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pythongh-120221: Support KeyboardInterrupt in asyncio REPL
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This switches the main pyrepl event loop to always be non-blocking so that it
can listen to incoming interruptions from other threads.

This also resolves invalid display of exceptions from other threads
(pythongh-123178).
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ambv committed Sep 6, 2024
1 parent d343f97 commit 49a0753
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Showing 4 changed files with 113 additions and 15 deletions.
74 changes: 74 additions & 0 deletions Lib/_pyrepl/_threading_handler.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,74 @@
from __future__ import annotations

from dataclasses import dataclass, field
import traceback


TYPE_CHECKING = False
if TYPE_CHECKING:
from threading import Thread
from types import TracebackType
from typing import Protocol

class ExceptHookArgs(Protocol):
@property
def exc_type(self) -> type[BaseException]: ...
@property
def exc_value(self) -> BaseException | None: ...
@property
def exc_traceback(self) -> TracebackType | None: ...
@property
def thread(self) -> Thread | None: ...

class ShowExceptions(Protocol):
def __call__(self) -> int: ...
def add(self, s: str) -> None: ...

from .reader import Reader


def install_threading_hook(reader: Reader) -> None:
import threading

@dataclass
class ExceptHookHandler:
lock: threading.Lock = field(default_factory=threading.Lock)
messages: list[str] = field(default_factory=list)

def show(self) -> int:
count = 0
with self.lock:
if not self.messages:
return 0
reader.restore()
for tb in self.messages:
count += 1
if tb:
print(tb)
self.messages.clear()
reader.scheduled_commands.append("ctrl-c")
reader.prepare()
return count

def add(self, s: str) -> None:
with self.lock:
self.messages.append(s)

def exception(self, args: ExceptHookArgs) -> None:
lines = traceback.format_exception(
args.exc_type,
args.exc_value,
args.exc_traceback,
colorize=reader.can_colorize,
) # type: ignore[call-overload]
pre = f"\nException in {args.thread.name}:\n" if args.thread else "\n"
tb = pre + "".join(lines)
self.add(tb)

def __call__(self) -> int:
return self.show()


handler = ExceptHookHandler()
reader.threading_hook = handler
threading.excepthook = handler.exception
42 changes: 28 additions & 14 deletions Lib/_pyrepl/reader.py
Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,7 @@

# types
Command = commands.Command
if False:
from .types import Callback, SimpleContextManager, KeySpec, CommandName
from .types import Callback, SimpleContextManager, KeySpec, CommandName


def disp_str(buffer: str) -> tuple[str, list[int]]:
Expand Down Expand Up @@ -247,6 +246,7 @@ class Reader:
lxy: tuple[int, int] = field(init=False)
scheduled_commands: list[str] = field(default_factory=list)
can_colorize: bool = False
threading_hook: Callback | None = None

## cached metadata to speed up screen refreshes
@dataclass
Expand Down Expand Up @@ -722,6 +722,24 @@ def do_cmd(self, cmd: tuple[str, list[str]]) -> None:
self.console.finish()
self.finish()

def run_hooks(self) -> None:
threading_hook = self.threading_hook
if threading_hook is None and 'threading' in sys.modules:
from ._threading_handler import install_threading_hook
install_threading_hook(self)
if threading_hook is not None:
try:
threading_hook()
except Exception:
pass

input_hook = self.console.input_hook
if input_hook:
try:
input_hook()
except Exception:
pass

def handle1(self, block: bool = True) -> bool:
"""Handle a single event. Wait as long as it takes if block
is true (the default), otherwise return False if no event is
Expand All @@ -732,16 +750,13 @@ def handle1(self, block: bool = True) -> bool:
self.dirty = True

while True:
input_hook = self.console.input_hook
if input_hook:
input_hook()
# We use the same timeout as in readline.c: 100ms
while not self.console.wait(100):
input_hook()
event = self.console.get_event(block=False)
else:
event = self.console.get_event(block)
if not event: # can only happen if we're not blocking
# We use the same timeout as in readline.c: 100ms
self.run_hooks()
self.console.wait(100)
event = self.console.get_event(block=False)
if not event:
if block:
continue
return False

translate = True
Expand All @@ -763,8 +778,7 @@ def handle1(self, block: bool = True) -> bool:
if cmd is None:
if block:
continue
else:
return False
return False

self.do_cmd(cmd)
return True
Expand Down
10 changes: 10 additions & 0 deletions Lib/asyncio/__main__.py
Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,15 @@ def run(self):

loop.call_soon_threadsafe(loop.stop)

def interrupt(self) -> None:
if not CAN_USE_PYREPL:
return

from _pyrepl.simple_interact import _get_reader
r = _get_reader()
if r.threading_hook is not None:
r.threading_hook.add("") # type: ignore


if __name__ == '__main__':
sys.audit("cpython.run_stdin")
Expand Down Expand Up @@ -184,6 +193,7 @@ def run(self):
keyboard_interrupted = True
if repl_future and not repl_future.done():
repl_future.cancel()
repl_thread.interrupt()
continue
else:
break
Expand Down
2 changes: 1 addition & 1 deletion Lib/test/test_repl.py
Original file line number Diff line number Diff line change
Expand Up @@ -270,7 +270,7 @@ def test_asyncio_repl_is_ok(self):
proc.kill()
exit_code = proc.wait()

self.assertEqual(exit_code, 0)
self.assertEqual(exit_code, 0, "".join(output))

class TestInteractiveModeSyntaxErrors(unittest.TestCase):

Expand Down

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