org.robotninjas.barge.rpc.ProtoRpcRaftClient.java Source code

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Here is the source code for org.robotninjas.barge.rpc.ProtoRpcRaftClient.java

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/**
 * Copyright 2013 David Rusek <dave dot rusek at gmail dot com>
 *
 * 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 org.robotninjas.barge.rpc;

import com.google.common.util.concurrent.AbstractFuture;
import com.google.common.util.concurrent.AsyncFunction;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.protobuf.RpcCallback;
import com.google.protobuf.RpcController;
import org.apache.commons.pool.ObjectPool;
import org.robotninjas.barge.ProtoUtils;
import org.robotninjas.barge.RaftException;
import org.robotninjas.barge.api.AppendEntries;
import org.robotninjas.barge.api.AppendEntriesResponse;
import org.robotninjas.barge.api.RequestVote;
import org.robotninjas.barge.api.RequestVoteResponse;
import org.robotninjas.barge.proto.RaftProto;
import org.robotninjas.protobuf.netty.client.ClientController;
import org.robotninjas.protobuf.netty.client.NettyRpcChannel;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import java.util.concurrent.TimeUnit;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.util.concurrent.Futures.immediateFailedFuture;
import static com.google.common.util.concurrent.Futures.transform;
import static com.google.common.util.concurrent.MoreExecutors.sameThreadExecutor;

//TODO write a protoc code generator for this bullshit
@Immutable
class ProtoRpcRaftClient implements RaftClient {

    private static final long DEFAULT_TIMEOUT = 2000;

    private final ObjectPool<ListenableFuture<NettyRpcChannel>> channelPool;

    ProtoRpcRaftClient(@Nonnull ObjectPool<ListenableFuture<NettyRpcChannel>> channelPool) {
        this.channelPool = checkNotNull(channelPool);
    }

    @Nonnull
    public ListenableFuture<RequestVoteResponse> requestVote(@Nonnull RequestVote request) {
        checkNotNull(request);
        return Futures.transform(call(RpcCall.requestVote(ProtoUtils.convert(request))),
                ProtoUtils.convertVoteResponse);
    }

    @Nonnull
    public ListenableFuture<AppendEntriesResponse> appendEntries(@Nonnull AppendEntries request) {
        checkNotNull(request);
        return Futures.transform(call(RpcCall.appendEntries(ProtoUtils.convert(request))),
                ProtoUtils.convertAppendResponse);
    }

    private <T> ListenableFuture<T> call(final RpcCall<T> call) {

        ListenableFuture<NettyRpcChannel> channel = null;
        try {

            channel = channelPool.borrowObject();
            ListenableFuture<T> response = transform(channel, new AsyncFunction<NettyRpcChannel, T>() {
                @Override
                public ListenableFuture<T> apply(NettyRpcChannel channel) throws Exception {
                    RaftProto.RaftService.Stub stub = RaftProto.RaftService.newStub(channel);
                    ClientController controller = new ClientController(channel);
                    controller.setTimeout(DEFAULT_TIMEOUT, TimeUnit.MILLISECONDS);
                    RpcHandlerFuture<T> responseHandler = new RpcHandlerFuture<T>(controller);
                    call.call(stub, controller, responseHandler);
                    return responseHandler;
                }
            });

            response.addListener(returnChannel(channel), sameThreadExecutor());

            return response;

        } catch (Exception e) {

            try {
                channelPool.invalidateObject(channel);
            } catch (Exception ignored) {
            }
            channel = null;
            return immediateFailedFuture(e);

        } finally {

            try {
                if (null != channel) {
                    channelPool.returnObject(channel);
                }
            } catch (Exception ignored) {
            }

        }
    }

    private Runnable returnChannel(final ListenableFuture<NettyRpcChannel> channel) {
        return new Runnable() {
            @Override
            public void run() {
                try {
                    channelPool.returnObject(channel);
                } catch (Exception ignored) {
                }
            }
        };
    }

    private static abstract class RpcCall<T> {

        abstract void call(RaftProto.RaftService.Stub stub, RpcController controller, RpcCallback<T> callback);

        static RpcCall<RaftProto.AppendEntriesResponse> appendEntries(final RaftProto.AppendEntries request) {
            return new RpcCall<RaftProto.AppendEntriesResponse>() {
                @Override
                public void call(RaftProto.RaftService.Stub stub, RpcController controller,
                        RpcCallback<RaftProto.AppendEntriesResponse> callback) {
                    stub.appendEntries(controller, request, callback);
                }
            };
        }

        static RpcCall<RaftProto.RequestVoteResponse> requestVote(final RaftProto.RequestVote request) {
            return new RpcCall<RaftProto.RequestVoteResponse>() {
                @Override
                public void call(RaftProto.RaftService.Stub stub, RpcController controller,
                        RpcCallback<RaftProto.RequestVoteResponse> callback) {
                    stub.requestVote(controller, request, callback);
                }
            };
        }

    }

    @Immutable
    private static class RpcHandlerFuture<T> extends AbstractFuture<T> implements RpcCallback<T> {

        @Nonnull
        private final ClientController controller;

        private RpcHandlerFuture(@Nonnull ClientController controller) {
            checkNotNull(controller);
            this.controller = controller;
        }

        @Override
        public void run(@Nullable T parameter) {

            if (isCancelled()) {
                return;
            }

            if (null == parameter) {
                setException(new RaftException(controller.errorText()));
            } else {
                set(parameter);
            }

        }

    }

}