Add resubscribe mechanism.

Author: dariusstefan

docs/event.md

@@ -48,7 +48,7 @@ If `callback` function is called with `None` as a parameter, it means that there
 
 ## Subscribing
 
-By default, the subscription will be permanent. If you want to set a timeout, you can use the `expires` parameter. The value should be an integer representing the number of seconds the subscription will be active.
+By default, the subscription will be permanent with a resubscribing interval of 1 hour. If you want to set a timeout, you can use the `expires` parameter. The value should be an integer representing the number of seconds the subscription will be active.
 
 ## How it works
 

opensips/event/event.py

@@ -23,6 +23,7 @@
 from threading import Thread, Event
 from ..mi import OpenSIPSMIException
 from .json_helper import extract_json
+import time
 
 class OpenSIPSEventException(Exception):
     """ Exceptions generated by OpenSIPS Events """
@@ -41,10 +42,17 @@ def __init__(self, handler, name: str, callback, expire=None):
         self.buf = b""
         self.json_queue = []
         self.retries = 0
+        if expire is not None:
+            self.expire = expire
+            self.reregister = False
+        else:
+            self.expire = 3600
+            self.reregister = True
 
         try:
             self.socket = self._handler.__new_socket__()
-            self._handler.__mi_subscribe__(self.name, self.socket.create(), expire)
+            self._handler.__mi_subscribe__(self.name, self.socket.create(), self.expire)
+            self.last_subscription = time.time()
             self._handler.events[self.name] = self
             self.thread = Thread(target=self.handle, args=(callback,))
             self.thread.start()
@@ -58,6 +66,16 @@ def __init__(self, handler, name: str, callback, expire=None):
     def handle(self, callback):
         """ Handles the event callbacks """
         while not self.thread_stop.is_set():
+            if self.reregister and time.time() - self.last_subscription > self.expire - 60:
+                try:
+                    self.resubscribe()
+                except Exception as e:
+                    callback(None)
+                    break
+            elif not self.reregister and time.time() - self.last_subscription > self.expire:
+                callback(None)
+                break
+
             data = self.socket.read()
             if not data:
                 continue
@@ -77,6 +95,16 @@ def handle(self, callback):
                 json_obj = self.json_queue.pop(0)
                 callback(json_obj)
 
+    def resubscribe(self):
+        """ Resubscribes for the event """
+        try:
+            self._handler.__mi_subscribe__(self.name, self.socket.sock_name, self.expire)
+            self.last_subscription = time.time()
+        except OpenSIPSEventException as e:
+            raise e
+        except OpenSIPSMIException as e:
+            raise e
+
     def unsubscribe(self):
         """ Unsubscribes the event """
         try:

opensips/event/handler.py

@@ -54,12 +54,9 @@ def subscribe(self, event_name: str, callback, expire=None):
     def unsubscribe(self, event_name: str):
         self.events[event_name].unsubscribe()
 
-    def __mi_subscribe__(self, event_name: str, sock_name: str, expire=None):
+    def __mi_subscribe__(self, event_name: str, sock_name: str, expire):
         try:
-            if expire is None:
-                ret_val = self.mi.execute("event_subscribe", [event_name, sock_name])
-            else:
-                ret_val = self.mi.execute("event_subscribe", [event_name, sock_name, expire])
+            ret_val = self.mi.execute("event_subscribe", [event_name, sock_name, expire])
 
             if ret_val != "OK":
                 raise OpenSIPSEventException("Failed to subscribe to event")