0fa5a4f7b1
This CL makes it easier to reason about thread safety by: 1) Adding Clang thread safety annotations according to comments. 2) Expanding a couple of variable names, without adding extra lines of code. 3) Adding const in a couple of places. 4) Replacing an always-non-null const pointer with a reference. 5) Fixing style warnings in the modified files. This CL does not annotate the DBImpl members that claim to be protected by the instance mutex, but are accessed without the mutex being held. Those members (and their unprotected accesses) will be addressed in future CLs. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=189354657
88 lines
2.6 KiB
C++
88 lines
2.6 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 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. It is safe to call when MemTable is being modified.
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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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