"""
Tests for the threading module.
"""

import test.support
from test.support import (verbose, import_module, cpython_only,
                          requires_type_collecting)
from test.support.script_helper import assert_python_ok, assert_python_failure

import random
import sys
import _thread
import threading
import time
import unittest
import weakref
import os
import subprocess
import signal

from test import lock_tests
from test import support


# Between fork() and exec(), only async-safe functions are allowed (issues
# #12316 and #11870), and fork() from a worker thread is known to trigger
# problems with some operating systems (issue #3863): skip problematic tests
# on platforms known to behave badly.
platforms_to_skip = ('netbsd5', 'hp-ux11')


# A trivial mutable counter.
class Counter(object):
    def __init__(self):
        self.value = 0
    def inc(self):
        self.value += 1
    def dec(self):
        self.value -= 1
    def get(self):
        return self.value

class TestThread(threading.Thread):
    def __init__(self, name, testcase, sema, mutex, nrunning):
        threading.Thread.__init__(self, name=name)
        self.testcase = testcase
        self.sema = sema
        self.mutex = mutex
        self.nrunning = nrunning

    def run(self):
        delay = random.random() / 10000.0
        if verbose:
            print('task %s will run for %.1f usec' %
                  (self.name, delay * 1e6))

        with self.sema:
            with self.mutex:
                self.nrunning.inc()
                if verbose:
                    print(self.nrunning.get(), 'tasks are running')
                self.testcase.assertLessEqual(self.nrunning.get(), 3)

            time.sleep(delay)
            if verbose:
                print('task', self.name, 'done')

            with self.mutex:
                self.nrunning.dec()
                self.testcase.assertGreaterEqual(self.nrunning.get(), 0)
                if verbose:
                    print('%s is finished. %d tasks are running' %
                          (self.name, self.nrunning.get()))


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

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


class ThreadTests(BaseTestCase):

    # Create a bunch of threads, let each do some work, wait until all are
    # done.
    def test_various_ops(self):
        # This takes about n/3 seconds to run (about n/3 clumps of tasks,
        # times about 1 second per clump).
        NUMTASKS = 10

        # no more than 3 of the 10 can run at once
        sema = threading.BoundedSemaphore(value=3)
        mutex = threading.RLock()
        numrunning = Counter()

        threads = []

        for i in range(NUMTASKS):
            t = TestThread("<thread %d>"%i, self, sema, mutex, numrunning)
            threads.append(t)
            self.assertIsNone(t.ident)
            self.assertRegex(repr(t), r'^<TestThread\(.*, initial\)>$')
            t.start()

        if hasattr(threading, 'get_native_id'):
            native_ids = set(t.native_id for t in threads) | {threading.get_native_id()}
            self.assertNotIn(None, native_ids)
            self.assertEqual(len(native_ids), NUMTASKS + 1)

        if verbose:
            print('waiting for all tasks to complete')
        for t in threads:
            t.join()
            self.assertFalse(t.is_alive())
            self.assertNotEqual(t.ident, 0)
            self.assertIsNotNone(t.ident)
            self.assertRegex(repr(t), r'^<TestThread\(.*, stopped -?\d+\)>$')
        if verbose:
            print('all tasks done')
        self.assertEqual(numrunning.get(), 0)

    def test_ident_of_no_threading_threads(self):
        # The ident still must work for the main thread and dummy threads.
        self.assertIsNotNone(threading.currentThread().ident)
        def f():
            ident.append(threading.currentThread().ident)
            done.set()
        done = threading.Event()
        ident = []
        with support.wait_threads_exit():
            tid = _thread.start_new_thread(f, ())
            done.wait()
            self.assertEqual(ident[0], tid)
        # Kill the "immortal" _DummyThread
        del threading._active[ident[0]]

    # run with a small(ish) thread stack size (256 KiB)
    def test_various_ops_small_stack(self):
        if verbose:
            print('with 256 KiB thread stack size...')
        try:
            threading.stack_size(262144)
        except _thread.error:
            raise unittest.SkipTest(
                'platform does not support changing thread stack size')
        self.test_various_ops()
        threading.stack_size(0)

    # run with a large thread stack size (1 MiB)
    def test_various_ops_large_stack(self):
        if verbose:
            print('with 1 MiB thread stack size...')
        try:
            threading.stack_size(0x100000)
        except _thread.error:
            raise unittest.SkipTest(
                'platform does not support changing thread stack size')
        self.test_various_ops()
        threading.stack_size(0)

    def test_foreign_thread(self):
        # Check that a "foreign" thread can use the threading module.
        def f(mutex):
            # Calling current_thread() forces an entry for the foreign
            # thread to get made in the threading._active map.
            threading.current_thread()
            mutex.release()

        mutex = threading.Lock()
        mutex.acquire()
        with support.wait_threads_exit():
            tid = _thread.start_new_thread(f, (mutex,))
            # Wait for the thread to finish.
            mutex.acquire()
        self.assertIn(tid, threading._active)
        self.assertIsInstance(threading._active[tid], threading._DummyThread)
        #Issue 29376
        self.assertTrue(threading._active[tid].is_alive())
        self.assertRegex(repr(threading._active[tid]), '_DummyThread')
        del threading._active[tid]

    # PyThreadState_SetAsyncExc() is a CPython-only gimmick, not (currently)
    # exposed at the Python level.  This test relies on ctypes to get at it.
    def test_PyThreadState_SetAsyncExc(self):
        ctypes = import_module("ctypes")

        set_async_exc = ctypes.pythonapi.PyThreadState_SetAsyncExc
        set_async_exc.argtypes = (ctypes.c_ulong, ctypes.py_object)

        class AsyncExc(Exception):
            pass

        exception = ctypes.py_object(AsyncExc)

        # First check it works when setting the exception from the same thread.
        tid = threading.get_ident()
        self.assertIsInstance(tid, int)
        self.assertGreater(tid, 0)

        try:
            result = set_async_exc(tid, exception)
            # The exception is async, so we might have to keep the VM busy until
            # it notices.
            while True:
                pass
        except AsyncExc:
            pass
        else:
            # This code is unreachable but it reflects the intent. If we wanted
            # to be smarter the above loop wouldn't be infinite.
            self.fail("AsyncExc not raised")
        try:
            self.assertEqual(result, 1) # one thread state modified
        except UnboundLocalError:
            # The exception was raised too quickly for us to get the result.
            pass

        # `worker_started` is set by the thread when it's inside a try/except
        # block waiting to catch the asynchronously set AsyncExc exception.
        # `worker_saw_exception` is set by the thread upon catching that
        # exception.
        worker_started = threading.Event()
        worker_saw_exception = threading.Event()

        class Worker(threading.Thread):
            def run(self):
                self.id = threading.get_ident()
                self.finished = False

                try:
                    while True:
                        worker_started.set()
                        time.sleep(0.1)
                except AsyncExc:
                    self.finished = True
                    worker_saw_exception.set()

        t = Worker()
        t.daemon = True # so if this fails, we don't hang Python at shutdown
        t.start()
        if verbose:
            print("    started worker thread")

        # Try a thread id that doesn't make sense.
        if verbose:
            print("    trying nonsensical thread id")
        result = set_async_exc(-1, exception)
        self.assertEqual(result, 0)  # no thread states modified

        # Now raise an exception in the worker thread.
        if verbose:
            print("    waiting for worker thread to get started")
        ret = worker_started.wait()
        self.assertTrue(ret)
        if verbose:
            print("    verifying worker hasn't exited")
        self.assertFalse(t.finished)
        if verbose:
            print("    attempting to raise asynch exception in worker")
        result = set_async_exc(t.id, exception)
        self.assertEqual(result, 1) # one thread state modified
        if verbose:
            print("    waiting for worker to say it caught the exception")
        worker_saw_exception.wait(timeout=10)
        self.assertTrue(t.finished)
        if verbose:
            print("    all OK -- joining worker")
        if t.finished:
            t.join()
        # else the thread is still running, and we have no way to kill it

    def test_limbo_cleanup(self):
        # Issue 7481: Failure to start thread should cleanup the limbo map.
        def fail_new_thread(*args):
            raise threading.ThreadError()
        _start_new_thread = threading._start_new_thread
        threading._start_new_thread = fail_new_thread
        try:
            t = threading.Thread(target=lambda: None)
            self.assertRaises(threading.ThreadError, t.start)
            self.assertFalse(
                t in threading._limbo,
                "Failed to cleanup _limbo map on failure of Thread.start().")
        finally:
            threading._start_new_thread = _start_new_thread

    def test_finalize_runnning_thread(self):
        # Issue 1402: the PyGILState_Ensure / _Release functions may be called
        # very late on python exit: on deallocation of a running thread for
        # example.
        import_module("ctypes")

        rc, out, err = assert_python_failure("-c", """if 1:
            import ctypes, sys, time, _thread

            # This lock is used as a simple event variable.
            ready = _thread.allocate_lock()
            ready.acquire()

            # Module globals are cleared before __del__ is run
            # So we save the functions in class dict
            class C:
                ensure = ctypes.pythonapi.PyGILState_Ensure
                release = ctypes.pythonapi.PyGILState_Release
                def __del__(self):
                    state = self.ensure()
                    self.release(state)

            def waitingThread():
                x = C()
                ready.release()
                time.sleep(100)

            _thread.start_new_thread(waitingThread, ())
            ready.acquire()  # Be sure the other thread is waiting.
            sys.exit(42)
            """)
        self.assertEqual(rc, 42)

    def test_finalize_with_trace(self):
        # Issue1733757
        # Avoid a deadlock when sys.settrace steps into threading._shutdown
        assert_python_ok("-c", """if 1:
            import sys, threading

            # A deadlock-killer, to prevent the
            # testsuite to hang forever
            def killer():
                import os, time
                time.sleep(2)
                print('program blocked; aborting')
                os._exit(2)
            t = threading.Thread(target=killer)
            t.daemon = True
            t.start()

            # This is the trace function
            def func(frame, event, arg):
                threading.current_thread()
                return func

            sys.settrace(func)