Commit Graph

205 Commits

Author SHA1 Message Date
Trustin Lee
3b941c2a7c [maven-release-plugin] prepare for next development iteration 2016-04-02 01:25:05 -04:00
Trustin Lee
7368ccc539 [maven-release-plugin] prepare release netty-4.1.0.CR6 2016-04-02 01:24:55 -04:00
Norman Maurer
cee38ed2b6 [maven-release-plugin] prepare for next development iteration 2016-03-29 16:45:13 +02:00
Norman Maurer
9cd9e7daeb [maven-release-plugin] prepare release netty-4.1.0.CR5 2016-03-29 16:44:33 +02:00
Scott Mitchell
61cfdd7671 e24a5d8 compile error
Motivation:
e24a5d8 was cherry-picked but had a compile error.

Modifications:
- Fix the compile error in e24a5d8

Result:
Build now compiles.
2016-03-25 12:51:13 -07:00
Eric Anderson
e24a5d8839 Map HTTP/2 Streams to Channels
Motivation:

This allows using handlers for Streams in normal Netty-style. Frames are
read/written to the channel as messages, not directly as a
callback/method call. Handlers allow mixing and can ease HTTP/1 and
HTTP/2 interoperability by eventually supporting HTTP/1 handlers in
HTTP/2 and vise versa.

Modifications:

New handler Http2MultiplexCodec that converts from the current HTTP/2
API to a message-based API and child channels for streams.

Result:

The basics are done for server-side: new streams trigger creation of new
channels in much the same appearance to how new connections trigger new
channel creation. The basic frames HEADERS and DATA are handled, but
also GOAWAY and RST_STREAM.

Inbound flow control is implemented, but outbound is not. That will be
done later, along with not completing write promises on the child
channel until the write actually completes on the parent.

There is not yet support for outbound priority/weight, push promises,
and many other features.

There is a generic Object that may be set on stream frames. This also
paves the way for client-side support which needs a way to refer to
yet-to-be-created streams (due to how HEADERS allocates a stream id, and
the allocation order must be the same as transmission order).
2016-03-25 12:14:44 -07:00
Carsten Varming
d6bf388343 Prevent nepotism with generational GCs.
Motivation:

If a single Encoder object is promoted to the old generation then every object
reachable from the promoted object will eventually be promoted as well. A queue
illustrates the problem very well. Say a sequence of inserts and deletions
generate an object graph:

   A -> B -> C -> D -> E -> F -> G -> H,

the head of the queue is E, the tail of the queue is H, and A, B, C, D are
dead. If all queue nodes are in the young generation, then a young gc will
clean up the object graph and leave us with:

   E -> F -> G -> H

on the other hand, if B and C were previously promoted to the old generation,
then a young collection assumes the refernece from C to D is from a live object
(this is a key result of generational gc, no need to mark the old generation).
Hence the young collection assumes the refence to D is a gc root and leave us
with the object graph:

   B-> C -> D -> E -> F -> G -> H.

Eventually D, E, F, G, H, and all queue nodes ever seen from this point on will
be promoted, regardless of their global live or dead status. It is generally
trivial to fix nepotism issues by simply breaking the reference chain after
dequeuing a node.

Currently Encoder objects do not null their references when removed from the
hash map. We have observed a 20X increase in promoted Encoder objects due to
nepotism.

Modifications:

Null before, after, and next fields when removing Encoder objects from maps.

Result:

Fewer promoted Encoder objects, fewer Encoder objects in the old generation,
shorter young collection times, old collections spaced further apart (nepotism
is just really bad). Enjoy.
2016-03-23 17:27:00 +01:00
Norman Maurer
28d03adbfe [maven-release-plugin] prepare for next development iteration 2016-03-21 11:51:50 +01:00
Norman Maurer
4653dc1d05 [maven-release-plugin] prepare release netty-4.1.0.CR4 2016-03-21 11:51:12 +01:00
Scott Mitchell
fc099292fd HTTP/2 DefaultHttp2ConnectionEncoder data frame size incorrect if error
Motivation:
If an error occurs during a write operation then DefaultHttp2ConnectionEncoder.FlowControlledData will clear the CoalescingBufferQueue which will reset the queue's readable bytes to 0. To recover from an error the DefaultHttp2RemoteFlowController will attempt to return bytes to the flow control window, but since the frame has reset its own size this will lead to invalid flow control accounting.

Modifications:
- DefaultHttp2ConnectionEncoder.FlowControlledData should not reset its size if an error occurs

Result:
No more flow controller errors due to DefaultHttp2ConnectionEncoder.FlowControlledData setting its size to 0 if an error occurs.
2016-03-18 11:38:01 -07:00
Norman Maurer
8ec594c6eb Change HttpServerUpgradeHandler.UpgradeCodec to allow aborting upgrade
Motivation:

HttpServerUpgradeHandler.UpgradeCodec.prepareUpgradeResponse should allow to abort the upgrade and so just continue with using HTTP. Beside this we should only pass in the response HttpHeaders as this is inline with the docs.

Modifications:

- UpgradeCodec.prepareUpgradeResponse now allows to return a boolean and so allows to specifiy if the upgrade should take place.
- Change the param from FullHttpResponse to HttpHeaders to be inline with the javadocs.

Result:

More flexible and correct handling of upgrades.
2016-03-18 17:01:59 +01:00
Norman Maurer
ed9d6c79bc [#4972] Remove misleading argument from HttpServerUpgradeHandler.UpgradeCodec.upgradeTo
Motivation:

upgradeTo(...) takes the response as paramater, but the respone itself was already written to the Channel. This gives the user the impression the response can be changed or even act on it which may not be safe anymore once it was written and has been released.

Modifications:

Remove the response param from the method.

Result:

Less confusion and safer usage.
2016-03-17 10:50:07 +01:00
Scott Mitchell
6a2425b846 HTTP/2 SimpleChannelPromiseAggregator don't fail fast
Motivation:
Http2Codec.SimpleChannelPromiseAggregator currently fails fast if as soon as a tryFailure or setFailure method is called. This can lead to write operations which pass the result of SimpleChannelPromiseAggregator.newPromise to multiple channel.write calls throwing exceptions due to the promise being already done. This behavior is not expected by most of the Netty codecs (SslHandler) and can also create unexpected leaks in the http2 codec (DefaultHttp2FrameWriter).

Modifications:
- Http2Codec.SimpleChannelPromiseAggregator shouldn't complete the promise until doneAllocatingPromises is called
- Usages of Http2Codec.SimpleChannelPromiseAggregator should be adjusted to handle the change in behavior
- What were leaks in DefaultHttp2FrameWriter should be fixed to catch any other cases where ctx.write may throw

Result:
SimpleChannelPromiseAggregator won't generate promises which are done when newPromise is called.
2016-03-14 11:00:21 -07:00
Scott Mitchell
45849b2fa8 Deprecate PromiseAggregator
Motivation:
PromiseAggregator's API allows for the aggregate promise to complete before the user is done adding promises. In order to support this use case the API structure would need to change in a breaking manner.

Modifications:
- Deprecate PromiseAggregator and subclasses
- Introduce PromiseCombiner which corrects these issues

Result:
PromiseCombiner corrects the deficiencies in PromiseAggregator.
2016-03-14 10:53:30 -07:00
Scott Mitchell
404666d247 HTTP/2 ByteBufUtil.writeUtf8 cleanup
Motiviation:
691bc1690e made writeUtf8 consistent with String.getBytes() so that it never throws.
94f27be59b provided a writeUtf8 method which takes a ByteBufAllocator to do an appropriately sized buffer allocation.

Result:
- Assume writeUtf8 will not throw in HTTP/2 codec
- Use the new writeUtf8 method

Result:
Cleaner code in codec-http2.
2016-03-11 14:24:45 -08:00
Scott Mitchell
bd6040a36e HTTP/2 DefaultHttp2Connection NPE
Motivation:
If while iterating the active streams a close operation occurs this will be queued and process after the iteration has completed to avoid a concurrent modification exception. However it is possible that during the iteration the stream which was closed could have been removed from the priority tree and its parent would be set to null. Then after the iteration completes the close operation will attempt to dereference the parent and results in a NPE.

Modifications:
- pending close operations should verify the stream's parent is not null before processing the event

Result:
No More NPE.
2016-03-11 07:41:04 -08:00
Scott Mitchell
900353af52 HTTP/2 Reduce Log Level
Motivation:
83c4aa6ad8 changed the log level to warn, but should have changed to debug.

Modifications:
- Change the log level to debug in Http2ConnectionHandler if the GO_AWAY fails to send. The write failure could be the result of the channel already being closed.

Result:
Fixes https://github.com/netty/netty/issues/4930.
2016-03-04 17:25:04 -08:00
Scott Mitchell
4b5b230802 HTTP/2 DefaultHttp2HeadersDecoder weighted average error
Motiviation:
cfcee5798d introduced code to resize the headers based upon a weighted average. The weight used for new entries was initialized using integer arithmetic when it should have been floating point arithmetic and so new values contribute 0 weight.

Modifications:
- Cast to float when initializing

Result:
Weighted average does not give 0 weight to new headers in DefaultHttp2HeadersDecoder.
2016-03-02 15:07:38 -08:00
Scott Mitchell
c4fbc0642d HTTP/2 stream removed from map before onStreamClosed called
Motivation:
The interface contract of Http2Connection.Listener.onStreamClosed says that the stream will be removed from the active stream map, and not necessarily the stream map. If the channel becomes inactive we may remove from the stream map before calling onStreamClosed.

Modifications:
- Don't remove from the stream map during iteration until after onStreamClosed is called

Result:
Expectations of onStreamClosed interface are not violated
2016-02-29 08:46:22 -08:00
Norman Maurer
ca443e42e0 [maven-release-plugin] prepare for next development iteration 2016-02-19 23:00:11 +01:00
Norman Maurer
f39eb9a6b2 [maven-release-plugin] prepare release netty-4.1.0.CR3 2016-02-19 22:59:52 +01:00
Scott Mitchell
83c4aa6ad8 HTTP/2 Writes GO_AWAY on channelInactive
Motivation:
Http2ConnectionHandler inherits from ByteToMessageDecoder. ByteToMessageDecoder.channelInactive will attempt to decode any remaining data by calling the abstract decode method. If the Http2ConnectionHandler is in server mode, and no data has been exchanged yet, it will try to treat this data as an invalid connection preface and write a GO_AWAY. This is noisy in the logs and creates an illusion that there is a protocol violation when there has not been.

Modifications:
- If the channel is inactive the connection preface decode should not be executed.

Result:
Log files don't include misleading error messages related to connection preface errors.
2016-02-18 19:47:42 -08:00
Brendt Lucas
41d0a81691 Use ByteBufAllocator to allocate ByteBuf for FullHttpMessage Motivation: When converting SPDY or HTTP/2 frames to HTTP/1.x, netty always used an unpooled heap ByteBuf.
Modifications:
When constructing the FullHttpMessage pass in the ByteBuf to use via the ByteBufAllocator assigned via the context.

Result:
The ByteBuf assigned to the FullHttpMessage can now be configured as a pooled/unpooled, direct/heap based ByteBuf via the ByteBufAllocator used.
2016-02-17 19:55:52 -08:00
Moses Nakamura
f0f0b69d90 fixed "sensative" typo to read "sensitive" 2016-02-17 08:18:11 -08:00
Scott Mitchell
06e29e0d1b HTTP/2 codec may not always call Http2Connection.onStreamRemoved
Motivation:
Http2Connection.onStreamRemoved is not always called if Http2Connection.onStreamAdded is called. This is problematic as users may rely on the onStreamRemoved method to be called to release ByteBuf objects and do other cleanup.

Modifications:
- Http2Connection.close will remove all streams existing streams and prevent new ones from being created
- Http2ConnectionHandler will call the new close method in channelInactive

Result:
Http2Connection.onStreamRemoved is always called when Http2Connection.onStreamRemoved is called to preserve the Http2Connection guarantees.
Fixes https://github.com/netty/netty/issues/4838
2016-02-12 16:01:37 -08:00
Scott Mitchell
56e6e07b25 HTTP/2 RST_STREAM Regression f990f99
Motivation:
Commit f990f99 introduced a bug into the RST_STREAM processing that would prevent a RST_STREAM from being sent when it should have been. The promise would be marked as successful even though the RST_STREAM frame would never be sent.

Modifications:
- Fix conditional in Http2ConnectionHandler.resetStream to allow reset streams to be sent in all stream states besides IDLE.

Result:
RST_STREAM frames are now sent when they are supposed to be sent
Fixes https://github.com/netty/netty/issues/4856
2016-02-10 13:47:53 -08:00
Norman Maurer
75a2ddd61c [maven-release-plugin] prepare for next development iteration 2016-02-04 16:51:44 +01:00
Norman Maurer
7eb3a60dba [maven-release-plugin] prepare release netty-4.1.0.CR2 2016-02-04 16:37:06 +01:00
Scott Mitchell
7a7160f176 HTTP/2 Buffer Leak if UTF8 Conversion Fails
Motivation:
Http2CodecUtil uses ByteBufUtil.writeUtf8 but does not account for it
throwing an exception. If an exception is thrown because the format is
not valid UTF16 encoded UTF8 then the buffer will leak.

Modifications:
- Make sure the buffer is released if an exception is thrown
- Ensure call sites of the Http2CodecUtil.toByteBuf can tolerate and
  exception being thrown

Result:
No leak if exception data can not be converted to UTF8.
2016-02-02 11:22:17 -08:00
Scott Mitchell
f990f9983d HTTP/2 Don't Flow Control Iniital Headers
Motivation:
Currently the initial headers for every stream is queued in the flow controller. Since the initial header frame may create streams the peer must receive these frames in the order in which they were created, or else this will be a protocol error and the connection will be closed. Tolerating the initial headers being queued would increase the complexity of the WeightedFairQueueByteDistributor and there is benefit of doing so is not clear.

Modifications:
- The initial headers will no longer be queued in the flow controllers

Result:
Fixes https://github.com/netty/netty/issues/4758
2016-02-01 13:37:43 -08:00
Scott Mitchell
5fb18e3415 InboundHttp2ToHttpAdapter leak and logic improvements
Motivation:
In HttpConversionUtil's toHttpRequest and toHttpResponse methods can
allocate FullHttpMessage objects, and if an exeception is thrown during
the header conversion then this object will not be released. If a
FullHttpMessage is not fired up the pipeline, and the stream is closed
then we remove from the map, but do not release the object. This leads
to a ByteBuf leak. Some of the logic related to stream lifetime management
and FullHttpMessage also predates the RFC being finalized and is not correct.

Modifications:
- Fix leaks in HttpConversionUtil
- Ensure the objects are released when they are removed from the map.
- Correct logic and unit tests where they are found to be incorrect.

Result:
Fixes https://github.com/netty/netty/issues/4780
Fixes https://github.com/netty/netty/issues/3619
2016-02-01 12:38:40 -08:00
Trustin Lee
4d6ab1d30d Fix missing trailing data on HTTP client upgrade
Motivation:

When HttpClientUpgradeHandler upgrades from HTTP/1 to another protocol,
it performs a two-step opertion:

1. Remove the SourceCodec (HttpClientCodec)
2. Add the UpgradeCodec

When HttpClientCodec is removed from the pipeline, the decoder being
removed triggers channelRead() event with the data left in its
cumulation buffer. However, this is not received by the UpgradeCodec
becuase it's not added yet. e.g. HTTP/2 SETTINGS frame sent by the
server can be missed out.

To fix the problem, we need to reverse the steps:

1. Add the UpgradeCodec
2. Remove the SourceCodec

However, this does not work as expected either, because UpgradeCodec can
send a greeting message such as HTTP/2 Preface. Such a greeting message
will be handled by the SourceCodec and will trigger an 'unsupported
message type' exception.

To fix the problem really, we need to make the upgrade process 3-step:

1. Remove/disable the encoder of SourceCodec
2. Add the UpgradeCodec
3. Remove the SourceCodec

Modifications:

- Add SourceCodec.prepareUpgradeFrom() so that SourceCodec can remove or
  disable its encoder
- Implement HttpClientCodec.prepareUpgradeFrom() properly
- Miscellaneous:
  - Log the related channel as well When logging the failure to send a
    GOAWAY

Result:

Cleartext HTTP/1-to-HTTP/2 upgrade works again.
2016-02-01 15:52:37 +01:00
Scott Mitchell
11bcb8790c Http2Connection stream id generation to support queueing
Motivation:
StreamBufferingEncoder provides queueing so that MAX_CONCURRENT_STREAMS is not violated. However the stream id generation provided by Http2Connection.nextStreamId() only returns the next stream id that is expected on the connection and does not account for queueing. The codec should provide a way to generate the next stream id for a given endpoint that functions with or without queueing.

Modifications:
- Change Http2Connection.nextStreamId to Http2Connection.incrementAndGetNextStreamId

Result:
Http2Connection can generate the next stream id in queued and non-queued scenarios.
Fixes https://github.com/netty/netty/issues/4704
2016-01-29 11:37:17 -08:00
Scott Mitchell
78b508a7eb AbstractHttp2ConnectionHandlerBuilder validateHeaders cannot be set with encoder/decoder
Motivation:
If validateHeaders is set in combination with the encoder/decoder it will be silently ignored. We should enforce the constraint that validateHeaders and encoder/decoder are mutually exclusive.

Modifications:
- Make sure either validateHeaders can be set or encoder/decoder.

Result:
AbstractHttp2ConnectionHandlerBuilder does not allow conflicting options to be set.
2016-01-29 00:33:45 -08:00
Scott Mitchell
e8850072e2 HTTP/2 DefaultHttp2RemoteFlowController frame merging with padding bug
Motivation:
DefaultHttp2RemoteFlowController does not correctly account for the padding in the event frames are merged. This causes the internal stat of DefaultHttp2RemoteFlowController to become corrupt and can result in attempting to write frames when there are none.

Modifications:
- Update DefaultHttp2RemoteFlowController to account for frame sizes not necessarily adding together.

Result:
DefaultHttp2RemoteFlowController internal state does not become corrupt when padding is present.
Fixes https://github.com/netty/netty/issues/4573
2016-01-27 14:52:00 -08:00
Norman Maurer
1c417e5f82 [maven-release-plugin] prepare for next development iteration 2016-01-21 15:35:55 +01:00
Norman Maurer
c681a40a78 [maven-release-plugin] prepare release netty-4.1.0.CR1 2016-01-21 15:28:21 +01:00
Alex Petrov
7bcae8919d Log the current channel in Http2FrameLogger
Motivation:
Currently it's impossible to distinguish which
connection the corresponding logged message	is
related to.

Modifications:
Http2FrameLogger is extended to support channel
id logging, usages in Inbound/Outbound Frame
Loggers are adjusted accordingly.

Result:
Logger outputs the channel id.
2016-01-18 10:52:08 +01:00
Scott Mitchell
7dba13f276 HttpConversionUtil remove throws from method signature
Motivation:
HttpConversionUtil.toHttp2Headers currently has a throws Exception as part of the signature. This comes from the signature of ByteProcessor.process, but is not necessary because the ByteProcessor used does not throw.

Modifications:
- Remove throws Exception from the signature of HttpConversionUtil.toHttp2Headers.

Result:
HttpConversionUtil.toHttp2Headers interface does not propagate a throws Exception when it is used.
2016-01-15 10:53:34 +01:00
Norman Maurer
8716b9d4bd Revert "Fix unnecessary boxing and incorrect Serializable"
This reverts commit 0ae6f17285.
2015-12-31 14:48:10 +01:00
Xiaoyan Lin
0ae6f17285 Fix unnecessary boxing and incorrect Serializable
Motivation:

- AbstractHttp2ConnectionHandlerBuilder.encoderEnforceMaxConcurrentStreams can be the primitive boolean
- SpdySession.StreamComparator should not be Serializable since SpdySession is not Serializable

Modifications:

Use boolean instead and remove Serializable

Result:

- Minor improvement for AbstractHttp2ConnectionHandlerBuilder
- StreamComparator is not Serializable any more
2015-12-31 10:45:24 +01:00
Xiaoyan Lin
475d901131 Fix errors reported by javadoc
Motivation:

Javadoc reports errors about invalid docs.

Modifications:

Fix some errors reported by javadoc.

Result:

A lot of javadoc errors are fixed by this patch.
2015-12-27 08:36:45 +01:00
Xiaoyan Lin
a96d52fe66 Fix javadoc links and tags
Motivation:

There are some wrong links and tags in javadoc.

Modifications:

Fix the wrong links and tags in javadoc.

Result:

These links will work correctly in javadoc.
2015-12-26 08:34:31 +01:00
Scott Mitchell
80cff236e4 HTTP/2 UniformStreamByteDistributor negative window shouldn't write
Motivation:
If the stream window is negative UniformStreamByteDistributor may write data. This is prohibited by the RFC https://tools.ietf.org/html/rfc7540#section-6.9.2.

Modifications:
- UniformStreamByteDistributor should use StreamState.isWriteAllowed()

Result:
UniformStreamByteDistributor is more complaint with HTTP/2 RFC.
Fixes https://github.com/netty/netty/issues/4545
2015-12-23 10:14:24 -08:00
Scott Mitchell
7b2f55ec2f HTTP/2 Remove RemoteFlowController.streamWritten
Motivation:
RemoteFlowController.streamWritten is not currently required. We should remove it to keep interfaces minimal.

Modifications:
- Remove RemoteFlowController.streamWritten

Result:
1 Less method in RemoteFlowController interface.
Fixes https://github.com/netty/netty/issues/4600
2015-12-22 16:59:40 -08:00
Scott Mitchell
72accceeac HTTP/2 remove PriorityStreamByteDistributor
Motivation:
PriorityStreamByteDistributor is now obsolete and can be replaced by WeightedFairQueueByteDistributor.

Modifications:
- Remove PriorityStreamByteDistributor and use WeightedFairQueueByteDistributor by default.

Result:
PriorityStreamByteDistributor no longer has to be maintained and is replaced by a better algorithm.
2015-12-21 08:56:50 -08:00
Scott Mitchell
9ac430f16f HTTP/2 DefaultHttp2RemoteFlowController Stream writability notification broken
Motivation:
DefaultHttp2RemoteFlowController.ListenerWritabilityMonitor no longer reliably detects when a stream's writability change occurs.

Modifications:
- Ensure writiability is reliabily reported by DefaultHttp2RemoteFlowController.ListenerWritabilityMonitor
- Fix infinite loop issue (https://github.com/netty/netty/issues/4588) detected when consolidating unit tests

Result:
Reliable stream writability change notification, and 1 less infinite loop in UniformStreamByteDistributor.
Fixes https://github.com/netty/netty/issues/4587
2015-12-21 10:01:33 +01:00
Trustin Lee
b39380ad83 Revamp InboundHttp2ToHttpAdapter builder API
Related: #4572 #4574

Motivation:

Consistency in our builder API design

Modifications:

- Add AbstractInboundHttp2ToHttpAdapterBuilder
- Replace the old 'Builder's with InboundHttp2ToHttpAdapterBuilder and
  InboundHttp2ToHttpPriorityAdapterBuilder

Result:

Builder API consistency
2015-12-18 12:44:46 +09:00
Scott Mitchell
904e70a4d4 HTTP/2 Weighted Fair Queue Byte Distributor
Motivation:
PriorityStreamByteDistributor uses a homegrown algorithm which distributes bytes to nodes in the priority tree. PriorityStreamByteDistributor has no concept of goodput which may result in poor utilization of network resources. PriorityStreamByteDistributor also has performance issues related to the tree traversal approach and number of nodes that must be visited. There also exists some more proven algorithms from the resource scheduling domain which PriorityStreamByteDistributor does not employ.

Modifications:
- Introduce a new ByteDistributor which uses elements from weighted fair queue schedulers

Result:
StreamByteDistributor which is sensitive to priority and uses a more familiar distribution concept.
Fixes https://github.com/netty/netty/issues/4462
2015-12-17 11:17:02 -08:00
Trustin Lee
2202e8f967 Revamp the Http2ConnectionHandler builder API
Related: #4572

Motivation:

- A user might want to extend Http2ConnectionHandler and define his/her
  own static inner Builder class that extends
  Http2ConnectionHandler.BuilderBase. This introduces potential
  confusion because there's already Http2ConnectionHandler.Builder. Your
  IDE will warn about this name duplication as well.
- BuilderBase exposes all setters with public modifier. A user's Builder
  might not want to expose them to enforce it to certain configuration.
  There's no way to hide them because it's public already and they are
  final.
- BuilderBase.build(Http2ConnectionDecoder, Http2ConnectionEncoder)
  ignores most properties exposed by BuilderBase, such as
  validateHeaders, frameLogger and encoderEnforceMaxConcurrentStreams.
  If any build() method ignores the properties exposed by the builder,
  there's something wrong.
- A user's Builder that extends BuilderBase might want to require more
  parameters in build(). There's no way to do that cleanly because
  build() is public and final already.

Modifications:

- Make BuilderBase and Builder top-level so that there's no duplicate
  name issue anymore.
  - Add AbstractHttp2ConnectionHandlerBuilder
  - Add Http2ConnectionHandlerBuilder
  - Add HttpToHttp2ConnectionHandlerBuilder
- Make all builder methods in AbstractHttp2ConnectionHandlerBuilder
  protected so that a subclass can choose which methods to expose
- Provide only a single build() method
  - Add connection() and codec() so that a user can still specify
    Http2Connection or Http2Connection(En|De)coder explicitly
  - Implement proper state validation mechanism so that it is prevented
    to invoke conflicting setters

Result:

Less confusing yet flexible builder API
2015-12-17 14:08:13 +09:00