Package io.netty.handler.codec.http2

Class StreamBufferingEncoder

java.lang.Object

io.netty.handler.codec.http2.DecoratingHttp2FrameWriter

io.netty.handler.codec.http2.DecoratingHttp2ConnectionEncoder

io.netty.handler.codec.http2.StreamBufferingEncoder

All Implemented Interfaces:

Http2ConnectionEncoder, Http2DataWriter, Http2FrameWriter, Http2SettingsReceivedConsumer, Closeable, AutoCloseable

public class StreamBufferingEncoder
extends DecoratingHttp2ConnectionEncoder

Implementation of a Http2ConnectionEncoder that dispatches all method call to another Http2ConnectionEncoder, until SETTINGS_MAX_CONCURRENT_STREAMS is reached.

When this limit is hit, instead of rejecting any new streams this implementation buffers newly created streams and their corresponding frames. Once an active stream gets closed or the maximum number of concurrent streams is increased, this encoder will automatically try to empty its buffer and create as many new streams as possible.

If a GOAWAY frame is received from the remote endpoint, all buffered writes for streams with an ID less than the specified lastStreamId will immediately fail with a StreamBufferingEncoder.Http2GoAwayException.

If the channel/encoder gets closed, all new and buffered writes will immediately fail with a StreamBufferingEncoder.Http2ChannelClosedException.

This implementation makes the buffering mostly transparent and is expected to be used as a drop-in decorator of DefaultHttp2ConnectionEncoder.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private final class	StreamBufferingEncoder.DataFrame
private static class	StreamBufferingEncoder.Frame
private static final class	StreamBufferingEncoder.GoAwayDetail
private final class	StreamBufferingEncoder.HeadersFrame
static final class	StreamBufferingEncoder.Http2ChannelClosedException	Thrown if buffered streams are terminated due to this encoder being closed.
static final class	StreamBufferingEncoder.Http2GoAwayException	Thrown by StreamBufferingEncoder if buffered streams are terminated due to receipt of a GOAWAY.
private static final class	StreamBufferingEncoder.PendingStream

Nested classes/interfaces inherited from interface io.netty.handler.codec.http2.Http2FrameWriter

Http2FrameWriter.Configuration

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	closed
private StreamBufferingEncoder.GoAwayDetail	goAwayDetail
private int	maxConcurrentStreams
private final TreeMap<Integer,StreamBufferingEncoder.PendingStream>	pendingStreams	Buffer for any streams and corresponding frames that could not be created due to the maximum concurrent stream limit being hit.

Constructor Summary

Constructors

Constructor	Description
StreamBufferingEncoder(Http2ConnectionEncoder delegate)
StreamBufferingEncoder(Http2ConnectionEncoder delegate, int initialMaxConcurrentStreams)

Method Summary

Modifier and Type	Method	Description
private void	cancelGoAwayStreams(StreamBufferingEncoder.GoAwayDetail goAwayDetail)
private boolean	canCreateStream()	Determines whether or not we're allowed to create a new stream right now.
void	close()	Closes this writer and frees any allocated resources.
private boolean	isExistingStream(int streamId)
int	numBufferedStreams()	Indicates the number of streams that are currently buffered, awaiting creation.
void	remoteSettings(Http2Settings settings)	Sets the settings for the remote endpoint of the HTTP/2 connection.
private void	tryCreatePendingStreams()
private void	updateMaxConcurrentStreams()
ChannelFuture	writeData(ChannelHandlerContext ctx, int streamId, ByteBuf data, int padding, boolean endOfStream, ChannelPromise promise)	Writes a DATA frame to the remote endpoint.
ChannelFuture	writeHeaders(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int padding, boolean endStream, ChannelPromise promise)	Writes a HEADERS frame to the remote endpoint.
ChannelFuture	writeHeaders(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int streamDependency, short weight, boolean exclusive, int padding, boolean endOfStream, ChannelPromise promise)	Writes a HEADERS frame with priority specified to the remote endpoint.
private ChannelFuture	writeHeaders0(ChannelHandlerContext ctx, int streamId, Http2Headers headers, boolean hasPriority, int streamDependency, short weight, boolean exclusive, int padding, boolean endOfStream, ChannelPromise promise)
ChannelFuture	writeRstStream(ChannelHandlerContext ctx, int streamId, long errorCode, ChannelPromise promise)	Writes a RST_STREAM frame to the remote endpoint.
ChannelFuture	writeSettingsAck(ChannelHandlerContext ctx, ChannelPromise promise)	Writes a SETTINGS acknowledgment to the remote endpoint.

Methods inherited from class io.netty.handler.codec.http2.DecoratingHttp2ConnectionEncoder

connection, consumeReceivedSettings, flowController, frameWriter, lifecycleManager, pollSentSettings

Methods inherited from class io.netty.handler.codec.http2.DecoratingHttp2FrameWriter

configuration, writeFrame, writeGoAway, writePing, writePriority, writePushPromise, writeSettings, writeWindowUpdate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.netty.handler.codec.http2.Http2ConnectionEncoder

writeFrame

Methods inherited from interface io.netty.handler.codec.http2.Http2FrameWriter

configuration, writeGoAway, writePing, writePriority, writePushPromise, writeSettings, writeWindowUpdate

Field Details

pendingStreams

private final TreeMap<Integer,StreamBufferingEncoder.PendingStream> pendingStreams

Buffer for any streams and corresponding frames that could not be created due to the maximum concurrent stream limit being hit.

maxConcurrentStreams

private int maxConcurrentStreams

closed

private boolean closed

goAwayDetail

private StreamBufferingEncoder.GoAwayDetail goAwayDetail

Constructor Details

StreamBufferingEncoder

public StreamBufferingEncoder(Http2ConnectionEncoder delegate)

StreamBufferingEncoder

public StreamBufferingEncoder(Http2ConnectionEncoder delegate,
 int initialMaxConcurrentStreams)

Method Details

numBufferedStreams

public int numBufferedStreams()

Indicates the number of streams that are currently buffered, awaiting creation.

writeHeaders

public ChannelFuture writeHeaders(ChannelHandlerContext ctx,
 int streamId,
 Http2Headers headers,
 int padding,
 boolean endStream,
 ChannelPromise promise)

Description copied from interface: Http2FrameWriter

Writes a HEADERS frame to the remote endpoint.

Specified by:

writeHeaders in interface Http2FrameWriter

Overrides:

writeHeaders in class DecoratingHttp2FrameWriter

Parameters:

ctx - the context to use for writing.

streamId - the stream for which to send the frame.

headers - the headers to be sent.

padding - additional bytes that should be added to obscure the true content size. Must be between 0 and 256 (inclusive).

endStream - indicates if this is the last frame to be sent for the stream.

promise - the promise for the write.

Returns:

the future for the write. Section 10.5.1 states the following:

 The header block MUST be processed to ensure a consistent connection state, unless the connection is closed.
 

If this call has modified the HPACK header state you MUST throw a connection error.

If this call has NOT modified the HPACK header state you are free to throw a stream error.

writeHeaders

public ChannelFuture writeHeaders(ChannelHandlerContext ctx,
 int streamId,
 Http2Headers headers,
 int streamDependency,
 short weight,
 boolean exclusive,
 int padding,
 boolean endOfStream,
 ChannelPromise promise)

Description copied from interface: Http2FrameWriter

Writes a HEADERS frame with priority specified to the remote endpoint.

Specified by:

writeHeaders in interface Http2FrameWriter

Overrides:

writeHeaders in class DecoratingHttp2FrameWriter

Parameters:

ctx - the context to use for writing.

streamId - the stream for which to send the frame.

headers - the headers to be sent.

streamDependency - the stream on which this stream should depend, or 0 if it should depend on the connection.

weight - the weight for this stream.

exclusive - whether this stream should be the exclusive dependant of its parent.

padding - additional bytes that should be added to obscure the true content size. Must be between 0 and 256 (inclusive).

endOfStream - indicates if this is the last frame to be sent for the stream.

promise - the promise for the write.

Returns:

the future for the write. Section 10.5.1 states the following:

 The header block MUST be processed to ensure a consistent connection state, unless the connection is closed.
 

If this call has modified the HPACK header state you MUST throw a connection error.

If this call has NOT modified the HPACK header state you are free to throw a stream error.

writeHeaders0

private ChannelFuture writeHeaders0(ChannelHandlerContext ctx,
 int streamId,
 Http2Headers headers,
 boolean hasPriority,
 int streamDependency,
 short weight,
 boolean exclusive,
 int padding,
 boolean endOfStream,
 ChannelPromise promise)

writeRstStream

public ChannelFuture writeRstStream(ChannelHandlerContext ctx,
 int streamId,
 long errorCode,
 ChannelPromise promise)

Description copied from interface: Http2FrameWriter

Writes a RST_STREAM frame to the remote endpoint.

Specified by:

writeRstStream in interface Http2FrameWriter

Overrides:

writeRstStream in class DecoratingHttp2FrameWriter

Parameters:

ctx - the context to use for writing.

streamId - the stream for which to send the frame.

errorCode - the error code indicating the nature of the failure.

promise - the promise for the write.

Returns:

the future for the write.

writeData

public ChannelFuture writeData(ChannelHandlerContext ctx,
 int streamId,
 ByteBuf data,
 int padding,
 boolean endOfStream,
 ChannelPromise promise)

Description copied from interface: Http2DataWriter

Writes a DATA frame to the remote endpoint. This will result in one or more frames being written to the context.

Specified by:

writeData in interface Http2DataWriter

Overrides:

writeData in class DecoratingHttp2FrameWriter

Parameters:

ctx - the context to use for writing.

streamId - the stream for which to send the frame.

data - the payload of the frame. This will be released by this method.

padding - additional bytes that should be added to obscure the true content size. Must be between 0 and 256 (inclusive). A 1 byte padding is encoded as just the pad length field with value 0. A 256 byte padding is encoded as the pad length field with value 255 and 255 padding bytes appended to the end of the frame.

endOfStream - indicates if this is the last frame to be sent for the stream.

promise - the promise for the write.

Returns:

the future for the write.

writeSettingsAck

public ChannelFuture writeSettingsAck(ChannelHandlerContext ctx,
 ChannelPromise promise)

Description copied from interface: Http2FrameWriter

Writes a SETTINGS acknowledgment to the remote endpoint.

Specified by:

writeSettingsAck in interface Http2FrameWriter

Overrides:

writeSettingsAck in class DecoratingHttp2FrameWriter

Parameters:

ctx - the context to use for writing.

promise - the promise for the write.

Returns:

the future for the write.

remoteSettings

public void remoteSettings(Http2Settings settings)
                    throws Http2Exception

Description copied from interface: Http2ConnectionEncoder

Sets the settings for the remote endpoint of the HTTP/2 connection.

Specified by:

remoteSettings in interface Http2ConnectionEncoder

Overrides:

remoteSettings in class DecoratingHttp2ConnectionEncoder

Throws:

Http2Exception

updateMaxConcurrentStreams

private void updateMaxConcurrentStreams()

close

public void close()

Description copied from interface: Http2FrameWriter

Closes this writer and frees any allocated resources.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface Http2FrameWriter

Overrides:

close in class DecoratingHttp2FrameWriter

tryCreatePendingStreams

private void tryCreatePendingStreams()

cancelGoAwayStreams

private void cancelGoAwayStreams(StreamBufferingEncoder.GoAwayDetail goAwayDetail)

canCreateStream

private boolean canCreateStream()

Determines whether or not we're allowed to create a new stream right now.

isExistingStream

private boolean isExistingStream(int streamId)