gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/handler/WebSocketClientHandler.java

/*
 * 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.tinkerpop.gremlin.driver.handler;

import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketClientHandshaker;
import io.netty.handler.codec.http.websocketx.WebSocketFrame;
import io.netty.util.CharsetUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author Stephen Mallette (http://stephen.genoprime.com)
 */
public final class WebSocketClientHandler extends SimpleChannelInboundHandler<Object> {
    private static final Logger logger = LoggerFactory.getLogger(WebSocketClientHandler.class);
    private final WebSocketClientHandshaker handshaker;
    private ChannelPromise handshakeFuture;

    public WebSocketClientHandler(final WebSocketClientHandshaker handshaker) {
        this.handshaker = handshaker;
    }

    public ChannelFuture handshakeFuture() {
        return handshakeFuture;
    }

    @Override
    public void handlerAdded(final ChannelHandlerContext ctx) throws Exception {
        handshakeFuture = ctx.newPromise();
    }

    @Override
    public void channelActive(final ChannelHandlerContext ctx) throws Exception {
        handshaker.handshake(ctx.channel());
    }

    @Override
    protected void channelRead0(final ChannelHandlerContext ctx, final Object msg) throws Exception {
        final Channel ch = ctx.channel();
        if (!handshaker.isHandshakeComplete()) {
            // web socket client connected
            handshaker.finishHandshake(ch, (FullHttpResponse) msg);
            handshakeFuture.setSuccess();
            return;
        }

        if (msg instanceof FullHttpResponse) {
            final FullHttpResponse response = (FullHttpResponse) msg;
            throw new Exception("Unexpected FullHttpResponse (getStatus=" + response.status() + ", content="
                    + response.content().toString(CharsetUtil.UTF_8) + ')');
        }

        // a close frame doesn't mean much here.  errors raised from closed channels will mark the host as dead
        final WebSocketFrame frame = (WebSocketFrame) msg;
        if (frame instanceof TextWebSocketFrame) {
            ctx.fireChannelRead(frame.retain(2));
        } else if (frame instanceof PingWebSocketFrame) {
            ctx.writeAndFlush(new PongWebSocketFrame());
        }else if (frame instanceof PongWebSocketFrame) {
            logger.debug("Received response from keep-alive request");
        } else if (frame instanceof BinaryWebSocketFrame) {
            ctx.fireChannelRead(frame.retain(2));
        } else if (frame instanceof CloseWebSocketFrame)
            ch.close();

    }

    @Override
    public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) throws Exception {
        if (!handshakeFuture.isDone()) handshakeFuture.setFailure(cause);

        // let the GremlinResponseHandler take care of exception logging, channel closing, and cleanup
        ctx.fireExceptionCaught(cause);
    }
}