6706: Add comments about what is going on with EventClient.close()

[arvados.git] / sdk / python / arvados / events.py

diff --git a/sdk/python/arvados/events.py b/sdk/python/arvados/events.py
index b1872002ebe5cd4b6df40fc102d137a61acbb9d1..4581f05b8ad9dd9830051ff2490b25c053379c8f 100644 (file)
--- a/sdk/python/arvados/events.py
+++ b/sdk/python/arvados/events.py
@@ -28,6 +28,7 @@ class EventClient(WebSocketClient):
         super(EventClient, self).__init__(url, ssl_options=ssl_options)
         self.filters = filters
         self.on_event = on_event
+        self.stop = threading.Event()
         self.last_log_id = last_log_id
 
     def opened(self):
@@ -36,12 +37,22 @@ class EventClient(WebSocketClient):
     def received_message(self, m):
         self.on_event(json.loads(str(m)))
 
-    def close_connection(self):
-        try:
-            self.sock.shutdown(socket.SHUT_RDWR)
-            self.sock.close()
-        except:
-            pass
+    def closed(self, code, reason=None):
+        self.stop.set()
+
+    def close(self, code=1000, reason=''):
+        # parent close() method sends a asynchronous "closed" event to the server
+        super(EventClient, self).close(code, reason)
+
+        # if server doesn't respond by finishing the close handshake, we'll be
+        # stuck in limbo forever.  We don't need to wait for the server to
+        # respond to go ahead and actually close the socket.
+        self.close_connection()
+
+        # wait for websocket thread to finish up (closed() is called by
+        # websocket thread in as part of terminate())
+        while not self.stop.is_set():
+            self.stop.wait(1)
 
     def subscribe(self, filters, last_log_id=None):
         m = {"method": "subscribe", "filters": filters}
@@ -53,7 +64,7 @@ class EventClient(WebSocketClient):
         self.send(json.dumps({"method": "unsubscribe", "filters": filters}))
 
 class PollClient(threading.Thread):
-    def __init__(self, api, filters, on_event, poll_time):
+    def __init__(self, api, filters, on_event, poll_time, last_log_id):
         super(PollClient, self).__init__()
         self.api = api
         if filters:
@@ -64,14 +75,18 @@ class PollClient(threading.Thread):
         self.poll_time = poll_time
         self.daemon = True
         self.stop = threading.Event()
+        self.last_log_id = last_log_id
 
     def run(self):
         self.id = 0
-        for f in self.filters:
-            items = self.api.logs().list(limit=1, order="id desc", filters=f).execute()['items']
-            if items:
-                if items[0]['id'] > self.id:
-                    self.id = items[0]['id']
+        if self.last_log_id != None:
+            self.id = self.last_log_id
+        else:
+            for f in self.filters:
+                items = self.api.logs().list(limit=1, order="id desc", filters=f).execute()['items']
+                if items:
+                    if items[0]['id'] > self.id:
+                        self.id = items[0]['id']
 
         self.on_event({'status': 200})
 
@@ -147,6 +162,6 @@ def subscribe(api, filters, on_event, poll_fallback=15, last_log_id=None):
         return _subscribe_websocket(api, filters, on_event, last_log_id)
     except Exception as e:
         _logger.warn("Falling back to polling after websocket error: %s" % e)
-    p = PollClient(api, filters, on_event, poll_fallback)
+    p = PollClient(api, filters, on_event, poll_fallback, last_log_id)
     p.start()
     return p