Motivation:
The buffer which the decoder allocates for the expansion can be
leaked if there is a subsequent issue writing to it.
Modifications:
The error handling has been improved so that the new buffer always
is released on failure in the expand.
Result:
The decoder will not leak in this scenario any more.
Fixes: https://github.com/netty/netty/issues/9812
Motivation:
Data flowing in from the decoder flows out in sequence，Whether decoder removed or not.
Modification:
fire data in out and clear out when hander removed
before call method handlerRemoved(ctx)
Result:
Fixes#9668 .
Motivation:
At the moment we do a ByteBuf.readBytes(...) on removal of the ByteToMessageDecoder if there are any bytes left and forward the returned ByteBuf to the next handler in the pipeline. This is not really needed as we can just forward the cumulation buffer directly and so eliminate the extra memory copy
Modifications:
Just forward the cumulation buffer directly on removal of the ByteToMessageDecoder
Result:
Less memory copies
Motivation:
ByteToMessageDecoder only looks at the last channelRead() in the batch
of channelRead()-s when determining whether or not it should call
ChannelHandlerContext#read() to consume more data when !isAutoRead. This
will lead to read() calls issued unnecessaily and unprompted if the very
last channelRead() didn't result in at least one decoded message, even
if there have been messages decoded from other channelRead()-s in the
current batch.
Modifications:
Track decode outcomes for the entire batch of channelRead() calls and
only issue a read in BTMD if the entire batch of channelRead() calls
yielded no complete messages.
Result:
ByteToMessageDecoder will no longer overread when the very last read
yielded no message, but the batch of reads did.
Motivation:
At the moment ByteToMessageDecoder always calls fireChannelReadComplete() when the handler is removed from the pipeline and the cumulation buffer is not null. We should only call it when we also call fireChannelRead(...), which only happens if the cumulation buffer is not null and readable.
Modifications:
Only call fireChannelReadComplete() if fireChannelRead(...) is called before during removal of the handler.
Result:
More correct semantics
Motivation:
As we now us java8 as minimum java version we can deprecate ChannelInboundHandlerAdapter / ChannelOutboundHandlerAdapter and just move the default implementations into the interfaces. This makes things a bit more flexible for the end-user and also simplifies the class-hierarchy.
Modifications:
- Mark ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter as deprecated
- Add default implementations to ChannelInboundHandler / ChannelOutboundHandler
- Refactor our code to not use ChannelInboundHandlerAdapter / ChannelOutboundHandlerAdapter anymore
Result:
Cleanup class-hierarchy and make things a bit more flexible.
Motivation:
We can just use Objects.requireNonNull(...) as a replacement for ObjectUtil.checkNotNull(....)
Modifications:
- Use Objects.requireNonNull(...)
Result:
Less code to maintain.
Motivation:
We have a utility method to check for > 0 and >0 arguments. We should use it.
Modification:
use checkPositive/checkPositiveOrZero instead of if statement.
Result:
Re-use utility method.
Motivation:
We can use lambdas now as we use Java8.
Modification:
use lambda function for all package, #8751 only migrate transport package.
Result:
Code cleanup.
Motivation:
We need to ensure the Cumulator always releases the input buffer if it can not take over the ownership of it as otherwise it may leak.
Modifications:
- Correctly ensure the buffer is always released.
- Add unit tests.
Result:
Ensure buffer is always released.
Motivation: Today when Netty encounters a general error while decoding
it treats this as a decoder exception. However, for fatal causes this
should not be treated as such, instead the fatal error should be carried
up the stack without the callee having to unwind causes.
Modifications: Instead of translating any error to a decoder exception,
we let those unwind out the stack (note that finally blocks still
execute).
Result: Fatal errors will not be treated as innocent decoder exceptions.
This reverts commit d63bb4811e as this not covered correctly all cases and so could lead to missing fireChannelReadComplete() calls. We will re-evalute d63bb4811e and resbumit a pr once we are sure all is handled correctly
Motivation:
Its wasteful and also confusing that channelReadComplete() is called even if there was no message forwarded to the next handler.
Modifications:
- Only call ctx.fireChannelReadComplete() if at least one message was decoded
- Add unit test
Result:
Less confusing behavior. Fixes [#4312].
Motivation:
ByteToMessageDecoder#handlerRemoved will immediately release the cumulation buffer, but it is possible that a child class may still be using this buffer, and therefore use a dereferenced buffer.
Modifications:
- ByteToMessageDecoder#handlerRemoved and ByteToMessageDecoder#decode should coordinate to avoid the case where a child class is using the cumulation buffer but ByteToMessageDecoder releases that buffer.
Result:
Child classes of ByteToMessageDecoder are less likely to reference a released buffer.
Motivation:
If a read-only ByteBuf is passed to the ByteToMessageDecoder.channelRead(...) method we need to make a copy of it once we try to merge buffers for cumulation. This usually is not the case but can for example happen if the local transport is used. This was the cause of the leak report we sometimes saw during the codec-http2 tests, as we are using the local transport and write a read-only buffer. This buffer will then be passed to the peer channel and fired through the pipeline and so end up as the cumulation buffer in the ByteToMessageDecoder. Once the next fragement is received we tried to merge these and failed with a ReadOnlyBufferException which then produced a leak.
Modifications:
Ensure we copy the buffer if its read-only.
Result:
No more exceptions and so leak when a read-only buffer is passed to ByteToMessageDecoder.channelRead(...)
Motivation:
We should ensure we null out the cumulation buffer before we fire it through the pipleine in handlerRemoved(...) as in theory it could be possible that another method is triggered as result of the fireChannelRead(...) or fireChannelReadComplete() that will try to access the cumulation.
Modifications:
Null out cumulation buffer early in handlerRemoved(...)
Result:
No possible to access the cumulation buffer that was already handed over.
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:
99dfc9ea79 introduced some code that will more frequently try to forward messages out of the list of decoded messages to reduce latency and memory footprint. Unfortunally this has the side-effect that RecycleableArrayList.clear() will be called more often and so introduce some overhead as ArrayList will null out the array on each call.
Modifications:
- Introduce a CodecOutputList which allows to not null out the array until we recycle it and also allows to access internal array with extra range checks.
- Add benchmark that add elements to different List implementations and clear them
Result:
Less overhead when decode / encode messages.
Benchmark (elements) Mode Cnt Score Error Units
CodecOutputListBenchmark.arrayList 1 thrpt 20 24853764.609 ± 161582.376 ops/s
CodecOutputListBenchmark.arrayList 4 thrpt 20 17310636.508 ± 930517.403 ops/s
CodecOutputListBenchmark.codecOutList 1 thrpt 20 26670751.661 ± 587812.655 ops/s
CodecOutputListBenchmark.codecOutList 4 thrpt 20 25166421.089 ± 166945.599 ops/s
CodecOutputListBenchmark.recyclableArrayList 1 thrpt 20 24565992.626 ± 210017.290 ops/s
CodecOutputListBenchmark.recyclableArrayList 4 thrpt 20 18477881.775 ± 157003.777 ops/s
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 246.748 sec - in io.netty.handler.codec.CodecOutputListBenchmark
Motivation:
b112673554 added ChannelInputShutdownEvent support to ByteToMessageDecoder but missed updating the code for ReplayingDecoder. This has the effect:
- If a ChannelInputShutdownEvent is fired ByteToMessageDecoder (the super-class of ReplayingDecoder) will call the channelInputClosed(...) method which will pass the incorrect buffer to the decode method of ReplayingDecoder.
Modifications:
Share more code between ByteToMessageDEcoder and ReplayingDecoder and so also support ChannelInputShutdownEvent correctly in ReplayingDecoder
Result:
ChannelInputShutdownEvent is corrrectly handle in ReplayingDecoder as well.
Motivation:
If the input buffer is empty we should not have decodeLast(...) call decode(...) as the user may not expect this.
Modifications:
- Not call decode(...) in decodeLast(...) if the input buffer is empty.
- Add testcases.
Result:
decodeLast(...) will not call decode(...) if input buffer is empty.
Motivation:
ByteToMessageDecoder must ensure that read components of the CompositeByteBuf can be discard by default when discardSomeReadBytes() is called. This may not be the case before as because of the default maxNumComponents that will cause consolidation.
Modifications:
Ensure we not do any consolidation to actually be abel to discard read components
Result:
Less memory usage and allocations.
Motivation:
b714297a44 introduced ChannelInputShutdownEvent support for HttpObjectDecoder. However this should have been added to the super class ByteToMessageDecoder, and ByteToMessageDecoder should not propegate a channelInactive event through the pipeline in this case.
Modifications:
- Move the ChannelInputShutdownEvent handling from HttpObjectDecoder to ByteToMessageDecoder
- ByteToMessageDecoder doesn't call ctx.fireChannelInactive() on ChannelInputShutdownEvent
Result:
Half closed events are treated more generically, and don't get translated into a channelInactive pipeline event.
Motivation:
We need to check if this handler was removed before continuing with decoding.
If it was removed, it is not safe to continue to operate on the buffer.
Modifications:
Check if decoder was removed after fire messages through the pipeline.
Result:
No illegal buffer access when decoder was removed.
Motivation:
At the moment we only forward decoded messages that were added the out List once the full decode loop was completed. This has the affect that resources may not be released as fast as possible and as an application may incounter higher latency if the user triggeres a writeAndFlush(...) as a result of the decoded messages.
Modifications:
- forward decoded messages after each decode call
Result:
Forwarding decoded messages through the pipeline in a more eager fashion.
Motivation:
If a remote peer writes fast enough it may take a long time to have fireChannelReadComplete(...) triggered. Because of this we need to take special care and ensure we try to discard some bytes if channelRead(...) is called to often in ByteToMessageDecoder.
Modifications:
- Add ByteToMessageDecoder.setDiscardAfterReads(...) which allows to set the number of reads after which we try to discard the read bytes
- Use default value of 16 for max reads.
Result:
No risk of OOME.
Motivation:
Our automatically handling of non-auto-read failed because it not detected the need of calling read again by itself if nothing was decoded. Beside this handling of non-auto-read never worked for SslHandler as it always triggered a read even if it decoded a message and auto-read was false.
This fixes [#3529] and [#3587].
Modifications:
- Implement handling of calling read when nothing was decoded (with non-auto-read) to ByteToMessageDecoder again
- Correctly respect non-auto-read by SslHandler
Result:
No more stales and correctly respecting of non-auto-read by SslHandler.
Motivation:
This will avoid one unncessary method invokation which will slightly improve performance.
Modifications:
Instead of calling isReadable we just check for the value of readableBytes()
Result:
Nothing functionally speaking change.
Related:
- 27a25e29f7
Motivation:
The commit mentioned above introduced a regression where
channelReadComplete() event is swallowed by a handler which was added
dynamically.
Modifications:
Do not suppress channelReadComplete() if the current handler's
channelRead() method was not invoked at all, so that a just-added
handler does not suppress channelReadComplete().
Result:
Regression is gone, and channelReadComplete() is invoked when necessary.
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:
Currently when there are bytes left in the cumulation buffer we do a byte copy to produce the input buffer for the decode method. This can put quite some overhead on the impl.
Modification:
- Use a CompositeByteBuf to eliminate the byte copy.
- Allow to specify if a CompositeBytebug should be used or not as some handlers can only act on one ByteBuffer in an efficient way (like SslHandler :( ).
Result:
Performance improvement as shown in the following benchmark.
Without this patch:
[xxx@xxx ~]$ ./wrk-benchmark
Running 5m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 20.19ms 38.34ms 1.02s 98.70%
Req/Sec 241.10k 26.50k 303.45k 93.46%
1153994119 requests in 5.00m, 155.84GB read
Requests/sec: 3846702.44
Transfer/sec: 531.93MB
With the patch:
[xxx@xxx ~]$ ./wrk-benchmark
Running 5m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 17.34ms 27.14ms 877.62ms 98.26%
Req/Sec 252.55k 23.77k 329.50k 87.71%
1209772221 requests in 5.00m, 163.37GB read
Requests/sec: 4032584.22
Transfer/sec: 557.64MB
Motivation:
We have some duplicated code that can be reused.
Modifications:
Create package private class called CodecUtil that now contains the shared code / helper method.
Result:
Less code-duplication
Motivation:
ByteToMessageDecoder and ReplayingDecoder have incorrect javadocs in some places.
Modifications:
Fix incorrect javadocs for both classes.
Result:
Correct javadocs for both classes
Motivation:
In ReplayingDecoder / ByteToMessageDecoder channelInactive(...) method we try to decode a last time and fire all decoded messages throw the pipeline before call ctx.fireChannelInactive(...). To keep the correct order of events we also need to call ctx.fireChannelReadComplete() if we read anything.
Modifications:
- Channel channelInactive(...) to call ctx.fireChannelReadComplete() if something was decoded
- Move out.recycle() to finally block
Result:
Correct order of events.
Motivation:
At the moment a user can not safetly call slice().retain() or duplicate.retain()in the ByteToMessageDecoder.decode(...) implementation without the risk to see coruption because we may call discardSomeReadBytes() to make room on the buffer once the handling is done.
Modifications:
Check for the refCnt() before call discardSomeReadBytes() and also check before call decode(...) to create a copy if needed.
Result:
The user can safetly call slice().retain() or duplicate.retain() in his/her ByteToMessageDecoder.decode(...) method.
Motivation:
Remove the synchronization bottleneck and so speed up things
Modifications:
Introduce a ThreadLocal cache that holds mappings between classes of ChannelHandlerAdapater implementations and the result of checking if the @Sharable annotation is present.
This way we only will need to do the real check one time and server the other calls via the cache. A ThreadLocal and WeakHashMap combo is used to implement the cache
as this way we can minimize the conditions while still be sure we not leak class instances in containers.
Result:
Less conditions during adding ChannelHandlerAdapter to the ChannelPipeline
This fixes#1664 and revert also the original commit which was meant to fix it 3b1881b523 . The problem with the original commit was that it could delay handlerRemove(..) calls and so mess up the order or forward bytes to late.
