116 lines
4.7 KiB
Python
116 lines
4.7 KiB
Python
from threading import local
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from django.core.urlresolvers import resolve
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from django.db import transaction
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from django.db.models.signals import pre_delete, post_save, m2m_changed
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from django.dispatch import receiver
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from django.http.response import HttpResponseServerError
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from orchestra.utils.python import OrderedSet
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from . import manager, Operation
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from .helpers import message_user
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from .models import BackendLog
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@receiver(post_save, dispatch_uid='orchestration.post_save_collector')
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def post_save_collector(sender, *args, **kwargs):
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if sender not in [BackendLog, Operation]:
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instance = kwargs.get('instance')
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OperationsMiddleware.collect(Operation.SAVE, **kwargs)
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@receiver(pre_delete, dispatch_uid='orchestration.pre_delete_collector')
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def pre_delete_collector(sender, *args, **kwargs):
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if sender not in [BackendLog, Operation]:
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OperationsMiddleware.collect(Operation.DELETE, **kwargs)
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@receiver(m2m_changed, dispatch_uid='orchestration.m2m_collector')
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def m2m_collector(sender, *args, **kwargs):
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# m2m relations without intermediary models are shit. Model.post_save is not sent and
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# by the time related.post_save is sent rel objects are not accessible via RelatedManager.all()
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if kwargs.pop('action') == 'post_add' and kwargs['pk_set']:
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OperationsMiddleware.collect(Operation.SAVE, **kwargs)
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class OperationsMiddleware(object):
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"""
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Stores all the operations derived from save and delete signals and executes them
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at the end of the request/response cycle
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It also works as a transaction middleware, making requets to run within an atomic block.
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"""
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# Thread local is used because request object is not available on model signals
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thread_locals = local()
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@classmethod
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def get_pending_operations(cls):
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# Check if an error poped up before OperationsMiddleware.process_request()
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if hasattr(cls.thread_locals, 'request'):
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request = cls.thread_locals.request
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if not hasattr(request, 'pending_operations'):
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request.pending_operations = OrderedSet()
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return request.pending_operations
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return set()
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@classmethod
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def get_route_cache(cls):
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""" chache the routes to save sql queries """
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if hasattr(cls.thread_locals, 'request'):
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request = cls.thread_locals.request
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if not hasattr(request, 'route_cache'):
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request.route_cache = {}
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return request.route_cache
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return {}
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@classmethod
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def collect(cls, action, **kwargs):
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""" Collects all pending operations derived from model signals """
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request = getattr(cls.thread_locals, 'request', None)
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if request is None:
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return
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kwargs['operations'] = cls.get_pending_operations()
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kwargs['route_cache'] = cls.get_route_cache()
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instance = kwargs.pop('instance')
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manager.collect(instance, action, **kwargs)
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def enter_transaction_management(self):
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type(self).thread_locals.transaction = transaction.atomic()
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type(self).thread_locals.transaction.__enter__()
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def leave_transaction_management(self, exception=None):
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locals = type(self).thread_locals
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if hasattr(locals, 'transaction'):
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# Don't fucking know why sometimes thread_locals does not contain a transaction
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locals.transaction.__exit__(exception, None, None)
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def process_request(self, request):
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""" Store request on a thread local variable """
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type(self).thread_locals.request = request
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self.enter_transaction_management()
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def process_exception(self, request, exception):
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"""Rolls back the database and leaves transaction management"""
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self.leave_transaction_management(exception)
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def process_response(self, request, response):
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""" Processes pending backend operations """
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if not isinstance(response, HttpResponseServerError):
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operations = self.get_pending_operations()
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if operations:
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try:
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scripts, serialize = manager.generate(operations)
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except Exception as exception:
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self.leave_transaction_management(exception)
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raise
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# We commit transaction just before executing operations
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# because here is when IntegrityError show up
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self.leave_transaction_management()
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logs = manager.execute(scripts, serialize=serialize)
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if logs and resolve(request.path).app_name == 'admin':
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message_user(request, logs)
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return response
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self.leave_transaction_management()
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return response
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