Add tornado.locks.Event.

Copied from Toro with small improvements.

diff --git a/tornado/locks.py b/tornado/locks.py
index 9338c8535ccc193a6ccf42f14ac23ff78f615588..6bf4b5bc74766090f7714115e9b87ce8506adbd5 100644 (file)
--- a/tornado/locks.py
+++ b/tornado/locks.py
@@ -14,7 +14,7 @@
 
 from __future__ import absolute_import, division, print_function, with_statement
 
-__all__ = ['Condition']
+__all__ = ['Condition', 'Event']
 
 import collections
 
@@ -79,3 +79,51 @@ class Condition(object):
             self._timeouts = 0
             self._waiters = collections.deque(
                 w for w in self._waiters if not w.done())
+
+_true_future = Future()
+_true_future.set_result(True)
+
+
+class Event(object):
+    """An event blocks coroutines until its internal flag is set to True.
+
+    Similar to `threading.Event`.
+    """
+    def __init__(self):
+        self.io_loop = ioloop.IOLoop.current()
+        self._condition = Condition()
+        self._flag = False
+
+    def __str__(self):
+        return '<%s %s>' % (
+            self.__class__.__name__, 'set' if self._flag else 'clear')
+
+    def is_set(self):
+        """Return ``True`` if the internal flag is true."""
+        return self._flag
+
+    def set(self):
+        """Set the internal flag to ``True``. All waiters are awakened.
+
+        Calling `.wait` once the flag is set will not block.
+        """
+        self._flag = True
+        self._condition.notify_all()
+
+    def clear(self):
+        """Reset the internal flag to ``False``.
+        
+        Calls to `.wait` will block until `.set` is called.
+        """
+        self._flag = False
+
+    def wait(self, deadline=None):
+        """Block until the internal flag is true.
+
+        Returns a `.Future` that resolves ``True`` if the condition is notified,
+        or ``False`` after a timeout.
+        """
+        if self._flag:
+            return _true_future
+        else:
+            return self._condition.wait(deadline)

diff --git a/tornado/test/event_test.py b/tornado/test/event_test.py
new file mode 100644 (file)
index 0000000..a51e050
--- /dev/null
+++ b/tornado/test/event_test.py
@@ -0,0 +1,66 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from datetime import timedelta
+import unittest
+
+from tornado import gen, locks
+from tornado.testing import gen_test, AsyncTestCase
+
+
+class TestEvent(AsyncTestCase):
+    def test_str(self):
+        event = locks.Event()
+        self.assertTrue('clear' in str(event))
+        self.assertFalse('set' in str(event))
+        event.set()
+        self.assertFalse('clear' in str(event))
+        self.assertTrue('set' in str(event))
+
+    @gen.coroutine
+    def _test_event(self, n):
+        e = locks.Event()
+        futures = [e.wait() for _ in range(n)]
+        e.set()
+        e.clear()
+        results = yield futures
+        self.assertTrue(all(results))
+
+    @gen_test
+    def test_event_1(self):
+        yield self._test_event(1)
+
+    @gen_test
+    def test_event_200(self):
+        yield self._test_event(200)
+
+    @gen_test
+    def test_event_timeout(self):
+        e = locks.Event()
+        result = yield e.wait(deadline=timedelta(seconds=0.01))
+        self.assertEqual(False, result)
+
+        # After a timed-out waiter, normal operation works.
+        self.io_loop.add_timeout(timedelta(seconds=0.01), e.set)
+        result = yield e.wait(deadline=timedelta(seconds=1))
+        self.assertTrue(result)
+
+    @gen_test
+    def test_event_nowait(self):
+        e = locks.Event()
+        e.set()
+        self.assertEqual(True, e.is_set())
+        self.assertTrue(e.wait().result())
+
+
+if __name__ == '__main__':
+    unittest.main()

diff --git a/tornado/test/runtests.py b/tornado/test/runtests.py
index 3f4aaa1e6887a778948c07f08cfc0d24dd25e187..1cdcdde0a0b8c29f008de7a60f185a52b748365f 100644 (file)
--- a/tornado/test/runtests.py
+++ b/tornado/test/runtests.py
@@ -28,6 +28,7 @@ TEST_MODULES = [
     'tornado.test.condition_test',
     'tornado.test.curl_httpclient_test',
     'tornado.test.escape_test',
+    'tornado.test.event_test',
     'tornado.test.gen_test',
     'tornado.test.httpclient_test',
     'tornado.test.httpserver_test',