global _monitor
_monitor = True
-def _die_if_already_running():
- """If a locked pidfile exists, issue a warning message and, unless
- ignore_existing_pidfile() has been called, terminate the program."""
- if _pidfile is None:
- return
- pid = read_pidfile_if_exists(_pidfile)
- if pid > 0:
- if not _overwrite_pidfile:
- msg = "%s: already running as pid %d" % (_pidfile, pid)
- logging.error("%s, aborting" % msg)
- sys.stderr.write("%s\n" % msg)
- sys.exit(1)
- else:
- logging.warn("%s: %s already running"
- % (get_pidfile(), ovs.util.PROGRAM_NAME))
+def _fatal(msg):
+ logging.error(msg)
+ sys.stderr.write("%s\n" % msg)
+ sys.exit(1)
def _make_pidfile():
"""If a pidfile has been configured, creates it and stores the running
process's pid in it. Ensures that the pidfile will be deleted when the
process exits."""
- if _pidfile is not None:
- # Create pidfile via temporary file, so that observers never see an
- # empty pidfile or an unlocked pidfile.
- pid = os.getpid()
- tmpfile = "%s.tmp%d" % (_pidfile, pid)
- ovs.fatal_signal.add_file_to_unlink(tmpfile)
+ pid = os.getpid()
- try:
- # This is global to keep Python from garbage-collecting and
- # therefore closing our file after this function exits. That would
- # unlock the lock for us, and we don't want that.
- global file
+ # Create a temporary pidfile.
+ tmpfile = "%s.tmp%d" % (_pidfile, pid)
+ ovs.fatal_signal.add_file_to_unlink(tmpfile)
+ try:
+ # This is global to keep Python from garbage-collecting and
+ # therefore closing our file after this function exits. That would
+ # unlock the lock for us, and we don't want that.
+ global file
- file = open(tmpfile, "w")
- except IOError, e:
- logging.error("%s: create failed: %s"
- % (tmpfile, os.strerror(e.errno)))
- return
+ file = open(tmpfile, "w")
+ except IOError, e:
+ _fatal("%s: create failed (%s)" % (tmpfile, e.strerror))
- try:
- fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
- except IOError, e:
- logging.error("%s: fcntl failed: %s"
- % (tmpfile, os.strerror(e.errno)))
- file.close()
- return
+ try:
+ s = os.fstat(file.fileno())
+ except IOError, e:
+ _fatal("%s: fstat failed (%s)" % (tmpfile, e.strerror))
- try:
- file.write("%s\n" % pid)
- file.flush()
- ovs.fatal_signal.add_file_to_unlink(_pidfile)
- except OSError, e:
- logging.error("%s: write failed: %s"
- % (tmpfile, os.strerror(e.errno)))
- file.close()
- return
-
+ try:
+ file.write("%s\n" % pid)
+ file.flush()
+ except OSError, e:
+ _fatal("%s: write failed: %s" % (tmpfile, e.strerror))
+
+ try:
+ fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
+ except IOError, e:
+ _fatal("%s: fcntl failed: %s" % (tmpfile, e.strerror))
+
+ # Rename or link it to the correct name.
+ if _overwrite_pidfile:
try:
os.rename(tmpfile, _pidfile)
except OSError, e:
- ovs.fatal_signal.remove_file_to_unlink(_pidfile)
- logging.error("failed to rename \"%s\" to \"%s\": %s"
- % (tmpfile, _pidfile, os.strerror(e.errno)))
- file.close()
- return
+ _fatal("failed to rename \"%s\" to \"%s\" (%s)"
+ % (tmpfile, _pidfile, e.strerror))
+ else:
+ while True:
+ try:
+ os.link(tmpfile, _pidfile)
+ error = 0
+ except OSError, e:
+ error = e.errno
+ if error == errno.EEXIST:
+ _check_already_running()
+ elif error != errno.EINTR:
+ break
+ if error:
+ _fatal("failed to link \"%s\" as \"%s\" (%s)"
+ % (tmpfile, _pidfile, os.strerror(error)))
- s = os.fstat(file.fileno())
- _pidfile_dev = s.st_dev
- _pidfile_ino = s.st_ino
+
+ # Ensure that the pidfile will get deleted on exit.
+ ovs.fatal_signal.add_file_to_unlink(_pidfile)
+
+ # Delete the temporary pidfile if it still exists.
+ if not _overwrite_pidfile:
+ error = ovs.fatal_signal.unlink_file_now(tmpfile)
+ if error:
+ _fatal("%s: unlink failed (%s)" % (tmpfile, os.strerror(error)))
+
+ _pidfile_dev = s.st_dev
+ _pidfile_ino = s.st_ino
def daemonize():
"""If configured with set_pidfile() or set_detach(), creates the pid file
_monitor_daemon(daemon_pid)
# Running in daemon process
- _die_if_already_running()
- _make_pidfile()
+ if _pidfile:
+ _make_pidfile()
def daemonize_complete():
"""If daemonization is configured, then this function notifies the parent
--overwrite-pidfile with --pidfile, start even if already running
""" % (ovs.dirs.RUNDIR, ovs.util.PROGRAM_NAME))
-def __read_pidfile(pidfile, must_exist):
+def __read_pidfile(pidfile, delete_if_stale):
if _pidfile_dev is not None:
try:
s = os.stat(pidfile)
pass
try:
- file = open(pidfile, "r")
+ file = open(pidfile, "r+")
except IOError, e:
- if e.errno == errno.ENOENT and not must_exist:
+ if e.errno == errno.ENOENT and delete_if_stale:
return 0
- logging.warning("%s: open: %s" % (pidfile, os.strerror(e.errno)))
+ logging.warning("%s: open: %s" % (pidfile, e.strerror))
return -e.errno
# Python fcntl doesn't directly support F_GETLK so we have to just try
- # to lock it. If we get a conflicting lock that's "success"; otherwise
- # the file is not locked.
+ # to lock it.
try:
fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
- # File isn't locked if we get here, so treat that as an error.
- logging.warning("%s: pid file is not locked" % pidfile)
- try:
- # As a side effect, this drops the lock.
+
+ # pidfile exists but wasn't locked by anyone. Now we have the lock.
+ if not delete_if_stale:
file.close()
+ logging.warning("%s: pid file is stale" % pidfile)
+ return -errno.ESRCH
+
+ # Is the file we have locked still named 'pidfile'?
+ try:
+ raced = False
+ s = os.stat(pidfile)
+ s2 = os.fstat(file.fileno())
+ if s.st_ino != s2.st_ino or s.st_dev != s2.st_dev:
+ raced = True
except IOError:
- pass
- return -errno.ESRCH
+ raced = True
+ if raced:
+ logging.warning("%s: lost race to delete pidfile" % pidfile)
+ return -errno.ALREADY
+
+ # We won the right to delete the stale pidfile.
+ try:
+ os.unlink(pidfile)
+ except IOError, e:
+ logging.warning("%s: failed to delete stale pidfile"
+ % (pidfile, e.strerror))
+ return -e.errno
+
+ logging.debug("%s: deleted stale pidfile" % pidfile)
+ file.close()
+ return 0
except IOError, e:
if e.errno not in [errno.EACCES, errno.EAGAIN]:
- logging.warn("%s: fcntl: %s" % (pidfile, os.strerror(e.errno)))
+ logging.warn("%s: fcntl: %s" % (pidfile, e.strerror))
return -e.errno
+ # Someone else has the pidfile locked.
try:
try:
return int(file.readline())
def read_pidfile(pidfile):
"""Opens and reads a PID from 'pidfile'. Returns the positive PID if
successful, otherwise a negative errno value."""
- return __read_pidfile(pidfile, True)
-
-def read_pidfile_if_exists(pidfile):
- """Opens and reads a PID from 'pidfile'. Returns 0 if 'pidfile' does not
- exist, the positive PID if successful, otherwise a negative errno value."""
return __read_pidfile(pidfile, False)
+def _check_already_running():
+ pid = __read_pidfile(_pidfile, True)
+ if pid > 0:
+ _fatal("%s: already running as pid %d, aborting" % (_pidfile, pid))
+ elif pid < 0:
+ _fatal("%s: pidfile check failed (%s), aborting"
+ % (_pidfile, os.strerror(pid)))
+
# XXX Python's getopt does not support options with optional arguments, so we
# have to separate --pidfile (with no argument) from --pidfile-name (with an
# argument). Need to write our own getopt I guess.
git://git.onelab.eu / sliver-openvswitch.git / blobdiff