Motivation:
The HTTP/2 codec has some duplication and the read/write interfaces are not cleanly exposed to users of the codec.
Modifications:
-Restructure the AbstractHttp2ConnectionHandler class to be able to extend write behavior before the outbound flow control gets the data
-Add Http2InboundConnectionHandler and Http2OutboundConnectionHandler interfaces and restructure external codec interface around these concepts
Result:
HTTP/2 codec provides a cleaner external interface which is easy to extend for read/write events.
Motivation:
The HTTP tranlsation layer uses a FullHttpMessage object after it has been fired up the pipeline.
Although the content ByteBuf is not used by default it is still not ideal to use a releasable object
after it has potentially been released.
Modifications:
-InboundHttp2ToHttpAdapter ordering issues will be corrected
Result:
Safer access to releasable objects in the HTTP/2 to HTTP translation layer.
Motivation:
To eliminate the tests as being a cause of leaks, removing the automatic
retaining of ByteBufs in Http2TestUtil.
Modifications:
Each test that relied on retaining buffers for validation has been
modified to copy the buffer into a list of Strings that are manually
validated after the message is received.
Result:
The HTTP/2 tests should (hopefully) no longer be reporting erroneous
leaks due to the testing code, itself.
Motivation:
The current implementation of the HTTP/2 decompression does not integrate with flow control properly.
The decompression code is giving the post-decompression size to the flow control algorithm which
results in flow control errors at incorrect times.
Modifications:
-DecompressorHttp2FrameReader.java will need to change where it hooks into the HTTP/2 codec
-Enhance unit tests to test this condition
Result:
No more flow control errors because of decompression design flaw
Motivation:
The current build is showing potential leaks in the HTTP/2 tests that
use Http2TestUtil.FrameCountDown, which copies the buffers when it
receives them from the decoder. The leak detecor sees this copy as the
source of a leak. It would be better all around to just retain, rather
than copying the buffer. This should help to lower the overall memory
footprint of the tests as well as potentially getting rid of the
reported "leaks".
Modifications:
Modified Http2TestUtil to use ByteBuf.retain() everywhere that was
previously calling ByteBuf.copy().
Result:
Smaller memory footprint for tests and hopefully getting rid of reported
leaks.
Motivation:
The HTTP/2 spec does not restrict headers to being String. The current
implementation of the HTTP/2 codec uses Strings as header keys and
values. We should change this so that header keys and values allow
binary values.
Modifications:
Making Http2Headers based on AsciiString, which is a wrapper around a
byte[].
Various changes throughout the HTTP/2 codec to use the new interface.
Result:
HTTP/2 codec no longer requires string headers.
Motivation:
The HTTP/2 unit tests are suffering from OOME on the master branch.
These unit tests allocating a large number of threads (~706 peak live) which may
be related to this memory pressure.
Modifications:
Each EventLoopGroup shutdown operation will have a `sync()` call.
Result:
Lower peek live thread count and less associated memory pressure.
Motivation:
The HTTP/2 tests do not always clean up ByteBuf resources reliably. There are issues with the refCnt, over allocating buffers, and potentially not waiting long enough to reclaim resources for stress tests.
Modifications:
Scrub the HTTP/2 unit tests for ByteBuf leaks.
Result:
Less leaks (hopefully none) in the HTTP/2 unit tests. No OOME from HTTP/2 unit tests.
Motivation:
The HTTP/2 codec does not provide a way to decompress data. This functionality is supported by the HTTP codec and is expected to be a commonly used feature.
Modifications:
-The Http2FrameReader will be modified to allow hooks for decompression
-New classes which detect the decompression from HTTP/2 header frames and uses that decompression when HTTP/2 data frames come in
-New unit tests
Result:
The HTTP/2 codec will provide a means to support data decompression
Motivation:
The ServerBootrap's child group would not be shutdown.
Modification:
Add missing shutdownGracefully() call.
Result:
The child group is shutdown correctly.
Motivation:
The HTTP/2 specification places restrictions on the cipher suites that can be used. There is no central place to pull the ciphers that are allowed by the specification, supported by different java versions, and recommended by the community.
Modifications:
-HTTP/2 will have a security utility class to define supported ciphers
-netty-handler will be modified to support filtering the supplied list of ciphers to the supported ciphers for the current SSLEngine
Result:
-Netty provides unified support for HTTP/2 cipher lists and ciphers can be pruned by currently supported ciphers
Motivation:
Outbound flow control does not properly remove the head of queue after
it's written. This will cause streams with multiple frames to get stuck
and not send all of the data.
Modifications:
Modified the DefaultHttp2OutboundFlowController to properly remove the
head of the pending write queue once a queued frame has been written.
Added an integration test that sends a large message to verify that all
DATA frames are properly collected at the other end.
Result:
Outbound flow control properly handles several queued messages.
Motivation:
We failed to release buffers on protocolErrors which caused buffer leaks when using HTTP/2
Modifications:
Release buffer on protocol errors
Result:
No more buffer leaks
Motivation:
Netty only supports a java NPN implementation provided by npn-api and npn-boot.
There is no java implementation for ALPN.
ALPN is needed to be compliant with the HTTP/2 spec.
Modifications:
-SslContext and JdkSslContext to support ALPN
-JettyNpn* class restructure for NPN and ALPN common aspects
-Pull in alpn-api and alpn-boot optional dependencies for ALPN java implementation
Result:
-Netty provides access to a java implementation of APLN
Motivation:
A recent refactoring of the outbound flow controller interface
introduced a bug when writing data. We're no longer properly handling
the completion of the write (i.e. updating stream state/handling error).
Modifications:
Updated AbstractHttp2ConnectionHandler.writeData to properly handle the
completion of the write future.
Result:
DATA writes now perform post-write cleanup.
Motivation:
We currently have a mix of "Observer" and "Listener" for interface
names. We should make them all "Listener" to be consistent.
Modifications:
Renamed Http2DataObserver->Http2DataListener and
Http2FrameObserver->Http2FrameListener.
Result:
Listener interface names are consistent.
Motivation:
The priority information reported by the HTTP/2 to HTTP tranlsation layer is not correct in all situations.
The HTTP translation layer is not using the Http2Connection.Listener interface to track tree restructures.
This incorrect information is being sent up to clients and is misleading.
Modifications:
-Restructure InboundHttp2ToHttpAdapter to allow a default data/header mode
-Extend this interface to provide an optional priority translation layer
Result:
-Priority information being correctly reported in HTTP/2 to HTTP translation layer
-Cleaner code with seperation of concerns (optional priority conversion).
Motivation:
Currently, window maintenance is automatically performed when a flow
control window drops below half its initial size. We should provide a
way for advanced applications to determine whether or not this should be
done on a per-stream basis.
Modifications:
Modifying DefaultHttp2InboundFlowController to allow enabling/disabling
of window maintenance per stream.
Result:
Inbound flow control window maintenance will be dynamically
configurable.
Motivation:
HTTP/2 draft 14 came out a couple of weeks ago and we need to keep up
with the spec.
Modifications:
-Revert back to dispatching FullHttpMessage objects instead of individual HttpObjects
-Corrections to HttpObject comparitors to support test cases
-New test cases to support sending headers immediatley
-Bug fixes cleaned up to ensure the message flow is terminated properly
Result:
Netty HTTP/2 to HTTP/1.x translation layer will support the HTTP/2 draft message flow.
Motivation:
This is just some general cleanup to get rid of the FrameWriter inner
interface withing Http2InboundFlowController. It's not necessary since
the flow controller can just use the Http2FrameWriter to send
WINDOW_UPDATE frames.
Modifications:
Updated DefaultHttp2InboundFlowController to use Http2FrameWriter.
Result:
The inbound flow control code is somewhat less smelly :).
Motivation:
We're currently out-of-spec with HTTP/2 in that we don't include padding
in the flow control logic.
Modifications:
Modified both DefaultHttp2InboundFlowController and
DefaultHttp2OutboundFlowController to properly take padding into
account. Outbound is more complicated since padding has to be properly
accounted for when splitting frames.
Result:
HTTP/2 codec properly flow controls padding.
Motivation:
The current interface and implementation for HTTP/2 priority tree events does not notify listeners of all parent change events. As a result operations which depend upon knowing about parent change events may be missing events and result in stale data. This interface also allows new listeners to easily consume priority tree change events.
Modifications:
-Http2Connection.Listener interface will change to support notifications on every node after the priority has changed and tree events have settled
-This will affect the outbound flow controller, DefaultHttp2Connection, and other listeners using the old interface
Result:
A modified (hopefully simplified and correct) Listener interface to get priority tree change event notification
Motivation:
This is addressing a TODO in the outbound flow controller. We currently
have a separate writer interface passed into the outbound flow
controller. This is confusing and limiting as to how the flow controller
can perform its writes (e.g. no control over flushing). Instead it would
be better to just let the flow controller use the Http2FrameWriter
directly.
Modifications:
- Added a new Http2DataWriter interface, which is extended by
Http2FrameWriter and Http2OutboundFlowController.
- Removed automatic flushing from Http2DataWriter in order to facilitate
optimizing the case where there are multiple writes.
- Updated DefaultHttp2OutboundFlowController to properly optimize
flushing of the ChannelHandlerContext when multiple writes occur.
Result:
Code is greatly simplified WRT outbound flow control and flushes are
optimized for flow-controlled DATA frames.
Motivation:
HTTP/2 draft 14 came out a couple of weeks ago and we need to keep up
with the spec.
Modifications:
- Removed use of segment throughout.
- Added new setting for MAX_FRAME_SIZE. Used by the frame reader/writer
rather than a constant.
- Added new setting for MAX_HEADER_LIST_SIZE. This is currently unused.
- Expanded the header size to 9 bytes. The frame length field is now 3
bytes and added logic for checking that it falls within the valid range.
Result:
Netty will support HTTP/2 draft 14 framing. There will still be some
work to do to be compliant with the HTTP adaptation layer.
Motivation:
The HTTP/2 codec currently provides direct callbacks to access stream events/data. The HTTP/2 codec provides the protocol support for HTTP/2 but it does not pass messages up the context pipeline. It would be nice to have a decoder which could collect the data framed by HTTP/2 and translate this into traditional HTTP type objects. This would allow the traditional Netty context pipeline to be used to separate processing concerns (i.e. HttpContentDecompressor). It would also be good to have a layer which can translate FullHttp[Request|Response] objects into HTTP/2 frame outbound events.
Modifications:
Introduce a new InboundHttp2ToHttpAdapter and supporting classes which will translate HTTP/2 stream events/data into HttpObject objects. Introduce a new DelegatingHttp2HttpConnectionHandler which will translate FullHttp[Request|Response] objects to HTTP/2 frame events.
Result:
Introduced HTTP/2 frame events to HttpObject layer.
Introduced FullHttp[Request|Response] to HTTP/2 frame events.
Introduced new unit tests to support new code.
Updated HTTP/2 client example to use new code.
Miscelaneous updates and bug fixes made to support new code.
Motivation:
There are still a few places in the HTTP/2 code that have the compressed
flag (from pre-draft 13). Need to remove this flag since it's no longer
used.
Modifications:
Various changes to remove the flag from the writing path.
Result:
No references to the compressed flag.
Motivation:
The current HTTP/2 ping handling replies with an ack using the same
buffer as the received ping. It doesn't call retain(), however, which
causes a ReferenceCountException since the buffer ends up getting
released twice (once by the write and once by the decoder).
Modifications:
Modified AbstractHttp2ConnectionHandler to retain() the buffer. Added a
ping to Http2ConnectionRoundtripTest.stressTest() to verify the problem
and that this fixes it.
Result:
Ping should no longer cause an exception.
Motivation:
Need to upgrade HTTP/2 implementation to latest draft.
Modifications:
Various changes to support draft 13.
Result:
Support for HTTP/2 draft 13.
Motivation:
All of the functionality has been merged into
AbstractHttp2ConnectionHandler.
Modifications:
Removed the Http2PrefaceHandler/Test and all uses.
Result:
Code cleaned up a bit.
Related pull request: #2481 written by @nmittler
Motivation:
Some tests were still sending requests from the test thread rather than
from the event loop.
Modifications:
- Modified the roundtrip tests to use a new utility Http2TestUtil to
perform the write operations in the event loop thread.
- Modified the Http2Client under examples to write all requests in the
event loop thread.
- Added HttpPrefaceHandler and its test which were missing.
- Fixed various inspector warnings
Result:
Tests and examples now send requests in the correct thread context.
Motivation:
An IDE's auto-completion often confuses between java.util.Collections
and io.netty.util.collection.Collections, and it's annoying to me. :-)
Modifications:
Use a different class name.
Result:
When I type Collections, it's always 'the' Collections.
Motivation:
Various small fixes/improvements to the interface to the HTTP/2 classes,
as well as some minor performance improvements.
Modifications:
- Added fix for IntObjectHashMap to ensure that capacity is always odd.
Even capacity can cause probing to fail.
- Cleaned the access to GOAWAY information in Http2Connection interface.
Endpoints now manage their own state for GOAWAY. Also added a goingAway
event handler.
- Added Endpoint methods for checking MAX_CONCURRENT_STREAMS or if the
number of streams for the endpoint have been exhausted. See
Endpoint.nextStreamId()/acceptingNewStreams().
- Changed DefaultHttp2Connection to use IntObjectHashMap. This should be
a slight memory improvement.
- Fixed check for MAX_CONCURRENT_STREAMS to correctly use the number of
active streams for the endpoint (not total active). See
DefaultHttp2Connection.checkNewStreamAllowed.
- Exposing a few methods to subclasses of AbstractHttp2ConnectionHandler
(e.g. exception handling).
- Cleaning up GOAWAY and RST_STREAM handling in
AbstractHttp2ConnectionHandler.
Result:
HTTP/2 code should provide more information to subclasses and will have
a reduced memory footprint.
Motivation:
Subclasses of AbstractHttp2ConnectionHandler have to implement all frame
handler methods, many of which can be ignored in many cases. Also there
is no easy way to access the connection object.
Modifications:
Added default implementations for frame handler methods to
AbstractHttp2ConnectionHandler, and added an accessor for the
connection.
Also fixed example test for HTTP/2 with cleartext upgrade. It must have
been broken by recent commits.
Result:
AbstractHttp2ConnectionHandler is more subclass-friendly.
Motivation:
The connection, priority tree, and inbound/outbound flow controllers
each maintain a separate map for stream information. This is wasteful
and complicates the design since as streams are added/removed, multiple
structures have to be updated.
Modifications:
- Merging the priority tree into Http2Connection. Then we can use
Http2Connection as the central stream repository.
- Adding observer pattern to Http2Connection so flow controllers can be
told when a new stream is created, closed, etc.
- Adding properties for inboundFlow/outboundFlow state to Http2Stream.
This allows the controller to access flow control state directly from
the stream without requiring additional structures.
- Separate out the StreamRemovalPolicy and created a "default"
implementation that runs periodic garbage collection. This used to be
internal to the outbound flow controller, but I think it is more general
than that.
Result:
HTTP/2 classes will require less storage for new streams.
Motivation:
At the moment we have some methods that return a ChannelFuture but still throw a Http2Exception too. This is confusing in terms of semantic. A method which returns a ChannelFuture should not throw an Http2Exception but just fail the ChannelFuture.
Modifications:
* Make sure we fail the returned ChannelFuture in cases of Http2Exception and remove the throws Http2Exception from the method signature.
* Also some cleanup
Result:
Make the API usage more clear.
Motivation:
The HTTP/2 connection preface logic is currently handled in two places.
Reading/writing the client preface string is handled by
Http2PrefaceHandler while the reading/writing of the initial settings
frame is handled by AbstractHttp2ConnectionHandler. Given that their
isn't much code in Http2PrefaceHandler, it makes sense to just merge it
into the preface handling logic of AbstractHttp2ConnectionHandler. This
will also make configuring the pipeline simpler for HTTP/2.
Modifications:
Removed Http2PrefaceHandler and added it's logic to
AbstractHttp2ConnectionHandler. Updated other classes depending on
Http2PrefaceHandler.
Result:
All of the HTTP/2 connection preface processing logic is now in one
place.
Motivation:
Previously local settings is applied on its transmission. But this
makes settings value out-of-sync with remote endpoint. The
application of local settings must be done after the remote endpoint
sends back its SETTINGS ACK. This synchronization is vital to the
protocol. Suppose that server sends SETTINGS_HEADER_TABLE_SIZE 0 on
connection establishment and resizes its header table size down to 0.
Meanwhile, client sends HEADERS which has header block encoded in
default 4096 header table size, because client has not seen the
SETTINGS from server. Server tries to decode received HEADERS but due
to the difference of header table size, decoding process may fail.
Modifications:
We don't apply settings on transmission. Instead, we keep track of
outstanding settings in FIFO queue. When we get ACK, we pop oldest
outstanding settings and apply its values.
Result:
The outstanding settings values are applied when its ACK is received,
which is compliant behavior to the HTTP/2 specification.
Motivation:
A few items were identified where the http2 codec is out of compliance
with the spec.
Modifications:
- Fixed handling of priority weight on the wire. Now adding 1 after
reading from the wire and subtracing 1 before writing.
- Fixed handling of next stream ID. Client streamIds were starting at 3,
but they need to start at 1 to allow the upgrade from HTTP/1.1. Also
making next stream ID logic more flexible. Allowing the next created
stream to be any number in the sequence following the previously created
stream.
- Disallowing SETTINGS frames with ENABLE_PUSH specified for server
endpoints. This means that attempts to write this frame from a server,
or read it from a client will fail.
Result:
The http2 implementation will be more inline with the spec.
Motivation:
The Http2FrameObserver isn't provided the ChannelHandlerContext when
it's called back. This will force observers to find an alternative means
of obtaining the context if they need to do things like copying buffers.
Modifications:
Changed the Http2FrameReader and Http2FrameObserver to include the
context. Updated all other uses of these interfaces.
Result:
Frame observers will now have the channel context.
Motivation:
The outbound flow controller currently has to walk the entire tree each
time to calculate the total available data for each subtree. For better
performance we should maintain a running total for each subtree as we
queue/write frames.
Modifications:
I've modified the DefaultHttp2OutboundFlowController to manage the state
of "priorityData" at each node in the priority tree, which is
essentially the total writable data for all streams in that subtree.
These totals do not take into account the connection window, as that is
applied when splitting the data across the streams at each level in the
tree.
The flow controller now sorts the children of a node by the product of
their data (for the subtree) and its weight. This is used since in
certain cases the algorithm might prefer nodes that appear later in the
list. Sorting helps keep nodes with similar characteristics (e.g. a lot
of data and a high priority) with similar output.
To help clean things up, I'm storing a FlowState for the root node as
well, which maintains the runnning total of the currently writable data
for all stream.
Another item of cleanup is that I created a GarbageCollector innerclass
within the outbound flow controller. This keeps all of the garbage
collection code in one place, away from the flow control code.
Also added some more unit tests for the flow controller.
Result:
The outbound flow controller is a bit cleaner and perhaps a bit more
fair when distributing outbound data across streams.
