Motiviation:
In the past we allowed to use different EventExecutors for different ChannelHandlers in the ChannelPipeline. This introduced a lot of complexity while not providing much gain. Also it made the pipeline racy in terms of adding / remove handlers in some situations. This feature is not really used in the wild and can be easily archived by offloading heavy logic to an Executor by the user itself.
Modifications:
- Remove the ability to provide custom EventExecutor when adding handlers to the pipeline.
- Remove testcode that is not needed any more
- Ensure a handler is correctly visible in the pipeline when asked for it by the user while not be used until the EventLoop runs. This ensures correct ordering and visibility.
- Correctly remove ChannelHandlers from pipeline when scheduling of handlerAdded(...) callbacks fail.
Result:
Remove races in DefaultChannelPipeline and simplify implementation of AbstractChannelHandlerContext.
Motivation:
We can use lambdas instead of anonymous inner class to improve readablity
Modification:
Replace anonymous inner class with lambda
Result:
Cleaner code that uses Java8 features
Motivation:
We need to update to a new checkstyle plugin to allow the usage of lambdas.
Modifications:
- Update to new plugin version.
- Fix checkstyle problems.
Result:
Be able to use checkstyle plugin which supports new Java syntax.
Motivation:
We need to release the message when we throw an IllegalArgumentException because of a validation failure of the promise to eliminate the risk of a memory leak.
Modifications:
- Consistently release the message before rethrow
- Add testcase.
Result:
Fixes https://github.com/netty/netty/issues/8765.
* 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 .
Motivation:
We should leave the responsibility to choose the EventExecutor for a ChannelHandler to the user for more flexibility and to keep things simple.
Modification:
- Change method signatures to take an EventExecutor and not an EventExecutorGroup
- Remove special ChannelOption that allowed to enable / disable EventExecutor pinning
Result:
Simpler and more flexible code.
Motivation:
Custom Netty ThreadLocalRandom and ThreadLocalRandomProvider classes are no longer needed and can be removed.
Modification:
Remove own ThreadLocalRandom
Result:
Less code to maintain
Motivation:
We can use the diamond operator these days.
Modification:
Use diamond operator whenever possible.
Result:
More modern code and less boiler-plate.
Motivation:
Netty uses own Integer.compare and Long.compare methods. Since Java 7 we can use Java implementation instead.
Modification:
Remove own implementation
Result:
Less code to maintain
Motivation:
Invoking ChannelHandlers is not free and can result in some overhead when the ChannelPipeline becomes very long. This is especially true if most handlers will just forward the call to the next handler in the pipeline. When the user extends Channel*HandlerAdapter we can easily detect if can just skip the handler and invoke the next handler in the pipeline directly. This reduce the overhead of dispatch but also reduce the call-stack in many cases.
Modifications:
Detect if we can skip the handler when walking the pipeline.
Result:
Reduce overhead for long pipelines.
Benchmark (extraHandlers) Mode Cnt Score Error Units
DefaultChannelPipelineBenchmark.propagateEventOld 4 thrpt 10 267313.031 ± 9131.140 ops/s
DefaultChannelPipelineBenchmark.propagateEvent 4 thrpt 10 824825.673 ± 12727.594 ops/s
Motivation:
While we are not yet quite sure if we want to require Java11 as minimum we are at least sure we want to use java8 as minimum.
Modifications:
Change minimum version to java8 and update some tests which failed compilation after this change.
Result:
Use Java8 as minimum and be able to use Java8 features.
Motivation:
testChannelInitializerEventExecutor() did sometimes fail as we sometimes miss to count down the latch. This can happen when we remove the handler from the pipeline before channelUnregistered(...) was called for it.
Modifications:
Countdown the latch in handlerRemoved(...).
Result:
Fix flaky test.
Motivation:
testWriteTaskRejected was racy as we did not ensure we dispatched all events to the executor before shutting it down.
Modifications:
Add a latch to ensure we dispatched everything.
Result:
Fix racy test that failed sometimes before.
Motiviation:
Because of how we implemented the registration / deregistration of an EventLoop it was not possible to wrap an EventLoop implementation and use it with a Channel.
Modification:
- Introduce EventLoop.Unsafe which is responsible for the actual registration.
- Move validation of EventLoop / Channel combo to the EventLoop
- Add unit test that verifies that wrapping works
Result:
Be able to wrap an EventLoop and so add some extra functionality.
Motivation:
At the moment it’s possible to have a Channel in Netty that is not registered / assigned to an EventLoop until register(...) is called. This is suboptimal as if the Channel is not registered it is also not possible to do anything useful with a ChannelFuture that belongs to the Channel. We should think about if we should have the EventLoop as a constructor argument of a Channel and have the register / deregister method only have the effect of add a Channel to KQueue/Epoll/... It is also currently possible to deregister a Channel from one EventLoop and register it with another EventLoop. This operation defeats the threading model assumptions that are wide spread in Netty, and requires careful user level coordination to pull off without any concurrency issues. It is not a commonly used feature in practice, may be better handled by other means (e.g. client side load balancing), and therefore we propose removing this feature.
Modifications:
- Change all Channel implementations to require an EventLoop for construction ( + an EventLoopGroup for all ServerChannel implementations)
- Remove all register(...) methods from EventLoopGroup
- Add ChannelOutboundInvoker.register(...) which now basically means we want to register on the EventLoop for IO.
- Change ChannelUnsafe.register(...) to not take an EventLoop as parameter (as the EventLoop is supplied on custruction).
- Change ChannelFactory to take an EventLoop to create new Channels and introduce ServerChannelFactory which takes an EventLoop and one EventLoopGroup to create new ServerChannel instances.
- Add ServerChannel.childEventLoopGroup()
- Ensure all operations on the accepted Channel is done in the EventLoop of the Channel in ServerBootstrap
- Change unit tests for new behaviour
Result:
A Channel always has an EventLoop assigned which will never change during its life-time. This ensures we are always be able to call any operation on the Channel once constructed (unit the EventLoop is shutdown). This also simplifies the logic in DefaultChannelPipeline a lot as we can always call handlerAdded / handlerRemoved directly without the need to wait for register() to happen.
Also note that its still possible to deregister a Channel and register it again. It's just not possible anymore to move from one EventLoop to another (which was not really safe anyway).
Fixes https://github.com/netty/netty/issues/8513.
Motivation:
We should remove the ChannelPool and related implementations. It is often the case that having protocol knowledge can result in more effective pooling and ChannelPool currently doesn’t have this knowledge. This responsibility is assumed to be implemented at layers higher in the stack than Netty.
Modifications:
Remove io.netty.channel.pool.*
Result:
Less code to maintain, fixes https://github.com/netty/netty/issues/8549.
Motivation:
Due a race in DefaultChannelPipeline / AbstractChannelHandlerContext it was possible to have only handlerRemoved(...) called during tearing down the pipeline, even when handlerAdded(...) was never called. We need to ensure we either call both of none to guarantee a proper lifecycle of the handler.
Modifications:
- Enforce handlerAdded(...) / handlerRemoved(...) semantics / ordering
- Add unit test.
Result:
Fixes https://github.com/netty/netty/issues/8676 / https://github.com/netty/netty/issues/6536 .
* Handling AUTO_READ should not be the responsibility of DefaultChannelPipeline but the Channel itself.
Motivation:
At the moment we do automatically call read() in the DefaultChannelPipeline when fireChannelReadComplete() / fireChannelActive() is called and the Channel is using auto read. This is nice in terms of sharing code but imho is not the responsibility of the ChannelPipeline implementation but the responsibility of the Channel implementation.
Modifications:
Move handing of auto read from DefaultChannelPipeline to Channel implementations.
Result:
More clear responsibiliy and not depending on implemention details of the ChannelPipeline.
Motivation:
executeAfterEventLoopIteration is an Unstable API and isnt used in Netty. We should remove it to reduce complexity.
Changes:
This reverts commit 77770374fb.
Result:
Simplify implementation / cleanup.
Motivation:
8331248671 did make some changes to fix a race in ChannelInitializer when using with a custom EventExecutor. Unfortunally these where a bit racy and so the testcase failed sometimes.
Modifications:
- More correct fix when using a custom EventExecutor
- Adjust the testcase to be more correct.
Result:
Proper fix for https://github.com/netty/netty/issues/8616.
Motivation:
The ChannelInitializer may be invoked multipled times when used with a custom EventExecutor as removal operation may be done asynchronously. We need to guard against this.
Modifications:
- Change Map to Set which is more correct in terms of how we use it.
- Ensure we only modify the internal Set when the handler was removed yet
- Add unit test.
Result:
Fixes https://github.com/netty/netty/issues/8616.
Motivation:
This transport is unique because it uses Java's blocking IO (java.io / java.net) under the hood. However it is not clear if this transport is actually useful so it should be removed.
Modifications:
- Remove OIO transport and RXTX transport which depend on it.
- Remove Oio*Sctp* implementations
- Remove PerThreadEventLoop* which was only used by OIO transport.
Result:
Fixes https://github.com/netty/netty/issues/8510.
Motivation:
When the Selector throws an IOException during our EventLoop processing we should rebuild it and transfer the registered Channels. At the moment we will continue trying to use it which will never work.
Modifications:
- Rebuild Selector when an IOException is thrown during any select*(...) methods.
- Add unit test.
Result:
Fixes https://github.com/netty/netty/issues/8566.
Motivation:
There is a racy UnsupportedOperationException instead because the task removal is delegated to MpscChunkedArrayQueue that does not support removal. This happens with SingleThreadEventExecutor that overrides the newTaskQueue to return an MPSC queue instead of the LinkedBlockingQueue returned by the base class such as NioEventLoop, EpollEventLoop and KQueueEventLoop.
Modifications:
- Catch the UnsupportedOperationException
- Add unit test.
Result:
Fix#8475
Motivation:
It has shown that the used test timeout may be too low when the CI is busy.
Modifications:
Increase timeout to 3 seconds.
Result:
Less false-positives.
Motivation:
Currently we may end up in the situation that we incremented the pending bytes before submitting the AbstractWriteTask but never decrement these again if the submitting of the task fails. This may result in incorrect watermark handling.
Modifications:
- Correctly decrement pending bytes if subimitting of task fails and also ensure we recycle it correctly.
- Add unit test.
Result:
Fixes https://github.com/netty/netty/issues/8343.
Motivation:
Unless the 'io.netty.noKeySetOptimization' system property is set,
registering a SelectableChannel instance to a NioEventLoop results
in a ClassCastException:
io.netty.channel.nio.SelectedSelectionKeySetSelector cannot be cast
to java.nio.channels.spi.AbstractSelector
Modifications:
Instead of 'selector', pass 'unwrappedSelector' to SelectableChannel.
Result:
It is possible to register a SelectableChannel instance without
setting the 'io.netty.noKeySetOptimization' system property.
Motivation:
c1a335446d reimplemented remove(...) and contains(...) in a way which made it not work anymore when used by the Selector.
Modifications:
Partly revert changes in c1a335446d.
Result:
Works again as expected
Motivation:
Our SelectedSelectionKeySet does not correctly implement various methods which can be done without any performance overhead.
Modifications:
Implement iterator(), contains(...) and remove(...)
Result:
Related to https://github.com/netty/netty/issues/8242.
Motivation:
We had a report that the exception may not be correctly propagated. This test shows it is.
Modifications:
Add testcase.
Result:
Test for https://github.com/netty/netty/issues/8158
Motivation:
There is a JDK bug which will return IP_TOS as supported option for ServerSocketChannel even if its not supported afterwards and cause an AssertionError.
See http://mail.openjdk.java.net/pipermail/nio-dev/2018-August/005365.html.
Modifications:
Add a workaround for the JDK bug.
Result:
ServerSocketChannel.config().getOptions() will not throw anymore and work as expected.
* Support the usage of SocketOption when nio is used and the java version >= 7.
Motivation:
The JDK uses SocketOption since java7 to support configuration options on the underyling Channel. We should allow to create a ChannelOption from a given SocketOption if nio is used. This also allows us to expose the same featureset in terms of configuration as the java nio implementation does without any extra effort.
Modifications:
- Add NioChannelOption which allows to wrap an existing SocketOption which then can be applied to the nio transport.
- Add test-cases
Result:
Support the same configuration options as the JDK. Also fixes https://github.com/netty/netty/issues/8072.
Motivation:
Currently, the vast majority of userEventTriggered() implementations
require the user to supply the boilerplate behavior of performing an
instanceof check, handling if appropriate, and calling
fireUserEventTriggered() otherwise.
We can simplify this very common use case by creating a class that only
matches user events of a given type, similar to the existing
SimpleChannelInboundHandler class.
Modifications:
Create a new SimpleUserEventChannelHandler class
Create accompanying SimpleUserEventChannelHandlerTest class
Result:
Users will be able to handle most events in a less verbose manner.
Motivation:
We should allow to schedule tasks with a delay up to Long.MAX_VALUE as we did pre 4.1.25.Final.
Modifications:
Just ensure we not overflow and put the correct max limits in place when schedule a timer. At worse we will get a wakeup to early and then schedule a new timeout.
Result:
Fixes https://github.com/netty/netty/issues/7970.
Motivation:
We added some code to guard against thread.interrupt() in NioEventLoop but did not added a test.
Modifications:
Add testcase.
Result:
Verify that we correctly handle interrupt().
Motivation:
ChannelReadHandler is used in tests added via f4d7e8de14. In the handler we verify the number of messages we receive per read() call but missed to sometimes reset the counter which resulted in exceptions.
Modifications:
Correctly reset read counter in all cases.
Result:
No more unexpected exceptions when running LocalChannel tests.
Motivation:
LocalChannel / LocalServerChannel did not respect read limits and just always read all of the messages.
Modifications:
- Correct respect MAX_MESSAGES_PER_READ settings
- Add unit tests
Result:
Fixes https://github.com/netty/netty/issues/7880.
Motivation:
Using a very huge delay when calling schedule(...) may cause an Selector error when calling select(...) later on. We should gaurd against such a big value.
Modifications:
- Add guard against a very huge value.
- Added tests.
Result:
Fixes [#7365]
Motivation:
We need to ensure we only reset readInProgress if the outboundBuffer is not empty as otherwise we may miss to call fireChannelRead(...) later on when using the LocalChannel.
Modifications:
Also check if the outboundBuffer is not empty before setting readInProgress to false again
Result:
Fixes https://github.com/netty/netty/issues/7855
Motivation:
Sometimes it is very convenient to remove the handler from pipeline without throwing the exception in case those handler doesn't exist in the pipeline.
Modification:
Added 3 overloaded methods to DefaultChannelPipeline, but not added to ChannelHandler due to back compatibility.
Result:
Fixes#7662
Motivation:
Our code was not correct in AbstractNioMessageChannel.closeOnReadError(....) which lead to the situation that we always tried to continue reading no matter what exception was thrown when using the NioServerSocketChannel. Also even on an IOException we should check if the Channel itself is still active or not and if not stop reading.
Modifications:
Fix closeOnReadError impl and added test.
Result:
Correctly stop reading on NioServerSocketChannel when error happens during read.
Motivation:
Right now PendingWriteQueue.removeAndWriteAll collects all promises to
PromiseCombiner instance which sets listener to each given promise throwing
IllegalStateException on VoidChannelPromise which breaks while loop
and "reports" operation as failed (when in fact part of writes might be
actually written).
Modifications:
Check if the promise is not void before adding it to the PromiseCombiner
instance.
Result:
PendingWriteQueue.removeAndWriteAll succesfully writes all pendings
even in case void promise was used.
Motiviation:
DefaultChannelPipeline and AbstractChannelHandlerContext maintain state
which indicates if a ChannelHandler should be invoked or not. However
the state is updated to allow the handler to be invoked only after the
handlerAdded method completes. If the handlerAdded method generates
events which may result in other methods being invoked on that handler
they will be missed.
Modifications:
- DefaultChannelPipeline should set the state before calling
handlerAdded
Result:
DefaultChannelPipeline will allow events to be processed during the
handlerAdded process.
Motivation:
We should fail fast when DefaultChannelPromise is constructed with null as Channel as otherwise it will fail with a NPE once we call setSuccess / setFailure.
Modifications:
Add null check and test.
Result:
Fail fast.
Motivation
There is currently no way to enforce the position of a handler in a ChannelPipeline and assume you wanted to write something like a custom Channel type that acts as a proxy between two other Channels.
ProxyChannel(Channel client, Channel server) {
client calls write(msg) -> server.write(msg)
client calls flush() -> server.flush()
server calls fireChannelRead(msg) -> client.write(msg)
server calls fireChannelReadComplete() -> client.flush()
}
In order to make it work reliably one needs to be able to scoop up the various events at the head and tail of the pipeline. The head side of the pipeline is covered by Unsafe and it's also relatively safe to count on the user to not use the addFirst() method to manipulate the pipeline. The tail side is always at a risk of getting broken because addLast() is the goto method to add handlers.
Modifications
Adding a few extra methods to DefaultChannelPipeline that expose some of the events that reach the pipeline's TailContext.
Result
Fixes#7484
* FIX: force a read operation for peer instead of self
Motivation:
When A is in `writeInProgress` and call self close, A should
`finishPeerRead` for B(A' peer).
Modifications:
Call `finishPeerRead` with peer in `LocalChannel#doClose`
Result:
Clear confuse of code logic
* FIX: preserves order of close after write in same event loop
Motivation:
If client and server(client's peer channel) are in same event loop, client writes data to
server in `ChannelActive`. Server receives the data and write it
back. The client's read can't be triggered becasue client's
`ChannelActive` is not finished at this point and its `readInProgress`
is false. Then server closes itself, it will also close the client's
channel. And client has no chance to receive the data.
Modifications:
1. Add a test case to demonstrate the problem
2. When `doClose` peer, we always call
`peer.eventLoop().execute()` and `registerInProgress` is not needed.
3. Remove test case
`testClosePeerInWritePromiseCompleteSameEventLoopPreservesOrder`. This
test case can't pass becasue of this commit. IMHO, I think it is OK,
becasue it is reasonable that the client flushes the data to socket,
then server close the channel without received the data.
4. For mismatch test in SniClientTest, the client should receive server's alert before closed(caused by server's close)
Result:
The problem is gone.
Motivation:
AdaptiveRecvByteBufAllocator currently adjusts the ByteBuf allocation size guess when readComplete is called. However the default configuration for number of reads before readComplete is called is 16. This means that there will be 16 reads done before any adjustment is done. If there is a large amount of data pending AdaptiveRecvByteBufAllocator will be slow to adjust the allocation size guess. In addition to being slow the result of only updating the guess in readComplete means that we must go back to the selector and wait to be woken up again when data is ready to read. Going back to the selector is an expensive operations and can add significant latency if there is large amount of data pending to read.
Modifications:
- AdaptiveRecvByteBufAllocator should check on each read if a step up is necessary. The step down process is left unchanged and can be more gradual at the cost of potentially over allocating.
Result:
AdaptiveRecvByteBufAllocator increases the guess size during the read loop to reduce latency when large amounts of data is being read.
Motivation:
`FixedChannelPool` allows users to configure `acquireTimeoutMillis`
and expects given value to be greater or equal to zero when timeout
action is supplied. However, validation error message said that
value is expected to be greater or equal to one. Code performs
check against zero.
Modifications:
Changed error message to say that value greater or equal to
zero is expected. Added test to check that zero is an acceptable
value.
Result:
Exception with right error message is thrown.
Motivation:
AbstractCoalescingBufferQueue#add accounts for void promises, but AbstractCoalescingBufferQueue#addFirst does not. These methods should be consistent.
Modifications:
- AbstractCoalescingBufferQueue#addFirst should account for void promises and share code with AbstractCoalescingBufferQueue#add
Result:
More correct void promise handling in AbstractCoalescingBufferQueue.
