Class: Stockshark::Process

Inherits:
Object
  • Object
show all
Defined in:
lib/stockshark/process.rb

Overview

Raw OS process lifecycle for a UCI-speaking engine — spawns it, writes lines to its stdin, and continuously drains stdout and stderr from dedicated reader threads so neither pipe can ever fill up and block the child. Draining stderr matters here specifically because the engine path is operator-configurable: nothing guarantees the binary behind it is a "pure" build that never writes to stderr, and if it did while nobody was reading that pipe, the child would block writing to it and every read on stdout would hang right along with it.

Zero chess/UCI knowledge on purpose — Engine owns the protocol, this only owns "a subprocess and its pipes."

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ Process

Returns a new instance of Process.



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# File 'lib/stockshark/process.rb', line 16

def initialize(path)
  @stdin, stdout, stderr, @wait_thread = Open3.popen3(path)
  @queue = Queue.new
  @readers = [ reader_thread(stdout, :stdout), reader_thread(stderr, :stderr) ]
rescue Errno::ENOENT, Errno::EACCES => e
  raise Stockshark::EngineNotFoundError, "could not start engine at #{path.inspect}: #{e.message}"
end

Instance Method Details

#alive? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/stockshark/process.rb', line 42

def alive?
  @wait_thread.alive?
end

#read_line(timeout:) ⇒ Object

Pops the next available line from either stream, tagged with which one it came from, waiting at most timeout seconds. Returns nil on timeout — never raises Timeout::Error, deliberately: cancellation here is just "give up waiting on the queue," not "interrupt whatever is actually blocking," which is what makes Ruby's Timeout.timeout unsafe to wrap around real IO.



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# File 'lib/stockshark/process.rb', line 38

def read_line(timeout:)
  @queue.pop(timeout: timeout)
end

#stop ⇒ Object

Safe to call more than once, and safe to call after the process has already died on its own.



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# File 'lib/stockshark/process.rb', line 48

def stop
  return unless alive?

  begin
    @stdin.puts("quit")
  rescue Errno::EPIPE, IOError
    # already gone — nothing left to say goodbye to.
  end

  unless @wait_thread.join(0.5)
    ::Process.kill("KILL", @wait_thread.pid)
    @wait_thread.join
  end
ensure
  @readers.each(&:kill)
  @stdin.close unless @stdin.closed?
end

#write_line(line) ⇒ Object 



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# File 'lib/stockshark/process.rb', line 24

def write_line(line)
  raise Stockshark::CrashedError, "engine process is not running" unless alive?

  @stdin.puts(line)
rescue Errno::EPIPE, IOError => e
  raise Stockshark::CrashedError, "could not write to engine: #{e.message}"
end