X-Git-Url: https://wannabe.guru.org/gitweb/?a=blobdiff_plain;f=lockfile.py;h=6993cb84d5e88f8dd6fc1a9d28a849f0cfd28713;hb=e8fbbb7306430478dec55d2c963eed116d8330cc;hp=4b6aadeffde8ec7bf255025873d720e2b3afda93;hpb=e6f32fdd9b373dfcd100c7accb41f57d83c2f0a1;p=python_utils.git diff --git a/lockfile.py b/lockfile.py index 4b6aade..6993cb8 100644 --- a/lockfile.py +++ b/lockfile.py @@ -1,25 +1,26 @@ #!/usr/bin/env python3 -from dataclasses import dataclass +"""File-based locking helper.""" + import datetime import json import logging import os import signal import sys -from typing import Optional import warnings +from dataclasses import dataclass +from typing import Optional import config import datetime_utils import decorator_utils - cfg = config.add_commandline_args(f'Lockfile ({__file__})', 'Args related to lockfiles') cfg.add_argument( '--lockfile_held_duration_warning_threshold_sec', type=float, - default=10.0, + default=60.0, metavar='SECONDS', help='If a lock is held for longer than this threshold we log a warning', ) @@ -27,14 +28,18 @@ logger = logging.getLogger(__name__) class LockFileException(Exception): + """An exception related to lock files.""" + pass @dataclass class LockFileContents: + """The contents we'll write to each lock file.""" + pid: int commandline: str - expiration_timestamp: float + expiration_timestamp: Optional[float] class LockFile(object): @@ -57,9 +62,10 @@ class LockFile(object): expiration_timestamp: Optional[float] = None, override_command: Optional[str] = None, ) -> None: - self.is_locked = False - self.lockfile = lockfile_path - self.override_command = override_command + self.is_locked: bool = False + self.lockfile: str = lockfile_path + self.locktime: Optional[int] = None + self.override_command: Optional[str] = override_command if do_signal_cleanup: signal.signal(signal.SIGINT, self._signal) signal.signal(signal.SIGTERM, self._signal) @@ -72,7 +78,7 @@ class LockFile(object): return not os.path.exists(self.lockfile) def try_acquire_lock_once(self) -> bool: - logger.debug(f"Trying to acquire {self.lockfile}.") + logger.debug("Trying to acquire %s.", self.lockfile) try: # Attempt to create the lockfile. These flags cause # os.open to raise an OSError if the file already @@ -82,13 +88,12 @@ class LockFile(object): contents = self._get_lockfile_contents() logger.debug(contents) f.write(contents) - logger.debug(f'Success; I own {self.lockfile}.') + logger.debug('Success; I own %s.', self.lockfile) self.is_locked = True return True except OSError: pass - msg = f'Could not acquire {self.lockfile}.' - logger.warning(msg) + logger.warning('Couldn\'t acquire %s.', self.lockfile) return False def acquire_with_retries( @@ -126,14 +131,11 @@ class LockFile(object): logger.warning(msg) raise LockFileException(msg) - def __exit__(self, type, value, traceback): + def __exit__(self, _, value, traceback): if self.locktime: ts = datetime.datetime.now().timestamp() duration = ts - self.locktime - if ( - duration - >= config.config['lockfile_held_duration_warning_threshold_sec'] - ): + if duration >= config.config['lockfile_held_duration_warning_threshold_sec']: str_duration = datetime_utils.describe_duration_briefly(duration) msg = f'Held {self.lockfile} for {str_duration}' logger.warning(msg) @@ -168,7 +170,7 @@ class LockFile(object): line = lines[0] line_dict = json.loads(line) contents = LockFileContents(**line_dict) - logger.debug(f'Blocking lock contents="{contents}"') + logger.debug('Blocking lock contents="%s"', contents) # Does the PID exist still? try: @@ -181,7 +183,7 @@ class LockFile(object): # Has the lock expiration expired? if contents.expiration_timestamp is not None: now = datetime.datetime.now().timestamp() - if now > contents.expiration_datetime: + if now > contents.expiration_timestamp: msg = f'Lockfile {self.lockfile} expiration time has passed; force acquiring' logger.warning(msg) self.release()