"""
Various tests for synchronization primitives.
"""

import sys
import time
from _thread import start_new_thread, TIMEOUT_MAX
import threading
import unittest
import weakref

from test import support


def _wait():
    # A crude wait/yield function not relying on synchronization primitives.
    time.sleep(0.01)

class Bunch(object):
    """
    A bunch of threads.
    """
    def __init__(self, f, n, wait_before_exit=False):
        """
        Construct a bunch of `n` threads running the same function `f`.
        If `wait_before_exit` is True, the threads won't terminate until
        do_finish() is called.
        """
        self.f = f
        self.n = n
        self.started = []
        self.finished = []
        self._can_exit = not wait_before_exit
        self.wait_thread = support.wait_threads_exit()
        self.wait_thread.__enter__()

        def task():
            tid = threading.get_ident()
            self.started.append(tid)
            try:
                f()
            finally:
                self.finished.append(tid)
                while not self._can_exit:
                    _wait()

        try:
            for i in range(n):
                start_new_thread(task, ())
        except:
            self._can_exit = True
            raise

    def wait_for_started(self):
        while len(self.started) < self.n:
            _wait()

    def wait_for_finished(self):
        while len(self.finished) < self.n:
            _wait()
        # Wait for threads exit
        self.wait_thread.__exit__(None, None, None)

    def do_finish(self):
        self._can_exit = True


class BaseTestCase(unittest.TestCase):
    def setUp(self):
        self._threads = support.threading_setup()

    def tearDown(self):
        support.threading_cleanup(*self._threads)
        support.reap_children()

    def assertTimeout(self, actual, expected):
        # The waiting and/or time.monotonic() can be imprecise, which
        # is why comparing to the expected value would sometimes fail
        # (especially under Windows).
        self.assertGreaterEqual(actual, expected * 0.6)
        # Test nothing insane happened
        self.assertLess(actual, expected * 10.0)


class BaseLockTests(BaseTestCase):
    """
    Tests for both recursive and non-recursive locks.
    """

    def test_constructor(self):
        lock = self.locktype()
        del lock

    def test_repr(self):
        lock = self.locktype()
        self.assertRegex(repr(lock), "<unlocked .* object (.*)?at .*>")
        del lock

    def test_locked_repr(self):
        lock = self.locktype()
        lock.acquire()
        self.assertRegex(repr(lock), "<locked .* object (.*)?at .*>")
        del lock

    def test_acquire_destroy(self):
        lock = self.locktype()
        lock.acquire()
        del lock

    def test_acquire_release(self):
        lock = self.locktype()
        lock.acquire()
        lock.release()
        del lock

    def test_try_acquire(self):
        lock = self.locktype()
        self.assertTrue(lock.acquire(False))
        lock.release()

    def test_try_acquire_contended(self):
        lock = self.locktype()
        lock.acquire()
        result = []
        def f():
            result.append(lock.acquire(False))
        Bunch(f, 1).wait_for_finished()
        self.assertFalse(result[0])
        lock.release()

    def test_acquire_contended(self):
        lock = self.locktype()
        lock.acquire()
        N = 5
        def f():
            lock.acquire()
            lock.release()

        b = Bunch(f, N)
        b.wait_for_started()
        _wait()
        self.assertEqual(len(b.finished), 0)
        lock.release()
        b.wait_for_finished()
        self.assertEqual(len(b.finished), N)

    def test_with(self):
        lock = self.locktype()
        def f():
            lock.acquire()
            lock.release()
        def _with(err=None):
            with lock:
                if err is not None:
                    raise err
        _with()
        # Check the lock is unacquired
        Bunch(f, 1).wait_for_finished()
        self.assertRaises(TypeError, _with, TypeError)
        # Check the lock is unacquired
        Bunch(f, 1).wait_for_finished()

    def test_thread_leak(self):
        # The lock shouldn't leak a Thread instance when used from a foreign
        # (non-threading) thread.
        lock = self.locktype()
        def f():
            lock.acquire()
            lock.release()
        n = len(threading.enumerate())
        # We run many threads in the hope that existing threads ids won't
        # be recycled.
        Bunch(f, 15).wait_for_finished()
        if len(threading.enumerate()) != n:
            # There is a small window during which a Thread instance's
            # target function has finished running, but the Thread is still
            # alive and registered.  Avoid spurious failures by waiting a
            # bit more (seen on a buildbot).
            time.sleep(0.4)
            self.assertEqual(n, len(threading.enumerate()))

    def test_timeout(self):
        lock = self.locktype()
        # Can't set timeout if not blocking
        self.assertRaises(ValueError, lock.acquire, 0, 1)
        # Invalid timeout values
        self.assertRaises(ValueError, lock.acquire, timeout=-100)
        self.assertRaises(OverflowError, lock.acquire, timeout=1e100)
        self.assertRaises(OverflowError, lock.acquire, timeout=TIMEOUT_MAX + 1)
        # TIMEOUT_MAX is ok
        lock.acquire(timeout=TIMEOUT_MAX)
        lock.release()
        t1 = time.monotonic()
        self.assertTrue(lock.acquire(timeout=5))
        t2 = time.monotonic()
        # Just a sanity test that it didn't actually wait for the timeout.
        self.assertLess(t2 - t1, 5)
        results = []
        def f():
            t1 = time.monotonic()
            results.append(lock.acquire(timeout=0.5))
            t2 = time.monotonic()
            results.append(t2 - t1)
        Bunch(f, 1).wait_for_finished()
        self.assertFalse(results[0])
        self.assertTimeout(results[1], 0.5)

    def test_weakref_exists(self):
        lock = self.locktype()
        ref = weakref.ref(lock)
        self.assertIsNotNone(ref())

    def test_weakref_deleted(self):
        lock = self.locktype()
        ref = weakref.ref(lock)
        del lock
        self.assertIsNone(ref())


class LockTests(BaseLockTests):
    """
    Tests for non-recursive, weak locks
    (which can be acquired and released from different threads).
    """
    def test_reacquire(self):
        # Lock needs to be released before re-acquiring.
        lock = self.locktype()
        phase = []

        def f():
            lock.acquire()
            phase.append(None)
            lock.acquire()
            phase.append(None)

        with support.wait_threads_exit():
            start_new_thread(f, ())
            while len(phase) == 0:
                _wait()
            _wait()
            self.assertEqual(len(phase), 1)
            lock.release()
            while len(phase) == 1:
                _wait()
            self.assertEqual(len(phase), 2)

    def test_different_thread(self):
        # Lock can be released from a different thread.
        lock = self.locktype()
        lock.acquire()
        def f():
            lock.release()
        b = Bunch(f, 1)
        b.wait_for_finished()
        lock.acquire()
        lock.release()

    def test_state_after_timeout(self):
        # Issue #11618: check that lock is in a proper state after a
        # (non-zero) timeout.
        lock = self.locktype()
        lock.acquire()
        self.assertFalse(lock.acquire(timeout=0.01))
        lock.release()
        self.assertFalse(lock.locked())
        self.assertTrue(lock.acquire(blocking=False))


class RLockTests(BaseLockTests):
    """
    Tests for recursive locks.
    """
    def test_reacquire(self):
        lock = self.locktype()
        lock.acquire()
        lock.acquire()
        lock.release()
        lock.acquire()
        lock.release()
        lock.release()

    def test_release_unacquired(self):
        # Cannot release an unacquired lock
        lock = self.locktype()
        self.assertRaises(RuntimeError, lock.release)
        lock.acquire()
        lock.acquire()
        lock.release()
        lock.acquire()
        lock.release()
        lock.release()
        self.assertRaises(RuntimeError, lock.release)

    def test_release_save_unacquired(self):
        # Cannot _release_save an unacquired lock
        lock = self.locktype()
        self.assertRaises(RuntimeError, lock._release_save)
        lock.acquire()
        lock.acquire()
        lock.release()
        lock.acquire()
        lock.release()
        lock.release()
        self.assertRaises(RuntimeError, lock._release_save)

    def test_different_thread(self):
        # Cannot release from a different thread
        lock = self.locktype()
        def f():
            lock.acquire()
        b = Bunch(f, 1, True)
        try:
            self.assertRaises(RuntimeError, lock.release)
        finally:
            b.do_finish()
        b.wait_for_finished()

    def test__is_owned(self):
        lock = self.locktype()
        self.assertFalse(lock._is_owned())
        lock.acquire()
        self.assertTrue(lock._is_owned())
        lock.acquire()
        self.assertTrue(lock._is_owned())
        result = []
        def f():
            result.append(lock._is_owned())
        Bunch(f, 1).wait_for_finished()
        self.assertFalse(result[0])
        lock.release()
        self.assertTrue(lock._is_owned())
        lock.release()
        self.assertFalse(lock._is_owned())


class EventTests(BaseTestCase):
    """
    Tests for Event objects.
    """

    def test_is_set(self):
        evt = self.eventtype()
        self.assertFalse(evt.is_set())
        evt.set()
        self.assertTrue(evt.is_set())