImmutableOptions& ioptions_;
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const FileOptions& file_options_;
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Cache* const cache_;
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std::string row_cache_id_;
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bool immortal_tables_;
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BlockCacheTracer* const block_cache_tracer_;
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Striped<port::Mutex, Slice> loader_mutex_;
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std::shared_ptr<IOTracer> io_tracer_;
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std::string db_session_id_;
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};
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} // namespace ROCKSDB_NAMESPACE
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