Add long_polling_jobs to API (#78)

src/api/api_server.py

@@ -55,15 +55,30 @@ def sorted_jobs(all_jobs, sort_by_date=True):
 @server.get('/api/jobs')
 def jobs_json():
     try:
-        hash_token = request.args.get('token', None)
         all_jobs = [x.json() for x in RenderQueue.all_jobs()]
         job_cache_int = int(json.dumps(all_jobs).__hash__())
         job_cache_token = num_to_alphanumeric(job_cache_int)
-        if hash_token and hash_token == job_cache_token:
-            return [], 204  # no need to update
         return {'jobs': all_jobs, 'token': job_cache_token}
     except Exception as e:
-        logger.exception(f"Exception fetching all_jobs_cached: {e}")
+        logger.exception(f"Exception fetching jobs_json: {e}")
+    return [], 500
+
+
+@server.get('/api/jobs_long_poll')
+def long_polling_jobs():
+    try:
+        hash_token = request.args.get('token', None)
+        start_time = time.time()
+        while True:
+            all_jobs = jobs_json()
+            if all_jobs['token'] != hash_token:
+                return all_jobs
+            # Break after 30 seconds to avoid gateway timeout
+            if time.time() - start_time > 30:
+                return [], 204
+            time.sleep(1)
+    except Exception as e:
+        logger.exception(f"Exception fetching long_polling_jobs: {e}")
     return [], 500