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# -*- coding: utf-8 -*- |
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# Copyright (C) 2014-2020 Greenbone Networks GmbH |
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# |
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# SPDX-License-Identifier: AGPL-3.0-or-later |
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# |
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# This program is free software: you can redistribute it and/or modify |
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# it under the terms of the GNU Affero General Public License as |
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# published by the Free Software Foundation, either version 3 of the |
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# License, or (at your option) any later version. |
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# |
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# This program is distributed in the hope that it will be useful, |
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# but WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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# GNU Affero General Public License for more details. |
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# |
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# You should have received a copy of the GNU Affero General Public License |
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# along with this program. If not, see <http://www.gnu.org/licenses/>. |
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import logging |
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import time |
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import fcntl |
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from pathlib import Path |
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logger = logging.getLogger(__name__) |
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class LockFile: |
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def __init__(self, path: Path): |
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self._lock_file_path = path |
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self._has_lock = False |
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self._fd = None |
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def has_lock(self) -> bool: |
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return self._has_lock |
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def _acquire_lock(self) -> "LockFile": |
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""" Acquite a lock by creating a lock file. |
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""" |
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if self.has_lock(): |
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return self |
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try: |
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# create parent directories recursively |
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parent_dir = self._lock_file_path.parent |
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parent_dir.mkdir(parents=True, exist_ok=True) |
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self._fd = self._lock_file_path.open('w') |
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except Exception as e: # pylint: disable=broad-except |
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logger.error( |
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"Failed to create lock file %s. %s", |
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str(self._lock_file_path), |
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e, |
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) |
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try: |
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self._fd.close() |
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self._fd = None |
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except Exception: # pylint: disable=broad-except |
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pass |
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return self |
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# Try to adquire the lock. |
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try: |
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fcntl.flock(self._fd, fcntl.LOCK_EX | fcntl.LOCK_NB) |
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self._has_lock = True |
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logger.debug("Created lock file %s.", str(self._lock_file_path)) |
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except BlockingIOError as e: |
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logger.error( |
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"Failed to lock the file %s. %s", str(self._lock_file_path), e, |
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) |
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try: |
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self._fd.close() |
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self._fd = None |
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except Exception: # pylint: disable=broad-except |
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pass |
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return self |
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def wait_for_lock(self): |
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while not self.has_lock(): |
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self._acquire_lock() |
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time.sleep(10) |
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return self |
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def _release_lock(self) -> None: |
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""" Release the lock by deleting the lock file |
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""" |
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if self.has_lock() and self._fd: |
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fcntl.flock(self._fd, fcntl.LOCK_UN) |
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self._fd.close() |
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self._fd = None |
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self._has_lock = False |
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logger.debug( |
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"Removed lock from file %s.", str(self._lock_file_path) |
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) |
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def __enter__(self): |
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self._acquire_lock() |
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return self |
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def __exit__(self, exc_type, exc_value, exc_tb): |
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self._release_lock() |
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greenbone /
ospd-openvas
