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fc0c399d2e
Summary: If ReadOptions.non_blocking_io is set to true, then KeyMayExists and Iterators will return data that is cached in RAM. If the Iterator needs to do IO from storage to serve the data, then the Iterator.status() will return Status::IsRetry(). Test Plan: Enhanced unit test DBTest.KeyMayExist to detect if there were are IOs issues from storage. Added DBTest.NonBlockingIteration to verify nonblocking Iterations. Reviewers: emayanke, haobo Reviewed By: haobo CC: leveldb Maniphest Tasks: T63 Differential Revision: https://reviews.facebook.net/D12531
78 lines
2.8 KiB
C++
78 lines
2.8 KiB
C++
// 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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#ifndef STORAGE_LEVELDB_DB_TABLE_CACHE_H_
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#define STORAGE_LEVELDB_DB_TABLE_CACHE_H_
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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 "rocksdb/env.h"
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#include "rocksdb/cache.h"
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#include "port/port.h"
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#include "table/table.h"
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namespace leveldb {
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class Env;
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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, int entries);
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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,
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const EnvOptions& toptions,
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uint64_t file_number,
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uint64_t file_size,
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Table** tableptr = nullptr,
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bool for_compaction = false);
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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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uint64_t file_number,
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uint64_t file_size,
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const Slice& k,
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void* arg,
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bool (*handle_result)(void*, const Slice&, const Slice&, bool),
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bool* table_io,
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void (*mark_key_may_exist)(void*) = nullptr);
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// Determine whether the table may contain the specified prefix. If
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// the table index of blooms are not in memory, this may cause an I/O
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bool PrefixMayMatch(const ReadOptions& options, uint64_t file_number,
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uint64_t file_size, const Slice& internal_prefix,
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bool* table_io);
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// Evict any entry for the specified file number
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void Evict(uint64_t file_number);
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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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std::shared_ptr<Cache> cache_;
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Status FindTable(const EnvOptions& toptions, uint64_t file_number,
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uint64_t file_size, Cache::Handle**, bool* table_io=nullptr,
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const bool no_io = false);
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};
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_DB_TABLE_CACHE_H_
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