Source code for maestral.daemon

# -*- coding: utf-8 -*-
"""
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  # type: ignore
from Pyro5.errors import CommunicationError  # type: ignore
from Pyro5.api import Daemon, Proxy, expose, register_dict_to_class  # type: ignore
import sdnotify  # type: ignore
from fasteners import InterProcessLock  # type: ignore

# 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: """A 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 or not 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 he 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 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