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3d1e92b05a
Summary: 1. The OpenForReadOnly() call should not lock the db. This is useful so that multiple processes can open the same database concurrently for reading. 2. GetUpdatesSince should not error out if the archive directory does not exist. 3. A new constructor for WriteBatch that can takes a serialized string as a parameter of the constructor. Test Plan: make clean check Reviewers: sheki Reviewed By: sheki CC: leveldb Differential Revision: https://reviews.facebook.net/D7449
71 lines
2 KiB
C++
71 lines
2 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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//
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// WriteBatch holds a collection of updates to apply atomically to a DB.
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//
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// The updates are applied in the order in which they are added
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// to the WriteBatch. For example, the value of "key" will be "v3"
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// after the following batch is written:
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//
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// batch.Put("key", "v1");
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// batch.Delete("key");
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// batch.Put("key", "v2");
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// batch.Put("key", "v3");
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//
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// Multiple threads can invoke const methods on a WriteBatch 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 WriteBatch must use
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// external synchronization.
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#ifndef STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_
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#define STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_
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#include <string>
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#include "leveldb/status.h"
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namespace leveldb {
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class Slice;
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class WriteBatch {
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public:
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WriteBatch();
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~WriteBatch();
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// Store the mapping "key->value" in the database.
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void Put(const Slice& key, const Slice& value);
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// If the database contains a mapping for "key", erase it. Else do nothing.
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void Delete(const Slice& key);
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// Clear all updates buffered in this batch.
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void Clear();
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// Support for iterating over the contents of a batch.
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class Handler {
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public:
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virtual ~Handler();
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virtual void Put(const Slice& key, const Slice& value) = 0;
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virtual void Delete(const Slice& key) = 0;
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};
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Status Iterate(Handler* handler) const;
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// Retrive the serialized version of this batch.
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std::string Data() { return rep_; }
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// Constructor with a serialized string object
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WriteBatch(std::string rep): rep_(rep) {}
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private:
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friend class WriteBatchInternal;
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std::string rep_; // See comment in write_batch.cc for the format of rep_
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// Intentionally copyable
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};
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_
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