"""One persistent KNP GPU detector process. Serialized by server admission lock."""
from pathlib import Path
import subprocess,threading,queue,time,atexit
R=Path.home()/'run/pets-knp';B=Path.home()/'KNP/build/bin'
class DetectorWorker:
 def __init__(self):self.process=None;self.queue=None;atexit.register(self.close)
 def close(self):
  p=self.process;self.process=None
  if p is not None:
   p.terminate()
   try:p.wait(timeout=3)
   except subprocess.TimeoutExpired:p.kill();p.wait()
 def start(self):
  self.close();self.queue=queue.Queue();p=subprocess.Popen([str(R/'pets_worker'),str(R/'detectors'),str(B/'libknp-altai-cuda-backend.so')],stdin=subprocess.PIPE,stdout=subprocess.PIPE,stderr=subprocess.STDOUT,text=True,bufsize=1);self.process=p;q=self.queue
  def read():
   with (R/'worker.log').open('a') as log:
    for line in p.stdout:
     log.write(line);log.flush()
     if line.startswith('RESULT '):q.put(line.strip()[7:])
   q.put(None)
  threading.Thread(target=read,daemon=True).start()
 def infer(self,image,prefix):
  if self.process is None or self.process.poll() is not None:self.start()
  try:
   self.process.stdin.write(str(image)+' '+str(prefix)+'\n');self.process.stdin.flush();received=self.queue.get(timeout=25)
   if received!=str(prefix):raise RuntimeError('KNP worker stopped or response mismatch')
  except Exception:self.close();raise