74 lines
2.1 KiB
C++
74 lines
2.1 KiB
C++
/*
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* EndpointGroup.h
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef FLOW_ENDPOINT_GROUP_H
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#define FLOW_ENDPOINT_GROUP_H
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#pragma once
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#include "flow.h"
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// EndpointGroup makes it easier to implement backward compatibility for interface serialization
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// It also provides a central place to implement more compact serialization for a group of related endpoints in the future.
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/* Typical usage:
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template <class Ar>
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void serialize(Ar& ar) {
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auto endpoints = endpointGroup(ar);
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endpoints.require( ar.protocolVersion() <= currentProtocolVersion );
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endpoints & apple & banana;
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endpoints.require( ar.protocolVersion() >= 0xabc ); // Following endpoints added in this version
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endpoints & cherry;
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endpoints.require( ar.protocolVersion() >= 0xdef ); // .. and then some more were added
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endpoints & date;
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}
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*/
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template <class Ar>
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struct EndpointGroup : NonCopyable {
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Ar& ar;
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bool enabled;
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explicit EndpointGroup( Ar& ar ) : ar(ar), enabled(true) {
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ASSERT( ar.protocolVersion() != 0 );
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}
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EndpointGroup( EndpointGroup&& g ) : ar(g.ar), enabled(g.enabled) {}
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EndpointGroup& require( bool condition ) {
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enabled = enabled && condition;
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return *this;
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}
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template <class T>
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EndpointGroup& operator & (PromiseStream<T>& stream) {
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if (enabled)
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ar & stream;
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else if (Ar::isDeserializing)
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stream.sendError( incompatible_protocol_version() );
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return *this;
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}
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};
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template <class Ar>
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EndpointGroup<Ar> endpointGroup( Ar& ar ) { return EndpointGroup<Ar>(ar); }
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#endif |