base job executor framing

photoapp/jobs.py

@@ -1,3 +1,4 @@
+import queue
 import cherrypy
 from photoapp.dbutils import create_db_sessionmaker, cursorwrap
 from photoapp.types import Job, JobTargetType, JobTarget
@@ -58,3 +59,72 @@ class JobsClient(object):
         """
         self.notifier(uuid)
 
+
+class PhotoappTask(object):
+    def get_targets(self):
+        raise NotImplementedError()
+
+    def run_targets(self):
+        raise NotImplementedError()
+
+
+class LolTask(PhotoappTask):
+    pass
+
+
+"""
+this is the list of job actions the system supports. The dict's keys match with the database Job objs' `job_name` column
+"""
+task_definitions = {
+    "loljob": LolTask
+}
+
+
+class JobServer(object):
+    """
+    job executor service. This object orchestrates job running by doing:
+        - in any case, locking the job rows via sql
+        - listening to notifications about new jobs
+            - populate JobTargetStatus
+        - looking for JobTargetStatus that can be claimed and worked on
+            - executing the work
+    """
+    def __init__(self, dbengine):
+        self.engine = dbengine
+        self.session = create_db_sessionmaker(self.engine)
+
+    @cursorwrap
+    def handle_notify(self, db, job_uuid):
+        # query the db for the target job, and lock it
+
+        # get the task we're running
+        task = task_definitions[xxx]()
+
+        # 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 ThreadJobServer(JobServer):
+    def __init__(self, dbengine):
+        """
+        a version of the jobserver that runs as a thread
+        """
+        super().__init__(dbengine)
+        self.notifyq = queue.Queue()
+
+    def queue_notify(self, job_uuid):
+        self.notifyq.put(job_uuid)
+
+    def run(self):
+        while True:
+            try:
+                job_uuid = self.notifyq.get(timeout=5.0)
+                self.handle_notify(job_uuid)
+            except queue.Empty:
+                pass