3d6e6136a9
* Decouble EventLoop details from the IO handling for each transport to allow easy re-use of code and customization
Motiviation:
As today extending EventLoop implementations to add custom logic / metrics / instrumentations is only possible in a very limited way if at all. This is due the fact that most implementations are final or even package-private. That said even if these would be public there are the ability to do something useful with these is very limited as the IO processing and task processing are very tightly coupled. All of the mentioned things are a big pain point in netty 4.x and need improvement.
Modifications:
This changeset decoubled the IO processing logic from the task processing logic for the main transport (NIO, Epoll, KQueue) by introducing the concept of an IoHandler. The IoHandler itself is responsible to wait for IO readiness and process these IO events. The execution of the IoHandler itself is done by the SingleThreadEventLoop as part of its EventLoop processing. This allows to use the same EventLoopGroup (MultiThreadEventLoupGroup) for all the mentioned transports by just specify a different IoHandlerFactory during construction.
Beside this core API change this changeset also allows to easily extend SingleThreadEventExecutor / SingleThreadEventLoop to add custom logic to it which then can be reused by all the transports. The ideas are very similar to what is provided by ScheduledThreadPoolExecutor (that is part of the JDK). This allows for example things like:
* Adding instrumentation / metrics:
* how many Channels are registered on an SingleThreadEventLoop
* how many Channels were handled during the IO processing in an EventLoop run
* how many task were handled during the last EventLoop / EventExecutor run
* how many outstanding tasks we have
...
...
* Implementing custom strategies for choosing the next EventExecutor / EventLoop to use based on these metrics.
* Use different Promise / Future / ScheduledFuture implementations
* decorate Runnable / Callables when submitted to the EventExecutor / EventLoop
As a lot of functionalities are folded into the MultiThreadEventLoopGroup and SingleThreadEventLoopGroup this changeset also removes:
* AbstractEventLoop
* AbstractEventLoopGroup
* EventExecutorChooser
* EventExecutorChooserFactory
* DefaultEventLoopGroup
* DefaultEventExecutor
* DefaultEventExecutorGroup
Result:
Fixes https://github.com/netty/netty/issues/8514 .
68 lines
2.3 KiB
Java
68 lines
2.3 KiB
Java
/*
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* Copyright 2012 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.util.concurrent;
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/**
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* The {@link EventExecutor} is a special {@link EventExecutorGroup} which comes
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* with some handy methods to see if a {@link Thread} is executed in a event loop.
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* Besides this, it also extends the {@link EventExecutorGroup} to allow for a generic
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* way to access methods.
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*
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*/
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public interface EventExecutor extends EventExecutorGroup {
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/**
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* Returns a reference to itself.
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*/
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@Override
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EventExecutor next();
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/**
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* Calls {@link #inEventLoop(Thread)} with {@link Thread#currentThread()} as argument
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*/
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boolean inEventLoop();
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/**
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* Return {@code true} if the given {@link Thread} is executed in the event loop,
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* {@code false} otherwise.
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*/
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boolean inEventLoop(Thread thread);
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/**
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* Return a new {@link Promise}.
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*/
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<V> Promise<V> newPromise();
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/**
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* Create a new {@link ProgressivePromise}.
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*/
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<V> ProgressivePromise<V> newProgressivePromise();
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/**
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* Create a new {@link Future} which is marked as succeeded already. So {@link Future#isSuccess()}
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* will return {@code true}. All {@link FutureListener} added to it will be notified directly. Also
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* every call of blocking methods will just return without blocking.
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*/
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<V> Future<V> newSucceededFuture(V result);
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/**
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* Create a new {@link Future} which is marked as failed already. So {@link Future#isSuccess()}
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* will return {@code false}. All {@link FutureListener} added to it will be notified directly. Also
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* every call of blocking methods will just return without blocking.
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*/
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<V> Future<V> newFailedFuture(Throwable cause);
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}
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