From 03c57bf67d0ddd02570b122f471a7d133c3b08a0 Mon Sep 17 00:00:00 2001
From: blakeblackshear <blakeb@blakeshome.com>
Date: Sun, 17 Feb 2019 13:12:27 -0600
Subject: [PATCH] use a condition to signal to the mqtt publisher that objects
 were parsed

---
 detect_objects.py | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/detect_objects.py b/detect_objects.py
index 097068f40..d69ff4c9e 100644
--- a/detect_objects.py
+++ b/detect_objects.py
@@ -93,9 +93,10 @@ def detect_objects(cropped_frame, sess, detection_graph, region_size, region_x_o
     return objects
 
 class ObjectParser(threading.Thread):
-    def __init__(self, objects_changed, object_arrays):
+    def __init__(self, objects_changed, objects_parsed, object_arrays):
         threading.Thread.__init__(self)
         self._objects_changed = objects_changed
+        self._objects_parsed = objects_parsed
         self._object_arrays = object_arrays
 
     def run(self):
@@ -103,6 +104,7 @@ class ObjectParser(threading.Thread):
         while True:
             detected_objects = []
             # wait until object detection has run
+            # TODO: what if something else changed while I was processing???
             with self._objects_changed:
                 self._objects_changed.wait()
 
@@ -120,6 +122,9 @@ class ObjectParser(threading.Thread):
                     })
                     object_index += 6
             DETECTED_OBJECTS = detected_objects
+            # notify that objects were parsed
+            with self._objects_parsed:
+                self._objects_parsed.notify_all()
 
 class MqttMotionPublisher(threading.Thread):
     def __init__(self, client, topic_prefix, motion_changed, motion_flags):
@@ -139,16 +144,17 @@ class MqttMotionPublisher(threading.Thread):
             motion_status = 'OFF'
             if any(obj.is_set() for obj in self.motion_flags):
                 motion_status = 'ON'
-                
+
             if last_sent_motion != motion_status:
                 last_sent_motion = motion_status
                 self.client.publish(self.topic_prefix+'/motion', motion_status, retain=False)
 
-class MqttPublisher(threading.Thread):
-    def __init__(self, client, topic_prefix, object_classes):
+class MqttObjectPublisher(threading.Thread):
+    def __init__(self, client, topic_prefix, objects_parsed, object_classes):
         threading.Thread.__init__(self)
         self.client = client
         self.topic_prefix = topic_prefix
+        self.objects_parsed = objects_parsed
         self.object_classes = object_classes
 
     def run(self):
@@ -156,10 +162,16 @@ class MqttPublisher(threading.Thread):
 
         last_sent_payload = ""
         while True:
+
             # initialize the payload
             payload = {}
             for obj in self.object_classes:
                 payload[obj] = []
+
+            # wait until objects have been parsed
+            with self.objects_parsed:
+                self.objects_parsed.wait()
+
             # loop over detected objects and populate
             # the payload
             detected_objects = DETECTED_OBJECTS.copy()
@@ -167,14 +179,12 @@ class MqttPublisher(threading.Thread):
                 if obj['name'] in self.object_classes:
                     payload[obj['name']].append(obj)
             
-            # send message for objects
+            # send message for objects if different
             new_payload = json.dumps(payload, sort_keys=True)
             if new_payload != last_sent_payload:
                 last_sent_payload = new_payload
                 self.client.publish(self.topic_prefix+'/objects', new_payload, retain=False)
 
-            time.sleep(0.1)
-
 def main():
     # Parse selected regions
     regions = []
@@ -218,6 +228,8 @@ def main():
     motion_changed = mp.Condition()
     # Condition for notifying that object detection ran
     objects_changed = mp.Condition()
+    # Condition for notifying that objects were parsed
+    objects_parsed = mp.Condition()
     # shape current frame so it can be treated as an image
     frame_arr = tonumpyarray(shared_arr).reshape(frame_shape)
 
@@ -251,7 +263,7 @@ def main():
         motion_process.daemon = True
         motion_processes.append(motion_process)
 
-    object_parser = ObjectParser(objects_changed, [region['output_array'] for region in regions])
+    object_parser = ObjectParser(objects_changed, objects_parsed, [region['output_array'] for region in regions])
     object_parser.start()
 
     client = mqtt.Client()
@@ -260,7 +272,7 @@ def main():
     client.loop_start()
     client.publish(MQTT_TOPIC_PREFIX+'/available', 'online', retain=True)
 
-    mqtt_publisher = MqttPublisher(client, MQTT_TOPIC_PREFIX, 
+    mqtt_publisher = MqttObjectPublisher(client, MQTT_TOPIC_PREFIX, objects_parsed,
         MQTT_OBJECT_CLASSES.split(','))
     mqtt_publisher.start()