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
	
	@deferred = deferred
	@pending = 0
	
	@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_size ⇒ Object (readonly)

Returns the value of attribute block_size.



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# File 'lib/async/io/stream.rb', line 70

def block_size
  @block_size
end

#io ⇒ Object (readonly)

Returns the value of attribute io.



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# File 'lib/async/io/stream.rb', line 68

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 186

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

#close ⇒ Object

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



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# File 'lib/async/io/stream.rb', line 219

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

#close_read ⇒ Object 



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# File 'lib/async/io/stream.rb', line 208

def close_read
	@io.close_read
end

#close_write ⇒ Object 



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# File 'lib/async/io/stream.rb', line 212

def close_write
	drain_write_buffer unless @write_buffer.empty?
ensure
	@io.close_write
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/io/stream.rb', line 204

def closed?
	@io.closed?
end

#connected? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/io/stream.rb', line 200

def connected?
	@io.connected?
end

#eof! ⇒ Object

Raises:

  • (EOFError) 


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# File 'lib/async/io/stream.rb', line 244

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 232

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

#flush(deferred: @deferred) ⇒ Object

Flushes buffered data to the stream.



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# File 'lib/async/io/stream.rb', line 151

def flush(deferred: @deferred)
	if deferred and task = Task.current?
		# Despite how it looks, this field is not actually directly related to whether or not writes should occur. It's actually used to control the logic of deferred flushing. Therefore, it should NOT be modified outside this method.
		@pending += 1
		
		if @pending == 1
			task.yield
			
			begin
				drain_write_buffer unless @write_buffer.empty?
			ensure
				# The write buffer no longer contains pending writes
				@pending = 0
			end
		end
	else
		drain_write_buffer unless @write_buffer.empty?
	end
end

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



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# File 'lib/async/io/stream.rb', line 146

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

#peek ⇒ Object 



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# File 'lib/async/io/stream.rb', line 140

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 192

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 73

def read(size = nil)
	return '' 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 104

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 94

def read_partial(size = nil)
	return '' 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 121

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 175

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