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Diffstat (limited to 'src/leap/platform_init/locks.py')
| -rw-r--r-- | src/leap/platform_init/locks.py | 405 |
1 files changed, 0 insertions, 405 deletions
diff --git a/src/leap/platform_init/locks.py b/src/leap/platform_init/locks.py deleted file mode 100644 index 39b18648..00000000 --- a/src/leap/platform_init/locks.py +++ /dev/null @@ -1,405 +0,0 @@ -# -*- coding: utf-8 -*- -# locks.py -# Copyright (C) 2013 LEAP -# -# 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/>. -""" -Utilities for handling multi-platform file locking mechanisms -""" -import logging -import errno -import os -import platform - -from leap.common.events import signal as signal_event -from leap.common.events import events_pb2 as proto -from leap import platform_init - -if platform_init.IS_UNIX: - from fcntl import flock, LOCK_EX, LOCK_NB -else: # WINDOWS - import datetime - import glob - import shutil - import time - - from tempfile import gettempdir - - from leap.util import get_modification_ts, update_modification_ts - -logger = logging.getLogger(__name__) - -if platform_init.IS_UNIX: - - class UnixLock(object): - """ - Uses flock to get an exclusive lock over a file. - See man 2 flock - """ - - def __init__(self, path): - """ - iniializes t he UnixLock with the path of the - desired lockfile - """ - - self._fd = None - self.path = path - - def get_lock(self): - """ - Tries to get a lock, and writes the running pid there if successful - """ - gotit, pid = self._get_lock_and_pid() - return gotit - - def get_pid(self): - """ - Returns the pid of the locking process - """ - gotit, pid = self._get_lock_and_pid() - return pid - - def _get_lock(self): - """ - Tries to get a lock, returning True if successful - - :rtype: bool - """ - self._fd = os.open(self.path, os.O_CREAT | os.O_RDWR) - - try: - flock(self._fd, LOCK_EX | LOCK_NB) - except IOError as exc: - # could not get the lock - #import ipdb; ipdb.set_trace() - - if exc.args[0] in (errno.EDEADLK, errno.EAGAIN): - # errno 11 or 35 - # Resource temporarily unavailable - return False - else: - raise - return True - - @property - def locked_by_us(self): - """ - Returns True if the pid in the pidfile - is ours. - - :rtype: bool - """ - gotit, pid = self._get_lock_and_pid() - return pid == os.getpid() - - def _get_lock_and_pid(self): - """ - Tries to get a lock over the file. - Returns (locked, pid) tuple. - - :rtype: tuple - """ - - if self._get_lock(): - self._write_to_pidfile() - return True, None - - return False, self._read_from_pidfile() - - def _read_from_pidfile(self): - """ - Tries to read pid from the pidfile, - returns False if no content found. - """ - - pidfile = os.read( - self._fd, 16) - if not pidfile: - return False - - try: - return int(pidfile.strip()) - except Exception as exc: - exc.args += (pidfile, self.lock_file) - raise - - def _write_to_pidfile(self): - """ - Writes the pid of the running process - to the pidfile - """ - fd = self._fd - os.ftruncate(fd, 0) - os.write(fd, '%d\n' % os.getpid()) - os.fsync(fd) - - -if platform_init.IS_WIN: - - # Time to wait (in secs) before assuming a raise window signal has not been - # ack-ed. - - RAISE_WINDOW_TIMEOUT = 2 - - # How many steps to do while checking lockfile ts update. - - RAISE_WINDOW_WAIT_STEPS = 10 - - def _release_lock(name): - """ - Tries to remove a folder path. - - :param name: folder lock to remove - :type name: str - """ - try: - shutil.rmtree(name) - return True - except WindowsError as exc: - if exc.errno in (errno.EPIPE, errno.ENOENT, - errno.ESRCH, errno.EACCES): - logger.warning( - 'exception while trying to remove the lockfile dir') - logger.warning('errno %s: %s' % (exc.errno, exc.args[1])) - # path does not exist - return False - else: - logger.debug('errno = %s' % (exc.errno,)) - # we did not foresee this error, better add it explicitely - raise - - class WindowsLock(object): - """ - Creates a lock based on the atomic nature of mkdir on Windows - system calls. - """ - LOCKBASE = os.path.join(gettempdir(), "leap-client-lock") - - def __init__(self): - """ - Initializes the lock. - Sets the lock name to basename plus the process pid. - """ - self._fd = None - pid = os.getpid() - self.name = "%s-%s" % (self.LOCKBASE, pid) - self.pid = pid - - def get_lock(self): - """ - Tries to get a lock, and writes the running pid there if successful - """ - gotit = self._get_lock() - return gotit - - def _get_lock(self): - """ - Tries to write to a file with the current pid as part of the name - """ - try: - self._fd = os.makedirs(self.name) - except OSError as exc: - # could not create the dir - if exc.args[0] == 183: - logger.debug('cannot create dir') - # cannot create dir with existing name - return False - else: - raise - return self._is_one_pidfile()[0] - - def _is_one_pidfile(self): - """ - Returns True, pid if there is only one pidfile with the expected - base path - - :rtype: tuple - """ - pidfiles = glob.glob(self.LOCKBASE + '-*') - if len(pidfiles) == 1: - pid = pidfiles[0].split('-')[-1] - return True, int(pid) - else: - return False, None - - def get_pid(self): - """ - Returns the pid of the locking process. - - :rtype: int - """ - # XXX assert there is only one? - _, pid = self._is_one_pidfile() - return pid - - def get_locking_path(self): - """ - Returns the pid path of the locking process. - - :rtype: str - """ - pid = self.get_pid() - if pid: - return "%s-%s" % (self.LOCKBASE, pid) - - def release_lock(self, name=None): - """ - Releases the pidfile dir for this process, by removing it. - """ - if not name: - name = self.name - _release_lock(name) - - @classmethod - def release_all_locks(self): - """ - Releases all locks. Used for clean shutdown. - """ - for lockdir in glob.glob("%s-%s" % (self.LOCKBASE, '*')): - _release_lock(lockdir) - - @property - def locked_by_us(self): - """ - Returns True if the pid in the pidfile - is ours. - - :rtype: bool - """ - _, pid = self._is_one_pidfile() - return pid == self.pid - - def update_ts(self): - """ - Updates the timestamp of the lock. - """ - if self.locked_by_us: - update_modification_ts(self.name) - - def write_port(self, port): - """ - Writes the port for windows control to the pidfile folder - Returns True if successful. - - :rtype: bool - """ - if not self.locked_by_us: - logger.warning("Tried to write control port to a " - "non-unique pidfile folder") - return False - port_file = os.path.join(self.name, "port") - with open(port_file, 'w') as f: - f.write("%s" % port) - return True - - def get_control_port(self): - """ - Reads control port of the main instance from the port file - in the pidfile dir - - :rtype: int - """ - pid = self.get_pid() - port_file = os.path.join(self.LOCKBASE + "-%s" % pid, "port") - port = None - try: - with open(port_file) as f: - port_str = f.read() - port = int(port_str.strip()) - except IOError as exc: - if exc.errno == errno.ENOENT: - logger.error("Tried to read port from non-existent file") - else: - # we did not know explicitely about this error - raise - return port - - def raise_window_ack(): - """ - This function is called from the windows callback that is registered - with the raise_window event. It just updates the modification time - of the lock file so we can signal an ack to the instance that tried - to raise the window. - """ - lock = WindowsLock() - lock.update_ts() - - -def we_are_the_one_and_only(): - """ - Returns True if we are the only instance running, False otherwise. - If we came later, send a raise signal to the main instance of the - application. - - Under windows we are not using flock magic, so we wait during - RAISE_WINDOW_TIMEOUT time, if not ack is - received, we assume it was a stalled lock, so we remove it and continue - with initialization. - - :rtype: bool - """ - _sys = platform.system() - - if _sys in ("Linux", "Darwin"): - locker = UnixLock('/tmp/leap-client.lock') - locker.get_lock() - we_are_the_one = locker.locked_by_us - if not we_are_the_one: - signal_event(proto.RAISE_WINDOW) - return we_are_the_one - - elif _sys == "Windows": - locker = WindowsLock() - locker.get_lock() - we_are_the_one = locker.locked_by_us - - if not we_are_the_one: - locker.release_lock() - lock_path = locker.get_locking_path() - ts = get_modification_ts(lock_path) - - nowfun = datetime.datetime.now - t0 = nowfun() - pause = RAISE_WINDOW_TIMEOUT / float(RAISE_WINDOW_WAIT_STEPS) - timeout_delta = datetime.timedelta(0, RAISE_WINDOW_TIMEOUT) - check_interval = lambda: nowfun() - t0 < timeout_delta - - # let's assume it's a stalled lock - we_are_the_one = True - signal_event(proto.RAISE_WINDOW) - - while check_interval(): - if get_modification_ts(lock_path) > ts: - # yay! someone claimed their control over the lock. - # so the lock is alive - logger.debug('Raise window ACK-ed') - we_are_the_one = False - break - else: - time.sleep(pause) - - if we_are_the_one: - # ok, it really was a stalled lock. let's remove all - # that is left, and put only ours there. - WindowsLock.release_all_locks() - WindowsLock().get_lock() - - return we_are_the_one - - else: - logger.warning("Multi-instance checker " - "not implemented for %s" % (_sys)) - # lies, lies, lies... - return True |