[Python-checkins] bpo-32528: Make asyncio.CancelledError a BaseException. (GH-13528)
Yury Selivanov
webhook-mailer at python.org
Mon May 27 08:45:16 EDT 2019
https://github.com/python/cpython/commit/431b540bf79f0982559b1b0e420b1b085f667bb7
commit: 431b540bf79f0982559b1b0e420b1b085f667bb7
branch: master
author: Yury Selivanov <yury at magic.io>
committer: GitHub <noreply at github.com>
date: 2019-05-27T14:45:12+02:00
summary:
bpo-32528: Make asyncio.CancelledError a BaseException. (GH-13528)
This will address the common mistake many asyncio users make:
an "except Exception" clause breaking Tasks cancellation.
In addition to this change, we stop inheriting asyncio.TimeoutError
and asyncio.InvalidStateError from their concurrent.futures.*
counterparts. There's no point for these exceptions to share the
inheritance chain.
In 3.9 we'll focus on implementing supervisors and cancel scopes,
which should allow better handling of all exceptions, including
SystemExit and KeyboardInterrupt
files:
A Misc/NEWS.d/next/Library/2019-05-23-17-37-22.bpo-32528.sGnkcl.rst
M Lib/asyncio/base_events.py
M Lib/asyncio/base_subprocess.py
M Lib/asyncio/events.py
M Lib/asyncio/exceptions.py
M Lib/asyncio/proactor_events.py
M Lib/asyncio/selector_events.py
M Lib/asyncio/sslproto.py
M Lib/asyncio/staggered.py
M Lib/asyncio/tasks.py
M Lib/asyncio/transports.py
M Lib/asyncio/unix_events.py
M Lib/asyncio/windows_events.py
M Lib/test/test_asyncio/test_base_events.py
M Lib/test/test_asyncio/test_tasks.py
M Modules/_asynciomodule.c
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index de9fa4f4f7f3..63b072b851e3 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -186,7 +186,7 @@ def _interleave_addrinfos(addrinfos, first_address_family_count=1):
def _run_until_complete_cb(fut):
if not fut.cancelled():
exc = fut.exception()
- if isinstance(exc, BaseException) and not isinstance(exc, Exception):
+ if isinstance(exc, (SystemExit, KeyboardInterrupt)):
# Issue #22429: run_forever() already finished, no need to
# stop it.
return
@@ -1196,7 +1196,7 @@ def _check_sendfile_params(self, sock, file, offset, count):
try:
await waiter
- except Exception:
+ except BaseException:
transport.close()
conmade_cb.cancel()
resume_cb.cancel()
@@ -1710,7 +1710,9 @@ def call_exception_handler(self, context):
if self._exception_handler is None:
try:
self.default_exception_handler(context)
- except Exception:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException:
# Second protection layer for unexpected errors
# in the default implementation, as well as for subclassed
# event loops with overloaded "default_exception_handler".
@@ -1719,7 +1721,9 @@ def call_exception_handler(self, context):
else:
try:
self._exception_handler(self, context)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
# Exception in the user set custom exception handler.
try:
# Let's try default handler.
@@ -1728,7 +1732,9 @@ def call_exception_handler(self, context):
'exception': exc,
'context': context,
})
- except Exception:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException:
# Guard 'default_exception_handler' in case it is
# overloaded.
logger.error('Exception in default exception handler '
diff --git a/Lib/asyncio/base_subprocess.py b/Lib/asyncio/base_subprocess.py
index f503f78fdda3..14d505192288 100644
--- a/Lib/asyncio/base_subprocess.py
+++ b/Lib/asyncio/base_subprocess.py
@@ -182,7 +182,9 @@ def kill(self):
for callback, data in self._pending_calls:
loop.call_soon(callback, *data)
self._pending_calls = None
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
if waiter is not None and not waiter.cancelled():
waiter.set_exception(exc)
else:
diff --git a/Lib/asyncio/events.py b/Lib/asyncio/events.py
index 9a923514db09..d381b1c59623 100644
--- a/Lib/asyncio/events.py
+++ b/Lib/asyncio/events.py
@@ -79,7 +79,9 @@ def cancelled(self):
def _run(self):
try:
self._context.run(self._callback, *self._args)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
cb = format_helpers._format_callback_source(
self._callback, self._args)
msg = f'Exception in callback {cb}'
diff --git a/Lib/asyncio/exceptions.py b/Lib/asyncio/exceptions.py
index cac31a54d253..e03602ef5762 100644
--- a/Lib/asyncio/exceptions.py
+++ b/Lib/asyncio/exceptions.py
@@ -5,19 +5,16 @@
'IncompleteReadError', 'LimitOverrunError',
'SendfileNotAvailableError')
-import concurrent.futures
-from . import base_futures
-
-class CancelledError(concurrent.futures.CancelledError):
+class CancelledError(BaseException):
"""The Future or Task was cancelled."""
-class TimeoutError(concurrent.futures.TimeoutError):
+class TimeoutError(Exception):
"""The operation exceeded the given deadline."""
-class InvalidStateError(concurrent.futures.InvalidStateError):
+class InvalidStateError(Exception):
"""The operation is not allowed in this state."""
diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
index a849be1cc147..7dfe29579a0d 100644
--- a/Lib/asyncio/proactor_events.py
+++ b/Lib/asyncio/proactor_events.py
@@ -212,7 +212,9 @@ def _eof_received(self):
try:
keep_open = self._protocol.eof_received()
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(
exc, 'Fatal error: protocol.eof_received() call failed.')
return
@@ -235,7 +237,9 @@ def _data_received(self, data):
if isinstance(self._protocol, protocols.BufferedProtocol):
try:
protocols._feed_data_to_buffered_proto(self._protocol, data)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(exc,
'Fatal error: protocol.buffer_updated() '
'call failed.')
@@ -625,7 +629,9 @@ def _loop_self_reading(self, f=None):
except exceptions.CancelledError:
# _close_self_pipe() has been called, stop waiting for data
return
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self.call_exception_handler({
'message': 'Error on reading from the event loop self pipe',
'exception': exc,
diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
index 6461d3077633..f5f43a9bfef3 100644
--- a/Lib/asyncio/selector_events.py
+++ b/Lib/asyncio/selector_events.py
@@ -208,12 +208,14 @@ def _accept_connection(
try:
await waiter
- except:
+ except BaseException:
transport.close()
raise
+ # It's now up to the protocol to handle the connection.
- # It's now up to the protocol to handle the connection.
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
if self._debug:
context = {
'message':
@@ -370,7 +372,9 @@ def _sock_recv(self, fut, sock, n):
data = sock.recv(n)
except (BlockingIOError, InterruptedError):
return # try again next time
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
fut.set_exception(exc)
else:
fut.set_result(data)
@@ -404,7 +408,9 @@ def _sock_recv_into(self, fut, sock, buf):
nbytes = sock.recv_into(buf)
except (BlockingIOError, InterruptedError):
return # try again next time
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
fut.set_exception(exc)
else:
fut.set_result(nbytes)
@@ -447,7 +453,9 @@ def _sock_sendall(self, fut, sock, view, pos):
n = sock.send(view[start:])
except (BlockingIOError, InterruptedError):
return
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
fut.set_exception(exc)
return
@@ -487,7 +495,9 @@ def _sock_connect(self, fut, sock, address):
fut.add_done_callback(
functools.partial(self._sock_write_done, fd))
self.add_writer(fd, self._sock_connect_cb, fut, sock, address)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
fut.set_exception(exc)
else:
fut.set_result(None)
@@ -507,7 +517,9 @@ def _sock_connect_cb(self, fut, sock, address):
except (BlockingIOError, InterruptedError):
# socket is still registered, the callback will be retried later
pass
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
fut.set_exception(exc)
else:
fut.set_result(None)
@@ -537,7 +549,9 @@ def _sock_accept(self, fut, registered, sock):
conn.setblocking(False)
except (BlockingIOError, InterruptedError):
self.add_reader(fd, self._sock_accept, fut, True, sock)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
fut.set_exception(exc)
else:
fut.set_result((conn, address))
@@ -785,7 +799,9 @@ def _read_ready__get_buffer(self):
buf = self._protocol.get_buffer(-1)
if not len(buf):
raise RuntimeError('get_buffer() returned an empty buffer')
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(
exc, 'Fatal error: protocol.get_buffer() call failed.')
return
@@ -794,7 +810,9 @@ def _read_ready__get_buffer(self):
nbytes = self._sock.recv_into(buf)
except (BlockingIOError, InterruptedError):
return
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(exc, 'Fatal read error on socket transport')
return
@@ -804,7 +822,9 @@ def _read_ready__get_buffer(self):
try:
self._protocol.buffer_updated(nbytes)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(
exc, 'Fatal error: protocol.buffer_updated() call failed.')
@@ -815,7 +835,9 @@ def _read_ready__data_received(self):
data = self._sock.recv(self.max_size)
except (BlockingIOError, InterruptedError):
return
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(exc, 'Fatal read error on socket transport')
return
@@ -825,7 +847,9 @@ def _read_ready__data_received(self):
try:
self._protocol.data_received(data)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(
exc, 'Fatal error: protocol.data_received() call failed.')
@@ -835,7 +859,9 @@ def _read_ready__on_eof(self):
try:
keep_open = self._protocol.eof_received()
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(
exc, 'Fatal error: protocol.eof_received() call failed.')
return
@@ -871,7 +897,9 @@ def write(self, data):
n = self._sock.send(data)
except (BlockingIOError, InterruptedError):
pass
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(exc, 'Fatal write error on socket transport')
return
else:
@@ -894,7 +922,9 @@ def _write_ready(self):
n = self._sock.send(self._buffer)
except (BlockingIOError, InterruptedError):
pass
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._loop._remove_writer(self._sock_fd)
self._buffer.clear()
self._fatal_error(exc, 'Fatal write error on socket transport')
@@ -970,7 +1000,9 @@ def _read_ready(self):
pass
except OSError as exc:
self._protocol.error_received(exc)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(exc, 'Fatal read error on datagram transport')
else:
self._protocol.datagram_received(data, addr)
@@ -1007,7 +1039,9 @@ def sendto(self, data, addr=None):
except OSError as exc:
self._protocol.error_received(exc)
return
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(
exc, 'Fatal write error on datagram transport')
return
@@ -1030,7 +1064,9 @@ def _sendto_ready(self):
except OSError as exc:
self._protocol.error_received(exc)
return
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._fatal_error(
exc, 'Fatal write error on datagram transport')
return
diff --git a/Lib/asyncio/sslproto.py b/Lib/asyncio/sslproto.py
index 97a6fc66a927..8546985fe63f 100644
--- a/Lib/asyncio/sslproto.py
+++ b/Lib/asyncio/sslproto.py
@@ -527,7 +527,9 @@ def data_received(self, data):
try:
ssldata, appdata = self._sslpipe.feed_ssldata(data)
- except Exception as e:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as e:
self._fatal_error(e, 'SSL error in data received')
return
@@ -542,7 +544,9 @@ def data_received(self, data):
self._app_protocol, chunk)
else:
self._app_protocol.data_received(chunk)
- except Exception as ex:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as ex:
self._fatal_error(
ex, 'application protocol failed to receive SSL data')
return
@@ -628,7 +632,9 @@ def _on_handshake_complete(self, handshake_exc):
raise handshake_exc
peercert = sslobj.getpeercert()
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
if isinstance(exc, ssl.CertificateError):
msg = 'SSL handshake failed on verifying the certificate'
else:
@@ -691,7 +697,9 @@ def _process_write_backlog(self):
# delete it and reduce the outstanding buffer size.
del self._write_backlog[0]
self._write_buffer_size -= len(data)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
if self._in_handshake:
# Exceptions will be re-raised in _on_handshake_complete.
self._on_handshake_complete(exc)
diff --git a/Lib/asyncio/staggered.py b/Lib/asyncio/staggered.py
index feec681b4371..27c665a9910a 100644
--- a/Lib/asyncio/staggered.py
+++ b/Lib/asyncio/staggered.py
@@ -105,7 +105,9 @@
try:
result = await coro_fn()
- except Exception as e:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as e:
exceptions[this_index] = e
this_failed.set() # Kickstart the next coroutine
else:
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index 1dc595298c55..78e76003b3ac 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -260,11 +260,11 @@ def __step(self, exc=None):
super().set_result(exc.value)
except exceptions.CancelledError:
super().cancel() # I.e., Future.cancel(self).
- except Exception as exc:
+ except (KeyboardInterrupt, SystemExit) as exc:
super().set_exception(exc)
+ raise
except BaseException as exc:
super().set_exception(exc)
- raise
else:
blocking = getattr(result, '_asyncio_future_blocking', None)
if blocking is not None:
@@ -318,7 +318,7 @@ def __step(self, exc=None):
def __wakeup(self, future):
try:
future.result()
- except Exception as exc:
+ except BaseException as exc:
# This may also be a cancellation.
self.__step(exc)
else:
@@ -858,7 +858,9 @@ def run_coroutine_threadsafe(coro, loop):
def callback():
try:
futures._chain_future(ensure_future(coro, loop=loop), future)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
if future.set_running_or_notify_cancel():
future.set_exception(exc)
raise
diff --git a/Lib/asyncio/transports.py b/Lib/asyncio/transports.py
index 233bbb53cb6a..47b37fa9b7f0 100644
--- a/Lib/asyncio/transports.py
+++ b/Lib/asyncio/transports.py
@@ -262,7 +262,9 @@ def _maybe_pause_protocol(self):
self._protocol_paused = True
try:
self._protocol.pause_writing()
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._loop.call_exception_handler({
'message': 'protocol.pause_writing() failed',
'exception': exc,
@@ -276,7 +278,9 @@ def _maybe_resume_protocol(self):
self._protocol_paused = False
try:
self._protocol.resume_writing()
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._loop.call_exception_handler({
'message': 'protocol.resume_writing() failed',
'exception': exc,
diff --git a/Lib/asyncio/unix_events.py b/Lib/asyncio/unix_events.py
index 1aa3b396086c..81d10b190cc6 100644
--- a/Lib/asyncio/unix_events.py
+++ b/Lib/asyncio/unix_events.py
@@ -194,7 +194,9 @@ def _make_write_pipe_transport(self, pipe, protocol, waiter=None,
self._child_watcher_callback, transp)
try:
await waiter
- except Exception:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException:
transp.close()
await transp._wait()
raise
@@ -390,7 +392,9 @@ def _sock_sendfile_native_impl(self, fut, registered_fd, sock, fileno,
else:
self._sock_sendfile_update_filepos(fileno, offset, total_sent)
fut.set_exception(exc)
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._sock_sendfile_update_filepos(fileno, offset, total_sent)
fut.set_exception(exc)
else:
@@ -641,7 +645,9 @@ def write(self, data):
n = os.write(self._fileno, data)
except (BlockingIOError, InterruptedError):
n = 0
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._conn_lost += 1
self._fatal_error(exc, 'Fatal write error on pipe transport')
return
@@ -661,7 +667,9 @@ def _write_ready(self):
n = os.write(self._fileno, self._buffer)
except (BlockingIOError, InterruptedError):
pass
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
self._buffer.clear()
self._conn_lost += 1
# Remove writer here, _fatal_error() doesn't it
@@ -879,7 +887,9 @@ def attach_loop(self, loop):
def _sig_chld(self):
try:
self._do_waitpid_all()
- except Exception as exc:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException as exc:
# self._loop should always be available here
# as '_sig_chld' is added as a signal handler
# in 'attach_loop'
diff --git a/Lib/asyncio/windows_events.py b/Lib/asyncio/windows_events.py
index 29750f18d80c..b5b2e24c5ba4 100644
--- a/Lib/asyncio/windows_events.py
+++ b/Lib/asyncio/windows_events.py
@@ -388,7 +388,9 @@ def loop_accept_pipe(f=None):
**kwargs)
try:
await waiter
- except Exception:
+ except (SystemExit, KeyboardInterrupt):
+ raise
+ except BaseException:
transp.close()
await transp._wait()
raise
diff --git a/Lib/test/test_asyncio/test_base_events.py b/Lib/test/test_asyncio/test_base_events.py
index f068fc781f5d..31018c5c5636 100644
--- a/Lib/test/test_asyncio/test_base_events.py
+++ b/Lib/test/test_asyncio/test_base_events.py
@@ -476,7 +476,7 @@ def test_run_until_complete_loop(self):
other_loop.run_until_complete, task)
def test_run_until_complete_loop_orphan_future_close_loop(self):
- class ShowStopper(BaseException):
+ class ShowStopper(SystemExit):
pass
async def foo(delay):
@@ -487,10 +487,8 @@ def throw():
self.loop._process_events = mock.Mock()
self.loop.call_soon(throw)
- try:
+ with self.assertRaises(ShowStopper):
self.loop.run_until_complete(foo(0.1))
- except ShowStopper:
- pass
# This call fails if run_until_complete does not clean up
# done-callback for the previous future.
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index 1c1f912ff8af..114dd76687cd 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -1527,7 +1527,7 @@ def gen():
async def sleeper():
await asyncio.sleep(10)
- base_exc = BaseException()
+ base_exc = SystemExit()
async def notmutch():
try:
@@ -1541,7 +1541,7 @@ def gen():
task.cancel()
self.assertFalse(task.done())
- self.assertRaises(BaseException, test_utils.run_briefly, loop)
+ self.assertRaises(SystemExit, test_utils.run_briefly, loop)
self.assertTrue(task.done())
self.assertFalse(task.cancelled())
diff --git a/Misc/NEWS.d/next/Library/2019-05-23-17-37-22.bpo-32528.sGnkcl.rst b/Misc/NEWS.d/next/Library/2019-05-23-17-37-22.bpo-32528.sGnkcl.rst
new file mode 100644
index 000000000000..375f426025d3
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-05-23-17-37-22.bpo-32528.sGnkcl.rst
@@ -0,0 +1,8 @@
+Make asyncio.CancelledError a BaseException.
+
+This will address the common mistake many asyncio users make: an "except
+Exception" clause breaking Tasks cancellation.
+
+In addition to this change, we stop inheriting asyncio.TimeoutError and
+asyncio.InvalidStateError from their concurrent.futures.* counterparts.
+There's no point for these exceptions to share the inheritance chain.
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index f9037c279ac9..ac15d0169b81 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -2672,8 +2672,10 @@ task_step_impl(TaskObj *task, PyObject *exc)
assert(o == Py_None);
Py_DECREF(o);
- if (!PyErr_GivenExceptionMatches(et, PyExc_Exception)) {
- /* We've got a BaseException; re-raise it */
+ if (PyErr_GivenExceptionMatches(et, PyExc_KeyboardInterrupt) ||
+ PyErr_GivenExceptionMatches(et, PyExc_SystemExit))
+ {
+ /* We've got a KeyboardInterrupt or a SystemError; re-raise it */
PyErr_Restore(et, ev, tb);
goto fail;
}
@@ -2950,11 +2952,6 @@ task_wakeup(TaskObj *task, PyObject *o)
}
PyErr_Fetch(&et, &ev, &tb);
- if (!PyErr_GivenExceptionMatches(et, PyExc_Exception)) {
- /* We've got a BaseException; re-raise it */
- PyErr_Restore(et, ev, tb);
- return NULL;
- }
if (!ev || !PyObject_TypeCheck(ev, (PyTypeObject *) et)) {
PyErr_NormalizeException(&et, &ev, &tb);
}
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