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351 lines
13 KiB
Python
351 lines
13 KiB
Python
#
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# Copyright 2009 Facebook
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Automatically restart the server when a source file is modified.
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Most applications should not access this module directly. Instead,
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pass the keyword argument ``autoreload=True`` to the
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`tornado.web.Application` constructor (or ``debug=True``, which
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enables this setting and several others). This will enable autoreload
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mode as well as checking for changes to templates and static
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resources. Note that restarting is a destructive operation and any
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requests in progress will be aborted when the process restarts. (If
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you want to disable autoreload while using other debug-mode features,
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pass both ``debug=True`` and ``autoreload=False``).
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This module can also be used as a command-line wrapper around scripts
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such as unit test runners. See the `main` method for details.
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The command-line wrapper and Application debug modes can be used together.
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This combination is encouraged as the wrapper catches syntax errors and
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other import-time failures, while debug mode catches changes once
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the server has started.
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This module will not work correctly when `.HTTPServer`'s multi-process
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mode is used.
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Reloading loses any Python interpreter command-line arguments (e.g. ``-u``)
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because it re-executes Python using ``sys.executable`` and ``sys.argv``.
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Additionally, modifying these variables will cause reloading to behave
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incorrectly.
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"""
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import os
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import sys
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# sys.path handling
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# -----------------
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#
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# If a module is run with "python -m", the current directory (i.e. "")
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# is automatically prepended to sys.path, but not if it is run as
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# "path/to/file.py". The processing for "-m" rewrites the former to
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# the latter, so subsequent executions won't have the same path as the
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# original.
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#
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# Conversely, when run as path/to/file.py, the directory containing
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# file.py gets added to the path, which can cause confusion as imports
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# may become relative in spite of the future import.
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#
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# We address the former problem by reconstructing the original command
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# line before re-execution so the new process will
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# see the correct path. We attempt to address the latter problem when
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# tornado.autoreload is run as __main__.
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if __name__ == "__main__":
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# This sys.path manipulation must come before our imports (as much
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# as possible - if we introduced a tornado.sys or tornado.os
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# module we'd be in trouble), or else our imports would become
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# relative again despite the future import.
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#
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# There is a separate __main__ block at the end of the file to call main().
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if sys.path[0] == os.path.dirname(__file__):
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del sys.path[0]
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import functools
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import importlib.abc
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import os
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import pkgutil
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import sys
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import traceback
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import types
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import subprocess
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import weakref
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from tornado import ioloop
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from tornado.log import gen_log
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from tornado import process
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try:
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import signal
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except ImportError:
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signal = None # type: ignore
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from typing import Callable, Dict, Optional, List, Union
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# os.execv is broken on Windows and can't properly parse command line
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# arguments and executable name if they contain whitespaces. subprocess
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# fixes that behavior.
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_has_execv = sys.platform != "win32"
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_watched_files = set()
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_reload_hooks = []
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_reload_attempted = False
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_io_loops: "weakref.WeakKeyDictionary[ioloop.IOLoop, bool]" = (
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weakref.WeakKeyDictionary()
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)
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_autoreload_is_main = False
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_original_argv: Optional[List[str]] = None
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_original_spec = None
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def start(check_time: int = 500) -> None:
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"""Begins watching source files for changes.
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.. versionchanged:: 5.0
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The ``io_loop`` argument (deprecated since version 4.1) has been removed.
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"""
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io_loop = ioloop.IOLoop.current()
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if io_loop in _io_loops:
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return
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_io_loops[io_loop] = True
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if len(_io_loops) > 1:
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gen_log.warning("tornado.autoreload started more than once in the same process")
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modify_times: Dict[str, float] = {}
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callback = functools.partial(_reload_on_update, modify_times)
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scheduler = ioloop.PeriodicCallback(callback, check_time)
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scheduler.start()
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def wait() -> None:
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"""Wait for a watched file to change, then restart the process.
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Intended to be used at the end of scripts like unit test runners,
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to run the tests again after any source file changes (but see also
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the command-line interface in `main`)
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"""
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io_loop = ioloop.IOLoop()
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io_loop.add_callback(start)
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io_loop.start()
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def watch(filename: str) -> None:
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"""Add a file to the watch list.
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All imported modules are watched by default.
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"""
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_watched_files.add(filename)
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def add_reload_hook(fn: Callable[[], None]) -> None:
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"""Add a function to be called before reloading the process.
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Note that for open file and socket handles it is generally
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preferable to set the ``FD_CLOEXEC`` flag (using `fcntl` or
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`os.set_inheritable`) instead of using a reload hook to close them.
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"""
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_reload_hooks.append(fn)
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def _reload_on_update(modify_times: Dict[str, float]) -> None:
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if _reload_attempted:
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# We already tried to reload and it didn't work, so don't try again.
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return
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if process.task_id() is not None:
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# We're in a child process created by fork_processes. If child
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# processes restarted themselves, they'd all restart and then
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# all call fork_processes again.
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return
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for module in list(sys.modules.values()):
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# Some modules play games with sys.modules (e.g. email/__init__.py
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# in the standard library), and occasionally this can cause strange
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# failures in getattr. Just ignore anything that's not an ordinary
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# module.
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if not isinstance(module, types.ModuleType):
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continue
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path = getattr(module, "__file__", None)
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if not path:
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continue
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if path.endswith(".pyc") or path.endswith(".pyo"):
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path = path[:-1]
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_check_file(modify_times, path)
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for path in _watched_files:
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_check_file(modify_times, path)
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def _check_file(modify_times: Dict[str, float], path: str) -> None:
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try:
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modified = os.stat(path).st_mtime
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except Exception:
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return
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if path not in modify_times:
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modify_times[path] = modified
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return
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if modify_times[path] != modified:
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gen_log.info("%s modified; restarting server", path)
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_reload()
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def _reload() -> None:
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global _reload_attempted
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_reload_attempted = True
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for fn in _reload_hooks:
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fn()
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if sys.platform != "win32":
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# Clear the alarm signal set by
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# ioloop.set_blocking_log_threshold so it doesn't fire
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# after the exec.
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signal.setitimer(signal.ITIMER_REAL, 0, 0)
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# sys.path fixes: see comments at top of file. If __main__.__spec__
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# exists, we were invoked with -m and the effective path is about to
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# change on re-exec. Reconstruct the original command line to
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# ensure that the new process sees the same path we did.
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if _autoreload_is_main:
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assert _original_argv is not None
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spec = _original_spec
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argv = _original_argv
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else:
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spec = getattr(sys.modules["__main__"], "__spec__", None)
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argv = sys.argv
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if spec and spec.name != "__main__":
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# __spec__ is set in two cases: when running a module, and when running a directory. (when
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# running a file, there is no spec). In the former case, we must pass -m to maintain the
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# module-style behavior (setting sys.path), even though python stripped -m from its argv at
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# startup. If sys.path is exactly __main__, we're running a directory and should fall
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# through to the non-module behavior.
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#
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# Some of this, including the use of exactly __main__ as a spec for directory mode,
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# is documented at https://docs.python.org/3/library/runpy.html#runpy.run_path
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argv = ["-m", spec.name] + argv[1:]
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if not _has_execv:
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subprocess.Popen([sys.executable] + argv)
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os._exit(0)
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else:
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os.execv(sys.executable, [sys.executable] + argv)
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_USAGE = """
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python -m tornado.autoreload -m module.to.run [args...]
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python -m tornado.autoreload path/to/script.py [args...]
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"""
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def main() -> None:
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"""Command-line wrapper to re-run a script whenever its source changes.
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Scripts may be specified by filename or module name::
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python -m tornado.autoreload -m tornado.test.runtests
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python -m tornado.autoreload tornado/test/runtests.py
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Running a script with this wrapper is similar to calling
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`tornado.autoreload.wait` at the end of the script, but this wrapper
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can catch import-time problems like syntax errors that would otherwise
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prevent the script from reaching its call to `wait`.
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"""
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# Remember that we were launched with autoreload as main.
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# The main module can be tricky; set the variables both in our globals
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# (which may be __main__) and the real importable version.
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#
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# We use optparse instead of the newer argparse because we want to
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# mimic the python command-line interface which requires stopping
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# parsing at the first positional argument. optparse supports
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# this but as far as I can tell argparse does not.
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import optparse
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import tornado.autoreload
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global _autoreload_is_main
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global _original_argv, _original_spec
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tornado.autoreload._autoreload_is_main = _autoreload_is_main = True
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original_argv = sys.argv
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tornado.autoreload._original_argv = _original_argv = original_argv
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original_spec = getattr(sys.modules["__main__"], "__spec__", None)
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tornado.autoreload._original_spec = _original_spec = original_spec
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parser = optparse.OptionParser(
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prog="python -m tornado.autoreload",
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usage=_USAGE,
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epilog="Either -m or a path must be specified, but not both",
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)
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parser.disable_interspersed_args()
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parser.add_option("-m", dest="module", metavar="module", help="module to run")
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parser.add_option(
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"--until-success",
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action="store_true",
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help="stop reloading after the program exist successfully (status code 0)",
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)
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opts, rest = parser.parse_args()
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if opts.module is None:
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if not rest:
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print("Either -m or a path must be specified", file=sys.stderr)
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sys.exit(1)
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path = rest[0]
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sys.argv = rest[:]
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else:
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path = None
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sys.argv = [sys.argv[0]] + rest
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# SystemExit.code is typed funny: https://github.com/python/typeshed/issues/8513
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# All we care about is truthiness
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exit_status: Union[int, str, None] = 1
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try:
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import runpy
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if opts.module is not None:
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runpy.run_module(opts.module, run_name="__main__", alter_sys=True)
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else:
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assert path is not None
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runpy.run_path(path, run_name="__main__")
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except SystemExit as e:
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exit_status = e.code
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gen_log.info("Script exited with status %s", e.code)
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except Exception as e:
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gen_log.warning("Script exited with uncaught exception", exc_info=True)
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# If an exception occurred at import time, the file with the error
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# never made it into sys.modules and so we won't know to watch it.
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# Just to make sure we've covered everything, walk the stack trace
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# from the exception and watch every file.
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for filename, lineno, name, line in traceback.extract_tb(sys.exc_info()[2]):
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watch(filename)
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if isinstance(e, SyntaxError):
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# SyntaxErrors are special: their innermost stack frame is fake
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# so extract_tb won't see it and we have to get the filename
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# from the exception object.
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if e.filename is not None:
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watch(e.filename)
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else:
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exit_status = 0
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gen_log.info("Script exited normally")
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# restore sys.argv so subsequent executions will include autoreload
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sys.argv = original_argv
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if opts.module is not None:
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assert opts.module is not None
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# runpy did a fake import of the module as __main__, but now it's
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# no longer in sys.modules. Figure out where it is and watch it.
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loader = pkgutil.get_loader(opts.module)
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if loader is not None and isinstance(loader, importlib.abc.FileLoader):
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watch(loader.get_filename())
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if opts.until_success and not exit_status:
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return
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wait()
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if __name__ == "__main__":
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# See also the other __main__ block at the top of the file, which modifies
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# sys.path before our imports
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main()
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