-# Copyright (c) 2010 Nicira Networks
+# Copyright (c) 2010, 2011 Nicira Networks
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# File descriptor used by daemonize_start() and daemonize_complete().
_daemonize_fd = None
+RESTART_EXIT_CODE = 5
+
def make_pidfile_name(name):
"""Returns the file name that would be used for a pidfile if 'name' were
provided to set_pidfile()."""
def get_pidfile():
"""Returns an absolute path to the configured pidfile, or None if no
- pidfile is configured. The caller must not modify or free the returned
- string."""
+ pidfile is configured."""
return _pidfile
def set_no_chdir():
return _chdir
def ignore_existing_pidfile():
- """Normally, die_if_already_running() will terminate the program with a
- message if a locked pidfile already exists. If this function is called,
- die_if_already_running() will merely log a warning."""
+ """Normally, daemonize() or daemonize_start() will terminate the program
+ with a message if a locked pidfile already exists. If this function is
+ called, an existing pidfile will be replaced, with a warning."""
global _overwrite_pidfile
_overwrite_pidfile = True
global _monitor
_monitor = True
-def _already_running():
- """If a pidfile has been configured and that pidfile already exists and is
- locked by a running process, returns True. Otherwise, returns False."""
- if _pidfile is not None:
- try:
- file = open(_pidfile, "r+")
- try:
- try:
- fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
- except IOError, e:
- if e.errno in [errno.EACCES, errno.EAGAIN]:
- return True
- logging.error("error locking %s (%s)"
- % (_pidfile, os.strerror(e.errno)))
- return False
- finally:
- # This releases the lock, which we don't really want.
- file.close()
- except IOError, e:
- if e.errno == errno.ENOENT:
- return False
- logging.error("error opening %s (%s)"
- % (_pidfile, os.strerror(e.errno)))
- return False
-
-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 _already_running():
- if not _overwrite_pidfile:
- sys.stderr.write("%s: already running\n" % get_pidfile())
- 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)))
+
+ global _pidfile_dev
+ global _pidfile_ino
+ _pidfile_dev = s.st_dev
+ _pidfile_ino = s.st_ino
def daemonize():
"""If configured with set_pidfile() or set_detach(), creates the pid file
# Running in parent process.
os.close(wfd)
ovs.fatal_signal.fork()
- try:
- s = os.read(rfd, 1)
- except OSError, e:
- s = ""
+ while True:
+ try:
+ s = os.read(rfd, 1)
+ error = 0
+ except OSError, e:
+ s = ""
+ error = e.errno
+ if error != errno.EINTR:
+ break
if len(s) != 1:
retval, status = _waitpid(pid, 0)
if (retval == pid and
os.close(fd)
def _should_restart(status):
+ global RESTART_EXIT_CODE
+
+ if os.WIFEXITED(status) and os.WEXITSTATUS(status) == RESTART_EXIT_CODE:
+ return True
+
if os.WIFSIGNALED(status):
for signame in ("SIGABRT", "SIGALRM", "SIGBUS", "SIGFPE", "SIGILL",
"SIGPIPE", "SIGSEGV", "SIGXCPU", "SIGXFSZ"):
- if (signame in signal.__dict__ and
- os.WTERMSIG(status) == signal.__dict__[signame]):
+ if os.WTERMSIG(status) == getattr(signal, signame, None):
return True
return False
_monitor_daemon(daemon_pid)
# Running in daemon process
- _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):
- """Opens and reads a PID from 'pidfile'. Returns the nonnegative PID if
- successful, otherwise a negative errno value."""
+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:
- logging.warning("%s: open: %s" % (pidfile, os.strerror(e.errno)))
+ if e.errno == errno.ENOENT and delete_if_stale:
+ return 0
+ 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.EALREADY
+
+ # We won the right to delete the stale pidfile.
+ try:
+ os.unlink(pidfile)
+ except IOError, e:
+ logging.warning("%s: failed to delete stale pidfile (%s)"
+ % (pidfile, e.strerror))
+ return -e.errno
+ else:
+ 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())
except IOError:
pass
+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, 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.