django-orchestra/orchestra/contrib/orchestration/managers.py

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import sys
from contextlib import ContextDecorator
from threading import local
from django.contrib.admin.models import LogEntry
from django.db.models.signals import m2m_changed, post_save, pre_delete
from django.dispatch import receiver
from orchestra.utils.python import OrderedSet
from . import Operation, helpers, manager
from .middlewares import OperationsMiddleware
from .models import BackendLog, BackendOperation
@receiver(post_save, dispatch_uid='orchestration.post_save_manager_collector')
def post_save_collector(sender, *args, **kwargs):
if sender not in (BackendLog, BackendOperation, LogEntry):
instance = kwargs.get('instance')
orchestrate.collect(Operation.SAVE, **kwargs)
@receiver(pre_delete, dispatch_uid='orchestration.pre_delete_manager_collector')
def pre_delete_collector(sender, *args, **kwargs):
if sender not in (BackendLog, BackendOperation, LogEntry):
orchestrate.collect(Operation.DELETE, **kwargs)
@receiver(m2m_changed, dispatch_uid='orchestration.m2m_manager_collector')
def m2m_collector(sender, *args, **kwargs):
# m2m relations without intermediary models are shit. Model.post_save is not sent and
# by the time related.post_save is sent rel objects are not accessible via RelatedManager.all()
if kwargs.pop('action') == 'post_add' and kwargs['pk_set']:
orchestrate.collect(Operation.SAVE, **kwargs)
class orchestrate(ContextDecorator):
"""
Context manager for triggering backend operations out of request-response cycle, e.g. shell
with orchestrate():
user = SystemUser.objects.get(username='rata')
user.shell = '/dev/null'
user.save(update_fields=('shell',))
"""
thread_locals = local()
thread_locals.pending_operations = None
thread_locals.route_cache = None
@classmethod
def collect(cls, action, **kwargs):
""" Collects all pending operations derived from model signals """
if cls.thread_locals.pending_operations is None:
# No active orchestrate context manager
return
kwargs['operations'] = cls.thread_locals.pending_operations
kwargs['route_cache'] = cls.thread_locals.route_cache
instance = kwargs.pop('instance')
manager.collect(instance, action, **kwargs)
def __enter__(self):
cls = type(self)
self.old_pending_operations = cls.thread_locals.pending_operations
cls.thread_locals.pending_operations = OrderedSet()
self.old_route_cache = cls.thread_locals.route_cache
cls.thread_locals.route_cache = {}
def __exit__(self, exc_type, exc_value, traceback):
cls = type(self)
if not exc_type:
operations = cls.thread_locals.pending_operations
if operations:
scripts, serialize = manager.generate(operations)
logs = manager.execute(scripts, serialize=serialize)
for t, msg in helpers.get_messages(logs):
if t == 'error':
sys.stderr.write('%s: %s\n' % (t, msg))
else:
sys.stdout.write('%s: %s\n' % (t, msg))
cls.thread_locals.pending_operations = self.old_pending_operations
cls.thread_locals.route_cache = self.old_route_cache