org.cloudata.core.commitlog.pipe.CloseState.java Source code

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Here is the source code for org.cloudata.core.commitlog.pipe.CloseState.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.cloudata.core.commitlog.pipe;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.cloudata.core.commitlog.PipeNormallyClosed;
import org.cloudata.core.commitlog.pipe.Pipe.Context;
import org.cloudata.core.common.Constants;

public class CloseState extends PipeState implements FaultInjectionIF {
    public static final ByteBuffer READY_TO_DISCONNECT_MSG = ByteBuffer.allocate(1);
    Log LOG = LogFactory.getLog(CloseState.class);

    ByteBuffer closeMessage = ByteBuffer.allocate(4);

    public static PipeState instance() {
        return new CloseState();
    }

    CloseState() {
        closeMessage.putInt(Constants.PIPE_DISCONNECT);
        closeMessage.flip();
    }

    public String getStateName() {
        return "Close State";
    }

    public void init(Context ctx) throws IOException {
        LOG.debug("CLOSE STATE!!!");
    }

    public void close(Context ctx) throws IOException {
        LOG.debug("CLOSE STATE!!!");
    }

    private boolean closeGracefully(Context ctx) throws IOException {
        //    ByteBuffer buf = ByteBuffer.allocate(1);
        //    int numRead = 0;
        //    try {
        //      numRead = ctx.prevChannel.read(buf);
        //    } catch (IOException e) {
        //      throw new PipeNormallyClosed();
        //    }
        //
        //    if (numRead < 0) {
        //      throw new PipeNormallyClosed();
        //    }
        //
        //    LOG.warn("WHAT THE HELL??");
        //    return true;
        throw new PipeNormallyClosed();
    }

    public boolean readFromPrev(Context ctx) throws IOException {
        LOG.debug("readFromPrev");

        if (ctx.status.readyToDisconnect) {
            LOG.debug("close gracefully");
            return closeGracefully(ctx);
        }

        return writeToNext(ctx);
    }

    public boolean writeToNext(Context ctx) throws IOException {
        LOG.debug("writeToNext");

        if (!ctx.isLastPipe) {
            LOG.debug("not last pipe");
            ByteBuffer msg = closeMessage.duplicate();
            msg.position(ctx.closeMessagePos);
            try {
                ctx.closeMessagePos = ctx.nextChannel.write(msg);
            } catch (IOException e) {
                throw new PipeNormallyClosed();
            }

            if (msg.hasRemaining()) {
                ctx.deregisterFromSelect(ctx.nextChannel, SelectionKey.OP_WRITE);
                return false;
            }
        } else {
            LOG.debug("send ok ack to prev");
            ctx.closeMessagePos = 0;
            ctx.ack.clear();
            ctx.ack.put(Constants.PIPE_DISCONNECT_OK);
            ctx.ack.flip();
            return writeToPrev(ctx);
        }

        return true;
    }

    public boolean readFromNext(Context ctx) throws IOException {
        ctx.ack.clear();
        boolean disconnected = false;
        try {
            disconnected = ctx.nextChannel.read(ctx.ack) < 0;
        } catch (IOException e) {
            LOG.info("strange close but continue : " + e);
            throw new PipeNormallyClosed();
        }

        if (disconnected) {
            LOG.info("strange close but continue");
            throw new PipeNormallyClosed();
        }

        ctx.ack.flip();
        ctx.status.readyToDisconnect = writeAckToPrev(ctx);
        return ctx.status.readyToDisconnect;
    }

    public boolean writeToPrev(Context ctx) throws IOException {
        LOG.debug("writeToPrev");
        ctx.status.readyToDisconnect = writeAckToPrev(ctx);
        return ctx.status.readyToDisconnect;
    }
}