make I/O non-blocking and handle dropped connections

server.py

@@ -1,3 +1,4 @@
+from datetime import datetime
 from typing import Dict
 
 import cv2
@@ -12,37 +13,64 @@ UDP_PORT = 5005
 
 sock = socket.socket(socket.AF_INET, # Internet
                      socket.SOCK_DGRAM) # UDP
+sock.setblocking(False)
 sock.bind((UDP_IP, UDP_PORT))
 
 HEIGHT = 480
 WIDTH = 640
 
-frames: Dict[str, np.ndarray] = {}
+class Client:
+    def __init__(self):
+        self.last_updated = datetime.now()
+        self.frame = np.ndarray((HEIGHT, WIDTH, 3), dtype=np.uint8)
+
+    def update(self, pkt: InterlacedPacket):
+        if pkt.even:
+            self.frame[y + 1:y + 32:2, x:x + 16] = arr
+        else:
+            self.frame[y:y + 32:2, x:x + 16] = arr
+        self.last_updated = datetime.now()
+
+    def latency(self) -> float:
+        return (datetime.now() - self.last_updated).total_seconds()
+
+    def read(self) -> np.ndarray:
+        return self.frame
+
+
+frames: Dict[str, Client] = {}
 
 while True:
     # break the array down into 16-bit chunks, then transmit them as UDP packets
-    for i in range(0, HEIGHT, 16):
-        for j in range(0, WIDTH, 16):
+    for repeats in range(10000):
+        try:
             data, addr = sock.recvfrom(InterlacedPacket.size)  # buffer size is 768 bytes
             # print("received packet from", addr)
-            pkt = from_bytes_int(data)
+            if data:
+                pkt = from_bytes_int(data)
 
-            uuid = str(pkt.uuid)
-            x = pkt.x
-            y = pkt.y
-            arr = pkt.array
+                uuid = str(pkt.uuid)
+                x = pkt.x
+                y = pkt.y
+                arr = pkt.array
 
-            if uuid not in frames.keys():
-                frames[uuid] = frame = np.ndarray((HEIGHT, WIDTH, 3), dtype=np.uint8)
+                if uuid not in frames.keys():
+                    print("New client acquired, naming %s", uuid)
+                    frames[uuid] = Client()
 
-            if pkt.even:
-                frames[uuid][y+1:y+32:2, x:x+16] = arr
-            else:
-                frames[uuid][y:y + 32:2, x:x + 16] = arr
+                frames[uuid].update(pkt)
+
+        except BlockingIOError:
+            pass
 
     # Display the resulting frame
-    for id in frames.keys():
-        cv2.imshow(id, frames[id])
+    for id in list(frames.keys()):
+        if frames[id].latency() >= 5:
+            print("Client likely lost connection, dropping %s", id)
+            cv2.destroyWindow(id)
+            frames.pop(id)
+        else:
+            cv2.imshow(id, frames[id].read())
 
     # Break the loop if 'q' key is pressed
     if cv2.waitKey(1) == ord('q'):