Motivation:
The current priority algorithm can yield poor per-stream goodput when either the number of streams is high or the connection window is small. When all priorities are the same (i.e. priority is disabled), we should be able to do better.
Modifications:
Added a new UniformStreamByteDistributor that ignores priority entirely and manages a queue of streams. Each stream is allocated a minimum of 1KiB on each iteration.
Result:
Improved goodput when priority is not used.
Motivation:
The `DefaultHttp2RemoteFlowController` does not correctly determine `hasFrame` when updating the stream state for the distributor. Adding a check to enforce `hasFrame` when `streamableBytes > 0` causes several test failures.
Modifications:
Modified `DefaultHttp2RemoteFlowController` to simplify the writing logic and to correct the bookkeeping for `hasFrame`.
Result:
The distributors are always called with valid arguments.
Motivation:
The twitter hpack project does not have the support that it used to have. See discussion here: https://github.com/netty/netty/issues/4403.
Modifications:
Created a new module in Netty and copied the latest from twitter hpack master.
Result:
Netty no longer depends on twitter hpack.
Motivation:
Recently a bug was found in DefaultHttp2Headers where the state of the headers could be corrupted due to the extra tracking to make pseudo headers first during iteration. Unit tests did not catch this bug.
Modifications:
- Update unit tests to cover more methods
Result:
Unit tests for DefaultHttp2Headers have better code coverage.
Motivation:
For many HTTP/2 applications (such as gRPC) it is necessary to autorefill the connection window in order to prevent application-level deadlocking.
Consider an application with 2 streams, A and B. A receives a stream of messages and the application pops off one message at a time and makes a request on stream B. However, if receiving of data on A has caused the connection window to collapse, B will not be able to receive any data and the application will deadlock. The only way (currently) to get around this is 1) use multiple connections, or 2) manually refill the connection window. Both are undesirable and could needlessly complicate the application code.
Modifications:
Add a configuration option to DefaultHttp2LocalFlowController, allowing it to autorefill the connection window.
Result:
Applications can configure HTTP/2 to avoid inter-stream deadlocking.
Motivation:
PriorityStreamByteDistributor saves exception state and attempts to reset state. This could be simplified by just throwing a connection error and closing the connection. PriorityStreamByteDistributor also does not handle or detect re-entry in the distribute method.
Motivation:
- PriorityStreamByteDistributor propagate an INTERNAL_ERROR if an exception occurs during writing
- PriorityStreamByteDistributor to handle re-entry on the write method
Result:
PriorityStreamByteDistributor exception code state simplified, and re-entry is detected.
Motivation:
Http2ConnectionHandler verifies if the first frame after the preface is
a SETTINGS frame. However, it does not reject the SETTING ack frame
which is not expected actually.
Modifications:
Reject a SETTINGS-ack frame as well
Result:
When the first frame is a SETTINGS-ack frame, connection does not
proceed to further frame handling. (simplicity)
Motivation:
The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-8.1.2) indicates that header names consist of ASCII characters. We currently use ByteString to represent HTTP/2 header names. The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-10.3) also eludes to header values inheriting the same validity characteristics as HTTP/1.x. Using AsciiString for the value type of HTTP/2 headers would allow for re-use of predefined HTTP/1.x values, and make comparisons more intuitive. The Headers<T> interface could also be expanded to allow for easier use of header types which do not have the same Key and Value type.
Motivation:
- Change Headers<T> to Headers<K, V>
- Change Http2Headers<ByteString> to Http2Headers<CharSequence, CharSequence>
- Remove ByteString. Having AsciiString extend ByteString complicates equality comparisons when the hash code algorithm is no longer shared.
Result:
Http2Header types are more representative of the HTTP/2 RFC, and relationship between HTTP/2 header name/values more directly relates to HTTP/1.x header names/values.
Motivation:
Http2ConnectionHandler.BaseBuilder is constructing objects which have 'close' methods, but is not calling these methods in the event of an exception.
Modifications:
- Objects which implement 'close' should have this method called if an exception is thrown and the build operation can not complete normally.
Result:
Objects are closed even if the build process encounters an error.
Motivation:
Remove encoderMaxConcurrentStreams(...) and use the default settings. Also throw an exception if server mode is used.
Modifications:
- Remove encoderMaxConcurrentStreams(...) method
- Throw exception if server mode is used and trying to enforce conncurrent streams.
Result:
Correctly support settings stuff via builder
Motivation:
We had an unused paramter on a method, we should just remove it to keep code clean.
Modifications:
- Remove parameter
- Fix typo in javadoc
Result:
Cleanup done.
Motivation:
DefaultHttp2ConnectionDecoder writes a ACK when receiving a ping frame and sends the same data buffer it received. The data buffer is also passed to the listener, but the indexes are shared between the send and the listener. We should ensure the indexes are independent for these two operations.
Modifications:
- Call slice on the buffer that is being sent
Result:
Listener now has access to a buffer that will not appear to be already consumed.
Motivation:
Using the builder pattern for Http2ConnectionHandler (and subclasses) would be advantageous for the following reasons:
1. Provides the consistent construction afforded by the builder pattern for 'optional' arguments. Users can specify these options 1 time in the builder and then re-use the builder after this.
2. Enforces that the Http2ConnectionHandler's internals (decoder Http2FrameListener) are initialized after construction.
Modifications:
- Add an extensible builder which can be used to build Http2ConnectionHandler objects
- Update classes which inherit from Http2ConnectionHandler
Result:
It is easier to specify options and construct Http2ConnectionHandler objects.
Motivation:
It is often the case that implementations of Http2FrameListener will want to send responses when data is read. The Http2FrameListener needs access to the Http2ConnectionHandler (or the encoder contained within) to be able to send responses. However the Http2ConnectionHandler requires a Http2FrameListener instance to be passed in during construction time. This creates a cyclic dependency which can make it difficult to cleanly accomplish this relationship.
Modifications:
- Add Http2ConnectionDecoder.frameListener(..) method to set the frame listener. This will allow the listener to be set after construction.
Result:
Classes which inherit from Http2ConnectionHandler can more cleanly set the Http2FrameListener.
Motivation:
For implementations that want to manage flow control down to the stream level it is useful to be notified when stream writability changes.
Modifications:
- Add writabilityChanged to Http2RemoteFlowController.Listener
- Add isWritable to Http2RemoteFlowController
Result:
The Http2RemoteFlowController provides notification when writability of a stream changes.
Motivation:
The DefaultHttp2RemoteFlowController has become very large and is getting difficult to understand and maintain. It is also desirable for some applications to be able to disable the priority algorithm altogether for performance reasons.
Modifications:
Abstract the stream byte assignment logic (renamed allocation->assignment for clarity) behind an interface `StreamByteAssigner` with a single implementation `PriorityStreamByteAssigner`.
Result:
Goes some way towards supporting #4246
Motivation:
DefaultHttp2RemoteFlowController's allocation algorithm may not allocate all bytes that are available in the connection window. If the 'fair share' based upon weight is not fully used by sibling nodes it was not correctly re-distributed to other sibilings which may be able to utilize part / all of that share.
Modifications:
- Add a unit test which demonstrates the issue.
- Modify the allocation algorithm to ensure all available bytes are allocated.
Result:
Fixes https://github.com/netty/netty/issues/4266
Motiviation:
The http2 spec https://tools.ietf.org/html/rfc7540#section-8.1.2.3 states that the :authority header should be copied into the HOST header when converting from HTTP/2 to HTTP/1.x. We currently have an extension header to preserve the authority.
Modifications:
- Remove AUTHORITY extension header
- HTTP/2 :authority should map to HOST header when converting to HTTP/1.x.
Result:
More spec compliant.
Motivation:
Buffer leak in StreamBufferingEncoderTest
Modifications:
- Make sure buffers are released in StreamBufferingEncoderTest
Result:
Fixes https://github.com/netty/netty/issues/4230
Motivation:
Http2LifecycleManager.onException takes a Throwable as a paramter and not an Exception. There are also onConnectionError and onStreamError methods in the codec. We should rename this method to onError for consistency and clarity.
Modifications:
- Rename Http2LifecycleManager.onException to Http2LifecycleManager.onError
Result:
More consistent and clarified interface.
Motivation:
DefaultHttp2RemoteFlowController attempts to write as many bytes as possible to transition the channel to not writable, and then relies on notification of channelWritabilityChange to continue writing. However the amount of bytes written by DefaultHttp2RemoteFlowController may not be the same number of bytes that is actually written to the channel due to other ChannelHandlers (SslHandler, compression, etc...) in the pipeline. This means there is a potential for the DefaultHttp2RemoteFlowController to be waiting for a channel writaiblity change event that will never come, and thus not write all queued data.
Modifications:
- DefaultHttp2RemoteFlowController should write pending bytes until there are no more, or until the channel is not writable.
Result:
DefaultHttp2RemoteFlowController will write all pending data.
Fixes https://github.com/netty/netty/issues/4242
Motivation:
We currently set the flow controller ChannelHandlerContexts to null when the channel becomes inactive. This is bad :)
Modifications:
Just remove that code in Http2ConnectionHandler
Result:
Fixes#4240
Motivation:
HttpConversionUtil.toHttp2Headers does not convert urlencoded uri to http2 path properly.
Modifications:
Use getRawPath(), getRawQuery(), getRawFragment() in java.net.URI when converts to http2 path
Result:
HttpConversionUtil.toHttp2Headers does not urldecode uri unproperly.
Motivation:
Http2CodecUtils has some static variables which are defined as Strings instead of CharSequence. One of these defines is used as a header name and should be AsciiString.
Modifications:
- Change the String defines in Http2CodecUtils to CharSequence
Result:
Types are more consistently using CharSequence and adding the upgrade header will require less work.
Motivation:
The DefaultHttp2Headers code is throwing a IllegalArgumentException if an invalid character is detected. This is being ignored by the HTTP/2 codec instead of generating a GOAWAY.
Modifications:
- Throw a Http2Exception of type PROTOCOL_ERROR in accordance with https://tools.ietf.org/html/rfc7540#section-8.1.2.6
- Update examples which were building invalid headers
Result:
More compliant with https://tools.ietf.org/html/rfc7540#section-8.1.2.6
Motivation:
The HTTP/2 spec states that the ping frame length must be 8 and is otherwise an error https://tools.ietf.org/html/rfc7540#section-6.7. The DefaultHttp2FrameReader enforces this, but the DefaultHttp2FrameWriter allows invalid frames to be written. We should not allow invalid ping frames to be written to the network.
Modifications:
- DefaultHttp2FrameWriter checks the frame size to be 8, or throws an exception
Result:
Fixes https://github.com/netty/netty/issues/3721
Motivation:
Currently there is a HttpConversionUtil.addHttp2ToHttpHeaders which requires a FullHttpMessage, but this may not always be available. There is no interface that can be used with just Http2Headers and HttpHeaders.
Modifications:
- add an overload for HttpConversionUtil.addHttp2ToHttpHeaders which does not take FullHttpMessage
Result:
An overload for HttpConversionUtil.addHttp2ToHttpHeaders exists which does not require FullHttpMessage.
Motivation:
The HTTP/2 codec has a few static buffers sent over the network which are allocated on the heap. This results in a copy operation when the buffer is sent out on the network.
Modifications:
- Ensure these static buffers are allocated using direct memory.
Result:
No copy operation necessary when writing static buffers to network.
Motivaion:
The HttpHeaders and DefaultHttpHeaders have methods deprecated due to being removed in future releases, but no replacement method to use in the current release. The deprecation policy should not be so aggressive as to not provide any non-deprecated method to use.
Modifications:
- Remove deprecated annotations and javadocs from methods which are the best we can do in terms of matching the master's api for 4.1
Result:
There should be non-deprecated methods available for HttpHeaders in 4.1.
Motivation:
The HTTP/2 header name validation was removed, and does not currently exist.
Modifications:
- Header name validation for HTTP/2 should be restored and set to the default mode of operation.
Result:
HTTP/2 header names are validated according to https://tools.ietf.org/html/rfc7540
Motivation:
The javadoc comments on Http2Headers.iterator() are incorrect.
Modifications:
- Correct and clarify the javadoc for Http2Headers.iterator()
Result:
Javadoc for Http2Headers.iterator() is more correct.
Motivation:
InboundHttp2ToHttpAdapterTest.bootstrapEnv does not wait for the serverConnectedChannel to be initialized before returning. Some methods rely only this behavior and throw a NPE because it may not be set.
Modifications:
- Add a CountDownLatch to ensure the serverConnectedChannel is initialized
Result:
No more NPE.
Motivation:
The SimplePromiseAggregator.setFailure allows a failure to occur before newPromise is called, but tryFailure doesn't. These methods should be consistent.
Modifications:
- tryFailure should use the same logic as setFailure
Result:
Consistent failure routines.
Motivation:
DefaultPropertyKey.index is currently private and accessed outside the class's scope.
Modifications:
- Change access level to package private
Result:
No chance of synthetic method generation for accessing this field
Motivation:
The latches in InboundHttp2ToHttpAdapterTest were volatile and reset during the tests. This resulted in race conditions and sometimes the tests would be waiting on old latches that were not the same latches being counted down when messages were received.
Modifications:
- Remove volatile latches from tests
Result:
More reliable tests with less race conditions.
Motivation:
There currently exists http.HttpUtil, http2.HttpUtil, and http.HttpHeaderUtil. Having 2 HttpUtil methods can be confusing and the utilty methods in the http package could be consolidated.
Modifications:
- Rename http2.HttpUtil to http2.HttpConversionUtil
- Move http.HttpHeaderUtil methods into http.HttpUtil
Result:
Consolidated utilities whose names don't overlap.
Fixes https://github.com/netty/netty/issues/4120
Motivation:
ByteToMessageDecoder may call decode after channelInactive is called. This will lead to a NPE.
Modifications:
- Call super.channelInactive() before we process the event in Http2ConnectionHandler
Result:
No more NPE in decode.
Motivation:
Commit 0d8ce23c83 failed to fix the Host header processing. Host is not a URI but is instead defined in https://tools.ietf.org/html/rfc3986#section-3.2.2 as host = IP-literal / IPv4address / reg-name
Modifications:
- Host should not be treated as a URI.
- We should be more explicit about required fields, and unexpected input by throwing exceptions.
Result:
Translation from HTTP/1.x to HTTP/2 is more correct.
Motivation:
If a SimpleChannelPromiseAggregator is failed before any new promises are generated, the failure is not propegated through to the aggregated promise.
Modifications:
- Failures should be allowed to occur even if no new promises have been generated
Result:
Failures are always allowed.
Motivation:
If any streams are still active the graceful shutdown code will wait until they are all closed before the connection is closed. In some situations this event may never occur, and thus a timeout should be supported so the socket can be closed even if all streams haven't been closed.
Modifications:
- Add a configurable timeout for when the graceful shutdown process is attempted.
- Update unit tests to be faster, and use this graceful timeout
Result:
Local endpoint can protect from local or remote issues which prevent the channel from being closed during the graceful shutdown process.
Motivation:
DefaultHttp2ConnectionEncoder.FlowControlledHeaders and DefaultHttp2ConnectionEncoder.FlowControlledData have private constructors which may result in static factory methods being generated to construct instances of these classes.
Modifications:
- Make constructors public for these private classes
Result:
Accessor for inner class constructor more correct and no possibiliy of synthetic method generation.
Motivation:
A degradation in performance has been observed from the 4.0 branch as documented in https://github.com/netty/netty/issues/3962.
Modifications:
- Simplify Headers class hierarchy.
- Restore the DefaultHeaders to be based upon DefaultHttpHeaders from 4.0.
- Make various other modifications that are causing hot spots.
Result:
Performance is now on par with 4.0.
