io.netty.channel.ChannelHandlerAdapter Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* Copyright 2013 The Netty Project
*
* The Netty Project 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:
*
* https://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 io.netty.channel;
import io.netty.channel.ChannelHandlerMask.Skip;
import io.netty.util.internal.InternalThreadLocalMap;
import java.util.Map;
/**
* Skeleton implementation of a {@link ChannelHandler}.
*/
public abstract class ChannelHandlerAdapter implements ChannelHandler {
// Not using volatile because it's used only for a sanity check.
boolean added;
/**
* Throws {@link IllegalStateException} if {@link ChannelHandlerAdapter#isSharable()} returns {@code true}
*/
protected void ensureNotSharable() {
if (isSharable()) {
throw new IllegalStateException("ChannelHandler " + getClass().getName() + " is not allowed to be shared");
}
}
/**
* Return {@code true} if the implementation is {@link Sharable} and so can be added
* to different {@link ChannelPipeline}s.
*/
public boolean isSharable() {
/**
* Cache the result of {@link Sharable} annotation detection to workaround a condition. We use a
* {@link ThreadLocal} and {@link WeakHashMap} to eliminate the volatile write/reads. Using different
* {@link WeakHashMap} instances per {@link Thread} is good enough for us and the number of
* {@link Thread}s are quite limited anyway.
*
* See #2289.
*/
Class clazz = getClass();
Map, Boolean> cache = InternalThreadLocalMap.get().handlerSharableCache();
Boolean sharable = cache.get(clazz);
if (sharable == null) {
sharable = clazz.isAnnotationPresent(Sharable.class);
cache.put(clazz, sharable);
}
return sharable;
}
/**
* Do nothing by default, sub-classes may override this method.
*/
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
// NOOP
}
/**
* Do nothing by default, sub-classes may override this method.
*/
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
// NOOP
}
/**
* Calls {@link ChannelHandlerContext#fireExceptionCaught(Throwable)} to forward
* to the next {@link ChannelHandler} in the {@link ChannelPipeline}.
*
* Sub-classes may override this method to change behavior.
*
* @deprecated is part of {@link ChannelInboundHandler}
*/
@Skip
@Override
@Deprecated
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.fireExceptionCaught(cause);
}
}