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