the implicit #fireChannelReadComplete() in EmbeddedChannel#writeInbound().
Motivation
We use EmbeddedChannels to implement a ProxyChannel of some sorts that shovels
messages between a source and a destination Channel. The latter are real network
channels (such as Epoll) and they may or may not be managed in a ChannelPool. We
could fuse both ends directly together but the EmbeddedChannel provides a nice
disposable section of a ChannelPipeline that can be used to instrument the messages
that are passing through the proxy portion.
The ideal flow looks abount like this:
source#channelRead() -> proxy#writeOutbound() -> destination#write()
source#channelReadComplete() -> proxy#flushOutbound() -> destination#flush()
destination#channelRead() -> proxy#writeInbound() -> source#write()
destination#channelReadComplete() -> proxy#flushInbound() -> source#flush()
The problem is that #writeOutbound() and #writeInbound() emit surplus #flush()
and #fireChannelReadComplete() events which in turn yield to surplus #flush()
calls on both ends of the pipeline.
Modifications
Introduce a new set of write methods that reain the same sematics as the #write()
method and #flushOutbound() and #flushInbound().
Result
It's possible to implement the above ideal flow.
Fix for EmbeddedChannel#ensureOpen() and Unit Tests for it
Some PR stuff.
Motivation:
To make it easier to debug why notification of a promise failed we should log extra info and make it consistent.
Modifications:
- Create a new PromiseNotificationUtil that has static methods that can be used to try notify a promise and log.
- Reuse this in AbstractChannelHandlerContext, ChannelOutboundBuffer and PromiseNotifier
Result:
Easier to debug why a promise could not be notified.
Motivation:
RFC7871 defines an extension which allows to request responses for a given subset.
Modifications:
- Add DnsOptPseudoRrRecord which can act as base class for extensions based on EDNS(0) as defined in RFC6891
- Add DnsOptEcsRecord to support the Client Subnet in DNS Queries extension
- Add tests
Result:
Client Subnet in DNS Queries extension is now supported.
Motivation:
For use cases that demand frequent updates of the write watermarks, an
API that requires immutable WriteWaterMark objects is not ideal, as it
implies a lot of object allocation.
For example, the HTTP/2 child channel API uses write watermarks for outbound
flow control and updates the write watermarks on every DATA frame write.
Modifications:
Remote @Deprecated tag from primitive getters and setters, however the corresponding
channel options remain deprecated.
Result:
Primitive getters and setters for write watermarks are no longer marked @Deprecated.
Motivation:
The JDK implementation of SocketChannel has an internal state that is tracked for its operations. Because of this we need to ensure we call finishConnect() before try to call read(...) / write(...) as otherwise it may produce a NotYetConnectedException.
Modifications:
First process OP_CONNECT flag.
Result:
No more possibility of NotYetConnectedException because OP_CONNECT is handled not early enough when processing interestedOps for a Channel.
Motivation:
The DefaultEventLoopGroup class extends MultithreadEventExecutorGroup but doesn't expose the ctor variants that accept a custom Executor like NioEventLoopGroup and EpollEventLoopGroup do.
Modifications:
Add missing constructor.
Result:
Be able to use custom Executor with DefaultEventLoopGroup.
Motivation:
When attempting to set the selectedKeys fields on the selector
implementation, JDK 9 can throw an inaccessible object exception.
Modications:
Catch and log this exception as an possible course of action if the
sun.nio.ch package is not exported from java.base.
Result:
The selector replacement will fail gracefully as an expected course of
action if the sun.nio.ch package is not exported from java.base.
Motivation:
The NIO transport used an IllegalStateException if a user tried to issue another connect(...) while the connect was still in process. For this case the JDK specified a ConnectPendingException which we should use. The same issues exists in the EPOLL transport. Beside this the EPOLL transport also does not throw the right exceptions for ENETUNREACH and EISCONN errno codes.
Modifications:
- Replace IllegalStateException with ConnectPendingException in NIO and EPOLL transport
- throw correct exceptions for ENETUNREACH and EISCONN in EPOLL transport
- Add test case
Result:
More correct error handling for connect attempts when using NIO and EPOLL transport
Motivation:
The API documentation in ChannelConfig states that a a channel is writable,
if the number of pending bytes is below the low watermark and a
channel is not writable, if the number of pending bytes exceeds the high
watermark.
Therefore, we should use < operators instead of <= as well as > instead of >=.
Using <= and >= is also problematic, if the low watermark is equal to the high watermark,
as then a channel could be both writable and unwritable with the same number of pending
bytes (depending on whether remove() or addMessage() is called first).
The use of <= and >= was introduced in PR https://github.com/netty/netty/pull/3036, but
I don't understand why, as there doesn't seem to have been any discussion around that.
Modifications:
Use < and > operators instead of <= and >=.
Result:
High and low watermarks are treated as stated in the API docs.
Motivation:
We need to ensure we also call fireChannelActive() if the Channel is directly closed in a ChannelFutureListener that is belongs to the promise for the connect. Otherwise we will see missing active events.
Modifications:
Ensure we always call fireChannelActive() if the Channel was active.
Result:
No missing events.
Motivation:
We use often javachannel().socket().* in NIO as these methods exists in java6. The problem is that these will throw often very general Exceptions (Like SocketException) while it is more expected to throw the Exceptions listed in the nio interfaces. When possible we should use the new methods available in java7+ which throw the correct exceptions.
Modifications:
Check for java version and depending on it using the socket or the javachannel.
Result:
Throw expected Exceptions.
Motivation:
To make it easier to debug connect exceptions we create new exceptions which also contain the remote address. For this we basically created a new instance and call setStackTrace(...). When doing this we pay an extra penality because it calls fillInStackTrace() when calling the super constructor.
Modifications:
Create special sub-classes of Exceptions that override the fillInStackTrace() method and so eliminate the overhead.
Result:
Less overhead when "annotate" connect exceptions.
Motivation:
Comments stating that AUTO_CLOSE will be removed in Netty 5.0 are wrong,
as there is no Netty 5.0.
Modifications:
Removed comment.
Result:
No more references to Netty 5.0
Motivation:
PendingWriteQueue should guard against re-entrant writes once removeAndWriteAll() is run.
Modifications:
Continue writing until queue is empty.
Result:
Correctly guard against re-entrance.
Motivation:
Instrumenting the NIO selector implementation requires special
permissions. Yet, the code for performing this instrumentation is
executed in a manner that would require all code leading up to the
initialization to have the requisite permissions. In a restrictive
environment (e.g., under a security policy that only grants the
requisite permissions the Netty transport jar but not to application
code triggering the Netty initialization), then instrumeting the
selector will not succeed even if the security policy would otherwise
permit it.
Modifications:
This commit marks the necessary blocks as privileged. This enables
access to the necessary resources for instrumenting the selector. The
idea is that we are saying the Netty code is trusted, and as long as the
Netty code has been granted the necessary permissions, then we will
allow the caller access to these resources even though the caller itself
might not have the requisite permissions.
Result:
The selector can be instrumented in a restrictive security environment.
Motivation:
Writing to a system property requires permissions. Yet the code for
setting sun.nio.ch.bugLevel is not marked as privileged. In a
restrictive environment (e.g., under a security policy that only grants
the requisite permissions the Netty transport jar but not to application
code triggering the Netty initialization), writing to this system
property will not succeed even if the security policy would otherwise
permit it.
Modifications:
This commt marks the necessary code block as privileged. This enables
writing to this system property. The idea is that we are saying the
Netty code is trusted, and as long as the Netty code has been granted
the necessary permissions, then we will allow the caller access to these
resources even though the caller itself might not have the requisite
permissions.
Result:
The system property sun.nio.ch.bugLevel can be written to in a
restrictive security environment.
Motivation:
If the user uses 0 as quiet period we should shutdown without any delay if possible.
Modifications:
Ensure we not introduce extra delay when a shutdown quit period of 0 is used.
Result:
EventLoop shutdown as fast as expected.
Motivation:
At the moment we call initChannel(...) in the channelRegistered(...) method which has the effect that if another ChannelInitializer is added within the initChannel(...) method the ordering of the added handlers is not correct and surprising. This is as the whole initChannel(...) method block is executed before the initChannel(...) block of the added ChannelInitializer is handled.
Modifications:
Call initChannel(...) from within handlerAdded(...) if the Channel is registered already. This is true in all cases for our DefaultChannelPipeline implementation. This way the ordering is always as expected. We still keep the old behaviour as well to not break code for other ChannelPipeline implementations (if someone ever wrote one).
Result:
Correct and expected ordering of ChannelHandlers.
Motivation:
When we try to close the Channel due a timeout we need to ensure we not log if the notification of the promise fails as it may be completed in the meantime.
Modifications:
Add another constructor to ChannelPromiseNotifier and PromiseNotifier which allows to log on notification failure.
Result:
No more miss-leading logs.
Motivation:
I received a report the its not possible to add another ChannelInitialiter in the initChannel(...) method, so we should add a test case for it.
Modifications:
Added testcase.
Result:
Validate that all works as expected.
Motivation:
When a ChannelInitializer is used via ServerBootstrap.handler(...) the users handlers may be added after the internal ServerBootstrapAcceptor. This should not happen.
Modifications:
Delay the adding of the ServerBootstrapAcceptor until the initChannel(....) method returns.
Result:
Correct order of handlers in the ServerChannels ChannelPipeline.
Motivation:
We used Promise.setFailure(...) when fail a Promise in SimpleChannelPool. As this happens in multiple levels this can result in stackoverflow as setFailure(...) may throw an IllegalStateException which then again is propergated.
Modifications:
Use tryFailure(...)
Result:
No more possibility to cause a stack overflow when failing the promise.
Motivation:
The SimpleChannelPool#notifyConnect() method will leak Channels if the user cancelled the Promise in between.
Modifications:
Release the channel if the Promise was complete before.
Result:
No more channel leaks.
Motiviation:
DefaultChannelId attempts to acquire a default process ID by determining
the process PID. However, to do this it attempts to punch through to the
system classloader, a permission that in the face of a restrictive
security manager is unlikely to be granted. Looking past this, it then
attempts to load a declared method off a reflectively loaded class,
another permission that is not likely to be granted in the face of a
restrictive security manager. However, neither of these permissions are
necessary as the punching through to the system security manager is
completely unneeded, and there is no need to load a public method as a
declared method.
Modifications:
Instead of punching through to the system classloader requiring
restricted permissions, we can just use current classloader. To address
the access declared method permission, we instead just reflectively
obtain the desired public method via Class#getMethod.
Result:
Acquiring the default process ID from the PID will succeed without
requiring the runtime permissions "getClassLoader" and
"accessDeclaredMembers".
Motivation:
In 4.0 AbstractNioByteChannel has a default of 16 max messages per read. However in 4.1 that constraint was applied at the NioSocketChannel which is not equivalent. In 4.1 AbstractEpollStreamChannel also did not have the default of 16 max messages per read applied.
Modifications:
- Make Nio consistent with 4.0
- Make Epoll consistent with Nio
Result:
Nio and Epoll both have consistent ChannelMetadata and are consistent with 4.0.
Motivation:
This change is part of the change done in PR #5395 to provide an `AUTO_FLUSH` capability.
Splitting this change will enable to try other ways of implementing `AUTO_FLUSH`.
Modifications:


Two methods:
```java
void executeAfterEventLoopIteration(Runnable task);


boolean removeAfterEventLoopIterationTask(Runnable task);
```
are added to `SingleThreadEventLoop` class for adding/removing a task to be executed at the end of current/next iteration of this `eventloop`.
In order to support the above, a few methods are added to `SingleThreadEventExecutor`
```java
protected void afterRunningAllTasks() { }
```
This is invoked after all tasks are run for this executor OR if the passed timeout value for `runAllTasks(long timeoutNanos)` is expired.
Added a queue of `tailTasks` to `SingleThreadEventLoop` to hold all tasks to be executed at the end of every iteration.


Result:


`SingleThreadEventLoop` now has the ability to execute tasks at the end of an eventloop iteration.
Motivation:
For some use-cases it would be useful to know the number of bytes queued in the PendingWriteQueue without the need to dequeue them.
Modifications:
Add PendingWriteQueue.bytes().
Result:
Be able to get the number of bytes queued.
Motivation:
Commit 4c048d069d moved the logic of calling handlerAdded(...) to the channelRegistered(...) callback of the head of the DefaultChannelPipeline. Unfortunatlly this may execute the callbacks to late as a user may add handlers to the pipeline in the ChannelFutureListener attached to the registration future. This can lead to incorrect ordering.
Modifications:
Ensure we always invoke ChannelHandler.handlerAdded(...) for all handlers before the registration promise is notified.
Result:
Not possible of incorrect ordering or missed events.
Motivation:
We pinned the EventExecutor for a Channel in DefaultChannelPipeline. Which means if the user added multiple handlers with the same EventExecutorGroup to the ChannelPipeline it will use the same EventExecutor for all of these handlers. This may be unexpected and even not what the user wants. If the user want to use the same one for all of them it can be done by obtain an EventExecutor and pass the same instance to the add methods. Because of this we should allow to not pin.
Modifications:
Allow to disable pinning of EventExecutor for Channel based on EventExecutorGroup via ChannelOption.
Result:
Less confusing and more flexible usage of EventExecutorGroup when adding ChannelHandlers to the ChannelPipeline.
Motivation
When I override ChannelHandler methods I usually (always) refire events myself via
ChannelHandlerContext instead of relieing on calling the super method (say
`super.write(ctx, ...)`). This works great and the IDE actually auto completes/generates
the right code for it except `#fireUserEventTriggered()` and `#userEventTriggered()`
which have a mismatching argument names and I have to manually "intervene".
Modification
Rename `ChannelHandlerContext#fireUserEventTriggered()` argument from `event` to `evt`
to match its handler counterpart.
Result
The IDE's auto generated code will reference the correct variable.
Motivation:
In commit f984870ccc I made a change which operated under invalide assumption that tasks executed by an EventExecutor will always be processed in a serial fashion. This is true for SingleThreadEventExecutor sub-classes but not part of the EventExecutor interface contract.
Because of this change implementations of EventExecutor which not strictly execute tasks in a serial fashion may miss events before handlerAdded(...) is called. This is strictly speaking not correct as there is not guarantee in this case that handlerAdded(...) will be called as first task (as there is no ordering guarentee).
Cassandra itself ships such an EventExecutor implementation which has no strict ordering to spread load across multiple threads.
Modifications:
- Add new OrderedEventExecutor interface and let SingleThreadEventExecutor / EventLoop implement / extend it.
- Only expose "restriction" of skipping events until handlerAdded(...) is called for OrderedEventExecutor implementations
- Add ThreadPoolEventExecutor implementation which executes tasks in an unordered fashion. This is used in added unit test but can also be used for protocols which not expose an strict ordering.
- Add unit test.
Result:
Resurrect the possibility to implement an EventExecutor which does not enforce serial execution of events and be able to use it with the DefaultChannelPipeline.
Motivation:
We should make it clear that each acquired Channel needs to be released in all cases.
Modifications:
More clear javadocs.
Result:
Harder for users to leak Channel.
Motivation:
The field can be read from arbitrary threads via Channel.(isWritable()|bytesBeforeWritable()|bytesBeforeUnwritable()), WriteAndFlushTask.newInstance(), PendingWriteQueue, etc.
Modifications:
Make AbstractChannel.outboundBuffer volatile.
Result:
More correct in a concurrent use case.
Motivation:
We used future in many method of ChannelDuplexHandler as argument name of ChannelPromise. We should make it more consistent and correct.
Modifications:
Replace future with promise.
Result:
More correct and consistent naming.
Motiviation:
Sometimes it is useful to allow to specify a custom strategy to handle rejected tasks. For example if someone tries to add tasks from outside the eventloop it may make sense to try to backoff and retries and so give the executor time to recover.
Modification:
Add RejectedEventExecutor interface and implementations and allow to inject it.
Result:
More flexible handling of executor overload.
Motivation:
To restrict the memory usage of a system it is sometimes needed to adjust the number of max pending tasks in the tasks queue.
Modifications:
- Add new constructors to modify the number of allowed pending tasks.
- Add system properties to configure the default values.
Result:
More flexible configuration.
Motivation:
We should merge ThrowableUtils into ThrowableUtil as this name is more consistent with the naming of utility classes in netty.
Modifications:
Merge classes.
Result:
More consistent naming
Motivation:
These methods were recently deprecated. However, they remained in use in several locations in Netty's codebase.
Modifications:
Netty's code will now access the bootstrap config to get the group or child group.
Result:
No impact on functionality.
Motivation:
If a user writes an own nio based transport which uses a special SelectorProvider it is useful to be able to get the SelectorProvider that is used by a NioEventLoop. This way this can be used when implement AbstractChannel.isCompatible(...) and check that the SelectorProvider is the correct one.
Modifications:
Expose the SelectorProvider.
Result:
Be able to get the SelectorProvider used by a NioEventLoop.
Motivation:
We use pre-instantiated exceptions in various places for performance reasons. These exceptions don't include a stacktrace which makes it hard to know where the exception was thrown. This is especially true as we use the same exception type (for example ChannelClosedException) in different places. Setting some StackTraceElements will provide more context as to where these exceptions original and make debugging easier.
Modifications:
Set a generated StackTraceElement on these pre-instantiated exceptions which at least contains the origin class and method name. The filename and linenumber are specified as unkown (as stated in the javadocs of StackTraceElement).
Result:
Easier to find the origin of a pre-instantiated exception.
Motivation:
To better debug why a Selector need to be rebuild it is useful to also log the instance of the Selector.
Modifications:
Add logger instance to the log message.
Result:
More useful log message.
Motivation:
When `ChannelFactory#newChannel` crashed, `AbstractBootstrap#initAndRegister` propagates the exception to the caller instead of failing the promise.
Modifications:
- Catch exceptions from `ChannelFactory#newChannel`.
- Notify promise of such failure.
Result:
`AbstractBootstrap` gracefully handles connect failures.
Motivation:
In case of exception in invokeExceptionCaught() only original exception passed to invokeExceptionCaught() will be logged on any log level.
+ AbstractChannelHandlerContext and CombinedChannelDuplexHandler log different exceptions.
Modifications:
Fix inconsistent logging code and add ability to see both stacktraces on DEBUG level.
Result:
Both handlers log now both original exception and thrown from invokeExceptionCaught. To see full stacktrace of exception thrown from invokeExceptionCaught DEBUG log level must be enabled.
Motivation:
JCTools supports both non-unsafe, unsafe versions of queues and JDK6 which allows us to shade the library in netty-common allowing it to stay "zero dependency".
Modifications:
- Remove copy paste JCTools code and shade the library (dependencies that are shaded should be removed from the <dependencies> section of the generated POM).
- Remove usage of OneTimeTask and remove it all together.
Result:
Less code to maintain and easier to update JCTools and less GC pressure as the queue implementation nt creates so much garbage
Motivation:
`Bootstrap` has a notion of a default resolver group, but it's hidden from the public. To allow callers to reset a `Bootstrap` instance's resolver group, we could either make `DEFAULT_RESOLVER` public, or we could allow callers to pass `null` as an argument to `Bootstrap#resolver(AddressResolverGroup<?>)`. This pull request does the latter.
Modifications:
- Allow `Bootstrap#resolver(AddressResolverGroup<?>)` to accept `null` as an argument
Result:
Callers may pass `null` to `Bootstrap#resolver(AddressResolverGroup<?>)` to cause the `Bootstrap` instance to use its default resolver group.
Motivation:
Sometimes it may be benefitially for an user to specify a custom algorithm when choose the next EventExecutor/EventLoop.
Modifications:
Allow to specify a custom EventExecutorChooseFactory that allows to customize algorithm.
Result:
More flexible api.
Motivation:
We need to ensure we not hold a lock while executor callHandlerRemoved(...) as this may lead to a deadlock if handlerRemoved(...) will call another method in DEfaultChannelPipeline from another thread that will need to obtain the lock as well and wait for the result.
Modifications:
Release the lock before call handlerRemoved0(...).
Result:
No more deadlock possible
Motivation:
We not correctly catched errors during resolving in bootstrap and so may not have notified the future correctly.
Modifications:
Move code into try / catch block and try to fail the promise.
Result:
Promise is always notified
Motivation:
The user may specify to use a different allocator then the default. In this case we need to ensure it is shared when creating the EmbeddedChannel inside of a ChannelHandler
Modifications:
Use the config of the "original" Channel in the EmbeddedChannel and so share the same allocator etc.
Result:
Same type of buffers are used.
Motivation:
There is a small race while adding handlers to the pipeline because callHandlerAddedForAllHandlers() may not be run when the user calls add* but the Channel is already registered.
Modifications:
Ensure we always delay handlerAdded(..) / handlerRemoved(...) until callHandlerAddedForAllHandlers() was called.
Result:
No more race on pipeline modifications possible.
Motivation:
We can remove the volatile keyword from the cached Runnables as at worse these will just be re-created.
Modifications:
Remove volatile.
Result:
Less overhead.
Motivation:
SingleThreadEventExecutor.pendingTasks() will call taskQueue.size() to get the number of pending tasks in the queue. This is not safe when using MpscLinkedQueue as size() is only allowed to be called by a single consumer.
Modifications:
Ensure size() is only called from the EventLoop.
Result:
No more livelock possible when call pendingTasks, no matter from which thread it is done.
Motivation:
While doing 8fe3c83e4c I made a change which disallowed using null as name for handlers in the pipeline (this generated a new name before).
Modifications:
Revert to old behaviour and adding test case.
Result:
Allow null name again
Motivation:
At the moment the user is responsible to increase the writer index of the composite buffer when a new component is added. We should add some methods that handle this for the user as this is the most popular usage of the composite buffer.
Modifications:
Add new methods that autoamtically increase the writerIndex when buffers are added.
Result:
Easier usage of CompositeByteBuf.
Motivation:
EventLoopGroup.register doesn't need the Channel paramter when ChannelPromise is provided as we can get the Channel from ChannelPromise. Resolves#2422.
Modifications:
- Add EventLoopGroup.register(ChannelPromise)
- Deprecate EventLoopGroup.register(Channel, ChannelPromise)
Result:
EventLoopGroup.register is more convenient as people only need to set one parameter.
Motivation:
DefaultChannelPipeline was tightly coupled to AbstractChannel which is not really needed.
Modifications:
Move logic of calling handlerAdded(...) for handlers that were added before the Channel was registered to DefaultChannelPipeline by making it part of the head context.
Result:
Less coupling and so be able to use DefaultChannelPipeline also with other Channel implementations that not extend AbstractChannel
Motivation:
We do a "blind" cast to AbstractChannel in AbstractChannelHandlerContext which we should better no do. It would be better to decouble AbstractChannelHandlerContext from AbstractChannel.
Modifications:
Decouble AbstractChannelHandlerContext from AbstractChannel by move logic to DefaultChannelPipeline
Result:
Less coubling and less casting.
Motivation:
If the user will use addLast(...) on the ChannelPipeline of EmbeddedChannel after its constructor was run it will break the EmbeddedChannel as it will not be able to collect inbound messages and exceptions.
Modifications:
Ensure addLast(...) work as expected by move the logic of handling messages and exceptions ti protected methods of DefaultChannelPipeline and use a custom implementation for EmbeddedChannel
Result:
addLast(...) works as expected when using EmbeddedChannel.
Motivation:
Recycler.recycle(...) should not be used anymore and be replaced by Handle.recycle().
Modifications:
Mark it as deprecated and update usage.
Result:
Correctly document deprecated api.
Motivation:
The Bootstrap class (applies also to AbstractBootstrap and ServerBootstrap) has a few package private getter methods and some things such as #attr() and #options() aren't exposed at all.
Modifications:
Expose "getters" for configured things in a safe-manner via the config() method.
Result:
Easier for the user to check what is configured for a Bootstrap/ServerBootstrap.
Motivation:
The DuplexChannel is currently incomplete and only supports shutting down the output side of a channel. This interface should also support shutting down the input side of the channel.
Modifications:
- Add shutdownInput and shutdown methods to the DuplexChannel interface
- Remove state in NIO and OIO for tracking input being shutdown independent of the underlying transport's socket type. Tracking the state independently may lead to inconsistent state.
Result:
DuplexChannel supports shutting down the input side of the channel
Fixes https://github.com/netty/netty/issues/5175
Motivation:
When a user has multiple EventLoops in an EventLoopGroup and calls pipeline.add* / remove* / replace from an EventLoop that belongs to another Channel it is possible to deadlock if the other EventLoop does the same.
Modification:
- Only ensure the actual modification takes place in a synchronized block and not wait until the handlerAdded(...) / handlerRemoved(...) method is called. This is ok as we submit the task to the executor while still holding the look and so ensure correct order of pipeline modifications.
- Ensure if an AbstractChannelHandlerContext is put in the linked-list structure but the handlerAdded(...) method was not called we skip it until handlerAdded(...) was called. This is needed to ensure handlerAdded(...) is always called first.
Result:
Its not possible to deadlock when modify the DefaultChannelPipeline.
Related: #4333#4421#5128
Motivation:
slice(), duplicate() and readSlice() currently create a non-recyclable
derived buffer instance. Under heavy load, an application that creates a
lot of derived buffers can put the garbage collector under pressure.
Modifications:
- Add the following methods which creates a non-recyclable derived buffer
- retainedSlice()
- retainedDuplicate()
- readRetainedSlice()
- Add the new recyclable derived buffer implementations, which has its
own reference count value
- Add ByteBufHolder.retainedDuplicate()
- Add ByteBufHolder.replace(ByteBuf) so that..
- a user can replace the content of the holder in a consistent way
- copy/duplicate/retainedDuplicate() can delegate the holder
construction to replace(ByteBuf)
- Use retainedDuplicate() and retainedSlice() wherever possible
- Miscellaneous:
- Rename DuplicateByteBufTest to DuplicatedByteBufTest (missing 'D')
- Make ReplayingDecoderByteBuf.reject() return an exception instead of
throwing it so that its callers don't need to add dummy return
statement
Result:
Derived buffers are now recycled when created via retainedSlice() and
retainedDuplicate() and derived from a pooled buffer
Motivation:
We tried to provide the ability for the user to change the semantics of the threading-model by delegate the invoking of the ChannelHandler to the ChannelHandlerInvoker. Unfortunually this not really worked out quite well and resulted in just more complexity and splitting of code that belongs together. We should remove the ChannelHandlerInvoker again and just do the same as in 4.0
Modifications:
Remove ChannelHandlerInvoker again and replace its usage in Http2MultiplexCodec
Result:
Easier code and less bad abstractions.
Motivation:
If a task was submitted when wakenUp value was true, the task didn't get a chance to call Selector#wakeup.
So we need to check task queue again before executing select operation. If we don't, the task might be pended until select operation was timed out.
It might be pended until idle timeout if IdleStateHandler existed in pipeline.
Modifications:
Execute Selector#select in a non-blocking manner if there's a task submitted when wakenUp value was true.
Result:
Every tasks in NioEventLoop will not be pended.
Motivation:
Users sometimes want to use Channel.voidPromise() when write to a Channel to reduce GC-pressure. This should be also possible when write via a ChannelGroup.
Modifications:
Add new write(...) and writeAndFlush(...) overloads which allow to signale that a VoidPromise should be used to write to the Channel
Result:
Users can write with VoidPromise when using ChannelGroup
Motivation:
ChannelHandlerContext, ChannelPipeline and Channel share various method signatures. We should provide an interface to share.
Modifications:
Add ChannelInboundInvoker and ChannelOutboundInvoker and extend these.
Result:
Better API abstraction.
Motivation:
To be more consistent we should use ConnectException when we fail the connect attempt because no LocalServerChannel exists with the given address.
Modifications:
Use correct exception.
Result:
More consistent handling of connection refused between different transports.
Motivation:
Bootstrap.connect(...) tries to obtain the EventLoop of a Channel before it may be registered. This will cause an IllegalStateException. We need to ensure we handle the cause of late registration and not throw in this case.
Modifications:
Ensure we only try to access the EventLoop after the Channel is registered and handle the case of late registration.
Result:
Bootstrap.connect(...) not fails on late registration.
Motivation:
EventExecutor.children uses generics in such a way that an entire colleciton must be cast to a specific type of object. This interface is not very flexible and is impossible to implement if the EventExecutor type must be wrapped. The current usage of this method also does not have any clear need within Netty. The Iterator interface allows for EventExecutor to be wrapped and forces the caller to make assumptions about types instead of building the assumptions into the interface.
Motivation:
- Remove EventExecutor.children and undeprecate the iterator() interface
Result:
EventExecutor interface has one less method and is easier to wrap.
Motivation:
The ChannelHandlerContext.attr(...) and ChannelHandlerContext.hasAttr(...) delegated to Channel for the attributes which is a semantic change compared to 4.0 releases. We should not change the semantic to not break users applications when upgrading to 4.1.0
Modifications:
- Revert semantic change
- Mark ChannelHandlerContext.attr(...) and hasAttr(...) as @deprecated so we can remove these later
Result:
Semantic of attribute operations on ChannelHandlerContext is the same in 4.1 as in 4.0 again.
Motivation:
We should not try to call bind if registration failed.
Modifications:
Only call doBind0(...) when the registration not failed.
Result:
Not try to to bind if the registration failed.
Motivation:
We use channel.unsafe().invoker().executor() in DefaultChannelPipeline.executorSafe(...) which is an unnecessary indirection to channel.eventLoop().
Modifications:
Remove indirection by using channel.eventLoop().
Result:
Cleaner code.
Motivation:
The LateListener logic is prone to infinite loops and relies on being processed in the EventExecutor's thread for synchronization, but this EventExecutor may not be constant. An infinite loop can occur if the EventExecutor's execute method does not introduce a context switch in LateListener.run. The EventExecutor can be changed by classes which inherit from DefaultPromise. For example the DefaultChannelPromise will return w/e EventLoop the channel is registered to, but this EventLoop can change (re-registration).
Modifications:
- Remove the LateListener concept and instead use a single Object to maintain the listeners while still preserving notification order
- Make the result member variable an atomic variable so it can be outside the synchronized(this) blocks
- Cleanup/simplify existing state management code
Result:
Fixes https://github.com/netty/netty/issues/5185
Motivation:
NioDatagramChannelConfig currently uses NetworkChannel in its static { } block and so fails to init on android which not has this class.
Modifications:
Use reflection to load the NetworkChannel.class
Result:
Be able to use NIO Datagram on android as well.
Motivation:
We may produce a NPE due a race that can happen while check if a resolution was done and failed.
Modifications:
Correctly first check if the resultion is done before try to detect if it failed and so remove the race that can produce a NPE.
Result:
No more race possible while resolve address during connect.
Motivation:
Reduce nag warnings when compiling, make it easier for IDEs to display what's deprecated.
Modifications:
Added @Deprecated in a few places
Result:
No more warnings.
Motivation:
If a channel is deregistered from an NioEventLoop the associated SelectionKey is cancelled. If the NioEventLoop has yet to process a pending event as a result of that SelectionKey then the NioEventLoop will see the SelecitonKey is invalid and close the channel. The NioEventLoop should not close a channel if it is not registered with that NioEventLoop.
Modifications:
- NioEventLoop.processSelectedKeys should check that the channel is still registered to itself before closing the channel
Result:
NioEventLoop doesn't close a channel that is no longer registered to it when the SelectionKey is invalid
Fixes https://github.com/netty/netty/issues/5125
