Add dummy_thread module (google#372)

m4ns0ur · trotterdylan · commit 6bdfc4bdd734 · 2017-07-25T21:12:32.000-07:00
diff --git a/Makefile b/Makefile
@@ -97,6 +97,7 @@ STDLIB_TESTS := \
   test/test_datetime \
   test/test_dict \
   test/test_dircache \
+  test/test_dummy_thread \
   test/test_fpformat \
   test/test_genericpath \
   test/test_list \
diff --git a/third_party/stdlib/dummy_thread.py b/third_party/stdlib/dummy_thread.py
@@ -0,0 +1,145 @@
+"""Drop-in replacement for the thread module.
+
+Meant to be used as a brain-dead substitute so that threaded code does
+not need to be rewritten for when the thread module is not present.
+
+Suggested usage is::
+
+    try:
+        import thread
+    except ImportError:
+        import dummy_thread as thread
+
+"""
+# Exports only things specified by thread documentation;
+# skipping obsolete synonyms allocate(), start_new(), exit_thread().
+__all__ = ['error', 'start_new_thread', 'exit', 'get_ident', 'allocate_lock',
+           'interrupt_main', 'LockType']
+
+import traceback as _traceback
+
+class error(Exception):
+    """Dummy implementation of thread.error."""
+
+    def __init__(self, *args):
+        self.args = args
+
+def start_new_thread(function, args, kwargs={}):
+    """Dummy implementation of thread.start_new_thread().
+
+    Compatibility is maintained by making sure that ``args`` is a
+    tuple and ``kwargs`` is a dictionary.  If an exception is raised
+    and it is SystemExit (which can be done by thread.exit()) it is
+    caught and nothing is done; all other exceptions are printed out
+    by using traceback.print_exc().
+
+    If the executed function calls interrupt_main the KeyboardInterrupt will be
+    raised when the function returns.
+
+    """
+    if type(args) != type(tuple()):
+        raise TypeError("2nd arg must be a tuple")
+    if type(kwargs) != type(dict()):
+        raise TypeError("3rd arg must be a dict")
+    global _main
+    _main = False
+    try:
+        function(*args, **kwargs)
+    except SystemExit:
+        pass
+    except:
+        _traceback.print_exc()
+    _main = True
+    global _interrupt
+    if _interrupt:
+        _interrupt = False
+        raise KeyboardInterrupt
+
+def exit():
+    """Dummy implementation of thread.exit()."""
+    raise SystemExit
+
+def get_ident():
+    """Dummy implementation of thread.get_ident().
+
+    Since this module should only be used when threadmodule is not
+    available, it is safe to assume that the current process is the
+    only thread.  Thus a constant can be safely returned.
+    """
+    return -1
+
+def allocate_lock():
+    """Dummy implementation of thread.allocate_lock()."""
+    return LockType()
+
+def stack_size(size=None):
+    """Dummy implementation of thread.stack_size()."""
+    if size is not None:
+        raise error("setting thread stack size not supported")
+    return 0
+
+class LockType(object):
+    """Class implementing dummy implementation of thread.LockType.
+
+    Compatibility is maintained by maintaining self.locked_status
+    which is a boolean that stores the state of the lock.  Pickling of
+    the lock, though, should not be done since if the thread module is
+    then used with an unpickled ``lock()`` from here problems could
+    occur from this class not having atomic methods.
+
+    """
+
+    def __init__(self):
+        self.locked_status = False
+
+    def acquire(self, waitflag=None):
+        """Dummy implementation of acquire().
+
+        For blocking calls, self.locked_status is automatically set to
+        True and returned appropriately based on value of
+        ``waitflag``.  If it is non-blocking, then the value is
+        actually checked and not set if it is already acquired.  This
+        is all done so that threading.Condition's assert statements
+        aren't triggered and throw a little fit.
+
+        """
+        if waitflag is None or waitflag:
+            self.locked_status = True
+            return True
+        else:
+            if not self.locked_status:
+                self.locked_status = True
+                return True
+            else:
+                return False
+
+    __enter__ = acquire
+
+    def __exit__(self, typ, val, tb):
+        self.release()
+
+    def release(self):
+        """Release the dummy lock."""
+        # XXX Perhaps shouldn't actually bother to test?  Could lead
+        #     to problems for complex, threaded code.
+        if not self.locked_status:
+            raise error
+        self.locked_status = False
+        return True
+
+    def locked(self):
+        return self.locked_status
+
+# Used to signal that interrupt_main was called in a "thread"
+_interrupt = False
+# True when not executing in a "thread"
+_main = True
+
+def interrupt_main():
+    """Set _interrupt flag to True to have start_new_thread raise
+    KeyboardInterrupt upon exiting."""
+    if _main:
+        raise KeyboardInterrupt
+    else:
+        global _interrupt
+        _interrupt = True
diff --git a/third_party/stdlib/test/test_dummy_thread.py b/third_party/stdlib/test/test_dummy_thread.py
@@ -0,0 +1,182 @@
+"""Generic thread tests.
+
+Meant to be used by dummy_thread and thread.  To allow for different modules
+to be used, test_main() can be called with the module to use as the thread
+implementation as its sole argument.
+
+"""
+import dummy_thread as _thread
+import time
+import Queue
+import random
+import unittest
+from test import test_support
+
+DELAY = 0 # Set > 0 when testing a module other than dummy_thread, such as
+          # the 'thread' module.
+
+class LockTests(unittest.TestCase):
+    """Test lock objects."""
+
+    def setUp(self):
+        # Create a lock
+        self.lock = _thread.allocate_lock()
+
+    def test_initlock(self):
+        #Make sure locks start locked
+        self.assertFalse(self.lock.locked(),
+                        "Lock object is not initialized unlocked.")
+
+    def test_release(self):
+        # Test self.lock.release()
+        self.lock.acquire()
+        self.lock.release()
+        self.assertFalse(self.lock.locked(),
+                        "Lock object did not release properly.")
+
+    def test_improper_release(self):
+        #Make sure release of an unlocked thread raises _thread.error
+        self.assertRaises(_thread.error, self.lock.release)
+
+    def test_cond_acquire_success(self):
+        #Make sure the conditional acquiring of the lock works.
+        self.assertTrue(self.lock.acquire(0),
+                        "Conditional acquiring of the lock failed.")
+
+    def test_cond_acquire_fail(self):
+        #Test acquiring locked lock returns False
+        self.lock.acquire(0)
+        self.assertFalse(self.lock.acquire(0),
+                        "Conditional acquiring of a locked lock incorrectly "
+                         "succeeded.")
+
+    def test_uncond_acquire_success(self):
+        #Make sure unconditional acquiring of a lock works.
+        self.lock.acquire()
+        self.assertTrue(self.lock.locked(),
+                        "Uncondional locking failed.")
+
+    def test_uncond_acquire_return_val(self):
+        #Make sure that an unconditional locking returns True.
+        self.assertIs(self.lock.acquire(1), True,
+                        "Unconditional locking did not return True.")
+        self.assertIs(self.lock.acquire(), True)
+
+    def test_uncond_acquire_blocking(self):
+        #Make sure that unconditional acquiring of a locked lock blocks.
+        def delay_unlock(to_unlock, delay):
+            """Hold on to lock for a set amount of time before unlocking."""
+            time.sleep(delay)
+            to_unlock.release()
+
+        self.lock.acquire()
+        start_time = int(time.time())
+        _thread.start_new_thread(delay_unlock,(self.lock, DELAY))
+        if test_support.verbose:
+            print
+            print "*** Waiting for thread to release the lock "\
+            "(approx. %s sec.) ***" % DELAY
+        self.lock.acquire()
+        end_time = int(time.time())
+        if test_support.verbose:
+            print "done"
+        self.assertGreaterEqual(end_time - start_time, DELAY,
+                        "Blocking by unconditional acquiring failed.")
+
+class MiscTests(unittest.TestCase):
+    """Miscellaneous tests."""
+
+    def test_exit(self):
+        #Make sure _thread.exit() raises SystemExit
+        self.assertRaises(SystemExit, _thread.exit)
+
+    def test_ident(self):
+        #Test sanity of _thread.get_ident()
+        self.assertIsInstance(_thread.get_ident(), int,
+                              "_thread.get_ident() returned a non-integer")
+        self.assertNotEqual(_thread.get_ident(), 0,
+                        "_thread.get_ident() returned 0")
+
+    def test_LockType(self):
+        #Make sure _thread.LockType is the same type as _thread.allocate_locke()
+        self.assertIsInstance(_thread.allocate_lock(), _thread.LockType,
+                              "_thread.LockType is not an instance of what "
+                              "is returned by _thread.allocate_lock()")
+
+    def test_interrupt_main(self):
+        #Calling start_new_thread with a function that executes interrupt_main
+        # should raise KeyboardInterrupt upon completion.
+        def call_interrupt():
+            _thread.interrupt_main()
+        self.assertRaises(KeyboardInterrupt, _thread.start_new_thread,
+                              call_interrupt, tuple())
+
+    def test_interrupt_in_main(self):
+        # Make sure that if interrupt_main is called in main threat that
+        # KeyboardInterrupt is raised instantly.
+        self.assertRaises(KeyboardInterrupt, _thread.interrupt_main)
+
+class ThreadTests(unittest.TestCase):
+    """Test thread creation."""
+
+    def test_arg_passing(self):
+        #Make sure that parameter passing works.
+        def arg_tester(queue, arg1=False, arg2=False):
+            """Use to test _thread.start_new_thread() passes args properly."""
+            queue.put((arg1, arg2))
+
+        testing_queue = Queue.Queue(1)
+        _thread.start_new_thread(arg_tester, (testing_queue, True, True))
+        result = testing_queue.get()
+        self.assertTrue(result[0] and result[1],
+                        "Argument passing for thread creation using tuple failed")
+        _thread.start_new_thread(arg_tester, tuple(), {'queue':testing_queue,
+                                                       'arg1':True, 'arg2':True})
+        result = testing_queue.get()
+        self.assertTrue(result[0] and result[1],
+                        "Argument passing for thread creation using kwargs failed")
+        _thread.start_new_thread(arg_tester, (testing_queue, True), {'arg2':True})
+        result = testing_queue.get()
+        self.assertTrue(result[0] and result[1],
+                        "Argument passing for thread creation using both tuple"
+                        " and kwargs failed")
+
+    def test_multi_creation(self):
+        #Make sure multiple threads can be created.
+        def queue_mark(queue, delay):
+            """Wait for ``delay`` seconds and then put something into ``queue``"""
+            time.sleep(delay)
+            queue.put(_thread.get_ident())
+
+        thread_count = 5
+        testing_queue = Queue.Queue(thread_count)
+        if test_support.verbose:
+            print
+            print "*** Testing multiple thread creation "\
+            "(will take approx. %s to %s sec.) ***" % (DELAY, thread_count)
+        for count in xrange(thread_count):
+            if DELAY:
+                local_delay = round(random.random(), 1)
+            else:
+                local_delay = 0
+            _thread.start_new_thread(queue_mark,
+                                     (testing_queue, local_delay))
+        time.sleep(DELAY)
+        if test_support.verbose:
+            print 'done'
+        self.assertEqual(testing_queue.qsize(), thread_count,
+                        "Not all %s threads executed properly after %s sec." %
+                        (thread_count, DELAY))
+
+def test_main(imported_module=None):
+    global _thread, DELAY
+    if imported_module:
+        _thread = imported_module
+        DELAY = 2
+    if test_support.verbose:
+        print
+        print "*** Using %s as _thread module ***" % _thread
+    test_support.run_unittest(LockTests, MiscTests, ThreadTests)
+
+if __name__ == '__main__':
+    test_main()
