TDuplexProtocolFactory.java

/*
 * Copyright (C) 2012-2016 Facebook, Inc.
 *
 * 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.
 */
package com.facebook.nifty.duplex;

import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.protocol.TProtocolFactory;
import org.apache.thrift.transport.TTransport;

/***
 * A factory for creating a pair of protocols (one for input, one for output). Gives more
 * flexibility to the factory to enforce protocol restrictions (e.g. header protocol requires
 * the input/output transport/protocol are the same, a duplex header protocol factory can enforce
 * the transport restriction because it can see both transports, and can guarantee both protocols
 * are the same because it can fill in the input/output slots of the protocol pair with the same
 * protocol object).
 */
public abstract class TDuplexProtocolFactory {
    public abstract TProtocolPair getProtocolPair(TTransportPair transportPair);

    public TProtocolFactory getInputProtocolFactory()
    {
        return new TProtocolFactory()
        {
            @Override
            public TProtocol getProtocol(TTransport trans)
            {
                return getProtocolPair(TTransportPair.fromSingleTransport(trans)).getInputProtocol();
            }
        };
    }

    public TProtocolFactory getOutputProtocolFactory()
    {
        return new TProtocolFactory()
        {
            @Override
            public TProtocol getProtocol(TTransport trans)
            {
                return getProtocolPair(TTransportPair.fromSingleTransport(trans)).getOutputProtocol();
            }
        };
    }

    public static TDuplexProtocolFactory fromSingleFactory(
            final TProtocolFactory protocolFactory
    )
    {
        return new TDuplexProtocolFactory() {
            @Override
            public TProtocolPair getProtocolPair(TTransportPair transportPair) {
                return TProtocolPair.fromSeparateProtocols(
                        protocolFactory.getProtocol(transportPair.getInputTransport()),
                        protocolFactory.getProtocol(transportPair.getOutputTransport()));
            }
        };
    }

    public static TDuplexProtocolFactory fromSeparateFactories(
            final TProtocolFactory inputProtocolFactory,
            final TProtocolFactory outputProtocolFactory
    )
    {
        return new TDuplexProtocolFactory() {
            @Override
            public TProtocolPair getProtocolPair(TTransportPair transportPair) {
                return TProtocolPair.fromSeparateProtocols(
                        inputProtocolFactory.getProtocol(transportPair.getInputTransport()),
                        outputProtocolFactory.getProtocol(transportPair.getOutputTransport())
                );
            }
        };
    }
}