364 lines
13 KiB
Python
364 lines
13 KiB
Python
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#
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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 (Python >= 3.4) or by setting the $PYTHONPATH environment
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# variable (Python < 3.4) 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 logging
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import os
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import pkgutil # type: ignore
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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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from tornado.util import exec_in
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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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import typing
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from typing import Callable, Dict
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if typing.TYPE_CHECKING:
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from typing import List, Optional, Union # noqa: F401
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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() # type: ignore
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_autoreload_is_main = False
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_original_argv = None # type: Optional[List[str]]
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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 = {} # type: 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 hasattr(signal, "setitimer"):
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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. If
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# __spec__ is not available (Python < 3.4), check instead if
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# sys.path[0] is an empty string and add the current directory to
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# $PYTHONPATH.
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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:
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argv = ["-m", spec.name] + argv[1:]
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else:
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path_prefix = "." + os.pathsep
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if sys.path[0] == "" and not os.environ.get("PYTHONPATH", "").startswith(
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path_prefix
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):
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os.environ["PYTHONPATH"] = path_prefix + os.environ.get("PYTHONPATH", "")
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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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try:
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os.execv(sys.executable, [sys.executable] + argv)
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except OSError:
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# Mac OS X versions prior to 10.6 do not support execv in
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# a process that contains multiple threads. Instead of
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# re-executing in the current process, start a new one
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# and cause the current process to exit. This isn't
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# ideal since the new process is detached from the parent
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# terminal and thus cannot easily be killed with ctrl-C,
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# but it's better than not being able to autoreload at
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# all.
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# Unfortunately the errno returned in this case does not
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# appear to be consistent, so we can't easily check for
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# this error specifically.
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os.spawnv(
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os.P_NOWAIT, sys.executable, [sys.executable] + argv # type: ignore
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)
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# At this point the IOLoop has been closed and finally
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# blocks will experience errors if we allow the stack to
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# unwind, so just exit uncleanly.
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os._exit(0)
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_USAGE = """\
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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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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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sys.argv = sys.argv[:]
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if len(sys.argv) >= 3 and sys.argv[1] == "-m":
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mode = "module"
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module = sys.argv[2]
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del sys.argv[1:3]
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elif len(sys.argv) >= 2:
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mode = "script"
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script = sys.argv[1]
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sys.argv = sys.argv[1:]
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else:
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print(_USAGE, file=sys.stderr)
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sys.exit(1)
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try:
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if mode == "module":
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import runpy
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runpy.run_module(module, run_name="__main__", alter_sys=True)
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elif mode == "script":
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with open(script) as f:
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# Execute the script in our namespace instead of creating
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# a new one so that something that tries to import __main__
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# (e.g. the unittest module) will see names defined in the
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# script instead of just those defined in this module.
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global __file__
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__file__ = script
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# If __package__ is defined, imports may be incorrectly
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# interpreted as relative to this module.
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global __package__
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del __package__
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exec_in(f.read(), globals(), globals())
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except SystemExit as e:
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logging.basicConfig()
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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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logging.basicConfig()
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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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watch(e.filename)
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else:
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logging.basicConfig()
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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 mode == "module":
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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(module)
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if loader is not None:
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watch(loader.get_filename()) # type: ignore
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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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