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93 righe
3.4 KiB
93 righe
3.4 KiB
// 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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// TableBuilder provides the interface used to build a Table
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// (an immutable and sorted map from keys to values).
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//
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// Multiple threads can invoke const methods on a TableBuilder without
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// external synchronization, but if any of the threads may call a
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// non-const method, all threads accessing the same TableBuilder must use
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// external synchronization.
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#ifndef STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_
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#define STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_
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#include <cstdint>
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#include "leveldb/export.h"
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#include "leveldb/options.h"
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#include "leveldb/status.h"
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namespace leveldb {
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class BlockBuilder;
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class BlockHandle;
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class WritableFile;
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class LEVELDB_EXPORT TableBuilder {
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public:
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// Create a builder that will store the contents of the table it is
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// building in *file. Does not close the file. It is up to the
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// caller to close the file after calling Finish().
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TableBuilder(const Options& options, WritableFile* file);
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TableBuilder(const TableBuilder&) = delete;
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TableBuilder& operator=(const TableBuilder&) = delete;
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// REQUIRES: Either Finish() or Abandon() has been called.
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~TableBuilder();
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// Change the options used by this builder. Note: only some of the
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// option fields can be changed after construction. If a field is
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// not allowed to change dynamically and its value in the structure
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// passed to the constructor is different from its value in the
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// structure passed to this method, this method will return an error
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// without changing any fields.
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Status ChangeOptions(const Options& options);
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// Add key,value to the table being constructed.
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// REQUIRES: key is after any previously added key according to comparator.
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// REQUIRES: Finish(), Abandon() have not been called
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void Add(const Slice& key, const Slice& value);
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// Advanced operation: flush any buffered key/value pairs to file.
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// Can be used to ensure that two adjacent entries never live in
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// the same data block. Most clients should not need to use this method.
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// REQUIRES: Finish(), Abandon() have not been called
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void Flush();
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// Return non-ok iff some error has been detected.
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Status status() const;
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// Finish building the table. Stops using the file passed to the
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// constructor after this function returns.
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// REQUIRES: Finish(), Abandon() have not been called
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Status Finish();
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// Indicate that the contents of this builder should be abandoned. Stops
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// using the file passed to the constructor after this function returns.
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// If the caller is not going to call Finish(), it must call Abandon()
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// before destroying this builder.
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// REQUIRES: Finish(), Abandon() have not been called
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void Abandon();
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// Number of calls to Add() so far.
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uint64_t NumEntries() const;
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// Size of the file generated so far. If invoked after a successful
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// Finish() call, returns the size of the final generated file.
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uint64_t FileSize() const;
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private:
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bool ok() const { return status().ok(); }
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void WriteBlock(BlockBuilder* block, BlockHandle* handle);
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void WriteRawBlock(const Slice& data, CompressionType, BlockHandle* handle);
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struct Rep;
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Rep* rep_;
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};
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_
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