Add Locking

compLib/IPService.py

@@ -5,6 +5,7 @@ import threading
 import time
 
 import systemd.daemon
+from compLib.Lock import Lock
 
 try:
     from compLib.LogstashLogging import Logging
@@ -29,6 +30,7 @@ RUN_IP_CHECK = False
 try:
     from compLib.Display import Display
     from compLib.Spi import Spi
+    from compLib import __version__
     RUN_IP_CHECK = True
 except Exception as e:
     print(f"Could not import display or spi for ip output {str(e)}")
@@ -58,13 +60,16 @@ def get_ip():
 def write_ip_to_screen():
     while os.getenv("IP_OUTPUT", "true") == "true":
         try:
-            ip = str(get_ip())
-            print(f"writing {ip} to display")
-            Display.write(2, f"FW. V{Spi.get_version()}")
-            Display.write(3, "IP:")
-            Display.write(4, ip)
-            Display.write(1, datetime.datetime.now().strftime("%b %d %H:%M:%S"))
-            time.sleep(5)
+            if not Lock.is_locked():
+                Lock.lock()
+                ip = str(get_ip())
+                print(f"writing {ip} to display")
+                Display.write(2, f"LIB: V{__version__}")
+                Display.write(3, f"FW: V{Spi.get_version()}")
+                Display.write(4, f"IP: {ip}")
+                Display.write(1, datetime.datetime.now().strftime("%b %d %H:%M:%S"))
+                Lock.unlock()
+                time.sleep(10)
         except Exception as e:
             print(f"Exception in write ip thread: {e}")
             time.sleep(5)
@@ -82,6 +87,7 @@ if __name__ == '__main__':
     if RUN_IP_CHECK and IP_OUTPUT:
         print("starting ip output")
         Logging.get_logger().info("starting ip output")
+        Lock.unlock()
         try:
             Spi.disable_health_check()
             ip_output = threading.Thread(target=write_ip_to_screen)

compLib/Lock.py

@@ -0,0 +1,25 @@
+from filelock import FileLock, Timeout
+import atexit
+
+FILELOCK_PATH = "/root/complib.lock"
+
+global_lock = FileLock(FILELOCK_PATH,  timeout=1)
+class Lock(object):
+    @staticmethod
+    def lock():
+        global_lock.acquire()
+
+    @staticmethod
+    def unlock():
+        global_lock.release()
+
+    @staticmethod
+    def is_locked():
+        try:
+            global_lock.acquire()
+            global_lock.release()
+            return False
+        except Timeout:
+            return True
+
+atexit.register(Lock.unlock)

compLib/__init__.py

@@ -1,9 +1,10 @@
 __version__ = "0.3.9-0"
 
+import sys
 import importlib
 import compLib.LogstashLogging
 import compLib.MetricsLogging
-
+from compLib.Lock import Lock
 
 apt_found = importlib.util.find_spec("apt") is not None
 spi_found = importlib.util.find_spec("spidev") is not None
@@ -25,6 +26,12 @@ if apt_found:
 else:
     print("apt is not installed! This is for local development only!")
     
+if Lock.is_locked():
+    print("Another program using compLib is still running! Delete /root/complib.lock if this is an error. Exiting...")
+    sys.exit()
+else:
+    Lock.lock()
+
 if spi_found:
     from compLib.Spi import Spi
     from compLib.Reset import Reset

complib.service

@@ -1,7 +1,7 @@
 [Unit]
 Description=Monitoring service
 [Service]
-ExecStart=/usr/bin/python3 /usr/local/lib/python3.7/dist-packages/compLib/VisionDaemon.py
+ExecStart=/usr/bin/python3 /usr/local/lib/python3.7/dist-packages/compLib/IPService.py
 Environment="debug=False"
 Restart=always
 RestartSec=5

postinstall.sh

@@ -23,7 +23,7 @@ install_package() {
 #install_package "spidev"
 #install_package "influxdb_client"
 
-pip3 install smbus requests flask python-logstash-async RPi.GPIO spidev influxdb_client
+pip3 install smbus requests flask python-logstash-async RPi.GPIO spidev influxdb_client filelock
 
 echo "Setting up opencv4"
 pkg-config --modversion opencv4