3 files changed, 83 insertions(+), 0 deletions(-)

M .rubocop.yml
M lib/em_fiberscheduler.rb
A lib/em_fiberscheduler/from_fiber_scheduler.rb

@@ 41,6 41,7 @@ Naming/MethodParameterName:
     - iq
     - db
     - to
+    - io
 
 Layout/IndentationStyle:
   Enabled: false

@@ 3,6 3,8 @@
 require "eventmachine"
 require "fiber"
 
+require_relative "em_fiberscheduler/from_fiber_scheduler"
+
 module EventMachine
 	def self.work_left?
 		if @timers.empty? && @next_tick_queue.empty? && defers_finished?

@@ 0,0 1,80 @@
+# frozen_string_literal: true
+
+# From https://github.com/bruno-/fiber_scheduler/blob/main/lib/fiber_scheduler/selector.rb
+# rubocop:disable Metrics/AbcSize
+# rubocop:disable Metrics/MethodLength
+if RUBY_VERSION >= "3.1.0"
+	module EventMachine
+		class FiberScheduler
+			EAGAIN = Errno::EAGAIN::Errno
+
+			def io_read(io, buffer, length)
+				offset = 0
+
+				loop do
+					maximum_size = buffer.size - offset
+
+					result = Fiber.new(blocking: true) {
+						io.read_nonblock(maximum_size, exception: false)
+					}.resume
+
+					case result
+					when :wait_readable
+						return -EAGAIN unless maximum_size.positive?
+
+						io_wait(io, IO::READABLE)
+					when :wait_writable
+						return -EAGAIN unless maximum_size.positive?
+
+						io_wait(io, IO::WRITABLE)
+					when nil
+						break
+					else
+						buffer.set_string(result, offset)
+
+						size = result.bytesize
+						offset += size
+						break if size >= length
+
+						length -= size
+					end
+				end
+
+				offset
+			end
+
+			def io_write(io, buffer, length)
+				offset = 0
+
+				loop do
+					maximum_size = buffer.size - offset
+
+					chunk = buffer.get_string(offset, maximum_size)
+					result = Fiber.new(blocking: true) {
+						io.write_nonblock(chunk, exception: false)
+					}.resume
+
+					case result
+					when :wait_readable
+						return -EAGAIN unless length.positive?
+
+						io_wait(io, IO::READABLE)
+					when :wait_writable
+						return -EAGAIN unless length.positive?
+
+						io_wait(io, IO::WRITABLE)
+					else
+						offset += result
+						break if result >= length
+
+						length -= result
+					end
+				end
+
+				offset
+			end
+		end
+	end
+end
+# rubocop:enable Metrics/AbcSize
+# rubocop:enable Metrics/MethodLength