org.apache.hadoop.hbase.ipc.BufferCallBeforeInitHandler.java Source code

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Here is the source code for org.apache.hadoop.hbase.ipc.BufferCallBeforeInitHandler.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.apache.hadoop.hbase.ipc;

import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.hadoop.hbase.classification.InterfaceAudience;

/**
 * We will expose the connection to upper layer before initialized, so we need to buffer the calls
 * passed in and write them out once the connection is established.
 */
@InterfaceAudience.Private
class BufferCallBeforeInitHandler extends ChannelDuplexHandler {

    private enum BufferCallAction {
        FLUSH, FAIL
    }

    public static final class BufferCallEvent {

        public final BufferCallAction action;

        public final IOException error;

        private BufferCallEvent(BufferCallBeforeInitHandler.BufferCallAction action, IOException error) {
            this.action = action;
            this.error = error;
        }

        public static BufferCallBeforeInitHandler.BufferCallEvent success() {
            return SUCCESS_EVENT;
        }

        public static BufferCallBeforeInitHandler.BufferCallEvent fail(IOException error) {
            return new BufferCallEvent(BufferCallAction.FAIL, error);
        }
    }

    private static final BufferCallEvent SUCCESS_EVENT = new BufferCallEvent(BufferCallAction.FLUSH, null);

    private final Map<Integer, Call> id2Call = new HashMap<>();

    @Override
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
        if (msg instanceof Call) {
            Call call = (Call) msg;
            id2Call.put(call.id, call);
            // The call is already in track so here we set the write operation as success.
            // We will fail the call directly if we can not write it out.
            promise.trySuccess();
        } else {
            ctx.write(msg, promise);
        }
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof BufferCallEvent) {
            BufferCallEvent bcEvt = (BufferCallBeforeInitHandler.BufferCallEvent) evt;
            switch (bcEvt.action) {
            case FLUSH:
                for (Call call : id2Call.values()) {
                    ctx.write(call);
                }
                break;
            case FAIL:
                for (Call call : id2Call.values()) {
                    call.setException(bcEvt.error);
                }
                break;
            }
            ctx.flush();
            ctx.pipeline().remove(this);
        } else if (evt instanceof CallEvent) {
            // just remove the call for now until we add other call event other than timeout and cancel.
            id2Call.remove(((CallEvent) evt).call.id);
        } else {
            ctx.fireUserEventTriggered(evt);
        }
    }
}