Class StreamBufferingEncoder

All Implemented Interfaces:
Http2ConnectionEncoder, Http2DataWriter, Http2FrameWriter, Http2SettingsReceivedConsumer, Closeable, AutoCloseable

@UnstableApi 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.

  • Field Details

  • Constructor Details

  • 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.

    • 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.
    • 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
    • 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)