"""Helper threading perform all the threading operations."""

import threading
from contextlib import contextmanager

import helper_random

try:
    import prctl
except ImportError:
    def set_thread_name(name):
        """Set the thread name for external use (visible from the OS)."""
        threading.current_thread().name = name
else:
    def set_thread_name(name):
        """Set a name for the thread for python internal use."""
        prctl.set_name(name)

    def _thread_name_hack(self):
        set_thread_name(self.name)
        threading.Thread.__bootstrap_original__(self)

    threading.Thread.__bootstrap_original__ = threading.Thread._Thread__bootstrap
    threading.Thread._Thread__bootstrap = _thread_name_hack


class StoppableThread(threading.Thread):
    name = None

    def __init__(self, name=None):
        if name:
            self.name = name
        super(StoppableThread, self).__init__(name=self.name)
        self.initStop()
        helper_random.seed()

    def initStop(self):
        self.stop = threading.Event()
        self._stopped = False

    def stopThread(self):
        self._stopped = True
        self.stop.set()


class BusyError(threading.ThreadError):
    pass


@contextmanager
def nonBlocking(lock):
    locked = lock.acquire(False)
    if not locked:
        raise BusyError
    try:
        yield
    finally:
        lock.release()