Use pubsub messages instead of a background thread to process changes (#92)

* Use pubsub messages instead of a background thread to process changes to the RenderQueue

* Misc logging improvements

src/engines/core/base_worker.py

@@ -103,7 +103,7 @@ class BaseRenderWorker(Base):
         self.watchdog_timeout = 120
 
     def __repr__(self):
-        return f"<{self.__class__.__name__}|{self.id}|{self.name}|{self.status}|{self.input_path}>"
+        return f"<Job id:{self.id} p{self.priority} {self.renderer}-{self.renderer_version} '{self.name}' status:{self.status.value}>"
 
     @property
     def total_frames(self):

src/render_queue.py

@@ -1,9 +1,8 @@
 import logging
 import os
-import threading
-import time
 from datetime import datetime
 
+from pubsub import pub
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 from sqlalchemy.orm.exc import DetachedInstanceError
@@ -39,21 +38,20 @@ class RenderQueue:
 
     @classmethod
     def start(cls):
+        logger.debug("Starting render queue updates")
         cls.is_running = True
-        cls.__eval_thread = threading.Thread(target=cls.__eval_loop, daemon=True)
+        cls.evaluate_queue()
-        cls.__eval_thread.start()
 
     @classmethod
-    def __eval_loop(cls):
+    def __local_job_status_changed(cls, job_id, old_status, new_status):
-        while cls.is_running:
+        render_job = RenderQueue.job_with_id(job_id, none_ok=True)
-            try:
+        if render_job and cls.is_running:  # ignore changes from render jobs not in the queue yet
+            logger.debug(f"RenderQueue detected job {job_id} has changed from {old_status} -> {new_status}")
             RenderQueue.evaluate_queue()
-            except Exception as e:
-                logger.exception(f"Uncaught error while evaluating queue: {e}")
-            time.sleep(cls.evaluation_inverval)
 
     @classmethod
     def stop(cls):
+        logger.debug("Stopping render queue updates")
         cls.is_running = False
 
     # --------------------------------------------
@@ -62,12 +60,14 @@ class RenderQueue:
 
     @classmethod
     def add_to_render_queue(cls, render_job, force_start=False):
-        logger.debug('Adding priority {} job to render queue: {}'.format(render_job.priority, render_job))
+        logger.info(f"Adding job to render queue: {render_job}")
         cls.job_queue.append(render_job)
-        if force_start and render_job.status in (RenderStatus.NOT_STARTED, RenderStatus.SCHEDULED):
+        if cls.is_running and force_start and render_job.status in (RenderStatus.NOT_STARTED, RenderStatus.SCHEDULED):
             cls.start_job(render_job)
         cls.session.add(render_job)
         cls.save_state()
+        if cls.is_running:
+            cls.evaluate_queue()
 
     @classmethod
     def all_jobs(cls):
@@ -113,6 +113,7 @@ class RenderQueue:
             cls.session = sessionmaker(bind=cls.engine)()
         from src.engines.core.base_worker import BaseRenderWorker
         cls.job_queue = cls.session.query(BaseRenderWorker).all()
+        pub.subscribe(cls.__local_job_status_changed, 'status_change')
 
     @classmethod
     def save_state(cls):
@@ -157,7 +158,7 @@ class RenderQueue:
 
     @classmethod
     def start_job(cls, job):
-        logger.info(f'Starting job: {job} - Priority {job.priority}')
+        logger.info(f'Starting job: {job}')
         job.start()
         cls.save_state()