"""Hooks management
This module defined the `Hook` class and registry and a set of abstract classes
for operations.
Hooks are called before / after any individual update of entities / relations
in the repository and on special events such as server startup or shutdown.
Operations may be registered by hooks during a transaction, which will be
fired when the pool is commited or rollbacked.
Entity hooks (eg before_add_entity, after_add_entity, before_update_entity,
after_update_entity, before_delete_entity, after_delete_entity) all have an
`entity` attribute
Relation (eg before_add_relation, after_add_relation, before_delete_relation,
after_delete_relation) all have `eidfrom`, `rtype`, `eidto` attributes.
Server start/maintenance/stop hooks (eg server_startup, server_maintenance,
server_shutdown) have a `repo` attribute, but *their `_cw` attribute is None*.
The `server_startup` is called on regular startup, while `server_maintenance`
is called on cubicweb-ctl upgrade or shell commands. `server_shutdown` is
called anyway.
Backup/restore hooks (eg server_backup, server_restore) have a `repo` and a
`timestamp` attributes, but *their `_cw` attribute is None*.
Session hooks (eg session_open, session_close) have no special attribute.
:organization: Logilab
:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
from __future__ import with_statement
__docformat__ = "restructuredtext en"
from warnings import warn
from logging import getLogger
from itertools import chain
from logilab.common.decorators import classproperty
from logilab.common.deprecation import deprecated
from logilab.common.logging_ext import set_log_methods
from cubicweb.cwvreg import CWRegistry, VRegistry
from cubicweb.selectors import (objectify_selector, lltrace, ExpectedValueSelector,
implements)
from cubicweb.appobject import AppObject
from cubicweb.server.session import security_enabled
ENTITIES_HOOKS = set(('before_add_entity', 'after_add_entity',
'before_update_entity', 'after_update_entity',
'before_delete_entity', 'after_delete_entity'))
RELATIONS_HOOKS = set(('before_add_relation', 'after_add_relation' ,
'before_delete_relation','after_delete_relation'))
SYSTEM_HOOKS = set(('server_backup', 'server_restore',
'server_startup', 'server_maintenance', 'server_shutdown',
'session_open', 'session_close'))
ALL_HOOKS = ENTITIES_HOOKS | RELATIONS_HOOKS | SYSTEM_HOOKS
class HooksRegistry(CWRegistry):
def register(self, obj, **kwargs):
try:
iter(obj.events)
except AttributeError:
raise
except:
raise Exception('bad .events attribute %s on %s.%s' % (
obj.events, obj.__module__, obj.__name__))
for event in obj.events:
if event not in ALL_HOOKS:
raise Exception('bad event %s on %s.%s' % (
event, obj.__module__, obj.__name__))
super(HooksRegistry, self).register(obj, **kwargs)
def call_hooks(self, event, session=None, **kwargs):
kwargs['event'] = event
if session is None:
for hook in sorted(self.possible_objects(session, **kwargs),
key=lambda x: x.order):
hook()
else:
# by default, hooks are executed with security turned off
with security_enabled(session, read=False):
hooks = sorted(self.possible_objects(session, **kwargs),
key=lambda x: x.order)
with security_enabled(session, write=False):
for hook in hooks:
hook()
VRegistry.REGISTRY_FACTORY['hooks'] = HooksRegistry
_MARKER = object()
def entity_oldnewvalue(entity, attr):
"""returns the couple (old attr value, new attr value)
NOTE: will only work in a before_update_entity hook
"""
# get new value and remove from local dict to force a db query to
# fetch old value
newvalue = entity.pop(attr, _MARKER)
oldvalue = getattr(entity, attr)
if newvalue is not _MARKER:
entity[attr] = newvalue
return oldvalue, newvalue
# some hook specific selectors #################################################
@objectify_selector
@lltrace
def _bw_is_enabled(cls, req, **kwargs):
if cls.enabled:
return 1
warn('[3.6] %s: enabled is deprecated' % cls)
return 0
@objectify_selector
@lltrace
def match_event(cls, req, **kwargs):
if kwargs.get('event') in cls.events:
return 1
return 0
@objectify_selector
@lltrace
def enabled_category(cls, req, **kwargs):
if req is None:
return True # XXX how to deactivate server startup / shutdown event
return req.is_hook_activated(cls)
@objectify_selector
@lltrace
def from_dbapi_query(cls, req, **kwargs):
if req.running_dbapi_query:
return 1
return 0
class rechain(object):
def __init__(self, *iterators):
self.iterators = iterators
def __iter__(self):
return iter(chain(*self.iterators))
class match_rtype(ExpectedValueSelector):
"""accept if parameters specified as initializer arguments are specified
in named arguments given to the selector
:param *expected: parameters (eg `basestring`) which are expected to be
found in named arguments (kwargs)
"""
def __init__(self, *expected, **more):
self.expected = expected
self.frometypes = more.pop('frometypes', None)
self.toetypes = more.pop('toetypes', None)
@lltrace
def __call__(self, cls, req, *args, **kwargs):
if kwargs.get('rtype') not in self.expected:
return 0
if self.frometypes is not None and \
req.describe(kwargs['eidfrom'])[0] not in self.frometypes:
return 0
if self.toetypes is not None and \
req.describe(kwargs['eidto'])[0] not in self.toetypes:
return 0
return 1
class match_rtype_sets(ExpectedValueSelector):
"""accept if parameters specified as initializer arguments are specified
in named arguments given to the selector
"""
def __init__(self, *expected):
self.expected = expected
@lltrace
def __call__(self, cls, req, *args, **kwargs):
for rel_set in self.expected:
if kwargs.get('rtype') in rel_set:
return 1
return 0
# base class for hook ##########################################################
class Hook(AppObject):
__registry__ = 'hooks'
__select__ = match_event() & enabled_category() & _bw_is_enabled()
# set this in derivated classes
events = None
category = None
order = 0
# XXX deprecated
enabled = True
@classproperty
def __regid__(cls):
warn('[3.6] %s.%s: please specify an id for your hook'
% (cls.__module__, cls.__name__), DeprecationWarning)
return str(id(cls))
@classmethod
def __registered__(cls, reg):
super(Hook, cls).__registered__(reg)
if getattr(cls, 'accepts', None):
warn('[3.6] %s.%s: accepts is deprecated, define proper __select__'
% (cls.__module__, cls.__name__), DeprecationWarning)
rtypes = []
for ertype in cls.accepts:
if ertype.islower():
rtypes.append(ertype)
else:
cls.__select__ = cls.__select__ & implements(ertype)
if rtypes:
cls.__select__ = cls.__select__ & match_rtype(*rtypes)
return cls
known_args = set(('entity', 'rtype', 'eidfrom', 'eidto', 'repo', 'timestamp'))
def __init__(self, req, event, **kwargs):
for arg in self.known_args:
if arg in kwargs:
setattr(self, arg, kwargs.pop(arg))
super(Hook, self).__init__(req, **kwargs)
self.event = event
def __call__(self):
if hasattr(self, 'call'):
cls = self.__class__
warn('[3.6] %s.%s: call is deprecated, implements __call__'
% (cls.__module__, cls.__name__), DeprecationWarning)
if self.event.endswith('_relation'):
self.call(self._cw, self.eidfrom, self.rtype, self.eidto)
elif 'delete' in self.event:
self.call(self._cw, self.entity.eid)
elif self.event.startswith('server_'):
self.call(self.repo)
elif self.event.startswith('session_'):
self.call(self._cw)
else:
self.call(self._cw, self.entity)
set_log_methods(Hook, getLogger('cubicweb.hook'))
# base classes for relation propagation ########################################
class PropagateSubjectRelationHook(Hook):
"""propagate some `main_rtype` relation on entities linked as object of
`subject_relations` or as subject of `object_relations` (the watched
relations).
This hook ensure that when one of the watched relation is added, the
`main_rtype` relation is added to the target entity of the relation.
"""
events = ('after_add_relation',)
# to set in concrete class
main_rtype = None
subject_relations = None
object_relations = None
def __call__(self):
assert self.main_rtype
for eid in (self.eidfrom, self.eidto):
etype = self._cw.describe(eid)[0]
if self.main_rtype not in self._cw.vreg.schema.eschema(etype).subjrels:
return
if self.rtype in self.subject_relations:
meid, seid = self.eidfrom, self.eidto
else:
assert self.rtype in self.object_relations
meid, seid = self.eidto, self.eidfrom
self._cw.execute(
'SET E %s P WHERE X %s P, X eid %%(x)s, E eid %%(e)s, NOT E %s P'\
% (self.main_rtype, self.main_rtype, self.main_rtype),
{'x': meid, 'e': seid}, ('x', 'e'))
class PropagateSubjectRelationAddHook(Hook):
"""propagate to entities at the end of watched relations when a `main_rtype`
relation is added
"""
events = ('after_add_relation',)
# to set in concrete class
subject_relations = None
object_relations = None
def __call__(self):
eschema = self._cw.vreg.schema.eschema(self._cw.describe(self.eidfrom)[0])
execute = self._cw.execute
for rel in self.subject_relations:
if rel in eschema.subjrels:
execute('SET R %s P WHERE X eid %%(x)s, P eid %%(p)s, '
'X %s R, NOT R %s P' % (self.rtype, rel, self.rtype),
{'x': self.eidfrom, 'p': self.eidto}, 'x')
for rel in self.object_relations:
if rel in eschema.objrels:
execute('SET R %s P WHERE X eid %%(x)s, P eid %%(p)s, '
'R %s X, NOT R %s P' % (self.rtype, rel, self.rtype),
{'x': self.eidfrom, 'p': self.eidto}, 'x')
class PropagateSubjectRelationDelHook(Hook):
"""propagate to entities at the end of watched relations when a `main_rtype`
relation is deleted
"""
events = ('after_delete_relation',)
# to set in concrete class
subject_relations = None
object_relations = None
def __call__(self):
eschema = self._cw.vreg.schema.eschema(self._cw.describe(self.eidfrom)[0])
execute = self._cw.execute
for rel in self.subject_relations:
if rel in eschema.subjrels:
execute('DELETE R %s P WHERE X eid %%(x)s, P eid %%(p)s, '
'X %s R' % (self.rtype, rel),
{'x': self.eidfrom, 'p': self.eidto}, 'x')
for rel in self.object_relations:
if rel in eschema.objrels:
execute('DELETE R %s P WHERE X eid %%(x)s, P eid %%(p)s, '
'R %s X' % (self.rtype, rel),
{'x': self.eidfrom, 'p': self.eidto}, 'x')
# abstract classes for operation ###############################################
class Operation(object):
"""an operation is triggered on connections pool events related to
commit / rollback transations. Possible events are:
precommit:
the pool is preparing to commit. You shouldn't do anything things which
has to be reverted if the commit fail at this point, but you can freely
do any heavy computation or raise an exception if the commit can't go.
You can add some new operation during this phase but their precommit
event won't be triggered
commit:
the pool is preparing to commit. You should avoid to do to expensive
stuff or something that may cause an exception in this event
revertcommit:
if an operation failed while commited, this event is triggered for
all operations which had their commit event already to let them
revert things (including the operation which made fail the commit)
rollback:
the transaction has been either rollbacked either
* intentionaly
* a precommit event failed, all operations are rollbacked
* a commit event failed, all operations which are not been triggered for
commit are rollbacked
order of operations may be important, and is controlled according to:
* operation's class
"""
def __init__(self, session, **kwargs):
self.session = session
self.__dict__.update(kwargs)
self.register(session)
# execution information
self.processed = None # 'precommit', 'commit'
self.failed = False
def register(self, session):
session.add_operation(self, self.insert_index())
def insert_index(self):
"""return the index of the lastest instance which is not a
LateOperation instance
"""
# faster by inspecting operation in reverse order for heavy transactions
i = None
for i, op in enumerate(reversed(self.session.pending_operations)):
if isinstance(op, (LateOperation, SingleLastOperation)):
continue
return -i or None
if i is None:
return None
return -(i + 1)
def handle_event(self, event):
"""delegate event handling to the opertaion"""
getattr(self, event)()
def precommit_event(self):
"""the observed connections pool is preparing a commit"""
def revertprecommit_event(self):
"""an error went when pre-commiting this operation or a later one
should revert pre-commit's changes but take care, they may have not
been all considered if it's this operation which failed
"""
def commit_event(self):
"""the observed connections pool is commiting"""
def revertcommit_event(self):
"""an error went when commiting this operation or a later one
should revert commit's changes but take care, they may have not
been all considered if it's this operation which failed
"""
def rollback_event(self):
"""the observed connections pool has been rollbacked
do nothing by default, the operation will just be removed from the pool
operation list
"""
def postcommit_event(self):
"""the observed connections pool has committed"""
@property
@deprecated('[3.6] use self.session.user')
def user(self):
return self.session.user
@property
@deprecated('[3.6] use self.session.repo')
def repo(self):
return self.session.repo
@property
@deprecated('[3.6] use self.session.vreg.schema')
def schema(self):
return self.session.repo.schema
@property
@deprecated('[3.6] use self.session.vreg.config')
def config(self):
return self.session.repo.config
set_log_methods(Operation, getLogger('cubicweb.session'))
class LateOperation(Operation):
"""special operation which should be called after all possible (ie non late)
operations
"""
def insert_index(self):
"""return the index of the lastest instance which is not a
SingleLastOperation instance
"""
# faster by inspecting operation in reverse order for heavy transactions
i = None
for i, op in enumerate(reversed(self.session.pending_operations)):
if isinstance(op, SingleLastOperation):
continue
return -i or None
if i is None:
return None
return -(i + 1)
class SingleOperation(Operation):
"""special operation which should be called once"""
def register(self, session):
"""override register to handle cases where this operation has already
been added
"""
operations = session.pending_operations
index = self.equivalent_index(operations)
if index is not None:
equivalent = operations.pop(index)
else:
equivalent = None
session.add_operation(self, self.insert_index())
return equivalent
def equivalent_index(self, operations):
"""return the index of the equivalent operation if any"""
for i, op in enumerate(reversed(operations)):
if op.__class__ is self.__class__:
return -(i+1)
return None
class SingleLastOperation(SingleOperation):
"""special operation which should be called once and after all other
operations
"""
def insert_index(self):
return None
class SendMailOp(SingleLastOperation):
def __init__(self, session, msg=None, recipients=None, **kwargs):
# may not specify msg yet, as
# `cubicweb.sobjects.supervision.SupervisionMailOp`
if msg is not None:
assert recipients
self.to_send = [(msg, recipients)]
else:
assert recipients is None
self.to_send = []
super(SendMailOp, self).__init__(session, **kwargs)
def register(self, session):
previous = super(SendMailOp, self).register(session)
if previous:
self.to_send = previous.to_send + self.to_send
def commit_event(self):
self.session.repo.threaded_task(self.sendmails)
def sendmails(self):
self.session.vreg.config.sendmails(self.to_send)
class RQLPrecommitOperation(Operation):
def precommit_event(self):
execute = self.session.execute
for rql in self.rqls:
execute(*rql)