4ca3c67bd3
Summary: This diff replaces compaction_filter_args and CompactionFilter with a single compaction_filter parameter. It gives CompactionFilter better encapsulation and a similar look to Comparator and MergeOpertor, which improves consistency of the overall interface. The change is not backward compatible. Nevertheless, the two references in fbcode are not in production yet. Test Plan: make check Reviewers: dhruba Reviewed By: dhruba CC: leveldb, zshao Differential Revision: https://reviews.facebook.net/D10773
47 lines
1.6 KiB
C++
47 lines
1.6 KiB
C++
// Copyright (c) 2013 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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#ifndef STORAGE_LEVELDB_INCLUDE_COMPACTION_FILTER_H_
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#define STORAGE_LEVELDB_INCLUDE_COMPACTION_FILTER_H_
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#include <string>
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namespace leveldb {
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class Slice;
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// CompactionFilter allows an application to modify/delete a key-value at
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// the time of compaction.
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class CompactionFilter {
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public:
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virtual ~CompactionFilter() {}
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// The compaction process invokes this
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// method for kv that is being compacted. A return value
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// of false indicates that the kv should be preserved in the
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// output of this compaction run and a return value of true
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// indicates that this key-value should be removed from the
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// output of the compaction. The application can inspect
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// the existing value of the key and make decision based on it.
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//
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// When the value is to be preserved, the application has the option
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// to modify the existing_value and pass it back through new_value.
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// value_changed needs to be set to true in this case.
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virtual bool Filter(int level,
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const Slice& key,
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const Slice& existing_value,
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std::string* new_value,
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bool* value_changed) const = 0;
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// Returns a name that identifies this compaction filter.
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// The name will be printed to LOG file on start up for diagnosis.
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virtual const char* Name() const = 0;
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};
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_INCLUDE_COMPACTION_FILTER_H_
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