73 lines
2.5 KiB
C++
73 lines
2.5 KiB
C++
/*
|
|
* LogProtocolMessage.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_LOGPROTOCOLMESSAGE_H
|
|
#define FDBSERVER_LOGPROTOCOLMESSAGE_H
|
|
#pragma once
|
|
|
|
#include "fdbclient/FDBTypes.h"
|
|
#include "fdbclient/CommitTransaction.h"
|
|
|
|
template <class Ar, class VersionOptions>
|
|
typename Ar::READER& applyVersionStartingHere(Ar& ar, VersionOptions vo) {
|
|
vo.read(ar);
|
|
return ar;
|
|
}
|
|
|
|
template <class Ar, class VersionOptions>
|
|
typename Ar::WRITER& applyVersionStartingHere(Ar& ar, VersionOptions vo) {
|
|
vo.write(ar);
|
|
return ar;
|
|
}
|
|
|
|
struct LogProtocolMessage {
|
|
// This message is pushed into the log system tag for each storage server to inform it what protocol version
|
|
// should be used to deserialize subsequent MutationRefs.
|
|
|
|
// It's legitimate to add extra information here (using the protocol version for backward compatibility) but
|
|
// currently there is none.
|
|
|
|
// This mechanism passes various ASSERTs in simulation, but has never been used in anger (because MutationRef's
|
|
// serialization format has never changed) so think about testing when it does change.
|
|
|
|
// Storage servers merging these messages with MutationRefs need to distinguish the two, so the first byte of
|
|
// the serialization of this message is a type code which is reserved in the MutationRef::Type enum and will thus
|
|
// never be the first byte of a MutationRef message.
|
|
|
|
LogProtocolMessage() {}
|
|
|
|
std::string toString() const {
|
|
return format("code: %d", MutationRef::Reserved_For_LogProtocolMessage);
|
|
}
|
|
|
|
template <class Ar>
|
|
void serialize(Ar& ar) {
|
|
uint8_t poly = MutationRef::Reserved_For_LogProtocolMessage;
|
|
ar & poly;
|
|
applyVersionStartingHere(ar, IncludeVersion());
|
|
}
|
|
|
|
static bool startsLogProtocolMessage(uint8_t byte) {
|
|
return byte == MutationRef::Reserved_For_LogProtocolMessage;
|
|
}
|
|
template <class Ar> static bool isNextIn(Ar& ar) { return startsLogProtocolMessage(*(const uint8_t*)ar.peekBytes(1)); }
|
|
};
|
|
|
|
#endif |