bpo-33238: Add InvalidStateError to concurrent.futures. (GH-7056)
Future.set_result and Future.set_exception now raise InvalidStateError
if the futures are not pending or running. This mirrors the behavior
of asyncio.Future, and prevents AssertionErrors in asyncio.wrap_future
when set_result is called multiple times.
diff --git a/Doc/library/concurrent.futures.rst b/Doc/library/concurrent.futures.rst
index 707d24d..6934acc 100644
--- a/Doc/library/concurrent.futures.rst
+++ b/Doc/library/concurrent.futures.rst
@@ -380,6 +380,11 @@
This method should only be used by :class:`Executor` implementations and
unit tests.
+ .. versionchanged:: 3.8
+ This method raises
+ :exc:`concurrent.futures.InvalidStateError` if the :class:`Future` is
+ already done.
+
.. method:: set_exception(exception)
Sets the result of the work associated with the :class:`Future` to the
@@ -388,6 +393,10 @@
This method should only be used by :class:`Executor` implementations and
unit tests.
+ .. versionchanged:: 3.8
+ This method raises
+ :exc:`concurrent.futures.InvalidStateError` if the :class:`Future` is
+ already done.
Module Functions
----------------
@@ -466,6 +475,13 @@
.. versionadded:: 3.7
+.. exception:: InvalidStateError
+
+ Raised when an operation is performed on a future that is not allowed
+ in the current state.
+
+ .. versionadded:: 3.8
+
.. currentmodule:: concurrent.futures.thread
.. exception:: BrokenThreadPool
diff --git a/Lib/asyncio/base_futures.py b/Lib/asyncio/base_futures.py
index 5182884..bd65bee 100644
--- a/Lib/asyncio/base_futures.py
+++ b/Lib/asyncio/base_futures.py
@@ -1,17 +1,13 @@
__all__ = ()
-import concurrent.futures._base
+import concurrent.futures
import reprlib
from . import format_helpers
-Error = concurrent.futures._base.Error
CancelledError = concurrent.futures.CancelledError
TimeoutError = concurrent.futures.TimeoutError
-
-
-class InvalidStateError(Error):
- """The operation is not allowed in this state."""
+InvalidStateError = concurrent.futures.InvalidStateError
# States for Future.
diff --git a/Lib/concurrent/futures/__init__.py b/Lib/concurrent/futures/__init__.py
index 8434fcf..d746aea 100644
--- a/Lib/concurrent/futures/__init__.py
+++ b/Lib/concurrent/futures/__init__.py
@@ -10,6 +10,7 @@
ALL_COMPLETED,
CancelledError,
TimeoutError,
+ InvalidStateError,
BrokenExecutor,
Future,
Executor,
diff --git a/Lib/concurrent/futures/_base.py b/Lib/concurrent/futures/_base.py
index 4f22f7e..d4416c6 100644
--- a/Lib/concurrent/futures/_base.py
+++ b/Lib/concurrent/futures/_base.py
@@ -53,6 +53,10 @@
"""The operation exceeded the given deadline."""
pass
+class InvalidStateError(Error):
+ """The operation is not allowed in this state."""
+ pass
+
class _Waiter(object):
"""Provides the event that wait() and as_completed() block on."""
def __init__(self):
@@ -513,6 +517,8 @@
Should only be used by Executor implementations and unit tests.
"""
with self._condition:
+ if self._state in {CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED}:
+ raise InvalidStateError('{}: {!r}'.format(self._state, self))
self._result = result
self._state = FINISHED
for waiter in self._waiters:
@@ -526,6 +532,8 @@
Should only be used by Executor implementations and unit tests.
"""
with self._condition:
+ if self._state in {CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED}:
+ raise InvalidStateError('{}: {!r}'.format(self._state, self))
self._exception = exception
self._state = FINISHED
for waiter in self._waiters:
diff --git a/Lib/test/test_concurrent_futures.py b/Lib/test/test_concurrent_futures.py
index b258a0e..f2c28ac 100644
--- a/Lib/test/test_concurrent_futures.py
+++ b/Lib/test/test_concurrent_futures.py
@@ -1206,6 +1206,34 @@
self.assertTrue(isinstance(f1.exception(timeout=5), OSError))
t.join()
+ def test_multiple_set_result(self):
+ f = create_future(state=PENDING)
+ f.set_result(1)
+
+ with self.assertRaisesRegex(
+ futures.InvalidStateError,
+ 'FINISHED: <Future at 0x[0-9a-f]+ '
+ 'state=finished returned int>'
+ ):
+ f.set_result(2)
+
+ self.assertTrue(f.done())
+ self.assertEqual(f.result(), 1)
+
+ def test_multiple_set_exception(self):
+ f = create_future(state=PENDING)
+ e = ValueError()
+ f.set_exception(e)
+
+ with self.assertRaisesRegex(
+ futures.InvalidStateError,
+ 'FINISHED: <Future at 0x[0-9a-f]+ '
+ 'state=finished raised ValueError>'
+ ):
+ f.set_exception(Exception())
+
+ self.assertEqual(f.exception(), e)
+
@test.support.reap_threads
def test_main():
diff --git a/Misc/NEWS.d/next/Library/2018-05-24-09-15-52.bpo-33238.ooDfoo.rst b/Misc/NEWS.d/next/Library/2018-05-24-09-15-52.bpo-33238.ooDfoo.rst
new file mode 100644
index 0000000..b03ab10
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-05-24-09-15-52.bpo-33238.ooDfoo.rst
@@ -0,0 +1,4 @@
+Add ``InvalidStateError`` to :mod:`concurrent.futures`.
+``Future.set_result`` and ``Future.set_exception`` now raise
+``InvalidStateError`` if the futures are not pending or running. Patch by
+Jason Haydaman.