Skip to content
Fetching contributors…
Cannot retrieve contributors at this time
526 lines (394 sloc) 14.2 KB
# -*- coding: utf-8 -*-
"""
celery.platforms
~~~~~~~~~~~~~~~~
Utilities dealing with platform specifics: signals, daemonization,
users, groups, and so on.
:copyright: (c) 2009 - 2011 by Ask Solem.
:license: BSD, see LICENSE for more details.
"""
from __future__ import absolute_import
import errno
import os
import platform as _platform
import shlex
import signal as _signal
import sys
from .local import try_import
_setproctitle = try_import("setproctitle")
resource = try_import("resource")
pwd = try_import("pwd")
grp = try_import("grp")
SYSTEM = _platform.system()
IS_OSX = SYSTEM == "Darwin"
IS_WINDOWS = SYSTEM == "Windows"
DAEMON_UMASK = 0
DAEMON_WORKDIR = "/"
DAEMON_REDIRECT_TO = getattr(os, "devnull", "/dev/null")
def pyimplementation():
if hasattr(_platform, "python_implementation"):
return _platform.python_implementation()
elif sys.platform.startswith("java"):
return "Jython %s" % (sys.platform, )
elif hasattr(sys, "pypy_version_info"):
v = ".".join(map(str, sys.pypy_version_info[:3]))
if sys.pypy_version_info[3:]:
v += "-" + "".join(map(str, sys.pypy_version_info[3:]))
return "PyPy %s" % (v, )
else:
return "CPython"
class LockFailed(Exception):
"""Raised if a pidlock can't be acquired."""
pass
def get_fdmax(default=None):
"""Returns the maximum number of open file descriptors
on this system.
:keyword default: Value returned if there's no file
descriptor limit.
"""
fdmax = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
if fdmax == resource.RLIM_INFINITY:
return default
return fdmax
class PIDFile(object):
"""PID lock file.
This is the type returned by :func:`create_pidlock`.
**Should not be used directly, use the :func:`create_pidlock`
context instead**
"""
#: Path to the pid lock file.
path = None
def __init__(self, path):
self.path = os.path.abspath(path)
def acquire(self):
"""Acquire lock."""
try:
self.write_pid()
except OSError, exc:
raise LockFailed(str(exc))
return self
__enter__ = acquire
def is_locked(self):
"""Returns true if the pid lock exists."""
return os.path.exists(self.path)
def release(self, *args):
"""Release lock."""
self.remove()
__exit__ = release
def read_pid(self):
"""Reads and returns the current pid."""
try:
fh = open(self.path, "r")
except IOError, exc:
if exc.errno == errno.ENOENT:
return
raise
line = fh.readline().strip()
fh.close()
try:
return int(line)
except ValueError:
raise ValueError("PID file %r contents invalid." % self.path)
def remove(self):
"""Removes the lock."""
try:
os.unlink(self.path)
except OSError, exc:
if exc.errno in (errno.ENOENT, errno.EACCES):
return
raise
def remove_if_stale(self):
"""Removes the lock if the process is not running.
(does not respond to signals)."""
try:
pid = self.read_pid()
except ValueError, exc:
sys.stderr.write("Broken pidfile found. Removing it.\n")
self.remove()
return True
if not pid:
self.remove()
return True
try:
os.kill(pid, 0)
except os.error, exc:
if exc.errno == errno.ESRCH:
sys.stderr.write("Stale pidfile exists. Removing it.\n")
self.remove()
return True
return False
def write_pid(self):
open_flags = (os.O_CREAT | os.O_EXCL | os.O_WRONLY)
open_mode = (((os.R_OK | os.W_OK) << 6) |
((os.R_OK) << 3) |
((os.R_OK)))
pidfile_fd = os.open(self.path, open_flags, open_mode)
pidfile = os.fdopen(pidfile_fd, "w")
try:
pid = os.getpid()
pidfile.write("%d\n" % (pid, ))
finally:
pidfile.close()
def create_pidlock(pidfile):
"""Create and verify pid file.
If the pid file already exists the program exits with an error message,
however if the process it refers to is not running anymore, the pid file
is deleted and the program continues.
The caller is responsible for releasing the lock before the program
exits.
:returns: :class:`PIDFile`.
**Example**:
.. code-block:: python
import atexit
pidlock = create_pidlock("/var/run/app.pid").acquire()
atexit.register(pidlock.release)
"""
pidlock = PIDFile(pidfile)
if pidlock.is_locked() and not pidlock.remove_if_stale():
raise SystemExit(
"ERROR: Pidfile (%s) already exists.\n"
"Seems we're already running? (PID: %s)" % (
pidfile, pidlock.read_pid()))
return pidlock
class DaemonContext(object):
_is_open = False
workdir = DAEMON_WORKDIR
umask = DAEMON_UMASK
def __init__(self, pidfile=None, workdir=None,
umask=None, **kwargs):
self.workdir = workdir or self.workdir
self.umask = self.umask if umask is None else umask
def open(self):
if not self._is_open:
self._detach()
os.chdir(self.workdir)
os.umask(self.umask)
for fd in reversed(range(get_fdmax(default=2048))):
try:
os.close(fd)
except OSError, exc:
if exc.errno != errno.EBADF:
raise
os.open(DAEMON_REDIRECT_TO, os.O_RDWR)
os.dup2(0, 1)
os.dup2(0, 2)
self._is_open = True
__enter__ = open
def close(self, *args):
if self._is_open:
self._is_open = False
__exit__ = close
def _detach(self):
if os.fork() == 0: # first child
os.setsid() # create new session
if os.fork() > 0: # second child
os._exit(0)
else:
os._exit(0)
return self
def detached(logfile=None, pidfile=None, uid=None, gid=None, umask=0,
workdir=None, **opts):
"""Detach the current process in the background (daemonize).
:keyword logfile: Optional log file. The ability to write to this file
will be verified before the process is detached.
:keyword pidfile: Optional pid file. The pid file will not be created,
as this is the responsibility of the child. But the process will
exit if the pid lock exists and the pid written is still running.
:keyword uid: Optional user id or user name to change
effective privileges to.
:keyword gid: Optional group id or group name to change effective
privileges to.
:keyword umask: Optional umask that will be effective in the child process.
:keyword workdir: Optional new working directory.
:keyword \*\*opts: Ignored.
**Example**:
.. code-block:: python
import atexit
from celery.platforms import detached, create_pidlock
with detached(logfile="/var/log/app.log", pidfile="/var/run/app.pid",
uid="nobody"):
# Now in detached child process with effective user set to nobody,
# and we know that our logfile can be written to, and that
# the pidfile is not locked.
pidlock = create_pidlock("/var/run/app.pid").acquire()
atexit.register(pidlock.release)
# Run the program
program.run(logfile="/var/log/app.log")
"""
if not resource:
raise RuntimeError("This platform does not support detach.")
workdir = os.getcwd() if workdir is None else workdir
signals.reset("SIGCLD") # Make sure SIGCLD is using the default handler.
set_effective_user(uid=uid, gid=gid)
# Since without stderr any errors will be silently suppressed,
# we need to know that we have access to the logfile.
logfile and open(logfile, "a").close()
# Doesn't actually create the pidfile, but makes sure it's not stale.
pidfile and create_pidlock(pidfile)
return DaemonContext(umask=umask, workdir=workdir)
def parse_uid(uid):
"""Parse user id.
uid can be an integer (uid) or a string (user name), if a user name
the uid is taken from the password file.
"""
try:
return int(uid)
except ValueError:
if pwd:
try:
return pwd.getpwnam(uid).pw_uid
except KeyError:
raise KeyError("User does not exist: %r" % (uid, ))
raise
def parse_gid(gid):
"""Parse group id.
gid can be an integer (gid) or a string (group name), if a group name
the gid is taken from the password file.
"""
try:
return int(gid)
except ValueError:
if grp:
try:
return grp.getgrnam(gid).gr_gid
except KeyError:
raise KeyError("Group does not exist: %r" % (gid, ))
raise
def setegid(gid):
"""Set effective group id."""
gid = parse_gid(gid)
if gid != os.getegid():
os.setegid(gid)
def seteuid(uid):
"""Set effective user id."""
uid = parse_uid(uid)
if uid != os.geteuid():
os.seteuid(uid)
def setgid(gid):
os.setgid(parse_gid(gid))
def setuid(uid):
os.setuid(parse_uid(uid))
def set_effective_user(uid=None, gid=None):
"""Change process privileges to new user/group.
If UID and GID is set the effective user/group is set.
If only UID is set, the effective user is set, and the group is
set to the users primary group.
If only GID is set, the effective group is set.
"""
uid = uid and parse_uid(uid)
gid = gid and parse_gid(gid)
if uid:
# If GID isn't defined, get the primary GID of the user.
if not gid and pwd:
gid = pwd.getpwuid(uid).pw_gid
setgid(gid)
setuid(uid)
else:
gid and setgid(gid)
class Signals(object):
"""Convenience interface to :mod:`signals`.
If the requested signal is not supported on the current platform,
the operation will be ignored.
**Examples**:
.. code-block:: python
>>> from celery.platforms import signals
>>> signals["INT"] = my_handler
>>> signals["INT"]
my_handler
>>> signals.supported("INT")
True
>>> signals.signum("INT")
2
>>> signals.ignore("USR1")
>>> signals["USR1"] == signals.ignored
True
>>> signals.reset("USR1")
>>> signals["USR1"] == signals.default
True
>>> signals.update(INT=exit_handler,
... TERM=exit_handler,
... HUP=hup_handler)
"""
ignored = _signal.SIG_IGN
default = _signal.SIG_DFL
def supported(self, signal_name):
"""Returns true value if ``signal_name`` exists on this platform."""
try:
return self.signum(signal_name)
except AttributeError:
pass
def signum(self, signal_name):
"""Get signal number from signal name."""
if isinstance(signal_name, int):
return signal_name
if not isinstance(signal_name, basestring) \
or not signal_name.isupper():
raise TypeError("signal name must be uppercase string.")
if not signal_name.startswith("SIG"):
signal_name = "SIG" + signal_name
return getattr(_signal, signal_name)
def reset(self, *signal_names):
"""Reset signals to the default signal handler.
Does nothing if the platform doesn't support signals,
or the specified signal in particular.
"""
self.update((sig, self.default) for sig in signal_names)
def ignore(self, *signal_names):
"""Ignore signal using :const:`SIG_IGN`.
Does nothing if the platform doesn't support signals,
or the specified signal in particular.
"""
self.update((sig, self.ignored) for sig in signal_names)
def __getitem__(self, signal_name):
return _signal.getsignal(self.signum(signal_name))
def __setitem__(self, signal_name, handler):
"""Install signal handler.
Does nothing if the current platform doesn't support signals,
or the specified signal in particular.
"""
try:
_signal.signal(self.signum(signal_name), handler)
except (AttributeError, ValueError):
pass
def update(self, _d_=None, **sigmap):
"""Set signal handlers from a mapping."""
for signal_name, handler in dict(_d_ or {}, **sigmap).iteritems():
self[signal_name] = handler
signals = Signals()
get_signal = signals.signum # compat
install_signal_handler = signals.__setitem__ # compat
reset_signal = signals.reset # compat
ignore_signal = signals.ignore # compat
def strargv(argv):
arg_start = 2 if "manage" in argv[0] else 1
if len(argv) > arg_start:
return " ".join(argv[arg_start:])
return ""
def set_process_title(progname, info=None):
"""Set the ps name for the currently running process.
Only works if :mod:`setproctitle` is installed.
"""
proctitle = "[%s]" % progname
proctitle = "%s %s" % (proctitle, info) if info else proctitle
if _setproctitle:
_setproctitle.setproctitle(proctitle)
return proctitle
def set_mp_process_title(progname, info=None, hostname=None):
"""Set the ps name using the multiprocessing process name.
Only works if :mod:`setproctitle` is installed.
"""
if hostname:
progname = "%s@%s" % (progname, hostname.split(".")[0])
try:
from multiprocessing.process import current_process
except ImportError:
return set_process_title(progname, info=info)
else:
return set_process_title("%s:%s" % (progname,
current_process().name), info=info)
def shellsplit(s, posix=True):
# posix= option to shlex.split first available in Python 2.6+
lexer = shlex.shlex(s, posix=not IS_WINDOWS)
lexer.whitespace_split = True
lexer.commenters = ''
return list(lexer)
Jump to Line
Something went wrong with that request. Please try again.