mirror of https://github.com/facebook/rocksdb.git
67 lines
2.7 KiB
C++
67 lines
2.7 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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#pragma once
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#include <memory>
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namespace rocksdb {
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class Iterator;
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struct ParsedInternalKey;
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class Slice;
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struct ReadOptions;
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struct TableProperties;
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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 TableReader {
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public:
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virtual ~TableReader() {}
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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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virtual Iterator* NewIterator(const ReadOptions&) = 0;
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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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virtual uint64_t ApproximateOffsetOf(const Slice& key) = 0;
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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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virtual void SetupForCompaction() = 0;
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virtual std::shared_ptr<const TableProperties> GetTableProperties() const = 0;
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// Calls (*result_handler)(handle_context, ...) repeatedly, starting with
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// the entry found after a call to Seek(key), until result_handler returns
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// false, where k is the actual internal key for a row found and v as the
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// value of the key. didIO is true if I/O is involved in the operation. May
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// not make such a call if filter policy says that key is not present.
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//
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// mark_key_may_exist_handler needs to be called when it is configured to be
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// memory only and the key is not found in the block cache, with
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// the parameter to be handle_context.
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//
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// readOptions is the options for the read
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// key is the key to search for
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virtual Status Get(
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const ReadOptions& readOptions, const Slice& key, void* handle_context,
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bool (*result_handler)(void* arg, const ParsedInternalKey& k,
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const Slice& v, bool didIO),
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void (*mark_key_may_exist_handler)(void* handle_context) = nullptr) = 0;
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};
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} // namespace rocksdb
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