Remove drain buffer.

lib/io/stream/generic.rb

@@ -29,7 +29,6 @@ def initialize(block_size: BLOCK_SIZE, maximum_read_size: MAXIMUM_READ_SIZE)
 
 			@read_buffer = StringBuffer.new
 			@write_buffer = StringBuffer.new
-			@drain_buffer = StringBuffer.new
 
 			# Used as destination buffer for underlying reads.
 			@input_buffer = StringBuffer.new
@@ -129,32 +128,37 @@ def gets(separator = $/, **options)
 			read_until(separator, **options)
 		end
 
+		private def drain(buffer)
+			begin
+				syswrite(buffer)
+			ensure
+				# If the write operation fails, we still need to clear this buffer, and the data is essentially lost.
+				buffer.clear
+			end
+		end
+
 		# Flushes buffered data to the stream.
 		def flush
 			return if @write_buffer.empty?
 
 			@writing.synchronize do
-				# Flip the write buffer and drain buffer:
-				@write_buffer, @drain_buffer = @drain_buffer, @write_buffer
-
-				begin
-					syswrite(@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
+				self.drain(@write_buffer)
 			end
 		end
 
 		# Writes `string` to the buffer. When the buffer is full or #sync is true the
 		# buffer is flushed to the underlying `io`.
 		# @param string the string to write to the buffer.
 		# @return the number of bytes appended to the buffer.
-		def write(string)
-			@write_buffer << string
-
-			if @write_buffer.bytesize >= @block_size
-				flush
+		def write(string, flush: false)
+			@writing.synchronize do
+				@write_buffer << string
+
+				flush |= @write_buffer.bytesize >= @block_size
+
+				if flush
+					self.drain(@write_buffer)
+				end
 			end
 
 			return string.bytesize
@@ -168,11 +172,15 @@ def <<(string)
 		end
 
 		def puts(*arguments, separator: $/)
-			arguments.each do |argument|
-				@write_buffer << argument << separator
-			end
+			return if arguments.empty?
 
-			flush
+			@writing.synchronize do
+				arguments.each do |argument|
+					@write_buffer << argument << separator
+				end
+
+				self.drain(@write_buffer)
+			end
 		end
 
 		def closed?
@@ -266,13 +274,13 @@ def fill_read_buffer(size = @block_size)
 
 			if @read_buffer.empty?
 				if sysread(size, @read_buffer)
-					# Console.logger.debug(self, name: "read") {@read_buffer.inspect}
+					# Console.info(self, name: "read") {@read_buffer.inspect}
 					return true
 				end
 			else
 				if chunk = sysread(size, @input_buffer)
 					@read_buffer << chunk
-					# Console.logger.debug(self, name: "read") {@read_buffer.inspect}
+					# Console.info(self, name: "read") {@read_buffer.inspect}
 
 					return true
 				end

test/io/stream/buffered.rb

@@ -397,10 +397,7 @@ def before
 			expect(task.wait).to be_a(Errno::EPIPE)
 
 			write_buffer = server.instance_variable_get(:@write_buffer)
-			drain_buffer = server.instance_variable_get(:@drain_buffer)
-
 			expect(write_buffer).to be(:empty?)
-			expect(drain_buffer).to be(:empty?)
 		end
 	end
 end