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gns3-server/gns3server/utils/file_watcher.py

104 lines
3.3 KiB
Python

#!/usr/bin/env python
#
# Copyright (C) 2016 GNS3 Technologies Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import zlib
import asyncio
import os
class FileWatcher:
"""
Watch for file change and call the callback when something happen
:param paths: A path or a list of file to watch
:param delay: Delay between file check (seconds)
:param strategy: File change strategy (mtime: modification time, hash: hash compute)
"""
def __init__(self, paths, callback, delay=1, strategy='mtime'):
self._paths = []
if not isinstance(paths, list):
paths = [paths]
for path in paths:
if not isinstance(path, str):
path = str(path)
self._paths.append(path)
self._callback = callback
self._delay = delay
self._closed = False
self._strategy = strategy
if self._strategy == 'mtime':
# Store modification time
self._mtime = {}
for path in self._paths:
try:
self._mtime[path] = os.stat(path).st_mtime_ns
except OSError:
self._mtime[path] = None
else:
# Store hash
self._hashed = {}
for path in self._paths:
try:
# Alder32 is a fast but insecure hash algorithm
self._hashed[path] = zlib.adler32(open(path, 'rb').read())
except OSError:
self._hashed[path] = None
asyncio.get_event_loop().call_later(self._delay, self._check_config_file_change)
def __del__(self):
self._closed = True
def close(self):
self._closed = True
def _check_config_file_change(self):
if self._closed:
return
changed = False
for path in self._paths:
if self._strategy == 'mtime':
try:
mtime = os.stat(path).st_mtime_ns
if mtime != self._mtime[path]:
changed = True
self._mtime[path] = mtime
except OSError:
self._mtime[path] = None
else:
try:
hashc = zlib.adler32(open(path, 'rb').read())
if hashc != self._hashed[path]:
changed = True
self._hashed[path] = hashc
except OSError:
self._hashed[path] = None
if changed:
self._callback(path)
asyncio.get_event_loop().call_later(self._delay, self._check_config_file_change)
@property
def callback(self):
return self._callback
@callback.setter
def callback(self, val):
self._callback = val