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https://github.com/google/leveldb.git
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36a5f8ed7f
- Replace raw slice comparison with a call to user comparator.
Added test for custom comparators.
- Fix end of namespace comments.
- Fixed bug in picking inputs for a level-0 compaction.
When finding overlapping files, the covered range may expand
as files are added to the input set. We now correctly expand
the range when this happens instead of continuing to use the
old range. For example, suppose L0 contains files with the
following ranges:
F1: a .. d
F2: c .. g
F3: f .. j
and the initial compaction target is F3. We used to search
for range f..j which yielded {F2,F3}. However we now expand
the range as soon as another file is added. In this case,
when F2 is added, we expand the range to c..j and restart the
search. That picks up file F1 as well.
This change fixes a bug related to deleted keys showing up
incorrectly after a compaction as described in Issue 44.
(Sync with upstream @25072954)
92 lines
2.7 KiB
C++
92 lines
2.7 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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#ifndef STORAGE_LEVELDB_DB_MEMTABLE_H_
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#define STORAGE_LEVELDB_DB_MEMTABLE_H_
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#include <string>
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#include "leveldb/db.h"
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#include "db/dbformat.h"
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#include "db/skiplist.h"
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#include "util/arena.h"
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namespace leveldb {
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class InternalKeyComparator;
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class Mutex;
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class MemTableIterator;
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class MemTable {
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public:
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// MemTables are reference counted. The initial reference count
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// is zero and the caller must call Ref() at least once.
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explicit MemTable(const InternalKeyComparator& comparator);
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// Increase reference count.
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void Ref() { ++refs_; }
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// Drop reference count. Delete if no more references exist.
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void Unref() {
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--refs_;
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assert(refs_ >= 0);
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if (refs_ <= 0) {
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delete this;
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}
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}
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// Returns an estimate of the number of bytes of data in use by this
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// data structure.
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//
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// REQUIRES: external synchronization to prevent simultaneous
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// operations on the same MemTable.
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size_t ApproximateMemoryUsage();
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// Return an iterator that yields the contents of the memtable.
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//
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// The caller must ensure that the underlying MemTable remains live
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// while the returned iterator is live. The keys returned by this
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// iterator are internal keys encoded by AppendInternalKey in the
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// db/format.{h,cc} module.
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Iterator* NewIterator();
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// Add an entry into memtable that maps key to value at the
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// specified sequence number and with the specified type.
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// Typically value will be empty if type==kTypeDeletion.
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void Add(SequenceNumber seq, ValueType type,
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const Slice& key,
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const Slice& value);
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// If memtable contains a value for key, store it in *value and return true.
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// If memtable contains a deletion for key, store a NotFound() error
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// in *status and return true.
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// Else, return false.
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bool Get(const LookupKey& key, std::string* value, Status* s);
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private:
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~MemTable(); // Private since only Unref() should be used to delete it
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struct KeyComparator {
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const InternalKeyComparator comparator;
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explicit KeyComparator(const InternalKeyComparator& c) : comparator(c) { }
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int operator()(const char* a, const char* b) const;
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};
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friend class MemTableIterator;
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friend class MemTableBackwardIterator;
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typedef SkipList<const char*, KeyComparator> Table;
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KeyComparator comparator_;
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int refs_;
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Arena arena_;
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Table table_;
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// No copying allowed
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MemTable(const MemTable&);
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void operator=(const MemTable&);
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};
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_DB_MEMTABLE_H_
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