com.datastax.oss.driver.internal.core.channel.ConnectInitHandler Maven / Gradle / Ivy
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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 com.datastax.oss.driver.internal.core.channel;
import com.datastax.oss.driver.internal.core.util.concurrent.PromiseCombiner;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import java.net.SocketAddress;
import net.jcip.annotations.NotThreadSafe;
/**
* A handler that delays the promise returned by {@code bootstrap.connect()}, in order to run a
* custom initialization process before making the channel available to clients.
*
* This handler is not shareable. It must be installed by the channel initializer, as the last
* channel in the pipeline.
*
*
It will be notified via {@link #onRealConnect(ChannelHandlerContext)} when the real underlying
* connection is established. It can then start sending messages on the connection, while external
* clients are still waiting on their promise. Once the custom initialization is finished, the
* clients' promise can be completed with {@link #setConnectSuccess()} or {@link
* #setConnectFailure(Throwable)}.
*/
@NotThreadSafe
public abstract class ConnectInitHandler extends ChannelDuplexHandler {
// the completion of the custom initialization process
private ChannelPromise initPromise;
private ChannelHandlerContext ctx;
@Override
public void connect(
ChannelHandlerContext ctx,
SocketAddress remoteAddress,
SocketAddress localAddress,
ChannelPromise callerPromise)
throws Exception {
this.ctx = ctx;
initPromise = ctx.channel().newPromise();
// the completion of the real underlying connection:
ChannelPromise realConnectPromise = ctx.channel().newPromise();
super.connect(ctx, remoteAddress, localAddress, realConnectPromise);
realConnectPromise.addListener(future -> onRealConnect(ctx));
// Make the caller's promise wait on the other two:
PromiseCombiner.combine(callerPromise, realConnectPromise, initPromise);
}
protected abstract void onRealConnect(ChannelHandlerContext ctx);
protected boolean setConnectSuccess() {
boolean result = initPromise.trySuccess();
if (result) {
ctx.pipeline().remove(this);
}
return result;
}
protected void setConnectFailure(Throwable cause) {
if (initPromise.tryFailure(cause)) {
ctx.channel().close();
}
}
}