Module: Protocol::HTTP2::FlowControlled

Included in:
Connection, Stream
Defined in:
lib/protocol/http2/flow_controlled.rb

Instance Method Summary collapse

Instance Method Details

#available_frame_size(maximum_frame_size = self.maximum_frame_size) ⇒ Object

This could be negative if the window has been overused due to a change in initial window size.



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# File 'lib/protocol/http2/flow_controlled.rb', line 17

def available_frame_size(maximum_frame_size = self.maximum_frame_size)
  available_size = self.available_size
  
  # puts "available_size=#{available_size} maximum_frame_size=#{maximum_frame_size}"
  
  if available_size < maximum_frame_size
    return available_size
  else
    return maximum_frame_size
  end
end

#available_size ⇒ Object 



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# File 'lib/protocol/http2/flow_controlled.rb', line 12

def available_size
  @remote_window.available
end

#consume_local_window(frame) ⇒ Object 



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# File 'lib/protocol/http2/flow_controlled.rb', line 48

def consume_local_window(frame)
  # For flow-control calculations, the 9-octet frame header is not counted.
  amount = frame.length
  @local_window.consume(amount)
end

#consume_remote_window(frame) ⇒ Object

Keep track of the amount of data sent, and fail if is too much.



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# File 'lib/protocol/http2/flow_controlled.rb', line 30

def consume_remote_window(frame)
  amount = frame.length
  
  # Frames with zero length with the END_STREAM flag set (that is, an empty DATA frame) MAY be sent if there is no available space in either flow-control window.
  if amount.zero? and frame.end_stream?
    # It's okay, we can send. No need to consume, it's empty anyway.
  elsif amount >= 0 and amount <= @remote_window.available
    @remote_window.consume(amount)
  else
    raise FlowControlError, "Trying to send #{frame.length} bytes, exceeded window size: #{@remote_window.available} (#{@remote_window})"
  end
end

#receive_window_update(frame) ⇒ Object 



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# File 'lib/protocol/http2/flow_controlled.rb', line 70

def receive_window_update(frame)
  amount = frame.unpack
  
  # Async.logger.info(self) {"expanding remote_window=#{@remote_window} by #{amount}"}
  
  if amount != 0
    @remote_window.expand(amount)
  else
    raise ProtocolError, "Invalid window size increment: #{amount}!"
  end
  
  # puts "expanded remote_window=#{@remote_window} by #{amount}"
end

#request_window_update ⇒ Object 



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# File 'lib/protocol/http2/flow_controlled.rb', line 54

def request_window_update
  if @local_window.limited?
    self.send_window_update(@local_window.wanted)
  end
end

#send_window_update(window_increment) ⇒ Object

Notify the remote end that we are prepared to receive more data:



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# File 'lib/protocol/http2/flow_controlled.rb', line 61

def send_window_update(window_increment)
  frame = WindowUpdateFrame.new(self.id)
  frame.pack window_increment
  
  write_frame(frame)
  
  @local_window.expand(window_increment)
end

#update_local_window(frame) ⇒ Object 



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# File 'lib/protocol/http2/flow_controlled.rb', line 43

def update_local_window(frame)
  consume_local_window(frame)
  request_window_update
end

#window_updated(size) ⇒ Boolean

The window has been expanded by the given amount.

Parameters:

  • size (Integer) —

    the maximum amount of data to send.

Returns:

  • (Boolean) —

    whether the window update was used or not.



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# File 'lib/protocol/http2/flow_controlled.rb', line 87

def window_updated(size)
  return false
end