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.
Motivation:
Our ci showed some buffer leaks in the http2 codec. This commit fixes all of these.
Modifications:
* Correctly release buffers in DefaultHttp2FrameWriter
* Fix buffer leaks in tests
Result:
Tests pass without leaks
Motivation:
Draft 12 has just arrived and has quite a few changes. Need to update in
order to keep current with the spec.
Modifications:
This is a rewrite of the original (draft 10) code. There are only 2
handlers now: preface and connection. The connection handler is now
callback based rather than frame based (there are no frame classes
anymore). AbstractHttp2ConnectionHandler is the base class for any
HTTP/2 handlers. All of the stream priority logic now resides in the
outbound flow controller, and its interface exposes methods for
adding/updating priority for streams.
Upgraded to hpack 0.7.0, which is used by draft12. Also removed
draft10 code and moved draft12 code to the ../http2 package
(no draft subpackage).
Result:
Addition of a HTTP/2 draft 12 support.
Motivation:
See: https://github.com/netty/netty/issues/2402
See: https://tools.ietf.org/html/draft-ietf-httpbis-http2-10#section-3.5
Only the client should send the preface string, the server should not.
"The server connection header consists of just a SETTINGS frame (Section 6.5)
that MUST be the first frame the server sends in the HTTP/2 connection."
Modifications:
Split out Http2ClientPrefaceWriter and Http2ServerPrefaceReader from
Http2FrameEncoder and Http2FrameDecoder. The new channel handlers are added
to the pipeline and remove themselves after the preface is written/read.
Result:
HTTP2 client sends preface, server does not, in compliance with spec.
Motivation:
HTTP2 is generally negotiated over SSL, makes more sense to provide an SSL example.
Modifications:
Copy the SDPY example to add SSL and NPN negotiation to the HTTP2 example.
Result:
Http2Server and Http2Client examples use SSL.
and initial settings frame were sent.
Motivation:
The current logic for marking the connection header and initial settings
frame is a bit complicated.
Modifications:
- Http2FrameEncoder, Http2ConnectionHandler: removed sent listeners and
set the sent flag immediately.
Result:
Just a code cleanup ... behavior is the same.
Motivation:
The current HTTP/2 support does not properly comply with the HTTP/2 spec
wrt startup.
Modifications:
Changed the frame codec as well as the connection handler to support
exchange of the connection preface, followed immediately by an initial
settings frame.
Result:
The HTTP/2 initialization handshake will be in compliance with the spec.
Will need more work to support the upgrade protocols, however :)
Motivation:
Provide some example code to show how to bootstrap client and server for
use with HTTP/2 framing.
Modifications:
- Fixed Http2ConnectionHandler to allow headers after stream creation.
Needed for response headers.
- Added toString() to all frame classes to help with debugging/logging
- Added example classes for HTTP/2
Result:
HTTP/2 connections now properly support response headers. Examples for
HTTP/2 provided with the distribution of examples module.
After your change, what will change.
Motivation:
Bring the http2 codec more inline with the rest of Netty's code-base.
Modifications:
- Add null checks in constructors
- Move private static methods into inner-classes where they are used
- Use getBytes(CharsetUtil.UTf8)
Result:
More consistent code-base
Motivation:
The use of the guava library library is fairly superficial and can
easily be removed to reduce the overall dependency list of the module.
Cleaning up the HTTP2 code to use common Netty utilities, etc.
Modifications:
- Various changes to remove use of guava preconditions and collections.
- Changed default charset to use CharsetUtil.UTF_8.
- Changed StreamState to use ArrayDeque instead of LinkedList.
- Changed precondition checks to throw NPE
- Changed implementation of Http2Headers to more closely mirror the SPDY
implementation.
Result:
The behavior of the HTTP2 module will remain unchanged.
Motivation:
Needed a rough performance comparison between SPDY and HTTP 2.0 framing.
Expected performance gains were seen in HTTP 2.0 due to header
compression.
Modifications:
Added a new codec-http2 module containing all of the new source and unit
tests. Updated the top-level pom.xml to add this as a child module.
Result:
Netty will have basic support for HTTP2.
