Class: HTTP2::Stream

Inherits:
Object
  • Object
show all
Includes:
Emitter, Error, FlowBuffer
Defined in:
lib/http/2/stream.rb

Overview

A single HTTP 2.0 connection can multiplex multiple streams in parallel: multiple requests and responses can be in flight simultaneously and stream data can be interleaved and prioritized.

This class encapsulates all of the state, transition, flow-control, and error management as defined by the HTTP 2.0 specification. All you have to do is subscribe to appropriate events (marked with “:” prefix in diagram below) and provide your application logic to handle request and response processing.

                      +--------+
                 PP   |        |   PP
             ,--------|  idle  |--------.
            /         |        |         \
           v          +--------+          v
    +----------+          |           +----------+
    |          |          | H         |          |
,---|:reserved |          |           |:reserved |---.
|   | (local)  |          v           | (remote) |   |
|   +----------+      +--------+      +----------+   |
|      | :active      |        |      :active |      |
|      |      ,-------|:active |-------.      |      |
|      | H   /   ES   |        |   ES   \   H |      |
|      v    v         +--------+         v    v      |
|   +-----------+          |          +-----------+  |
|   |:half_close|          |          |:half_close|  |
|   |  (remote) |          |          |  (local)  |  |
|   +-----------+          |          +-----------+  |
|        |                 v                |        |
|        |    ES/R    +--------+    ES/R    |        |
|        `----------->|        |<-----------'        |
| R                   | :close |                   R |
`-------------------->|        |<--------------------'
                      +--------+

Constant Summary collapse

STREAM_OPEN_STATES = 
%i[open half_closed_local half_closing closing].freeze

Constants included from FlowBuffer

FlowBuffer::MAX_WINDOW_SIZE

Instance Attribute Summary collapse

Attributes included from FlowBuffer

#send_buffer

Instance Method Summary collapse

Methods included from Emitter

#emit, #on, #once

Methods included from FlowBuffer

#buffered_amount, #flush

Constructor Details

#initialize(connection:, id:, weight: 16, dependency: 0, exclusive: false, parent: nil, state: :idle) ⇒ Stream

Initializes new stream.

Note that you should never have to call this directly. To create a new client initiated stream, use Connection#new_stream. Similarly, Connection will emit new stream objects, when new stream frames are received.

Parameters:

  • id (Integer)
  • weight (Integer) (defaults to: 16)
  • dependency (Integer) (defaults to: 0)
  • exclusive (Boolean) (defaults to: false)
  • window (Integer)
  • parent (Stream) (defaults to: nil)
  • state (Symbol) (defaults to: :idle) 


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# File 'lib/http/2/stream.rb', line 78

def initialize(connection:, id:, weight: 16, dependency: 0, exclusive: false, parent: nil, state: :idle)
  stream_error(:protocol_error, msg: "stream can't depend on itself") if id == dependency

  @connection = connection
  @id = id
  @weight = weight
  @dependency = dependency

  # from mixins
  @listeners = Hash.new { |hash, key| hash[key] = [] }
  @send_buffer = FrameBuffer.new

  process_priority(weight: weight, dependency: dependency, exclusive: exclusive)
  @local_window_max_size = connection.local_settings[:settings_initial_window_size]
  @local_window = connection.local_settings[:settings_initial_window_size]
  @remote_window = connection.remote_settings[:settings_initial_window_size]
  @parent = parent
  @state  = state
  @error  = false
  @closed = false
  @_method = @_content_length = @_status_code = @_trailers = nil
  @_waiting_on_trailers = false
  @received_data = false
  @activated = false

  on(:window) { |v| @remote_window = v }
  on(:local_window) { |v| @local_window_max_size = @local_window = v }
end

Instance Attribute Details

#closed ⇒ Object (readonly)

Reason why connection was closed.



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# File 'lib/http/2/stream.rb', line 63

def closed
  @closed
end

#dependency ⇒ Object (readonly)

Returns the value of attribute dependency.



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# File 'lib/http/2/stream.rb', line 56

def dependency
  @dependency
end

#id ⇒ Object (readonly)

Stream ID (odd for client initiated streams, even otherwise).



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# File 'lib/http/2/stream.rb', line 46

def id
  @id
end

#local_window ⇒ Object (readonly) Also known as: window

Size of current stream flow control window.



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# File 'lib/http/2/stream.rb', line 59

def local_window
  @local_window
end

#parent ⇒ Object (readonly)

Request parent stream of push stream.



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# File 'lib/http/2/stream.rb', line 52

def parent
  @parent
end

#remote_window ⇒ Object (readonly)

Returns the value of attribute remote_window.



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# File 'lib/http/2/stream.rb', line 56

def remote_window
  @remote_window
end

#state ⇒ Object (readonly)

Stream state as defined by HTTP 2.0.



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# File 'lib/http/2/stream.rb', line 49

def state
  @state
end

#weight ⇒ Object (readonly)

Stream priority as set by initiator.



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# File 'lib/http/2/stream.rb', line 55

def weight
  @weight
end

Instance Method Details

#calculate_content_length(data_length) ⇒ Object 



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# File 'lib/http/2/stream.rb', line 185

def calculate_content_length(data_length)
  return unless @_content_length && data_length

  @_content_length -= data_length
  return if @_content_length >= 0

  stream_error(:protocol_error, msg: "received more data than what was defined in content-length")
end

#cancel ⇒ Object

Sends a RST_STREAM indicating that the stream is no longer needed.



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# File 'lib/http/2/stream.rb', line 287

def cancel
  send(type: :rst_stream, error: :cancel)
end

#chunk_data(payload, max_size) ⇒ Object

Chunk data into max_size, yield each chunk, then return final chunk



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# File 'lib/http/2/stream.rb', line 268

def chunk_data(payload, max_size)
  total = payload.bytesize
  cursor = 0
  while (total - cursor) > max_size
    yield payload.byteslice(cursor, max_size)
    cursor += max_size
  end
  payload.byteslice(cursor, total - cursor)
end

#close(error = :stream_closed) ⇒ Object

Sends a RST_STREAM frame which closes current stream - this does not close the underlying connection.

Parameters:

  • error (:Symbol) (defaults to: :stream_closed) —

    optional reason why stream was closed



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# File 'lib/http/2/stream.rb', line 282

def close(error = :stream_closed)
  send(type: :rst_stream, error: error)
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/http/2/stream.rb', line 107

def closed?
  @state == :closed
end

#data(payload, end_stream: true) ⇒ Object

Sends DATA frame containing response payload.

Parameters:

  • payload (String)
  • end_stream (Boolean) (defaults to: true) —

    indicates last response DATA frame



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# File 'lib/http/2/stream.rb', line 250

def data(payload, end_stream: true)
  # Split data according to each frame is smaller enough
  # TODO: consider padding?
  max_size = @connection.remote_settings[:settings_max_frame_size]

  if payload.bytesize > max_size
    payload = chunk_data(payload, max_size) do |chunk|
      send(type: :data, flags: [], payload: chunk)
    end
  end

  flags = []
  flags << :end_stream if end_stream
  send(type: :data, flags: flags, payload: payload)
end

#headers(headers, end_headers: true, end_stream: false) ⇒ Object

Sends a HEADERS frame containing HTTP response headers. All pseudo-header fields MUST appear in the header block before regular header fields.

Parameters:

  • headers (Array or Hash) —

    Array of key-value pairs or Hash

  • end_headers (Boolean) (defaults to: true) —

    indicates that no more headers will be sent

  • end_stream (Boolean) (defaults to: false) —

    indicates that no payload will be sent



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# File 'lib/http/2/stream.rb', line 221

def headers(headers, end_headers: true, end_stream: false)
  flags = []
  flags << :end_headers if end_headers
  flags << :end_stream  if end_stream || @_method == "HEAD"

  send(type: :headers, flags: flags, payload: headers)
end

#promise(headers, end_headers: true, &block) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/http/2/stream.rb', line 229

def promise(headers, end_headers: true, &block)
  raise ArgumentError, "must provide callback" unless block

  flags = end_headers ? [:end_headers] : []
  emit(:promise, self, headers, flags, &block)
end

#receive(frame) ⇒ Object Also known as: <<

Processes incoming HTTP 2.0 frames. The frames must be decoded upstream.

Parameters:

  • frame (Hash) 


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# File 'lib/http/2/stream.rb', line 114

def receive(frame)
  transition(frame, false)

  case frame[:type]
  when :data
    # 6.1. DATA
    # If a DATA frame is received whose stream is not in "open" or
    # "half closed (local)" state, the recipient MUST respond with a
    # stream error (Section 5.4.2) of type STREAM_CLOSED.
    stream_error(:stream_closed) unless STREAM_OPEN_STATES.include?(@state) ||
                                        (@state == :closed && @closed == :local_rst)
    @received_data = true
    calculate_content_length(frame[:length])
    update_local_window(frame)
    # Emit DATA frame
    emit(:data, frame[:payload]) unless frame[:ignore]
    calculate_window_update(@local_window_max_size)
  when :headers
    stream_error(:stream_closed) if (@state == :closed && @closed != :local_rst) ||
                                    @state == :remote_closed
    @_method ||= frame[:method]
    @_status_code ||= frame[:status]
    @_content_length ||= frame[:content_length]
    @_trailers ||= frame[:trailer]
    if @_waiting_on_trailers ||
       (@received_data &&
           (!@_status_code || @_status_code >= 200))

      # An endpoint that receives a HEADERS frame without the END_STREAM flag set after receiving a final
      # (non-informational) status code MUST treat the corresponding request or response as malformed.
      verify_trailers(frame)
    end
    emit(:headers, frame[:payload]) unless frame[:ignore]
    @_waiting_on_trailers = !@_trailers.nil?
  when :push_promise
    emit(:promise_headers, frame[:payload]) unless frame[:ignore]
  when :continuation
    stream_error(:stream_closed) if (@state == :closed && @closed != :local_rst) || @state == :remote_closed
    stream_error(:protocol_error) if @received_data
  when :priority
    process_priority(frame)
  when :window_update
    process_window_update(frame: frame)
  when :altsvc
    # 4.  The ALTSVC HTTP/2 Frame
    # An ALTSVC frame on a
    # stream other than stream 0 containing non-empty "Origin" information
    # is invalid and MUST be ignored.
    emit(frame[:type], frame) if !frame[:origin] || frame[:origin].empty?
  when :blocked
    emit(frame[:type], frame)
  end

  complete_transition(frame)
end

#refuse ⇒ Object

Sends a RST_STREAM indicating that the stream has been refused prior to performing any application processing.



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# File 'lib/http/2/stream.rb', line 293

def refuse
  send(type: :rst_stream, error: :refused_stream)
end

#reprioritize(weight: 16, dependency: 0, exclusive: false) ⇒ Object

Sends a PRIORITY frame with new stream priority value (can only be performed by the client).

Parameters:

  • weight (Integer) (defaults to: 16) —

    new stream weight value

  • dependency (Integer) (defaults to: 0) —

    new stream dependency stream



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# File 'lib/http/2/stream.rb', line 241

def reprioritize(weight: 16, dependency: 0, exclusive: false)
  stream_error if @id.even?
  send(type: :priority, weight: weight, dependency: dependency, exclusive: exclusive)
end

#send(frame) ⇒ Object

Processes outgoing HTTP 2.0 frames. Data frames may be automatically split and buffered based on maximum frame size and current stream flow control window size.

Parameters:

  • frame (Hash) 


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# File 'lib/http/2/stream.rb', line 199

def send(frame)
  case frame[:type]
  when :data
    # stream state management is maintained in send_data
    return send_data(frame)
  when :window_update
    @local_window += frame[:increment]
  when :priority
    process_priority(frame)
  end

  manage_state(frame) do
    emit(:frame, frame)
  end
end

#verify_trailers(frame) ⇒ Object 



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# File 'lib/http/2/stream.rb', line 171

def verify_trailers(frame)
  stream_error(:protocol_error, msg: "trailer headers frame must close the stream") unless end_stream?(frame)
  return unless @_trailers

  trailers = frame[:payload]
  return unless trailers.respond_to?(:each)

  trailers.each do |field, _| # rubocop:disable Style/HashEachMethods
    @_trailers.delete(field)
    break if @_trailers.empty?
  end
  stream_error(:protocol_error, msg: "didn't receive all expected trailer headers") unless @_trailers.empty?
end

#window_update(increment) ⇒ Object

Sends a WINDOW_UPDATE frame to the peer.

Parameters:

  • increment (Integer) 


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# File 'lib/http/2/stream.rb', line 300

def window_update(increment)
  # emit stream-level WINDOW_UPDATE unless stream is closed
  return if @state == :closed || @state == :remote_closed

  send(type: :window_update, increment: increment)
end