foundationdb/fdbserver/IVersionedStore.h

79 lines
3.3 KiB
C++

/*
* IVersionedStore.h
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FDBSERVER_IVERSIONEDSTORE_H
#define FDBSERVER_IVERSIONEDSTORE_H
#pragma once
#include "fdbserver/IKeyValueStore.h"
#include "flow/flow.h"
#include "fdbclient/FDBTypes.h"
class IStoreCursor {
public:
virtual Future<Void> findEqual(KeyRef key) = 0;
virtual Future<Void> findFirstEqualOrGreater(KeyRef key, bool needValue, int prefetchNextBytes) = 0;
virtual Future<Void> findLastLessOrEqual(KeyRef key, bool needValue, int prefetchPriorBytes) = 0;
virtual Future<Void> next(bool needValue) = 0;
virtual Future<Void> prev(bool needValue) = 0;
virtual bool isValid() = 0;
virtual KeyRef getKey() = 0;
//virtual StringRef getCompressedKey() = 0;
virtual ValueRef getValue() = 0;
virtual void invalidateReturnedStrings() = 0;
virtual void addref() = 0;
virtual void delref() = 0;
virtual std::string toString() const = 0;
};
class IVersionedStore : public IClosable {
public:
virtual KeyValueStoreType getType() = 0;
virtual bool supportsMutation(int op) = 0; // If this returns true, then mutate(op, ...) may be called
virtual StorageBytes getStorageBytes() = 0;
// Writes are provided in an ordered stream.
// A write is considered part of (a change leading to) the version determined by the previous call to setWriteVersion()
// A write shall not become durable until the following call to commit() begins, and shall be durable once the following call to commit() returns
virtual void set(KeyValueRef keyValue) = 0;
virtual void clear(KeyRangeRef range) = 0;
virtual void mutate(int op, StringRef param1, StringRef param2) = 0;
virtual void setWriteVersion(Version) = 0; // The write version must be nondecreasing
virtual void forgetVersions(Version begin, Version end) = 0; // Versions [begin, end) no longer readable
virtual Future<Void> commit() = 0;
virtual Future<Version> getLatestVersion() = 0;
// readAtVersion() may only be called on a version which has previously been passed to setWriteVersion() and never previously passed
// to forgetVersion. The returned results when violating this precondition are unspecified; the store is not required to be able to detect violations.
// The returned read cursor provides a consistent snapshot of the versioned store, corresponding to all the writes done with write versions less
// than or equal to the given version.
// If readAtVersion() is called on the *current* write version, the given read cursor MAY reflect subsequent writes at the same
// write version, OR it may represent a snapshot as of the call to readAtVersion().
virtual Reference<IStoreCursor> readAtVersion(Version) = 0;
};
#endif