cadc1adffa
Summary: We added multiple fields to FileMetaData recently and are planning to add more. This refactoring separate the minimum information for accessing the file. This object is copyable (FileMetaData is not copyable since the ref counter). I hope this refactoring can enable further improvements: (1) use it to design a more efficient data structure to speed up read queries. (2) in the future, when we add information of storage level, we can easily do the encoding, instead of enlarge this structure, which might expand memory work set for file meta data. The definition is same as current EncodedFileMetaData used in two level iterator, so now the logic in two level iterator is easier to understand. Test Plan: make all check Reviewers: haobo, igor, ljin Reviewed By: ljin Subscribers: leveldb, dhruba, yhchiang Differential Revision: https://reviews.facebook.net/D18933
94 lines
3.7 KiB
C++
94 lines
3.7 KiB
C++
// Copyright (c) 2013, 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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//
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// Thread-safe (provides internal synchronization)
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#pragma once
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#include <string>
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#include <stdint.h>
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#include "db/dbformat.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/table.h"
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#include "table/table_reader.h"
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namespace rocksdb {
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class Env;
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class Arena;
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struct FileDescriptor;
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class TableCache {
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public:
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TableCache(const std::string& dbname, const Options* options,
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const EnvOptions& storage_options, Cache* cache);
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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 "tableptr" is
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// non-nullptr, also sets "*tableptr" 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 "*tableptr" object is owned by
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// 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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Iterator* NewIterator(const ReadOptions& options, const EnvOptions& toptions,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& file_fd,
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TableReader** table_reader_ptr = nullptr,
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bool for_compaction = false, Arena* arena = nullptr);
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// If a seek to internal key "k" in specified file finds an entry,
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// call (*handle_result)(arg, found_key, found_value) repeatedly until
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// it returns false.
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Status Get(const ReadOptions& options,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& file_fd, const Slice& k, void* arg,
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bool (*handle_result)(void*, const ParsedInternalKey&,
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const Slice&, bool),
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bool* table_io, void (*mark_key_may_exist)(void*) = nullptr);
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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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// Find table reader
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Status FindTable(const EnvOptions& toptions,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& file_fd, Cache::Handle**,
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bool* table_io = nullptr, const bool no_io = false);
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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(const EnvOptions& 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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bool no_io = false);
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// Release the handle from a cache
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void ReleaseHandle(Cache::Handle* handle);
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private:
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Env* const env_;
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const std::string dbname_;
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const Options* options_;
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const EnvOptions& storage_options_;
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Cache* const cache_;
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};
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} // namespace rocksdb
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