refactor some callback receiver code

the bigint migration removed the foreign key constraints for:

- host_id
- job_id (and projectupdate_id, etc...)

because of this, we don't really need to check explicitly for a host_id
IntegrityError anymore (because it won't occur)

additionally, while it's possible to insert an event with a mismatched
job_id now (for example, you can totally start a long-running job, and
delete the job record in the background using the ORM or psql), doing
so results in DoesNotExist errors in the code that handles the
playbook_on_stats events

awx/main/dispatch/worker/callback.py

@@ -11,7 +11,7 @@ import traceback
 from django.conf import settings
 from django.utils.timezone import now as tz_now
 from django.db import DatabaseError, OperationalError, connection as django_connection
-from django.db.utils import InterfaceError, InternalError, IntegrityError
+from django.db.utils import InterfaceError, InternalError
 
 import psutil
 
@@ -120,20 +120,12 @@ class CallbackBrokerWorker(BaseWorker):
                     e.modified = now
                 try:
                     cls.objects.bulk_create(events)
-                except Exception as exc:
+                except Exception:
                     # if an exception occurs, we should re-attempt to save the
                     # events one-by-one, because something in the list is
-                    # broken/stale (e.g., an IntegrityError on a specific event)
+                    # broken/stale
                     for e in events:
                         try:
-                            if (
-                                isinstance(exc, IntegrityError) and
-                                getattr(e, 'host_id', '')
-                            ):
-                                # this is one potential IntegrityError we can
-                                # work around - if the host disappears before
-                                # the event can be processed
-                                e.host_id = None
                             e.save()
                         except Exception:
                             logger.exception('Database Error Saving Job Event')

awx/main/models/events.py

@@ -5,6 +5,7 @@ import logging
 from collections import defaultdict
 
 from django.conf import settings
+from django.core.exceptions import ObjectDoesNotExist
 from django.db import models, DatabaseError, connection
 from django.utils.dateparse import parse_datetime
 from django.utils.text import Truncator
@@ -349,31 +350,36 @@ class BasePlaybookEvent(CreatedModifiedModel):
                 pass
 
             if isinstance(self, JobEvent):
-                hostnames = self._hostnames()
-                self._update_host_summary_from_stats(set(hostnames))
-                if self.job.inventory:
-                    try:
-                        self.job.inventory.update_computed_fields()
-                    except DatabaseError:
-                        logger.exception('Computed fields database error saving event {}'.format(self.pk))
+                try:
+                    job = self.job
+                except ObjectDoesNotExist:
+                    job = None
+                if job:
+                    hostnames = self._hostnames()
+                    self._update_host_summary_from_stats(set(hostnames))
+                    if job.inventory:
+                        try:
+                            job.inventory.update_computed_fields()
+                        except DatabaseError:
+                            logger.exception('Computed fields database error saving event {}'.format(self.pk))
 
-                # find parent links and progagate changed=T and failed=T
-                changed = self.job.job_events.filter(changed=True).exclude(parent_uuid=None).only('parent_uuid').values_list('parent_uuid', flat=True).distinct()  # noqa
-                failed = self.job.job_events.filter(failed=True).exclude(parent_uuid=None).only('parent_uuid').values_list('parent_uuid', flat=True).distinct()  # noqa
+                    # find parent links and progagate changed=T and failed=T
+                    changed = job.job_events.filter(changed=True).exclude(parent_uuid=None).only('parent_uuid').values_list('parent_uuid', flat=True).distinct()  # noqa
+                    failed = job.job_events.filter(failed=True).exclude(parent_uuid=None).only('parent_uuid').values_list('parent_uuid', flat=True).distinct()  # noqa
 
-                JobEvent.objects.filter(
-                    job_id=self.job_id, uuid__in=changed
-                ).update(changed=True)
-                JobEvent.objects.filter(
-                    job_id=self.job_id, uuid__in=failed
-                ).update(failed=True)
+                    JobEvent.objects.filter(
+                        job_id=self.job_id, uuid__in=changed
+                    ).update(changed=True)
+                    JobEvent.objects.filter(
+                        job_id=self.job_id, uuid__in=failed
+                    ).update(failed=True)
 
-                # send success/failure notifications when we've finished handling the playbook_on_stats event
-                from awx.main.tasks import handle_success_and_failure_notifications  # circular import
+                    # send success/failure notifications when we've finished handling the playbook_on_stats event
+                    from awx.main.tasks import handle_success_and_failure_notifications  # circular import
 
-                def _send_notifications():
-                    handle_success_and_failure_notifications.apply_async([self.job.id])
-                connection.on_commit(_send_notifications)
+                    def _send_notifications():
+                        handle_success_and_failure_notifications.apply_async([job.id])
+                    connection.on_commit(_send_notifications)
 
 
         for field in ('playbook', 'play', 'task', 'role'):
@@ -497,7 +503,11 @@ class JobEvent(BasePlaybookEvent):
 
     def _update_host_summary_from_stats(self, hostnames):
         with ignore_inventory_computed_fields():
-            if not self.job or not self.job.inventory:
+            try:
+                if not self.job or not self.job.inventory:
+                    logger.info('Event {} missing job or inventory, host summaries not updated'.format(self.pk))
+                    return
+            except ObjectDoesNotExist:
                 logger.info('Event {} missing job or inventory, host summaries not updated'.format(self.pk))
                 return
             job = self.job