add static route expiry support

src/sonic-bgpcfgd/bgpcfgd/static_rt_timer.py

@@ -0,0 +1,57 @@
+from .log import log_err, log_info, log_debug
+from swsscommon import swsscommon
+import time
+
+class StaticRouteTimer(object):
+    """ This class checks the static routes and deletes those entries that have not been refreshed """
+    def __init__(self):
+        self.db = swsscommon.SonicV2Connector()
+        self.db.connect(self.db.APPL_DB)
+        self.timer = None
+        self.start = None
+
+    DEFAULT_TIMER = 180
+    DEFAULT_SLEEP = 60
+    MAX_TIMER     = 1800
+
+    def set_timer(self):
+        """ Check for custom route expiry time in STATIC_ROUTE:EXPIRY_TIME """
+        timer = self.db.get(self.db.APPL_DB, "STATIC_ROUTE_EXPIRY_TIME", "time")
+        if timer is not None:
+            timer = int(timer)     
+            if timer > 0 and timer <= self.MAX_TIMER:
+                self.timer = timer
+                return
+            log_err("Custom static route expiry time of {}s is invalid!".format(timer))
+        return
+
+    def alarm(self):
+        """ Clear unrefreshed static routes """
+        static_routes = self.db.keys(self.db.APPL_DB, "STATIC_ROUTE:*")
+        if static_routes is not None:
+            for sr in static_routes:
+                expiry = self.db.get(self.db.APPL_DB, sr, "expiry")
+                if expiry == "false":
+                    continue
+                refresh = self.db.get(self.db.APPL_DB, sr, "refresh")
+                if refresh == "true":
+                    self.db.set(self.db.APPL_DB, sr, "refresh", "false")
+                    log_debug("Refresh status of static route {} is set to false".format(sr))
+                else:
+                    self.db.delete(self.db.APPL_DB, sr)
+                    log_debug("Static route {} deleted".format(sr))
+        self.start = time.time()
+        return
+
+    def run(self):
+        self.start = time.time()
+        while True:
+            self.set_timer()
+            if self.timer:
+                log_info("Static route expiry set to {}s".format(self.timer))
+                time.sleep(self.timer)
+                self.alarm()
+            else:
+                time.sleep(self.DEFAULT_SLEEP)
+                if time.time() - self.start >= self.DEFAULT_TIMER:
+                    self.alarm()