Project

General

Profile

Actions

Feature #18411

closed

Introduce `Fiber.blocking` for disabling scheduler.

Added by ioquatix (Samuel Williams) over 2 years ago. Updated over 1 year ago.

Status:
Closed
Target version:
-
[ruby-core:106707]

Description

When implementing pure-ruby IO scheduler, we may need to invoke some Ruby IO operations without entering the scheduler.

def io_write(fiber, io, buffer, length)
  offset = 0
  
  while length > 0
    # From offset until the end:
    chunk = buffer.to_str(offset, length)
    case result = io.write_nonblock(chunk, exception: false)
    when :wait_readable
      self.io_wait(fiber, io, IO::READABLE)
    when :wait_writable
      self.io_wait(fiber, io, IO::WRITABLE)
    else
      offset += result
      length -= result
    end
  end
  
  return offset
end

There are some cases where even in this code read_nonblock can invoke fiber scheduler creating infinite recursion.

Therefore, I propose to introduce Fiber.blocking{...} which has almost identical implementation to Fiber.new(blocking: true) {}.resume.

In the above code, we change the line:

    case result = io.write_nonblock(chunk, exception: false)

to

    case result = Fiber.blocking{io.write_nonblock(chunk, exception: false)}

This ensures that write_nonblock can never enter the scheduler again.

Actions

Also available in: Atom PDF

Like0
Like0Like0Like0Like0Like0Like0Like0