diff options
Diffstat (limited to 'src/leap/platform_init/locks.py')
| -rw-r--r-- | src/leap/platform_init/locks.py | 133 |
1 files changed, 113 insertions, 20 deletions
diff --git a/src/leap/platform_init/locks.py b/src/leap/platform_init/locks.py index c40c31d0..39b18648 100644 --- a/src/leap/platform_init/locks.py +++ b/src/leap/platform_init/locks.py @@ -28,12 +28,16 @@ from leap import platform_init if platform_init.IS_UNIX: from fcntl import flock, LOCK_EX, LOCK_NB -else: +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: @@ -144,6 +148,38 @@ if platform_init.IS_UNIX: 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 @@ -200,7 +236,7 @@ if platform_init.IS_WIN: def get_pid(self): """ - Returns the pid of the locking process + Returns the pid of the locking process. :rtype: int """ @@ -208,25 +244,31 @@ if platform_init.IS_WIN: _, pid = self._is_one_pidfile() return pid - def release_lock(self): + 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. """ - try: - shutil.rmtree(self.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 + 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): @@ -239,6 +281,13 @@ if platform_init.IS_WIN: _, 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 @@ -277,12 +326,27 @@ if platform_init.IS_WIN: 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 + 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 """ @@ -300,9 +364,38 @@ def we_are_the_one_and_only(): locker = WindowsLock() locker.get_lock() we_are_the_one = locker.locked_by_us + if not we_are_the_one: locker.release_lock() - signal_event(proto.RAISE_WINDOW) + 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: |