"""
This module defines functions to start and stop the sync daemon and retrieve proxy
objects for a running daemon.
"""
# system imports
import sys
import os
import time
import signal
import enum
import threading
import fcntl
import struct
import warnings
import argparse
import re
from pprint import pformat
from shlex import quote
from typing import Optional, Any, Union, Dict, Iterable, Type, TYPE_CHECKING
from types import TracebackType
# external imports
import Pyro5
from Pyro5.errors import CommunicationError
from Pyro5.api import Daemon, Proxy, expose, register_dict_to_class
import sdnotify
from fasteners import InterProcessLock
# local imports
from .errors import SYNC_ERRORS, GENERAL_ERRORS, MaestralApiError
from .utils import exc_info_tuple
from .utils.appdirs import get_runtime_path
from .constants import IS_MACOS, ENV
if TYPE_CHECKING:
from .main import Maestral
__all__ = [
"Stop",
"Start",
"Lock",
"maestral_lock",
"get_maestral_pid",
"sockpath_for_config",
"lockpath_for_config",
"wait_for_startup",
"is_running",
"freeze_support",
"start_maestral_daemon",
"start_maestral_daemon_process",
"stop_maestral_daemon_process",
"MaestralProxy",
"CommunicationError",
]
# systemd environment
INVOCATION_ID = os.getenv("INVOCATION_ID")
NOTIFY_SOCKET = os.getenv("NOTIFY_SOCKET")
WATCHDOG_PID = os.getenv("WATCHDOG_PID")
WATCHDOG_USEC = os.getenv("WATCHDOG_USEC")
IS_WATCHDOG = WATCHDOG_USEC and (
WATCHDOG_PID is None or int(WATCHDOG_PID) == os.getpid()
)
URI = "PYRO:maestral.{0}@{1}"
Pyro5.config.THREADPOOL_SIZE_MIN = 2
[docs]def freeze_support() -> None:
"""
Call this as early as possible in the main entry point of a frozen executable.
This call will start the sync daemon if a matching command line arguments are
detected and do nothing otherwise.
"""
parser = argparse.ArgumentParser(add_help=False)
parser.add_argument("-c")
parsed_args, _ = parser.parse_known_args()
if parsed_args.c:
template = r'.*start_maestral_daemon\("(?P<config_name>\S+)"\).*'
match = re.match(template, parsed_args.c)
if match:
start_maestral_daemon(match["config_name"])
sys.exit()
[docs]class Stop(enum.Enum):
"""Enumeration of daemon exit results"""
Ok = 0
Killed = 1
NotRunning = 2
Failed = 3
[docs]class Start(enum.Enum):
"""Enumeration of daemon start results"""
Ok = 0
AlreadyRunning = 1
Failed = 2
# ==== error serialization =============================================================
def serpent_deserialize_api_error(class_name: str, d: dict) -> MaestralApiError:
"""
Deserializes a MaestralApiError.
:param class_name: Name of class to deserialize.
:param d: Dictionary of serialized class.
:returns: Class instance.
"""
# Import maestral.errors for evaluation.
# This import needs to be absolute to reconstruct the Exception class. Note that the
# eval is safe here because ``serpent_deserialize_api_error`` is only registered for
# strings that match an error class name.
import maestral.errors # noqa: F401
cls = eval(class_name)
err = cls(*d["args"])
for a_name, a_value in d["attributes"].items():
setattr(err, a_name, a_value)
return err
for err_cls in (*SYNC_ERRORS, *GENERAL_ERRORS):
register_dict_to_class(
err_cls.__module__ + "." + err_cls.__name__, serpent_deserialize_api_error
)
# ==== interprocess locking ============================================================
[docs]class Lock:
"""An inter-process and inter-thread lock
This internally uses :class:`fasteners.InterProcessLock` but provides non-blocking
acquire. It also guarantees thread-safety when using the :meth:`singleton` class
method to create / retrieve a lock instance.
:param path: Path of the lock file to use / create.
"""
_instances: Dict[str, "Lock"] = {}
_singleton_lock = threading.Lock()
[docs] @classmethod
def singleton(cls, path: str) -> "Lock":
"""
Retrieve an existing lock object with a given 'name' or create a new one. Use
this method for thread-safe locks.
:param path: Path of the lock file to use / create.
"""
with cls._singleton_lock:
path = os.path.abspath(path)
if path not in cls._instances:
cls._instances[path] = cls(path)
return cls._instances[path]
def __init__(self, path: str) -> None:
self.path = path
self.pid = os.getpid()
self._external_lock = InterProcessLock(self.path)
self._lock = threading.RLock()
[docs] def acquire(self) -> bool:
"""
Attempts to acquire the given lock.
:returns: Whether the acquisition succeeded.
"""
with self._lock:
if self._external_lock.acquired:
return False
return self._external_lock.acquire(blocking=False)
[docs] def release(self) -> None:
"""Release the previously acquired lock."""
with self._lock:
if not self._external_lock.acquired:
raise RuntimeError(
"Cannot release a lock, it was acquired by a different process"
)
self._external_lock.release()
[docs] def locked(self) -> bool:
"""
Checks if the lock is currently held by any thread or process.
:returns: Whether the lock is acquired.
"""
with self._lock:
gotten = self.acquire()
if gotten:
self.release()
return not gotten
[docs] def locking_pid(self) -> Optional[int]:
"""
Returns the PID of the process which currently holds the lock or ``None``. This
should work on macOS, OpenBSD and Linux but may fail on some platforms. Always
use :meth:`locked` to check if the lock is held by any process.
:returns: The PID of the process which currently holds the lock or ``None``.
"""
with self._lock:
if self._external_lock.acquired:
return self.pid
try:
fh = open(self._external_lock.path, "a")
except OSError:
return None
if IS_MACOS:
fmt = "qqihh"
pid_index = 2
flock = struct.pack(fmt, 0, 0, 0, fcntl.F_WRLCK, 0)
else:
fmt = "hhqqih"
pid_index = 4
flock = struct.pack(fmt, fcntl.F_WRLCK, 0, 0, 0, 0, 0)
lockdata = fcntl.fcntl(fh.fileno(), fcntl.F_GETLK, flock)
lockdata_list = struct.unpack(fmt, lockdata)
pid = lockdata_list[pid_index]
if pid > 0:
return pid
return None
# ==== helpers for daemon management ===================================================
def _send_signal(pid: int, sig: int) -> None:
try:
os.kill(pid, sig)
except ProcessLookupError:
pass
[docs]def maestral_lock(config_name: str) -> Lock:
"""
Returns an inter-process and inter-thread lock for Maestral. This is a wrapper
around :class:`Lock` which fills out the appropriate lockfile path for the given
config name.
:param config_name: The name of the Maestral configuration.
:returns: Lock instance for the config name
"""
name = f"{config_name}.lock"
path = get_runtime_path("maestral")
return Lock.singleton(os.path.join(path, name))
[docs]def sockpath_for_config(config_name: str) -> str:
"""
Returns the unix socket location to be used for the config. This should default to
the apps runtime directory + 'CONFIG_NAME.sock'.
:param config_name: The name of the Maestral configuration.
:returns: Socket path.
"""
return get_runtime_path("maestral", f"{config_name}.sock")
[docs]def lockpath_for_config(config_name: str) -> str:
"""
Returns the lock file location to be used for the config. This will be the apps
runtime directory + 'CONFIG_NAME.lock'.
:param config_name: The name of the Maestral configuration.
:returns: Path of lock file to use.
"""
return get_runtime_path("maestral", f"{config_name}.lock")
[docs]def get_maestral_pid(config_name: str) -> Optional[int]:
"""
Returns the PID of the daemon if it is running, ``None`` otherwise.
:param config_name: The name of the Maestral configuration.
:returns: The daemon's PID.
"""
return maestral_lock(config_name).locking_pid()
[docs]def is_running(config_name: str) -> bool:
"""
Checks if a daemon is currently running.
:param config_name: The name of the Maestral configuration.
:returns: Whether the daemon is running.
"""
return maestral_lock(config_name).locked()
[docs]def wait_for_startup(config_name: str, timeout: float = 30) -> None:
"""
Waits until we can communicate with the maestral daemon for ``config_name``.
:param config_name: Configuration to connect to.
:param timeout: Timeout it seconds until we raise an error.
:raises CommunicationError: if we cannot communicate with the daemon within the
given timeout.
"""
sock_name = sockpath_for_config(config_name)
maestral_daemon = Proxy(URI.format(config_name, "./u:" + sock_name))
t0 = time.time()
while True:
try:
maestral_daemon._pyroBind()
return
except Exception as exc:
if time.time() - t0 > timeout:
raise exc
else:
time.sleep(0.2)
finally:
maestral_daemon._pyroRelease()
# ==== main functions to manage daemon =================================================
[docs]def start_maestral_daemon(
config_name: str = "maestral", log_to_stderr: bool = False
) -> None:
"""
Starts the Maestral daemon with event loop in the current thread.
Startup is race free: there will never be more than one daemon running with the same
config name. The daemon is a :class:`maestral.main.Maestral` instance which is
exposed as Pyro daemon object and listens for requests on a unix domain socket. This
call starts an asyncio event loop to process client requests and blocks until the
event loop shuts down. On macOS, the event loop is integrated with Cocoa's
CFRunLoop. This allows processing Cocoa events and callbacks, for instance for
desktop notifications.
:param config_name: The name of the Maestral configuration to use.
:param log_to_stderr: If ``True``, write logs to stderr.
:raises RuntimeError: if a daemon for the given ``config_name`` is already running.
"""
import asyncio
from .main import Maestral
from .logging import scoped_logger, setup_logging
setup_logging(config_name, log_to_stderr)
dlogger = scoped_logger(__name__, config_name)
sd_notifier = sdnotify.SystemdNotifier()
dlogger.info("Starting daemon")
# ==== Process and thread management ===========================================
if threading.current_thread() is not threading.main_thread():
dlogger.error("Must run daemon in main thread")
return
dlogger.debug("Environment:\n%s", pformat(os.environ.copy()))
# Acquire PID lock file.
lock = maestral_lock(config_name)
if lock.acquire():
dlogger.debug("Acquired daemon lock: %r", lock.path)
else:
dlogger.error("Could not acquire lock, daemon is already running")
return
try:
# Nice ourselves to give other processes priority.
os.nice(10)
# ==== System integration ======================================================
# Integrate with CFRunLoop in macOS.
if IS_MACOS:
dlogger.debug("Integrating with CFEventLoop")
from rubicon.objc.eventloop import EventLoopPolicy # type: ignore
asyncio.set_event_loop_policy(EventLoopPolicy())
# Get the default event loop.
loop = asyncio.get_event_loop()
# Notify systemd that we have started.
if NOTIFY_SOCKET:
dlogger.debug("Running as systemd notify service")
dlogger.debug("NOTIFY_SOCKET = %s", NOTIFY_SOCKET)
sd_notifier.notify("READY=1")
# Notify systemd periodically if alive.
if IS_WATCHDOG and WATCHDOG_USEC:
async def periodic_watchdog() -> None:
if WATCHDOG_USEC:
sleep = int(WATCHDOG_USEC)
while True:
sd_notifier.notify("WATCHDOG=1")
await asyncio.sleep(sleep / (2 * 10 ** 6))
dlogger.debug("Running as systemd watchdog service")
dlogger.debug("WATCHDOG_USEC = %s", WATCHDOG_USEC)
dlogger.debug("WATCHDOG_PID = %s", WATCHDOG_PID)
loop.create_task(periodic_watchdog())
# ==== Run Maestral as Pyro server =============================================
# Get socket for config name.
sockpath = sockpath_for_config(config_name)
dlogger.debug("Socket path: %r", sockpath)
# Clean up old socket.
try:
os.remove(sockpath)
except (FileNotFoundError, NotADirectoryError):
pass
# Expose maestral as Pyro server.
dlogger.debug("Creating Pyro daemon")
maestral_daemon = expose(Maestral)(config_name, log_to_stderr=log_to_stderr)
dlogger.debug("Starting event loop")
with Daemon(unixsocket=sockpath) as daemon:
daemon.register(maestral_daemon, f"maestral.{config_name}")
# Reduce Pyro's housekeeping frequency from 2 sec to 20 sec.
# This avoids constantly waking the CPU when we are idle.
if daemon.transportServer.housekeeper:
daemon.transportServer.housekeeper.waittime = 20
for socket in daemon.sockets:
loop.add_reader(socket.fileno(), daemon.events, daemon.sockets)
# Handle sigterm gracefully.
signals = (signal.SIGHUP, signal.SIGTERM, signal.SIGINT)
for s in signals:
loop.add_signal_handler(s, maestral_daemon.shutdown_daemon)
loop.run_until_complete(maestral_daemon.shutdown_complete)
for socket in daemon.sockets:
loop.remove_reader(socket.fileno())
# Prevent Pyro housekeeping from blocking shutdown.
daemon.transportServer.housekeeper = None
except Exception as exc:
dlogger.error(exc.args[0], exc_info=True)
finally:
if NOTIFY_SOCKET:
# Notify systemd that we are shutting down.
sd_notifier.notify("STOPPING=1")
lock.release()
[docs]def start_maestral_daemon_process(
config_name: str = "maestral", timeout: float = 30
) -> Start:
"""
Starts the Maestral daemon in a new process by calling :func:`start_maestral_daemon`.
Startup is race free: there will never be more than one daemon running for the same
config name. This function will use :obj:`sys.executable` as a Python executable to
start the daemon.
Environment variables from the current process will be preserved and updated with
the environment variables defined in :const:`constants.ENV`.
:param config_name: The name of the Maestral configuration to use.
:param timeout: Time in sec to wait for daemon to start.
:returns: :attr:`Start.Ok` if successful, :attr:`Start.AlreadyRunning` if the daemon
was already running or :attr:`Start.Failed` if startup failed. It is possible
that :attr:`Start.Ok` may be returned instead of :attr:`Start.AlreadyRunning`
in case of a race but the daemon is nevertheless started only once.
"""
if is_running(config_name):
return Start.AlreadyRunning
# Protect against injection.
cc = quote(config_name).strip("'")
script = f'import maestral.daemon; maestral.daemon.start_maestral_daemon("{cc}")'
env = os.environ.copy()
env.update(ENV)
pid = os.spawnve(os.P_NOWAIT, sys.executable, [sys.executable, "-c", script], env)
try:
wait_for_startup(config_name, timeout)
except Exception as exc:
from .logging import scoped_logger, setup_logging
setup_logging(config_name, log_to_stderr=False)
clogger = scoped_logger(__name__, config_name)
clogger.error("Could not communicate with daemon", exc_info=exc_info_tuple(exc))
# Let's check if the daemon is running
try:
os.kill(pid, 0)
clogger.error("Daemon is running but not responsive, killing now")
except OSError:
clogger.error("Daemon quit unexpectedly")
else:
os.kill(pid, signal.SIGTERM)
return Start.Failed
else:
return Start.Ok
[docs]def stop_maestral_daemon_process(
config_name: str = "maestral", timeout: float = 10
) -> Stop:
"""Stops a maestral daemon process by finding its PID and shutting it down.
This function first tries to shut down Maestral gracefully. If this fails and we
know its PID, it will send SIGTERM. If that fails as well, it will send SIGKILL to
the process.
:param config_name: The name of the Maestral configuration to use.
:param timeout: Number of sec to wait for daemon to shut down before killing it.
:returns: :attr:`Stop.Ok` if successful, :attr:`Stop.Killed` if killed,
:attr:`Stop.NotRunning` if the daemon was not running and :attr:`Stop.Failed`
if killing the process failed because we could not retrieve its PID.
"""
if not is_running(config_name):
return Stop.NotRunning
pid = get_maestral_pid(config_name)
if not pid:
# Cannot send SIGTERM to process if we don't know its pid.
return Stop.Failed
_send_signal(pid, signal.SIGTERM)
while timeout > 0:
if not is_running(config_name):
return Stop.Ok
else:
time.sleep(0.2)
timeout -= 0.2
# Kill.
_send_signal(pid, signal.SIGKILL)
return Stop.Killed
[docs]class MaestralProxy:
"""A Proxy to the Maestral daemon
All methods and properties of Maestral's public API are accessible and calls /
access will be forwarded to the corresponding Maestral instance. This class can be
used as a context manager to close the connection to the daemon on exit.
:Example:
Use MaestralProxy as a context manager:
>>> with MaestralProxy() as m:
... print(m.status)
Use MaestralProxy directly:
>>> m = MaestralProxy()
>>> print(m.status)
>>> m._disconnect()
:ivar _is_fallback: Whether we are using an actual Maestral instance as fallback
instead of a Proxy.
:param config_name: The name of the Maestral configuration to use.
:param fallback: If ``True``, a new instance of Maestral will be created in the
current process when the daemon is not running.
:raises CommunicationError: if the daemon is running but cannot be reached or if the
daemon is not running and ``fallback`` is ``False``.
"""
_m: Union["Maestral", Proxy]
def __init__(self, config_name: str = "maestral", fallback: bool = False) -> None:
self._config_name = config_name
self._is_fallback = False
if is_running(config_name):
sock_name = sockpath_for_config(config_name)
# print remote tracebacks locally
sys.excepthook = Pyro5.errors.excepthook
self._m = Proxy(URI.format(config_name, "./u:" + sock_name))
try:
self._m._pyroBind()
except CommunicationError:
self._m._pyroRelease()
raise
else:
# If daemon is not running, fall back to new Maestral instance
# or raise a CommunicationError if fallback not allowed.
if fallback:
from .main import Maestral
self._m = Maestral(config_name)
else:
raise CommunicationError(f"Could not get proxy for '{config_name}'")
self._is_fallback = not isinstance(self._m, Proxy)
def _disconnect(self) -> None:
if isinstance(self._m, Proxy):
self._m._pyroRelease()
def __enter__(self) -> "MaestralProxy":
return self
def __exit__(
self, exc_type: Type[Exception], exc_value: Exception, tb: TracebackType
) -> None:
self._disconnect()
del self._m
def __getattr__(self, item: str) -> Any:
if item.startswith("_"):
super().__getattribute__(item)
elif isinstance(self._m, Proxy):
return self._m.__getattr__(item)
else:
return self._m.__getattribute__(item)
def __setattr__(self, key, value) -> None:
if key.startswith("_"):
super().__setattr__(key, value)
else:
self._m.__setattr__(key, value)
def __dir__(self) -> Iterable[str]:
own_result = dir(self.__class__) + list(self.__dict__.keys())
proxy_result = [k for k in self._m.__dir__() if not k.startswith("_")]
return sorted(set(own_result) | set(proxy_result))
def __repr__(self) -> str:
return (
f"<{self.__class__.__name__}(config={self._config_name!r}, "
f"is_fallback={self._is_fallback})>"
)
def get_maestral_proxy(
config_name: str = "maestral", fallback: bool = False
) -> Union["Maestral", Proxy]:
warnings.warn(
"'get_maestral_proxy' is deprecated, please use 'MaestralProxy' instead",
DeprecationWarning,
)
m = MaestralProxy(config_name, fallback=fallback)
return m._m