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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
Revert d0943dcd30. Delaying the notification of writability change may lead to notification being missed. This is a ABA type of concurrency problem.
Modifications:
- Revert d0943dcd30.
Result:
channelWritabilityChange will be called on every change, and will not be suppressed due to ABA scenario.
Motivation:
When always triggered fireChannelWritabilityChanged() directly when the update the pending bytes in the ChannelOutboundBuffer was made from within the EventLoop. This is problematic as this can cause some re-entrance issue if the user has a custom ChannelOutboundHandler that does multiple writes from within the write(...) method and also has a handler that will intercept the channelWritabilityChanged event and trigger another write when the Channel is writable. This can also easily happen if the user just use a MessageToMessageEncoder subclass and triggers a write from channelWritabilityChanged().
Beside this we also triggered fireChannelWritabilityChanged() too often when a user did a write from outside the EventLoop. In this case we increased the pending bytes of the outboundbuffer before scheduled the actual write and decreased again before the write then takes place. Both of this may trigger a fireChannelWritabilityChanged() event which then may be re-triggered once the actual write ends again in the ChannelOutboundBuffer.
The third gotcha was that a user may get multiple events even if the writability of the channel not changed.
Modification:
- Always invoke the fireChannelWritabilityChanged() later on the EventLoop.
- Only trigger the fireChannelWritabilityChanged() if the channel is still active and if the writability of the channel changed. No need to cause events that were already triggered without a real writability change.
- when write(...) is called from outside the EventLoop we only increase the pending bytes in the outbound buffer (so that Channel.isWritable() is updated directly) but not cause a fireChannelWritabilityChanged(). The fireChannelWritabilityChanged() is then triggered once the task is picked up by the EventLoop as usual.
Result:
No more re-entrance possible because of writes from within channelWritabilityChanged(...) method and no events without a real writability change.
Motivation:
If a handler is added to the pipeline within ChannelInitializer::initChannel via
addFirst(...) then it will not receive the channelRegistered event. The same
handler added via addLast(...) will receive the event. This different behavior
is unlikely to be expected by users and can cause confusion.
Modifications:
Let ChannelInitializer::channelRegistered propagate the event by passing it to
the pipeline instead of firing it on the ChannelHandlerContext.
Result:
The channelRegistered event is propagated to handlers regardless of the method
used to add it to the pipeline (addFirst/addLast).
Motivation:
We need to ensure we run all pending tasks before doing any flush in writeOutbound(...) to ensure all pending tasks are run first. Also we should remove the assert of the future and just add a listener to it so it is processed later if needed. This is true as a user may schedule a write for later execution.
Modifications:
- Remove assert of future in writeOutbound(...)
- Correctly run pending tasks before doing the flush and also before doing the close of the channel.
- Add unit tests to proof the defect is fixed.
Result:
Correclty handle the situation of delayed writes.
Motivation:
Often the user uses EmbeddedChannel within unit tests where the only "important" thing is to know if any pending messages were in the buffer and then release these.
We should provide methods for this so the user not need to manually loop through these and release.
Modifications:
Add methods to easily handle releasing of messages.
Result:
Less boiler-plate code for the user to write.
Motivation:
PendingWriteQueue should guard against re-entrant writes once
removeAndFailAll() is run.
Modifications:
removeAndFailAll() should repeat until the queue is finally empty.
Result:
assertEmpty() will always hold.
Motivation:
e2f5012 added unit tests which did not verify the buffer was released as it was intended to.
Modification:
- Unit tests must verify release is called
Result:
Unit tests enforce that ByteBufs are released.
Motivation:
DefaultChannelHandlerInvoker.invokeWrite calls a utility method validatePromise which may throw if the arguments are not valid. If this method throws then the message will not be released.
Modifications:
- If an exception is thrown the message should be released
Result:
No more leak in DefaultChannelHandlerInvoker.invokeWrite
Motiviation:
We should ensure that handlerAdded(...) and handlerRemoved(...) is always called from the EventExecutor that also invokes the other methods of the ChannelHandler. Also we need to ensure we always call handlerAdded(...) before any other method can be calld to ensure correct ordering.
Motifications:
- Ensure that the right thread is used to call the methods
- Ensure correct ordering
- Add tests
Result:
Respect the thread-model for handlerAdded(...) and handlerRemoved(...) and preserve correct ordering in all cases.
Motivation:
When a channel was registered before and is re-registered we need to respect ChannelConfig.isAutoRead() and so start reading one the registration task completes. This was done "by luck" before 15162202fb.
Modifications:
Explicit start reading once a Channel was re-registered if isAutoRead() is true.
Result:
Correctly receive data after re-registration completes.
Motivation:
Due a regression introduced by e969b6917c we missed to pass the original ChannelPromise to the next ChannelOutboundHandler and so
may never notify the origin ChannelPromise. This is related to #4805.
Modifications:
- Correctly pass the ChannelPromise
- Add unit test.
Result:
Correctly pass the ChannelPromise on deregister(...)
Motivation:
The AbstractChannel(Channel parent) constructor was previously hard-coded to always
call DefaultChannelId.newInstance(), and this made it difficult to use a custom
ChannelId implementation with some commonly used Channel implementations.
Modifications:
Introduced newId() method in AbstractChannel, which by default returns
DefaultChannelId.newInstance() but can be overridden by subclasses. Added
ensureDefaultChannelId() test to AbstractChannelTest, to ensure the prior
behavior of calling DefaultChannelId.newInstance() still holds with the
AbstractChannel(Channel parent) constructor.
Result:
AbstractChannel now has the protected newId() method, but there is no functional
difference.
Motivation:
ChannelInboundHandler and ChannelOutboundHandler both can implement exceptionCaught(...) method and so we need to dispatch to both of them.
Modifications:
- Correctly first dispatch exceptionCaught to the ChannelInboundHandler but also make sure the next handler it will be dispatched to will be the ChannelOutboundHandler
- Add removeInboundHandler() and removeOutboundHandler() which allows to remove one of the combined handlers
- Let *Codec extends it and not ChannelHandlerAppender
- Remove ChannelHandlerAppender
Result:
Correctly handle events and also have same behavior as in 4.0
Motivation:
Our contract in Channels is that the promise should always be notified before the actual callbacks of the ChannelInboundHandler are called. This was not done in the LocalChannel and so the behavior was different to other Channel implementations.
Modifications:
- First complete the ChannelPromise then call fireChannelActive()
- Guard against NPE when doClose() was called before the task was executed.
Result:
Consistent behavior between LocalChannel and other Channel implementations.
Motivation:
In AbstractChannelTest we not correctly mocked some methods which could lead to test errors. That said it only showed up here when running from the IDE and not from the cmdLine.
Modifications:
Mock methods that are needed for the test
Result:
Test pass in the IDE as well.
Motivation:
At the moment EmbeddedChannel always handle close() and disconnect() the same way which also means that ChannelOutboundHandler.disconnect(...) will never called. We should allow to specify if these are handle different or not to make the use of EmbeddedChannel more flexible.
Modifications:
Add 2 other constructors which allow to specify if disconnect / close are handled the same way or differently.
Result:
More flexible usage of EmbeddedChannel possible.
Motivation:
As discussed in #4529, NameResolver design shouldn't be resolving SocketAddresses (or String name + port) and return InetSocketAddresses. It should resolve String names and return InetAddresses.
This SocketAddress to InetSocketAddresses resolution is actually a different concern, used by Bootstrap.
Modifications:
Extract SocketAddress to InetSocketAddresses resolution concern to a new class hierarchy named AddressResolver.
These AddressResolvers delegate to NameResolvers.
Result:
Better separation of concerns.
Note that new AddressResolvers generate a bit more allocations because of the intermediate Promise and List<InetAddress>.
Motivation:
ChannelMetadata has a field minMaxMessagesPerRead which can be confusing. There are also some cases where static instances are used and the default value for channel type is not being applied.
Modifications:
- use a default value which is set unconditionally to simplify
- make sure static instances of MaxMessagesRecvByteBufAllocator are not used if the intention is that the default maxMessagesPerRead should be derived from the channel type.
Result:
Less confusing interfaces in ChannelMetadata and ChannelConfig. Default maxMessagesPerRead is correctly applied.
Motivation:
The CoalescingBufferQueueTest is somewhat relaxed with its releasing of test buffers, using safeRelease to generically deal with tests that may or may not release the buffers. SafeRelease generates logs, however, when the release fails.
Modifications:
Tightened up the individual test methods to verify that the buffers are released properly.
Result:
Fixes#4497
Motivation:
The previous DefaultChannelPipeline#destroy() implementation, introduced in #3156, is suboptimal as it can cause the for loop to continuously spin if the executor used by a given handler is unable to "recognize" the event loop.
It could be objected that it's the custom executor responsibility to properly implement the inEventLoop() method, but some implementetaions might not be able to do that for performance reasons, and even so, it's always better to be safe against API misuse, in particular when it is not possible to fail fast and the alternative is rather some sutle behaviour.
Modifications:
The patch simply avoids the recursive spin by explicitly passing the "in event loop" condition as a boolean parameter, preserving the same guarantees offered by #3156. A unit test has also been added.
Result:
All channel events are correctly called and no high CPU usage is seen anymore.
Motivation:
Once a FixedChannelPool was closed we must not allow to acquire or release Channels to prevent assert errors.
Modifications:
Fail release and acquire calls when FixedChannelPool is closed.
Result:
No more assert errors.1
Motivation:
EmbeddedChannelId#hashCode() and equals() do not behave correctly if an
instance is serialized and then deserialized. Additionally,
EmbeddedChannel does not allow use of any other type of ChannelId, and
EmbeddedChannelId is (mostly) a singleton instance. This creates a
problem for unit tests that construct multiple EmbeddedChannels and
expect each channel to have a unique ID.
Modifications:
EmbeddedChannelId is modified so equals() will return true and
hashCode() will return the same value for any instance of the class.
EmbeddedChannel is modified to allow a ChannelId to be specified when
the channel is constructed. Tests added for both changes.
Result:
EmbeddedChannelId now behaves correctly when deserialized, and
EmbeddedChannels can now have unique IDs.
Motivation:
PendingWriteQueueTest needs some cleanup.
Modifications:
- Cleanup code to remove deprecation warnings
- use static imports
Result:
No more warnings
Motivation:
We missed to run all pending tasks when EmbeddedChannel.close(...) or disconnect(...) was called. Because of this channelInactive(...) / channelUnregistered(...) of the handlers were never called.
Modifications:
Correctly run all pending tasks and cancel all not ready scheduled tasks when close or disconnect was called.
Result:
Correctly run tasks on close / disconnect and have channelInactive(...) / channelUnregistered(...) called.
Motivation:
If LocalChannel doWrite executes while the peer's state changes from CONNECTED to CLOSED it is possible that some promise's won't be completed and buffers will be leaked.
Modifications:
- Check the peer's state in doWrite to avoid a race condition
Result:
All write operations should release, and the associated promise should be completed.
Motivation:
https://github.com/netty/netty/pull/4143 addressed a few ordering issues but an ordering issue still remained if the Promise for a write completes, and a listener of that promise does a write on a peer channel. The ordering was subject to how potentially 2 different executors would run a task, but it should be coordinated such that the first write is read first.
Modifications:
- Keep track of the finishPeerRead task run on the executor if necessary and ensure it completes before current channel read occurs
Result:
Ordering of events for echo type situations is preserved.
Motivation:
When a LocalChannel write operation occurs, the promise associated with the write operation is marked successful when it is added to the peer's queue, but before the peer has actually received the data. If the promise callback closes the channel then a race condition exists where the close event may occur before the data is delivered. We should preserve ordering of events.
Modifications:
- LocalChannel should track when a write is in progress, and if a close operation happens make sure the peer gets all pending read operations.
Result:
LocalChannel preserves order of operations.
Fixes https://github.com/netty/netty/issues/4118
Related issues:
- #3971
- #3973
- #3976
- #4035
Motivation:
1. Previously, DnsNameResolver.query() retried the request query by its
own. It prevents a user from deciding when to retry or stop. It is also
impossible to get the response object whose code is not NOERROR.
2. NameResolver does not have an operation that resolves a host name
into multiple addresses, like InetAddress.getAllByName()
Modifications:
- Changes related with DnsNameResolver.query()
- Make query() not retry
- Move the retry logic to DnsNameResolver.resolve() instead.
- Make query() fail the promise only when I/O error occurred or it
failed to get a response
- Add DnsNameResolverException and use it when query() fails so that
the resolver can give more information about the failure
- query() does not cache anymore.
- Changes related with NameResolver.resolveAll()
- Add NameResolver.resolveAll()
- Add SimpleNameResolver.doResolveAll()
- Changes related with DnsNameResolver.resolve() and resolveAll()
- Make DnsNameResolveContext abstract so that DnsNameResolver can
decide to get single or multiple addresses from it
- Re-implement cache so that the cache works for resolve() and
resolveAll()
- Add 'traceEnabled' property to enable/disable trace information
- Miscellaneous changes
- Use ObjectUtil.checkNotNull() wherever possible
- Add InternetProtocolFamily.addressType() to remove repetitive
switch-case blocks in DnsNameResolver(Context)
- Do not raise an exception when decoding a truncated DNS response
Result:
- Full control over query()
- A user can now retrieve all addresses via (Dns)NameResolver.resolveAll()
- DNS cache works only for resolve() and resolveAll() now.
Motivation:
When releasing unhealthy channel back to a pool we don't have to offer it since on acquire it will be discarded anyways.
Also checking healthiness at release is a good idea so we don't end up having tons of unhealthy channels in the pool(unless they became unhealthy after being offered)
Modifications:
private SimpleChannelPool.offerIfHealthy() method added that is called from SimpleChannelPool.doReleaseChannel(). SimpleChannelPool.offerIfHealthy() offers channel back to pool only if channel is healthy.
Otherwise it throws setFailure exception to the promise.
Result:
The pool is now much cleaner and not spammed with unhealthy channels.
Added ability to choose if channel health has to be validated on release by passing boolean flag.
Motivation:
Depending on performance preferences and individual use cases sometimes we would like to be able force health check of a channel at release time and do not offer it back to the pool. Other times we would want to just release channel and offer it back to the pool and check health only when we try to acquire that channel from the pool. See more details here: https://github.com/netty/netty/issues/4077#issuecomment-130461684
Modifications:
Future<Void> release(Channel channel, Promise<Void> promise, boolean offerHealthyOnly);
The offerHealthyOnly boolean flag allows developers to choose whether to do channel validation before offering it back to pool or not.
Appropriate modifications made to hierarchy of implementations of ChannelPool. offerHealthyOnly=true will force channel health to be checked before offering back to pool. offerHealthyOnly=false will ignore channel health check and will just try just offer it back to the pool
offerHealthyOnly=true by default.
Result:
Channel health check before offer back to pool is controlled by a flag now.
Code changed to satisfy checkstyle requirements.
Motivation:
Code needs to satisfy checkstyle requirements.
Modifications:
SimpleChannelPool.java:279 line split to be less then 120 characters.
SimpleChannelPool.java:280:31 space added after '{'
SimpleChannelPool.java:282:17 space added after '{'
SimpleChannelPoolTest.java:198 - extra white space line removed.
Result:
Code satisfies checkstyle requirements.
offerHealthyOnly is passed as a constructor parameter now.
Motivation:
Instead of passing offerHealthyOnly as a method parameter it is better to pass it in as SimpleChannelPool or FixedChannelPool constructor.
Modifications:
Redundant release method that takes offerHealthyOnly removed from ChannelPool.
offerHealthyOnly parameter added to constructor for FixedChannelPool and SimpleChannelPool.
Result:
SimpleChannelPool and FixedChannelPool are now take offerHealthyOnly as a constructor parameter. Default behavior is: offerHealthyOnly=true.
Code changed to satisfy checkstyle requirements.
Motivation:
Code needs to satisfy checkstyle requirements.
Modifications:
SimpleChannelPool.java:84: line made to be no longer then 120 characters.
SimpleChannelPool.java:237: extra white space line removed.
Result:
Code satisfies checkstyle requirements.
Tests do not need to be too copled to the code. Exception message should not be validated
Motivation:
We don't need our tests to be too coupled to the code. Exception type validation in tests is just good enough.
Modifications:
Exception validation message removed from SimpleChannelPoolTest.testUnhealthyChannelIsNotOffered() test.
Result:
The SimpleChannelPoolTest test is less coupled to the code now.
Stack trace set to empty for UNHEALTHY_NON_OFFERED_TO_POOL.
Motivation:
We don't need stack trace for UNHEALTHY_NON_OFFERED_TO_POOL.
Modifications:
Added UNHEALTHY_NON_OFFERED_TO_POOL.setStackTrace(EmptyArrays.EMPTY_STACK_TRACE) to static init block.
Result:
UNHEALTHY_NON_OFFERED_TO_POOL's stack trace set to empty.
Minor code re-factorings.
Motivation:
For better code readability we need to apply several minor code re-factorings.
Modifications:
javadocs true -> {@code true}
offerHealthyOnly variable name changed to releaseHeathCheck
<p/> -> <p> in javadocs
offerHealthyOnly removed from doReleaseChannel as it not needed there.
Result:
Code quality is improved.
Code changed to satisfy checkstyle requirements.
Motivation:
Code needs to satisfy checkstyle requirements.
Modifications:
SimpleChannelPool.java:87: line made to be no longer then 120 characters.
Result:
Code satisfies checkstyle requirements.
Pull request needs to contain only necessary changes
Motivation:
The pull request should not contain unnecessary changes that are not needed as part of required functionality of pull request.
Modifications:
private void doReleaseChannel(final Channel channel, final Promise<Void> promise) - > private void doReleaseChannel(Channel channel, Promise<Void> promise)
Result:
Pull request contains less unnecessary modifications.
Motivation:
The acquire channel function resulted in calling itself several times in case when channel polled from the pool queue was unhealthy, which resulted FixedChannelPool to be called several times which in it's turn caused FixedChannelPool.acquire() to be called and resulted into acquireChannelCount to be unnecessary increased.
Example use case:
1) Create FixedChannelPool instance with one channel in the pool: new FixedChannelPool(cb, handler, 1)
2) Acquire channel A from the pool
3) close the channel A
4) Return it back to the pool
5) Acquire channel from the same pool again
Expected result:
new channel created and acquired, channel A that has been closed discarded and removed from the pool from being unhealthy
Actual result:
Channel A had been removed from the pool, how ever the new channel had never be acquired, instead the request to acquire had been added to the pending queue in FixedChannelPool and the acquireChannelCount is increased by one. The reason is that at the time when SimpleChannelPool figured out that the channel was unhealthy called FixedChannelPool.acquire to try to acquire new channel, how ever the request was added to the pendingTakQueue because by the time when FixedChannelPool.acquire was called, the acquireChannelCount was already "1" so new channel ould not be created cause of maxChannelsLimit=1.
Modifications:
The suggested approach modifies the SimpleChannelPool in a way so that when channel detected to be unhealthy it calls private method SimpleChannelPool.acquireHealthyFromPoolOrNew() which guarantees that SimpleChannelPool actually either finds a healthy channel in the pool and returns it or causes the promise.cause() in case when new channel was failed to be created.
Result:
The ```acquiredChannelCount``` is now calculated correctly as a result of SimpleChannelPool.acquire() of not being recursive on overridable acquire method.
Motivation:
If the Channel is already closed when the PendingWriteQueue is created it will generate a NPE when add or remove is called later.
Modifications:
Add null checks to guard against NPE.
Result:
No more NPE possible.
Motivation:
Test was leaving composite buffers taken from the queue unreleased.
Modifications:
Make the test release buffers.
Result:
Nagging about leaked buffers should stop.
Motivation:
Simplifies writing code that needs to merge or slice a sequence of buffer & promise pairs into chunks of arbitrary sizes.
For example in HTTP2 we merge or split buffers across fixed-size DATA frame boundaries.
Modifications:
Add new utility class CoalescingBufferQueue
Result:
Following this change HTTP2 code will switch to use it instead of CompositeByteBuffer for DATA frame coalescing.
Motivation:
While cherry-picked 11f9e9084b I changed the EmbeddedChannel implementation to not allow no ChannelHandlers when constructing it.
This was done by mistake.
Modifications:
Revert change and add unit test.
Result:
Restore old behavior.
Motivation:
At the moment we directly closed the Channel when an exception accoured durring initChannel(...) without giving the user any way to do extra or special handling.
Modifications:
Handle the exception in exceptionCaught(...) of the ChannelInitializer which will by default log and close the Channel. This way the user can override this.
Result:
More felixible handling of exceptions.
Motivation:
Currently in EmbeddedChannel we add the ChannelHandlers before the Channel is registered which leads to have the handlerAdded(...) callback
be called from outside the EventLoop and also prevent the user to obtain a reference to the EventLoop in the callback itself.
Modifications:
Delay adding ChannelHandlers until EmbeddedChannel is registered.
Result:
Correctly call handlerAdded(...) after EmbeddedChannel is registered.
Motivation:
If you set a ChannelHandler via ServerBootstrap.handler(...) it is added to the ChannelPipeline before the Channel is registered. This will lead to and IllegalStateException if a user tries to access the EventLoop in the ChannelHandler.handlerAdded(...) method.
Modifications:
Delay the adding of the ChannelHandler until the Channel was registered.
Result:
No more IllegalStateException.
Motivation:
SingleThreadEventLoopTest.testScheduleTaskAtFixedRate() fails often due to:
- too little tolerance
- incorrect assertion (it compares only with the previous timestamp)
Modifications:
- Increase the timestamp difference tolerance from 10ms to 20ms
- Improve the timestamp assertion so that the comparison is performed against the first recorded timestamp
- Misc: Fix broken Javadoc tag
Result:
More build stability
Motivation:
Many projects need some kind a Channel/Connection pool implementation. While the protocols are different many things can be shared, so we should provide a generic API and implementation.
Modifications:
Add ChannelPool / ChannelPoolMap API and implementations.
Result:
Reusable / Generic pool implementation that users can use.
Motivation:
At the moment when EmbeddedChannel is used and a ChannelHandler tries to schedule and task it will throw an UnsupportedOperationException. This makes it impossible to test these handlers or even reuse them with EmbeddedChannel.
Modifications:
- Factor out reusable scheduling code into AbstractSchedulingEventExecutor
- Let EmbeddedEventLoop and SingleThreadEventExecutor extend AbstractSchedulingEventExecutor
- add EmbbededChannel.runScheduledPendingTasks() which allows to run all scheduled tasks that are ready
Result:
Embeddedchannel is now usable even with ChannelHandler that try to schedule tasks.
Motivation:
We should allow to get a ChannelOption/AttributeKey from a String. This will make it a lot easier to make use of configuration files in applications.
Modifications:
- Add exists(...), newInstance(...) method to ChannelOption and AttributeKey and alter valueOf(...) to return an existing instance for a String or create one.
- Add unit tests.
Result:
Much more flexible usage of ChannelOption and AttributeKey.
Motivation:
Even if a handler called ctx.fireChannelReadComplete(), the next handler
should not get its channelReadComplete() invoked if fireChannelRead()
was not invoked before.
Modifications:
- Ensure channelReadComplete() is invoked only when the handler of the
current context actually produced a message, because otherwise there's
no point of triggering channelReadComplete().
i.e. channelReadComplete() must follow channelRead().
- Fix a bug where ctx.read() was not called if the handler of the
current context did not produce any message, making the connection
stall. Read the new comment for more information.
Result:
- channelReadComplete() is invoked only when it makes sense.
- No stale connection
Motivation:
Because of a re-entrance bug in PendingWriteQueue it was possible to get the queue corrupted and also trigger an IllegalStateException caused by multiple recycling of the internal PendingWrite objects.
Modifications:
- Correctly guard against re-entrance
Result:
No more IllegalStateException possible
Related: #3212
Motivation:
When SslHandler and ChunkedWriteHandler exists in a pipeline together,
it is possible that ChunkedWriteHandler.channelWritabilityChanged()
invokes SslHandler.flush() and vice versa. Because they can feed each
other (i.e. ChunkedWriteHandler.channelWritabilityChanged() ->
SslHandler.flush() -> ChunkedWriteHandler.channelWritabilityChanged() ->
..), they can fall into an inconsistent state due to reentrance (e.g.
bad MAC record at the remote peer due to incorrect ordering.)
Modifications:
- Trigger channelWritabilityChanged() using EventLoop.execute() when
there's a chance where channelWritabilityChanged() can cause a
reentrance issue
- Fix test failures caused by the modification
Result:
Fix the handler reentrance issues related with a
channelWritabilityChanged() event
Related: #3212
Motivation:
PendingWriteQueue.recycle() updates its data structure after triggering
a channelWritabilityChanged() event. It causes a rare corruption such as
double free when channelWritabilityChanged() method accesses the
PendingWriteQueue.
Modifications:
Update the state of PendingWriteQueue before triggering an event.
Result:
Fix a rare double-free problem
Motivation:
AbstractUnsafe considers two possibilities during channel registration. First,
the channel may be an outgoing connection, in which case it will be registered
before becoming active. Second, the channel may be an incoming connection in,
which case the channel will already be active when it is registered. To handle
the second case, AbstractUnsafe checks if the channel is active after
registration and calls ChannelPipeline.fireChannelActive() if so. However, if
an active channel is deregistered and then re-registered this logic causes a
second fireChannelActive() to be invoked. This is unexpected; it is reasonable
for handlers to assume that this method will only be invoked once per channel.
Modifications:
This change introduces a flag into AbstractUnsafe to recognize if this is the
first or a subsequent registration. ChannelPipeline.fireChannelActive() is only
possible for the first registration.
Result:
ChannelPipeline.fireChannelActive() is only called once.
Related: #2945
Motivation:
Some special handlers such as TrafficShapingHandler need to override the
writability of a Channel to throttle the outbound traffic.
Modifications:
Add a new indexed property called 'user-defined writability flag' to
ChannelOutboundBuffer so that a handler can override the writability of
a Channel easily.
Result:
A handler can override the writability of a Channel using an unsafe API.
For example:
Channel ch = ...;
ch.unsafe().outboundBuffer().setUserDefinedWritability(1, false);
Motivation:
So far, we relied on the domain name resolution mechanism provided by
JDK. It served its purpose very well, but had the following
shortcomings:
- Domain name resolution is performed in a blocking manner.
This becomes a problem when a user has to connect to thousands of
different hosts. e.g. web crawlers
- It is impossible to employ an alternative cache/retry policy.
e.g. lower/upper bound in TTL, round-robin
- It is impossible to employ an alternative name resolution mechanism.
e.g. Zookeeper-based name resolver
Modification:
- Add the resolver API in the new module: netty-resolver
- Implement the DNS-based resolver: netty-resolver-dns
.. which uses netty-codec-dns
- Make ChannelFactory reusable because it's now used by
io.netty.bootstrap, io.netty.resolver.dns, and potentially by other
modules in the future
- Move ChannelFactory from io.netty.bootstrap to io.netty.channel
- Deprecate the old ChannelFactory
- Add ReflectiveChannelFactory
Result:
It is trivial to resolve a large number of domain names asynchronously.
Motivation:
We used the wrong EventExecutor to notify for bind failures if a late registration was done.
Modifications:
Use the correct EventExecutor to notify and only use the GlobelEventExecutor if the registration fails itself.
Result:
The correct Thread will do the notification.
Motivation:
Because of an incorrect logic in teh EmbeddedChannel constructor it is not possible to use EmbeddedChannel with a ChannelInitializer as constructor argument. This is because it adds the internal LastInboundHandler to its ChannelPipeline before it register itself to the EventLoop.
Modifications:
First register self to EventLoop before add LastInboundHandler to the ChannelPipeline.
Result:
It's now possible to use EmbeddedChannel with ChannelInitializer.
Motivation:
Sometimes ChannelHandler need to queue writes to some point and then process these. We currently have no datastructure for this so the user will use an Queue or something like this. The problem is with this Channel.isWritable() will not work as expected and so the user risk to write to fast. That's exactly what happened in our SslHandler. For this purpose we need to add a special datastructure which will also take care of update the Channel and so be sure that Channel.isWritable() works as expected.
Modifications:
- Add PendingWriteQueue which can be used for this purpose
- Make use of PendingWriteQueue in SslHandler
Result:
It is now possible to queue writes in a ChannelHandler and still have Channel.isWritable() working as expected. This also fixes#2752.
Motivation:
We did various changes related to the ChannelOutboundBuffer in 4.0 branch. This commit port all of them over and so make sure our branches are synced in terms of these changes.
Related to [#2734], [#2709], [#2729], [#2710] and [#2693] .
Modification:
Port all changes that was done on the ChannelOutboundBuffer.
This includes the port of the following commits:
- 73dfd7c01b
- 997d8c32d2
- e282e504f1
- 5e5d1a58fd
- 8ee3575e72
- d6f0d12a86
- 16e50765d1
- 3f3e66c31a
Result:
- Less memory usage by ChannelOutboundBuffer
- Same code as in 4.0 branch
- Make it possible to use ChannelOutboundBuffer with Channel implementation that not extends AbstractChannel
Motivation:
ChannelOutboundBuffer is basically a circular array queue of its entry
objects. Once an entry is created in the array, it is never nulled out
to reduce the allocation cost.
However, because it is a circular queue, the array almost always ends up
with as many entry instances as the size of the array, regardless of the
number of pending writes.
At worst case, a channel might have only 1 pending writes at maximum
while creating 32 entry objects, where 32 is the initial capacity of the
array.
Modifications:
- Reduce the initial capacity of the circular array queue to 4.
- Make the initial capacity of the circular array queue configurable
Result:
We spend 4 times less memory for entry objects under certain
circumstances.
Motivation:
When a bind fails AbstractBootstrap will use the GlobalEventExecutor to notify the ChannelPromise. We should use the EventLoop of the Channel if possible.
Modification:
Use EventLoop of the Channel if possible to use the correct Thread to notify and so guaranteer the right order of events.
Result:
Use the correct EventLoop for notification
Motivation:
LocalServerChannel.doClose() calls LocalChannelRegistry.unregister(localAddress); without check if localAddress is null and so produce a NPE when pass null the used ConcurrentHashMapV8
Modification:
Check for localAddress != null before try to remove it from Map. Also added a unit test which showed the stacktrace of the error.
Result:
No more NPE during doClose().
Motivation:
At the moment AbstractBoostrap.bind(...) will always use the GlobalEventExecutor to notify the returned ChannelFuture if the registration is not done yet. This should only be done if the registration fails later. If it completes successful we should just notify with the EventLoop of the Channel.
Modification:
Use EventLoop of the Channel if possible to use the correct Thread to notify and so guaranteer the right order of events.
Result:
Use the correct EventLoop for notification
Motivation:
Each of DefaultChannelPipeline instance creates an head and tail that wraps a handler. These are used to chain together other DefaultChannelHandlerContext that are created once a new ChannelHandler is added. There are a few things here that can be improved in terms of memory usage and initialization time.
Modification:
- Only generate the name for the tail and head one time as it will never change anyway
- Rename DefaultChannelHandlerContext to AbstractChannelHandlerContext and make it abstract
- Create a new DefaultChannelHandlerContext that is used when a ChannelHandler is added to the DefaultChannelPipeline
- Rename TailHandler to TailContext and HeadHandler to HeadContext and let them extend AbstractChannelHandlerContext. This way we can save 2 object creations per DefaultChannelPipeline
Result:
- Less memory usage because we have 2 less objects per DefaultChannelPipeline
- Faster creation of DefaultChannelPipeline as we not need to generate the name for the head and tail
Motivation:
On some ill-configured systems, InetAddress.getLocalHost() fails. NioSocketChannelTest calls java.net.Socket.connect() and it internally invoked InetAddress.getLocalHost(), which causes the test failures in NioSocketChannelTes on such an ill-configured system.
Modifications:
Use NetUtil.LOCALHOST explicitly.
Result:
NioSocketChannelTest should not fail anymore.
Motivation:
DefaultChannelPipeline.firstContext() should return null when the ipeline is empty. This is not the case atm.
Modification:
Fix incorrect check in DefaultChannelPipeline.firstContext() and add unit tests.
Result:
Correctly return null when DefaultChannelPipeline.firstContext() is called on empty pipeline.
Motivation:
As discussed in #2250, it will become much less complicated to implement
deregistration and reregistration of a channel once #2250 is resolved.
Therefore, there's no need to deprecate deregister() and
channelUnregistered().
Modification:
- Undeprecate deregister() and channelUnregistered()
- Remove SuppressWarnings annotations where applicable
Result:
We (including @jakobbuchgraber) are now ready to play with #2250 at
master
Motivation:
4 and 5 were diverged long time ago and we recently reverted some of the
early commits in master. We must make sure 4.1 and master are not very
different now.
Modification:
Remove ChannelHandlerInvoker.writeAndFlush(...) and the related
implementations.
Result:
4.1 and master got closer.
Motivation:
I had the NioSocketChannelTest.testFlushCloseReentrance() fail sometimes on one of my linux installation. This change let it pass all the time.
Modification:
Set the SO_SNDBUF to a small value to force split writes
Result:
Test is passing all the time where it was sometimes fail before.
Motivation:
At the moment it is not possible to deregister a LocalChannel from its EventLoop and register it to another one as the LocalChannel is closed during the deregister.
Modification:
Not close the LocalChannel during dergister
Result:
It is now possible to deregister a LocalChannel and register it to another EventLoop
Motivation:
At the moment it is possible to see a NPE when the LocalSocketChannels doRegister() method is called and the LocalSocketChannels doClose() method is called before the registration was completed.
Modifications:
Make sure we delay the actual close until the registration task was executed.
Result:
No more NPE
Motivation:
At the moment an IllegalArgumentException will be thrown if a ChannelPromise is cancelled while propagate through the ChannelPipeline. This is not correct, we should just stop to propagate it as it is valid to cancel at any time.
Modifications:
Stop propagate the operation through the ChannelPipeline once a ChannelPromise is cancelled.
Result:
No more IllegalArgumentException when cancel a ChannelPromise while moving through the ChannelPipeline.
Motivation:
LocalEventLoopGroup and LocalEventLoop are not really special for LocalChannels. It can be used for other channel implementations as long as they don't require special handling.
Modifications:
- Add DefaultEventLoopGroup and DefaultEventLoop
- Deprecate LocalEventLoopGroup and make it extend DefaultEventLoopGroup
- Add DefaultEventLoop and remove LocalEventLoop
- Fix inspector warnings
Result:
- Better class names.
This also does factor out some logic of ChannelOutboundBuffer. Mainly we not need nioBuffers() for many
transports and also not need to copy from heap to direct buffer. So this functionality was moved to
NioSocketChannelOutboundBuffer. Also introduce a EpollChannelOutboundBuffer which makes use of
memory addresses for all the writes to reduce GC pressure
- Related: #2163
- Add ResourceLeakHint to allow a user to provide a meaningful information about the leak when touching it
- DefaultChannelHandlerContext now implements ResourceLeakHint to tell where the message is going.
- Cleaner resource leak report by excluding noisy stack trace elements
- Fixes#1810
- Add a new interface ChannelId and its default implementation which generates globally unique channel ID.
- Replace AbstractChannel.hashCode with ChannelId.hashCode() and ChannelId.shortValue()
- Add variants of ByteBuf.hexDump() which accept byte[] instead of ByteBuf.
- Fixes#2060
- Ensure to return a future/promise implementation that does not fail with 'not registered to an event loop' error for registration operations
- If there is no usable event loop available, GlobalEventExecutor.INSTANCE is used as a fallback.
- Merge MessageList into ChannelOutboundBuffer
- Make ChannelOutboundBuffer a queue-like data structure so that it is nearly impossible to leak a message
- Make ChannelOutboundBuffer public so that AbstractChannel can expose it to its subclasses.
- TODO: Re-enable gathering write in NioSocketChannel
- write() now accepts a ChannelPromise and returns ChannelFuture as most
users expected. It makes the user's life much easier because it is
now much easier to get notified when a specific message has been
written.
- flush() does not create a ChannelPromise nor returns ChannelFuture.
It is now similar to what read() looks like.
- Remove channelReadSuspended because it's actually same with messageReceivedLast
- Rename messageReceived to channelRead
- Rename messageReceivedLast to channelReadComplete
We renamed messageReceivedLast to channelReadComplete because it
reflects what it really is for. Also, we renamed messageReceived to
channelRead for consistency in method names.
I must admit MesageList was pain in the ass. Instead of forcing a
handler always loop over the list of messages, this commit splits
messageReceived(ctx, list) into two event handlers:
- messageReceived(ctx, msg)
- mmessageReceivedLast(ctx)
When Netty reads one or more messages, messageReceived(ctx, msg) event
is triggered for each message. Once the current read operation is
finished, messageReceivedLast() is triggered to tell the handler that
the last messageReceived() was the last message in the current batch.
Similarly, for outbound, write(ctx, list) has been split into two:
- write(ctx, msg)
- flush(ctx, promise)
Instead of writing a list of message with a promise, a user is now
supposed to call write(msg) multiple times and then call flush() to
actually flush the buffered messages.
Please note that write() doesn't have a promise with it. You must call
flush() to get notified on completion. (or you can use writeAndFlush())
Other changes:
- Because MessageList is completely hidden, codec framework uses
List<Object> instead of MessageList as an output parameter.
- SimpleChannelInboundHandler now has a constructor parameter to let a
user decide to enable automatic message release. (the default is to
enable), which makes ChannelInboundConsumingHandler of less value.
The API changes made so far turned out to increase the memory footprint
and consumption while our intention was actually decreasing them.
Memory consumption issue:
When there are many connections which does not exchange data frequently,
the old Netty 4 API spent a lot more memory than 3 because it always
allocates per-handler buffer for each connection unless otherwise
explicitly stated by a user. In a usual real world load, a client
doesn't always send requests without pausing, so the idea of having a
buffer whose life cycle if bound to the life cycle of a connection
didn't work as expected.
Memory footprint issue:
The old Netty 4 API decreased overall memory footprint by a great deal
in many cases. It was mainly because the old Netty 4 API did not
allocate a new buffer and event object for each read. Instead, it
created a new buffer for each handler in a pipeline. This works pretty
well as long as the number of handlers in a pipeline is only a few.
However, for a highly modular application with many handlers which
handles connections which lasts for relatively short period, it actually
makes the memory footprint issue much worse.
Changes:
All in all, this is about retaining all the good changes we made in 4 so
far such as better thread model and going back to the way how we dealt
with message events in 3.
To fix the memory consumption/footprint issue mentioned above, we made a
hard decision to break the backward compatibility again with the
following changes:
- Remove MessageBuf
- Merge Buf into ByteBuf
- Merge ChannelInboundByte/MessageHandler and ChannelStateHandler into ChannelInboundHandler
- Similar changes were made to the adapter classes
- Merge ChannelOutboundByte/MessageHandler and ChannelOperationHandler into ChannelOutboundHandler
- Similar changes were made to the adapter classes
- Introduce MessageList which is similar to `MessageEvent` in Netty 3
- Replace inboundBufferUpdated(ctx) with messageReceived(ctx, MessageList)
- Replace flush(ctx, promise) with write(ctx, MessageList, promise)
- Remove ByteToByteEncoder/Decoder/Codec
- Replaced by MessageToByteEncoder<ByteBuf>, ByteToMessageDecoder<ByteBuf>, and ByteMessageCodec<ByteBuf>
- Merge EmbeddedByteChannel and EmbeddedMessageChannel into EmbeddedChannel
- Add SimpleChannelInboundHandler which is sometimes more useful than
ChannelInboundHandlerAdapter
- Bring back Channel.isWritable() from Netty 3
- Add ChannelInboundHandler.channelWritabilityChanges() event
- Add RecvByteBufAllocator configuration property
- Similar to ReceiveBufferSizePredictor in Netty 3
- Some existing configuration properties such as
DatagramChannelConfig.receivePacketSize is gone now.
- Remove suspend/resumeIntermediaryDeallocation() in ByteBuf
This change would have been impossible without @normanmaurer's help. He
fixed, ported, and improved many parts of the changes.
- Use the local transport in a correct way (i.e. no need to trigger channelActive et al by ourselves)
- Use Promise/Future instead of CountDownLatch where they simplifies
shutdownGracefully() provides two optional parameters that give more
control over when an executor has to be shut down.
- Related issue: #1307
- Add shutdownGracefully(..) and isShuttingDown()
- Deprecate shutdown() / shutdownNow()
- Replace lastAccessTime with lastExecutionTime and update it after task
execution for accurate quiet period check
- runAllTasks() and runShutdownTasks() update it automatically.
- Add updateLastExecutionTime() so that subclasses can update it
- Add a constructor parameter that tells not to add an unncessary wakeup
task in execute() if addTask() wakes up the executor thread
automatically. Previously, execute() always called wakeup() after
addTask(), which often caused an extra dummy task in the task queue.
- Use shutdownGracefully() wherever possible / Deprecation javadoc
- Reduce the running time of SingleThreadEventLoopTest from 40s to 15s
using custom graceful shutdown parameters
- Other changes made along with this commit:
- takeTask() does not throw InterruptedException anymore.
- Returns null on interruption or wakeup
- Make sure runShutdownTasks() return true even if an exception was
raised while running the shutdown tasks
- Remove unnecessary isShutdown() checks
- Consistent use of SingleThreadEventExecutor.nanoTime()
Replace isWakeupOverridden with a constructor parameter
- Fixes#1308
freeInboundBuffer() and freeOutboundBuffer() were introduced in the early days of the new API when we did not have reference counting mechanism in the buffer. A user did not want Netty to free the handler buffers had to override these methods.
However, now that we have reference counting mechanism built into the buffer, a user who wants to retain the buffers beyond handler's life cycle can simply return the buffer whose reference count is greater than 1 in newInbound/OutboundBuffer().
This change also introduce a few other changes which was needed:
* ChannelHandler.beforeAdd(...) and ChannelHandler.beforeRemove(...) were removed
* ChannelHandler.afterAdd(...) -> handlerAdded(...)
* ChannelHandler.afterRemoved(...) -> handlerRemoved(...)
* SslHandler.handshake() -> SslHandler.hanshakeFuture() as the handshake is triggered automatically after
the Channel becomes active
