Class: Protocol::HTTP2::Stream

Inherits:
Object
  • Object
show all
Includes:
FlowControl
Defined in:
lib/protocol/http2/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.

                  +--------+
          send PP |        | recv PP
         ,--------|  idle  |--------.
        /         |        |         \
       v          +--------+          v
+----------+          |           +----------+
|          |          | send H /  |          |

,——| reserved | | recv H | reserved |——. | | (local) | | | (remote) | | | ---------- v ---------- | | | -------- | | | | recv ES | | send ES | | | send H | ,——-| open |——-. | recv H | | | / | | \ | | | v v -------- v v | | ---------- | ---------- | | | half | | | half | | | | closed | | send R / | closed | | | | (remote) | | recv R | (local) | | | ---------- | ---------- | | | | | | | | send ES / | recv ES / | | | | send R / v send R / | | | | recv R -------- recv R | | | send R / ‘———–>| |<———–’ send R / | | recv R | closed | recv R | ‘———————–>| |<———————-’

                      +--------+

send:   endpoint sends this frame
recv:   endpoint receives this frame

H:  HEADERS frame (with implied CONTINUATIONs)
PP: PUSH_PROMISE frame (with implied CONTINUATIONs)
ES: END_STREAM flag
R:  RST_STREAM frame

State transition methods use a trailing “!”.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from FlowControl

#available_frame_size, #available_size, #consume_local_window, #consume_window, #receive_window_update, #request_window_update, #send_window_update, #update_local_window, #window_updated

Constructor Details

#initialize(connection, id, state = :idle) ⇒ Stream

Returns a new instance of Stream.



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# File 'lib/protocol/http2/stream.rb', line 85

def initialize(connection, id, state = :idle)
  @connection = connection
  @id = id
  
  @state = state
  
  @local_window = Window.new(@connection.local_settings.initial_window_size)
  @remote_window = Window.new(@connection.remote_settings.initial_window_size)
  
  @dependency = @connection.dependency_for(@id)
end

Instance Attribute Details

#connection ⇒ Object (readonly)

The connection this stream belongs to.



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# File 'lib/protocol/http2/stream.rb', line 98

def connection
  @connection
end

#dependency ⇒ Object (readonly)

Returns the value of attribute dependency.



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# File 'lib/protocol/http2/stream.rb', line 106

def dependency
  @dependency
end

#id ⇒ Object (readonly)

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



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# File 'lib/protocol/http2/stream.rb', line 101

def id
  @id
end

#local_window ⇒ Object (readonly)

Returns the value of attribute local_window.



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# File 'lib/protocol/http2/stream.rb', line 108

def local_window
  @local_window
end

#remote_window ⇒ Object (readonly)

Returns the value of attribute remote_window.



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# File 'lib/protocol/http2/stream.rb', line 109

def remote_window
  @remote_window
end

#state ⇒ Object

Stream state, e.g. ‘idle`, `closed`.



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# File 'lib/protocol/http2/stream.rb', line 104

def state
  @state
end

Class Method Details

.create(connection, id) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 77

def self.create(connection, id)
  stream = self.new(connection, id)
  
  connection.streams[id] = stream
  
  return stream
end

Instance Method Details

#accept_push_promise_stream(stream_id, headers) ⇒ Object

Override this function to implement your own push promise logic.



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# File 'lib/protocol/http2/stream.rb', line 428

def accept_push_promise_stream(stream_id, headers)
  @connection.accept_push_promise_stream(stream_id)
end

#active? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/http2/stream.rb', line 144

def active?
  @state != :closed && @state != :idle
end

#children ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 127

def children
  @dependency&.streams
end

#close(error = nil) ⇒ Object

The stream is being closed because the connection is being closed.



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# File 'lib/protocol/http2/stream.rb', line 132

def close(error = nil)
  @connection.delete(@id)
end

#close!(error_code = nil) ⇒ Object

Transition the stream into the closed state.

Parameters:

  • error_code (Integer) (defaults to: nil) —

    the error code if the stream was closed due to a stream reset.



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# File 'lib/protocol/http2/stream.rb', line 248

def close!(error_code = nil)
  @state = :closed
  
  if error_code
    error = StreamError.new("Stream closed!", error_code)
  end
  
  self.close(error)
  
  return self
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/http2/stream.rb', line 148

def closed?
  @state == :closed
end

#consume_remote_window(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 201

def consume_remote_window(frame)
  super
  
  @connection.consume_remote_window(frame)
end

#create_push_promise_stream(headers) ⇒ Object

Override this function to implement your own push promise logic.



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# File 'lib/protocol/http2/stream.rb', line 408

def create_push_promise_stream(headers)
  @connection.create_push_promise_stream
end

#ignore_data(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 325

def ignore_data(frame)
  # Async.logger.warn(self) {"Received headers in state: #{@state}!"}
end

#ignore_reset_stream(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 355

def ignore_reset_stream(frame)
  # Async.logger.warn(self) {"Received reset stream (#{error_code}) in state: #{@state}!"}
end

#inspect ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 443

def inspect
  "\#<#{self.class} id=#{@id} state=#{@state}>"
end

#maximum_frame_size ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 136

def maximum_frame_size
  @connection.available_frame_size
end

#open! ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 236

def open!
  if @state == :idle
    @state = :open
  else
    raise ProtocolError, "Cannot open stream in state: #{@state}"
  end
  
  return self
end

#parent=(stream) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 123

def parent=(stream)
  @dependency.parent = stream.dependency
end

#priority ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 115

def priority
  @dependency.priority
end

#priority=(priority) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 119

def priority= priority
  @dependency.priority = priority
end

#process_data(frame) ⇒ String

Returns the data that was received.

Returns:

  • (String) —

    the data that was received.



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# File 'lib/protocol/http2/stream.rb', line 321

def process_data(frame)
  frame.unpack
end

#process_headers(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 273

def process_headers(frame)
  # Receiving request headers:
  priority, data = frame.unpack
  
  if priority
    @dependency.process_priority(priority)
  end
  
  @connection.decode_headers(data)
end

#receive_data(frame) ⇒ Object

DATA frames are subject to flow control and can only be sent when a stream is in the “open” or “half-closed (remote)” state. The entire DATA frame payload is included in flow control, including the Pad Length and Padding fields if present. 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 of type STREAM_CLOSED.



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# File 'lib/protocol/http2/stream.rb', line 330

def receive_data(frame)
  if @state == :open
    update_local_window(frame)
    
    if frame.end_stream?
      @state = :half_closed_remote
    end
    
    process_data(frame)
  elsif @state == :half_closed_local
    update_local_window(frame)
    
    process_data(frame)
    
    if frame.end_stream?
      close!
    end
  elsif self.closed?
    ignore_data(frame)
  else
    # 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.
    self.send_reset_stream(Error::STREAM_CLOSED)
  end
end

#receive_headers(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 288

def receive_headers(frame)
  if @state == :idle
    if frame.end_stream?
      @state = :half_closed_remote
    else
      open!
    end
    
    process_headers(frame)
  elsif @state == :reserved_remote
    process_headers(frame)
    
    @state = :half_closed_local
  elsif @state == :open
    process_headers(frame)
    
    if frame.end_stream?
      @state = :half_closed_remote
    end
  elsif @state == :half_closed_local
    process_headers(frame)
    
    if frame.end_stream?
      close!
    end
  elsif self.closed?
    ignore_headers(frame)
  else
    self.send_reset_stream(Error::STREAM_CLOSED)
  end
end

#receive_push_promise(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 432

def receive_push_promise(frame)
  promised_stream_id, data = frame.unpack
  headers = @connection.decode_headers(data)
  
  stream = self.accept_push_promise_stream(promised_stream_id, headers)
  stream.parent = self
  stream.reserved_remote!
  
  return stream, headers
end

#receive_reset_stream(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 359

def receive_reset_stream(frame)
  if @state == :idle
    # If a RST_STREAM frame identifying an idle stream is received, the recipient MUST treat this as a connection error (Section 5.4.1) of type PROTOCOL_ERROR.
    raise ProtocolError, "Cannot receive reset stream in state: #{@state}!"
  elsif self.closed?
    ignore_reset_stream(frame)
  else
    error_code = frame.unpack
    
    close!(error_code)
    
    return error_code
  end
end

#reserved_local! ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 391

def reserved_local!
  if @state == :idle
    @state = :reserved_local
  else
    raise ProtocolError, "Cannot reserve stream in state: #{@state}"
  end
end

#reserved_remote! ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 399

def reserved_remote!
  if @state == :idle
    @state = :reserved_remote
  else
    raise ProtocolError, "Cannot reserve stream in state: #{@state}"
  end
end

#send_data(*arguments, **options) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 218

def send_data(*arguments, **options)
  if @state == :open
    frame = write_data(*arguments, **options)
    
    if frame.end_stream?
      @state = :half_closed_local
    end
  elsif @state == :half_closed_remote
    frame = write_data(*arguments, **options)
    
    if frame.end_stream?
      close!
    end
  else
    raise ProtocolError, "Cannot send data in state: #{@state}"
  end
end

#send_headers(*args) ⇒ Object

The HEADERS frame is used to open a stream, and additionally carries a header block fragment. HEADERS frames can be sent on a stream in the “idle”, “reserved (local)”, “open”, or “half-closed (remote)” state.



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# File 'lib/protocol/http2/stream.rb', line 171

def send_headers(*args)
  if @state == :idle
    frame = write_headers(*args)
    
    if frame.end_stream?
      @state = :half_closed_local
    else
      open!
    end
  elsif @state == :reserved_local
    frame = write_headers(*args)
    
    @state = :half_closed_remote
  elsif @state == :open
    frame = write_headers(*args)
    
    if frame.end_stream?
      @state = :half_closed_local
    end
  elsif @state == :half_closed_remote
    frame = write_headers(*args)
    
    if frame.end_stream?
      close!
    end
  else
    raise ProtocolError, "Cannot send headers in state: #{@state}"
  end
end

#send_headers? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/http2/stream.rb', line 152

def send_headers?
  @state == :idle or @state == :reserved_local or @state == :open or @state == :half_closed_remote
end

#send_push_promise(headers) ⇒ Object

Server push is semantically equivalent to a server responding to a request; however, in this case, that request is also sent by the server, as a PUSH_PROMISE frame.

Parameters:

  • headers (Hash) —

    contains a complete set of request header fields that the server attributes to the request.



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# File 'lib/protocol/http2/stream.rb', line 414

def send_push_promise(headers)
  if @state == :open or @state == :half_closed_remote
    promised_stream = self.create_push_promise_stream(headers)
    promised_stream.reserved_local!
    
    write_push_promise(promised_stream.id, headers)
    
    return promised_stream
  else
    raise ProtocolError, "Cannot send push promise in state: #{@state}"
  end
end

#send_reset_stream(error_code = 0) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 260

def send_reset_stream(error_code = 0)
  if @state != :idle and @state != :closed
    frame = ResetStreamFrame.new(@id)
    frame.pack(error_code)
    
    write_frame(frame)
    
    close!
  else
    raise ProtocolError, "Cannot send reset stream (#{error_code}) in state: #{@state}"
  end
end

#to_s ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 447

def to_s
  inspect
end

#weight ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 111

def weight
  @dependency.weight
end

#write_frame(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 140

def write_frame(frame)
  @connection.write_frame(frame)
end