# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Tests for L{twisted.python.threadable}.
"""


import pickle
import sys

from unittest import skipIf

try:
    import threading
except ImportError:
    threadingSkip = True
else:
    threadingSkip = False

from twisted.trial.unittest import SynchronousTestCase, FailTest

from twisted.python import threadable


class TestObject:
    synchronized = ["aMethod"]

    x = -1
    y = 1

    def aMethod(self):
        for i in range(10):
            self.x, self.y = self.y, self.x
            self.z = self.x + self.y
            assert self.z == 0, "z == %d, not 0 as expected" % (self.z,)


threadable.synchronize(TestObject)


class SynchronizationTests(SynchronousTestCase):
    def setUp(self):
        """
        Reduce the CPython check interval so that thread switches happen much
        more often, hopefully exercising more possible race conditions.  Also,
        delay actual test startup until the reactor has been started.
        """
        self.addCleanup(sys.setswitchinterval, sys.getswitchinterval())
        sys.setswitchinterval(0.0000001)

    def test_synchronizedName(self):
        """
        The name of a synchronized method is inaffected by the synchronization
        decorator.
        """
        self.assertEqual("aMethod", TestObject.aMethod.__name__)

    @skipIf(threadingSkip, "Platform does not support threads")
    def test_isInIOThread(self):
        """
        L{threadable.isInIOThread} returns C{True} if and only if it is called
        in the same thread as L{threadable.registerAsIOThread}.
        """
        threadable.registerAsIOThread()
        foreignResult = []
        t = threading.Thread(
            target=lambda: foreignResult.append(threadable.isInIOThread())
        )
        t.start()
        t.join()
        self.assertFalse(foreignResult[0], "Non-IO thread reported as IO thread")
        self.assertTrue(
            threadable.isInIOThread(), "IO thread reported as not IO thread"
        )

    @skipIf(threadingSkip, "Platform does not support threads")
    def testThreadedSynchronization(self):
        o = TestObject()

        errors = []

        def callMethodLots():
            try:
                for i in range(1000):
                    o.aMethod()
            except AssertionError as e:
                errors.append(str(e))

        threads = []
        for x in range(5):
            t = threading.Thread(target=callMethodLots)
            threads.append(t)
            t.start()

        for t in threads:
            t.join()

        if errors:
            raise FailTest(errors)

    def testUnthreadedSynchronization(self):
        o = TestObject()
        for i in range(1000):
            o.aMethod()


class SerializationTests(SynchronousTestCase):
    @skipIf(threadingSkip, "Platform does not support threads")
    def testPickling(self):
        lock = threadable.XLock()
        lockType = type(lock)
        lockPickle = pickle.dumps(lock)
        newLock = pickle.loads(lockPickle)
        self.assertIsInstance(newLock, lockType)

    def testUnpickling(self):
        lockPickle = b"ctwisted.python.threadable\nunpickle_lock\np0\n(tp1\nRp2\n."
        lock = pickle.loads(lockPickle)
        newPickle = pickle.dumps(lock, 2)
        pickle.loads(newPickle)
