import unittest

import os

import tempfile

import signal

import threading

import time

class testLogLock(unittest.TestCase):

    def test_ThreadingAndLocks(self):

        #create a thread, have that thread grab a lock, and sleep.

        fd, file = tempfile.mkstemp('.nonlog')

        _lock = threading.RLock()

        os.close(fd)

        def locker():

            os.write(fd, 'Thread acquiring lock\n')

            _lock.acquire()

            os.write(fd, 'Thread acquired lock\n')

            time.sleep(0.4)

            os.write(fd, 'Thread releasing lock\n')

            _lock.release()

            os.write(fd, 'Thread released lock\n')

        #Then in the main thread, throw a signal to self

        def handleSignal(sigNum, frame):

            os.write(fd, 'Main Thread acquiring lock\n')

            lock = False

            endtime = time.time() + 1.0

            while not lock:

                lock = _lock.acquire(blocking=0)

                time.sleep(0.01)

                if time.time() > endtime:

                    break

            if not lock:

                os.write(fd, 'Main Thread could not acquire lock\n')

                return

            os.write(fd, 'Main Thread acquired lock\n')

            os.write(fd, 'Main Thread releasing lock\n')

            _lock.release()

            os.write(fd, 'Main Thread released lock\n')

        sighndlr = signal.signal(signal.SIGUSR1, handleSignal)

        try:

            fd = os.open(file, os.O_SYNC | os.O_WRONLY | os.O_CREAT)

            thread = threading.Thread(target=locker)

            thread.start()

            time.sleep(0.1)

            os.kill(os.getpid(), signal.SIGUSR1)

            thread.join()

            #check the results

            os.close(fd)

            fileconts = open(file, 'r').read()

            self.assertTrue('Main Thread released lock' in fileconts)

            self.assertEqual(fileconts,

                '''Thread acquiring lock

Thread acquired lock

Main Thread acquiring lock

Thread releasing lock

Thread released lock

Main Thread acquired lock

Main Thread releasing lock

Main Thread released lock

''')

            #Now try after acquiring the lock from the main thread

            fd = os.open(file, os.O_SYNC | os.O_WRONLY | os.O_CREAT)

            _lock.acquire()

            thread = threading.Thread(target=locker)

            thread.start()

            time.sleep(0.1)

            os.kill(os.getpid(), signal.SIGUSR1)

            _lock.release()

            thread.join()

            os.close(fd)

            fileconts = open(file, 'r').read()

            self.assertEqual(fileconts,

                '''Thread acquiring lock

Main Thread acquiring lock

Main Thread acquired lock

Main Thread releasing lock

Main Thread released lock

Thread acquired lock

Thread releasing lock

Thread released lock

''')

        finally:

            signal.signal(signal.SIGUSR1, sighndlr)

            try:

                os.close(fd)

            except OSError:

                pass

            try:

                os.unlink(file)

            except OSError:

                pass