job server planning

photoapp/jobs.py

@@ -100,6 +100,33 @@ class JobServer(BaseJobServer):
         self.engine = dbengine
         self.session = create_db_sessionmaker(self.engine)
 
+    def handle_notify(self, c, job_uuid):
+        """
+        notify the jobserver that a job needs to be processed. The job may be in any state, including locked. The job
+        should be processed as follows:
+        JobStatus.paused: do nothing
+        JobStatus.done: do nothing
+        JobStatus.error: do nothing
+        JobStatus.ready: change to running state and begin processing
+        JobStatus.running: begin processing.
+
+        processing:
+        - the job is added to a list of "watched" jobs
+        - we issue a query looking for work
+            - if no work is found, the job status is changed to Done (or error if any done work has error status?)
+        """
+        raise NotImplementedError()
+
+
+class ThreadedJobServer(JobServer):
+    def __init__(self, dbengine):
+        """
+        a version of the jobserver that runs as a thread
+        """
+        super().__init__(dbengine)
+        self.notifyq = queue.Queue()
+        self.work_notifyq = queue.Queue()
+
     @cursorwrap
     def handle_notify(self, c, job_uuid):
         # query the db for the target job, and lock it
@@ -133,26 +160,7 @@ class JobServer(BaseJobServer):
             for photo_id in photo_ids:
                 c.add(JobTargetStatus(target_id=target.id, job_id=job.id, photo_id=photo_id))
 
-            c.commit()  # if this fails, somebody else is handling the job
-
-        # query for Photos targeted by the task and allow the job to filter them
-        # query...
-        # for each target
-        # get photo, but also the associated set (and maybe tag)
-        # filter
-        # add a JobTargetStatus if the filter allows it
-
-        # end our transaction, thus unlocking the job
-
-
-class ThreadedJobServer(JobServer):
-    def __init__(self, dbengine):
-        """
-        a version of the jobserver that runs as a thread
-        """
-        super().__init__(dbengine)
-        self.notifyq = queue.Queue()
-        self.work_notifyq = queue.Queue()
+            c.commit()  # if this fails, somebody else is handling job
 
     def queue_notify(self, job_uuid):
         self.notifyq.put(job_uuid)