5f4166c90e
Summary: ReadaheadRandomAccessFile acts as a transparent layer on top of RandomAccessFile. When a Read() request is issued, it issues a much bigger request to the OS and caches the result. When a new request comes in and we already have the data cached, it doesn't have to issue any requests to the OS. We add ReadaheadRandomAccessFile layer only when file is read during compactions. D45105 was incorrectly closed by Phabricator because I committed it to a separate branch (not master), so I'm resubmitting the diff. Test Plan: make check Reviewers: MarkCallaghan, sdong Reviewed By: sdong Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D45123
111 lines
4.4 KiB
C++
111 lines
4.4 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 <vector>
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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 "rocksdb/options.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 GetContext;
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class HistogramImpl;
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class TableCache {
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public:
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TableCache(const ImmutableCFOptions& ioptions,
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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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HistogramImpl* file_read_hist = 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,
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GetContext* get_context, HistogramImpl* file_read_hist = 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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const bool no_io = false, bool record_read_stats = true,
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HistogramImpl* file_read_hist = nullptr);
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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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// 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 EnvOptions& toptions,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& fd);
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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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// Build a table reader
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Status GetTableReader(const EnvOptions& env_options,
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const InternalKeyComparator& internal_comparator,
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const FileDescriptor& fd, bool sequential_mode,
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bool record_read_stats, HistogramImpl* file_read_hist,
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unique_ptr<TableReader>* table_reader);
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const ImmutableCFOptions& ioptions_;
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const EnvOptions& env_options_;
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Cache* const cache_;
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std::string row_cache_id_;
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};
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} // namespace rocksdb
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