Module: Protocol::HTTP::Body::Stream::Reader

Included in:
Protocol::HTTP::Body::Stream
Defined in:
lib/protocol/http/body/stream.rb

Overview

This provides a read-only interface for data, which is surprisingly tricky to implement correctly.

Instance Method Summary collapse

Instance Method Details

#read(length = nil, buffer = nil) ⇒ Object

read behaves like IO#read. Its signature is read([length, [buffer]]). If given, length must be a non-negative Integer (>= 0) or nil, and buffer must be a String and may not be nil. If length is given and not nil, then this method reads at most length bytes from the input stream. If length is not given or nil, then this method reads all data until EOF. When EOF is reached, this method returns nil if length is given and not nil, or “” if length is not given or is nil. If buffer is given, then the read data will be placed into buffer instead of a newly created String object.

Parameters:

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

    the amount of data to read

  • buffer (String) (defaults to: nil) —

    the buffer which will receive the data

Returns:

  • a buffer containing the data



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# File 'lib/protocol/http/body/stream.rb', line 53

def read(length = nil, buffer = nil)
	return '' if length == 0
	
	buffer ||= Async::IO::Buffer.new

	# Take any previously buffered data and replace it into the given buffer.
	if @buffer
		buffer.replace(@buffer)
		@buffer = nil
	else
		buffer.clear
	end
	
	if length
		while buffer.bytesize < length and chunk = read_next
			buffer << chunk
		end
		
		# This ensures the subsequent `slice!` works correctly.
		buffer.force_encoding(Encoding::BINARY)

		# This will be at least one copy:
		@buffer = buffer.byteslice(length, buffer.bytesize)
		
		# This should be zero-copy:
		buffer.slice!(length, buffer.bytesize)
		
		if buffer.empty?
			return nil
		else
			return buffer
		end
	else
		while chunk = read_next
			buffer << chunk
		end
		
		return buffer
	end
end

#read_nonblock(length, buffer = nil) ⇒ Object 



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# File 'lib/protocol/http/body/stream.rb', line 116

def read_nonblock(length, buffer = nil)
	@buffer ||= read_next
	chunk = nil
	
	unless @buffer
		buffer&.clear
		return
	end
	
	if @buffer.bytesize > length
		chunk = @buffer.byteslice(0, length)
		@buffer = @buffer.byteslice(length, @buffer.bytesize)
	else
		chunk = @buffer
		@buffer = nil
	end
	
	if buffer
		buffer.replace(chunk)
	else
		buffer = chunk
	end
	
	return buffer
end

#read_partial(length = nil) ⇒ Object

Read at most ‘length` bytes from the stream. Will avoid reading from the underlying stream if possible.



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# File 'lib/protocol/http/body/stream.rb', line 95

def read_partial(length = nil)
	if @buffer
		buffer = @buffer
		@buffer = nil
	else
		buffer = read_next
	end
	
	if buffer and length
		if buffer.bytesize > length
			# This ensures the subsequent `slice!` works correctly.
			buffer.force_encoding(Encoding::BINARY)

			@buffer = buffer.byteslice(length, buffer.bytesize)
			buffer.slice!(length, buffer.bytesize)
		end
	end
	
	return buffer
end