Class: Async::IO::Stream

Inherits:
Object
  • Object
show all
Defined in:
lib/async/io/stream.rb

Constant Summary collapse

BLOCK_SIZE =
IO::BLOCK_SIZE

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io, block_size: BLOCK_SIZE, maximum_read_size: MAXIMUM_READ_SIZE, sync: true, deferred: false) ⇒ Stream

Returns a new instance of Stream.


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# File 'lib/async/io/stream.rb', line 45

def initialize(io, block_size: BLOCK_SIZE, maximum_read_size: MAXIMUM_READ_SIZE, sync: true, deferred: false)
	@io = io
	@eof = false
	
	@pending = 0
	# This field is ignored, but used to mean, try to buffer packets in a single iteration of the reactor.
	# @deferred = deferred
	
	@writing = Async::Semaphore.new(1)
	
	# We don't want Ruby to do any IO buffering.
	@io.sync = sync
	
	@block_size = block_size
	@maximum_read_size = maximum_read_size
	
	@read_buffer = Buffer.new
	@write_buffer = Buffer.new
	@drain_buffer = Buffer.new
	
	# Used as destination buffer for underlying reads.
	@input_buffer = Buffer.new
end

Instance Attribute Details

#block_sizeObject (readonly)

Returns the value of attribute block_size


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# File 'lib/async/io/stream.rb', line 71

def block_size
  @block_size
end

#ioObject (readonly)

Returns the value of attribute io


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# File 'lib/async/io/stream.rb', line 69

def io
  @io
end

Class Method Details

.open(path, mode = "r+", **options) ⇒ Object


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# File 'lib/async/io/stream.rb', line 33

def self.open(path, mode = "r+", **options)
	stream = self.new(File.open(path, mode), **options)
	
	return stream unless block_given?
	
	begin
		yield stream
	ensure
		stream.close
	end
end

Instance Method Details

#<<(string) ⇒ Object

Writes `string` to the stream and returns self.


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# File 'lib/async/io/stream.rb', line 183

def <<(string)
	write(string)
	
	return self
end

#closeObject

Best effort to flush any unwritten data, and then close the underling IO.


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# File 'lib/async/io/stream.rb', line 216

def close
	return if @io.closed?
	
	begin
		flush
	rescue
		# We really can't do anything here unless we want #close to raise exceptions.
	ensure
		@io.close
	end
end

#close_readObject


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# File 'lib/async/io/stream.rb', line 205

def close_read
	@io.close_read
end

#close_writeObject


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# File 'lib/async/io/stream.rb', line 209

def close_write
	flush
ensure
	@io.close_write
end

#closed?Boolean

Returns:

  • (Boolean)

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# File 'lib/async/io/stream.rb', line 201

def closed?
	@io.closed?
end

#connected?Boolean

Returns:

  • (Boolean)

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# File 'lib/async/io/stream.rb', line 197

def connected?
	@io.connected?
end

#eof!Object

Raises:

  • (EOFError)

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# File 'lib/async/io/stream.rb', line 241

def eof!
	@read_buffer.clear
	@eof = true
	
	raise EOFError
end

#eof?Boolean Also known as: eof

Returns true if the stream is at file which means there is no more data to be read.

Returns:

  • (Boolean)

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# File 'lib/async/io/stream.rb', line 229

def eof?
	if !@read_buffer.empty?
		return false
	elsif @eof
		return true
	else
		return @io.eof?
	end
end

#flushObject

Flushes buffered data to the stream.


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# File 'lib/async/io/stream.rb', line 152

def flush
	return if @write_buffer.empty?
	
	@writing.acquire do
		# Flip the write buffer and drain buffer:
		@write_buffer, @drain_buffer = @drain_buffer, @write_buffer
		
		begin
			@io.write(@drain_buffer)
		ensure
			# If the write operation fails, we still need to clear this buffer, and the data is essentially lost.
			@drain_buffer.clear
		end
	end
end

#gets(separator = $/, **options) ⇒ Object


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# File 'lib/async/io/stream.rb', line 147

def gets(separator = $/, **options)
	read_until(separator, **options)
end

#peekObject


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# File 'lib/async/io/stream.rb', line 141

def peek
	until yield(@read_buffer) or @eof
		fill_read_buffer
	end
end

#puts(*arguments, separator: $/) ⇒ Object


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# File 'lib/async/io/stream.rb', line 189

def puts(*arguments, separator: $/)
	arguments.each do |argument|
		@write_buffer << argument << separator
	end
	
	flush
end

#read(size = nil) ⇒ Object

Reads `size` bytes from the stream. If size is not specified, read until end of file.


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# File 'lib/async/io/stream.rb', line 74

def read(size = nil)
	return String.new(encoding: Encoding::BINARY) if size == 0
	
	if size
		until @eof or @read_buffer.bytesize >= size
			# Compute the amount of data we need to read from the underlying stream:
			read_size = size - @read_buffer.bytesize
			
			# Don't read less than @block_size to avoid lots of small reads:
			fill_read_buffer(read_size > @block_size ? read_size : @block_size)
		end
	else
		until @eof
			fill_read_buffer
		end
	end
	
	return consume_read_buffer(size)
end

#read_exactly(size, exception: EOFError) ⇒ Object

Raises:

  • (exception)

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# File 'lib/async/io/stream.rb', line 105

def read_exactly(size, exception: EOFError)
	if buffer = read(size)
		if buffer.bytesize != size
			raise exception, "could not read enough data"
		end
		
		return buffer
	end
	
	raise exception, "encountered eof while reading data"
end

#read_partial(size = nil) ⇒ Object Also known as: readpartial

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


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# File 'lib/async/io/stream.rb', line 95

def read_partial(size = nil)
	return String.new(encoding: Encoding::BINARY) if size == 0

	if !@eof and @read_buffer.empty?
		fill_read_buffer
	end
	
	return consume_read_buffer(size)
end

#read_until(pattern, offset = 0, chomp: true) ⇒ String

Efficiently read data from the stream until encountering pattern.

Parameters:

  • pattern (String)

    The pattern to match.

Returns:

  • (String)

    The contents of the stream up until the pattern, which is consumed but not returned.


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# File 'lib/async/io/stream.rb', line 122

def read_until(pattern, offset = 0, chomp: true)
	# We don't want to split on the pattern, so we subtract the size of the pattern.
	split_offset = pattern.bytesize - 1
	
	until index = @read_buffer.index(pattern, offset)
		offset = @read_buffer.bytesize - split_offset
		
		offset = 0 if offset < 0
		
		return unless fill_read_buffer
	end
	
	@read_buffer.freeze
	matched = @read_buffer.byteslice(0, index+(chomp ? 0 : pattern.bytesize))
	@read_buffer = @read_buffer.byteslice(index+pattern.bytesize, @read_buffer.bytesize)
	
	return matched
end

#write(string) ⇒ Object

Writes `string` to the buffer. When the buffer is full or #sync is true the buffer is flushed to the underlying `io`.

Parameters:

  • string

    the string to write to the buffer.

Returns:

  • the number of bytes appended to the buffer.


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# File 'lib/async/io/stream.rb', line 172

def write(string)
	@write_buffer << string
	
	if @write_buffer.bytesize >= @block_size
		flush
	end
	
	return string.bytesize
end