evennia/src/server/oobhandler.py

"""
OOBHandler - Out Of Band Handler

The OOBHandler is called directly by out-of-band protocols. It supplies three
pieces of functionality:

    function execution - the oob protocol can execute a function directly on
                         the server. Only functions specified in settings.OOB_PLUGIN_MODULE.OOB_FUNCS
                         are valid for this use.
    repeat func execution - the oob protocol can request a given function be executed repeatedly
                            at a regular interval.
    tracking - the oob protocol can request Evennia to track changes to fields/properties on
               objects, as well as changes in Attributes. This is done by dynamically adding
               tracker-objects on entities. The behaviour of those objects can be customized
               via settings.OOB_PLUGIN_MODULE.OOB_TRACKERS.

oob functions have the following call signature:
    function(caller, *args, **kwargs)

oob trackers should inherit from the OOBTracker class in this
    module and implement a minimum of the same functionality.

"""

from inspect import isfunction
from django.conf import settings
from src.server.models import ServerConfig
from src.server.sessionhandler import SESSIONS
from src.scripts.scripts import Script
from src.utils.create import create_script
from src.utils.dbserialize import dbserialize, dbunserialize, pack_dbobj
from src.utils import logger
from src.utils.utils import all_from_module, to_str, is_iter, make_iter

_SA = object.__setattr__
_GA = object.__getattribute__
_DA = object.__delattr__

# load from plugin module
_OOB_FUNCS = dict((key, func) for key, func in all_from_module(settings.OOB_PLUGIN_MODULE).items() if isfunction(func))
_OOB_ERROR = _OOB_FUNCS.get("oob_error", None)


class TrackerHandler(object):
    """
    This object is dynamically assigned to objects whenever one of its fields
    are to be tracked. It holds an internal dictionary mapping to the fields
    on that object. Each field can be tracked by any number of trackers (each
    tied to a different callback).
    """
    def __init__(self, obj):
        """
        This is initiated and stored on the object as a property _trackerhandler.
        """
        self.obj = obj.dbobj
        self.ntrackers = 0
        # initiate store only with valid on-object fieldnames
        self.tracktargets = dict((key, {}) for key in _GA(_GA(self.obj, "_meta"), "get_all_field_names")())

    def add(self, fieldname, trackerkey, trackerobj):
        """
        Add tracker to the handler. Raises KeyError if fieldname
        does not exist.
        """
        self.tracktargets[fieldname][trackerkey] = trackerobj
        self.ntrackers += 1

    def remove(self, fieldname, trackerkey, *args, **kwargs):
        """
        Remove tracker from handler. Raises KeyError if tracker
        is not found.
        """
        oobobj = self.tracktargets[fieldname][trackerkey]
        try:
            oobobj.at_delete(*args, **kwargs)
        except Exception:
            logger.log_trace()
        del oobobj
        self.ntrackers -= 1
        if self.ntrackers <= 0:
            # if there are no more trackers, clean this handler
            del self

    def update(self, fieldname, new_value):
        """
        Called by the field when it updates to a new value
        """
        for trackerobj in self.tracktargets[fieldname].values():
            try:
                trackerobj.update(fieldname, new_value)
            except Exception:
                logger.log_trace()

class TrackerBase(object):
    """
    Base class for OOB Tracker objects.
    """
    def __init__(self, *args, **kwargs):
        pass
    def update(self, *args, **kwargs):
        "Called by tracked objects"
        pass
    def at_remove(self, *args, **kwargs):
        "Called when tracker is removed"
        pass

# Default tracker OOB class

class OOBTracker(TrackerBase):
    """
    A OOB object that passively sends data to a stored sessid whenever
    a named database field changes.
    """
    def __init__(self, fieldname, sessid, *args, **kwargs):
        """
        name - name of entity to track, such as "db_key"
        track_type - one of "field", "prop" or "attr" for Database fields,
                     non-database Property or Attribute
        sessid - sessid of session to report to
        """
        self.fieldname = fieldname
        self.sessid = sessid

    def update(self, new_value, *args, **kwargs):
        "Called by cache when updating the tracked entitiy"
        SESSIONS.session_from_sessid(self.sessid).msg(oob=("trackreturn",
                                                           (self.fieldname, new_value)))

class _RepeaterPool(object):
    """
    This maintains a pool of _RepeaterScript scripts, ordered one per interval. It
    will automatically cull itself once a given interval's script has no more
    subscriptions.
    """

    class _RepeaterScript(Script):
        """
        Repeating script for triggering OOB functions. Maintained in the pool.
        """
        def at_script_creation(self):
            "Called when script is initialized"
            self.key = "oob_func"
            self.desc = "OOB functionality script"
            self.persistent = False #oob scripts should always be non-persistent
            self.ndb.subscriptions = {}

        def at_repeat(self):
            """
            Calls subscriptions every self.interval seconds
            """
            for (func_key, caller, interval, args, kwargs) in self.ndb.subscriptions.values():
                try:
                    _OOB_FUNCS[func_key](caller, *args, **kwargs)
                except Exception:
                    logger.log_trace()

        def subscribe(self, store_key, caller, func_key, interval, *args, **kwargs):
            """
            Sign up a subscriber to this oobfunction. Subscriber is
            a database object with a dbref.
            """
            self.ndb.subscriptions[store_key] = (func_key, caller, interval, args, kwargs)

        def unsubscribe(self, store_key):
            """
            Unsubscribe from oobfunction. Returns True if removal was
            successful, False otherwise
            """
            self.ndb.subscriptions.pop(store_key, None)

    def __init__(self):
        self.scripts = {}

    def add(self, store_key, caller, func_key, interval, *args, **kwargs):
        """
        Add a new tracking
        """
        if interval not in self.scripts:
            # if no existing interval exists, create new script to fill the gap
            new_tracker = create_script(self._RepeaterScript, key="oob_repeater_%is" % interval, interval=interval)
            self.scripts[interval] = new_tracker
        self.scripts[interval].subscribe(store_key, caller, func_key, interval, *args, **kwargs)

    def remove(self, store_key, interval):
        """
        Remove tracking
        """
        if interval in self.scripts:
            self.scripts[interval].unsubscribe(store_key)
            if len(self.scripts[interval].ndb.subscriptions) == 0:
                # no more subscriptions for this interval. Clean out the script.
                self.scripts[interval].stop()


# Main OOB Handler

class OOBHandler(object):
    """
    The OOBHandler maintains all dynamic on-object oob hooks. It will store the
    creation instructions and and re-apply them at a server reload (but not after
    a server shutdown)
    """
    def __init__(self):
        """
        Initialize handler
        """
        self.sessionhandler = SESSIONS
        self.oob_tracker_storage = {}
        self.oob_repeat_storage = {}
        self.oob_tracker_pool = _RepeaterPool()

    def save(self):
        """
        Save the command_storage as a serialized string into a temporary
        ServerConf field
        """
        if self.oob_tracker_storage:
            ServerConfig.objects.conf(key="oob_tracker_storage", value=dbserialize(self.oob_tracker_storage))
        if  self.oob_repeat_storage:
            ServerConfig.objects.conf(key="oob_repeat_storage", value=dbserialize(self.oob_repeat_storage))

    def restore(self):
        """
        Restore the command_storage from database and re-initialize the handler from storage.. This is
        only triggered after a server reload, not after a shutdown-restart
        """
        # load stored command instructions and use them to re-initialize handler
        tracker_storage = ServerConfig.objects.conf(key="oob_tracker_storage")
        if tracker_storage:
            self.oob_tracker_storage = dbunserialize(tracker_storage)
            for tracker_key, (obj, sessid, fieldname, args, kwargs) in self.oob_tracker_storage.items():
                self.track(obj, sessid, fieldname, tracker_key, *args, **kwargs)

        repeat_storage = ServerConfig.objects.conf(key="oob_repeat_storage")
        if repeat_storage:
            self.oob_repeat_storage = dbunserialize(repeat_storage)
            for func_key, (caller, func_key, interval, args, kwargs) in self.oob_repeat_storage.items():
                self.repeat(caller, func_key, interval, *args, **kwargs)


    def track(self, obj, sessid, fieldname, oobclass, *args, **kwargs):
        """
        Create an OOB obj of class _oob_MAPPING[tracker_key] on obj. args,
        kwargs will be used to initialize the OOB hook  before adding
        it to obj.
        If property_key is not given, but the OOB has a class property property_name, this
        will be used as the property name when assigning the OOB to
        obj, otherwise tracker_key is ysed as the property name.
        """
        oobclass = _OOB_TRACKERS[tracker_key] # raise traceback if not found
        if not "_trackerhandler" in _GA(obj, "__dict__"):
            # assign trackerhandler to object
            _SA(obj, "_trackerhandler", TrackerHandler(obj))
        # initialize object
        oob = oobclass(obj, sessid, fieldname, *args, **kwargs)
        _GA(obj, "_trackerhandler").add(oob, fieldname)

        # store calling arguments as a pickle for retrieval later
        storekey = (pack_dbobj(obj), sessid, fieldname)
        stored = (obj, sessid, fieldname, args, kwargs)
        self.oob_tracker_storage[storekey] = stored

    def untrack(self, obj, sessid, fieldname, tracker_key, *args, **kwargs):
        """
        Remove the OOB from obj. If oob implements an
        at_delete hook, this will be called with args, kwargs
        """
        try:
            # call at_delete hook
            _GA(obj, "_trackerhandler").remove(fieldname, tracker_key, *args, **kwargs)
        except AttributeError:
            pass
        # remove the pickle from storage
        store_key = (pack_dbobj(obj), sessid, fieldname)
        self.oob_tracker_storage.pop(store_key, None)

    def track_field(self, obj, sessid, field_name, tracker_key="oobtracker"):
        """
        Shortcut wrapper method for specifically tracking a database field.
        Uses OOBTracker by default (change tracker_key to redirect)
        Will create a tracker with a property name that the field cache
        expects
        """
        # all database field names starts with db_*
        field_name = field_name if field_name.startswith("db_") else "db_%s" % field_name
        oob_tracker_name = "_track_%s_change" % field_name # field cache looks for name on this form
        self.track(obj, tracker_key, field_name, sessid, property_name=oob_tracker_name)

    def track_attribute(self, obj, sessid, attr_name, tracker_key="oobtracker"):
        """
        Shortcut wrapper method for specifically tracking the changes of an
        Attribute on an object. Will create a tracker on the Attribute Object and
        name in a way the Attribute expects.
        """
        # get the attribute object if we can
        attrobj = _GA(obj, "attributes").get(attr_name, return_obj=True)
        if attrobj:
            oob_tracker_name = "_track_db_value_change"
            self.track(attrobj, tracker_key, attr_name, sessid, property_name=oob_tracker_name)

    def repeat(self, caller, func_key, interval=20, *args, **kwargs):
        """
        Start a repeating action. Every interval seconds,
        the oobfunc corresponding to func_key is called with
        args and kwargs.
        """
        if not func_key in _OOB_FUNCS:
            raise KeyError("%s is not a valid OOB function name.")
        store_key = (pack_dbobj(caller), func_key, interval)
        # prepare to store
        self.oob_repeat_storage[store_key] = (caller, func_key, interval, args, kwargs)
        self.oob_tracker_pool.add(store_key, caller, func_key, interval, *args, **kwargs)

    def unrepeat(self, caller, func_key, interval=20):
        """
        Stop a repeating action
        """
        store_key = (pack_dbobj(caller), func_key, interval)
        self.oob_tracker_pool.remove(store_key, interval)
        self.oob_repeat_storage.pop(store_key, None)

    def msg(self, sessid, funcname, *args, **kwargs):
        "Shortcut to relay oob data back to portal"
        session = self.sessionhandler.session_from_sessid(sessid)
        if session:
            session.msg(oob=(funcname, args, kwargs))

    def execute_cmd(self, session, func_key, *args, **kwargs):
        """
        Retrieve oobfunc from OOB_FUNCS and execute it immediately
        using *args and **kwargs
        """
        try:
            oobfunc = _OOB_FUNCS[func_key] # raise traceback if not found
            oobfunc(self, session, *args, **kwargs)
        except KeyError:
            errmsg = "OOB Error: function '%s' not recognized." % func_key
            if _OOB_ERROR:
                _OOB_ERROR(self, session, errmsg, *args, **kwargs)
            else:
                logger.log_trace(errmsg)
        except Exception, err:
            errmsg = "OOB Error: Exception in '%s'(%s, %s):\n%s" % (func_key, args, kwargs, err)
            if _OOB_ERROR:
                _OOB_ERROR(self, session, errmsg, *args, **kwargs)
            else:
                logger.log_trace(errmsg)
# access object
OOB_HANDLER = OOBHandler()