transmission.py: Don't request session id in subsequent requests.

If session id from previous request to Transmission is present, try using it and
retry the request with new session id only if the first try fails with status
code 409. This will decrease number of required requests by half.

headphones/transmission.py

@@ -25,9 +25,9 @@ import headphones
 # This is just a simple script to send torrents to transmission. The
 # intention is to turn this into a class where we can check the state
 # of the download, set the download dir, etc.
-# TODO: Store the session id so we don't need to make 2 calls
-#       Store torrent id so we can check up on it
+# TODO: Store torrent id so we can check up on it
 
+_session_id = None
 
 def addTorrent(link, data=None):
     method = 'torrent-add'
@@ -127,6 +127,7 @@ def removeTorrent(torrentid, remove_data=False):
 
 
 def torrentAction(method, arguments):
+    global _session_id
     host = headphones.CONFIG.TRANSMISSION_HOST
     username = headphones.CONFIG.TRANSMISSION_USERNAME
     password = headphones.CONFIG.TRANSMISSION_PASSWORD
@@ -148,43 +149,34 @@ def torrentAction(method, arguments):
         parts[2] += "/transmission/rpc"
 
     host = urlparse.urlunparse(parts)
-
-    # Retrieve session id
-    auth = (username, password) if username and password else None
-    response = request.request_response(host, auth=auth,
-                                        whitelist_status_code=[401, 409])
-
-    if response is None:
-        logger.error("Error gettings Transmission session ID")
-        return
-
-    # Parse response
-    if response.status_code == 401:
-        if auth:
-            logger.error("Username and/or password not accepted by " \
-                         "Transmission")
-        else:
-            logger.error("Transmission authorization required")
-
-        return
-    elif response.status_code == 409:
-        session_id = response.headers['x-transmission-session-id']
-
-        if not session_id:
-            logger.error("Expected a Session ID from Transmission")
-            return
-
-    # Prepare next request
-    headers = {'x-transmission-session-id': session_id}
     data = {'method': method, 'arguments': arguments}
+    data_json = json.dumps(data)
+    auth = (username, password) if username and password else None
+    for retry in range(2):
+        if _session_id is not None:
+            headers = {'x-transmission-session-id': _session_id}
+            response = request.request_response(host, method="POST",
+                data=data_json, headers=headers, auth=auth,
+                whitelist_status_code=[200, 401, 409])
+        else:
+            response = request.request_response(host, auth=auth,
+                                            whitelist_status_code=[401, 409])
+        if response.status_code == 401:
+            if auth:
+                logger.error("Username and/or password not accepted by " \
+                            "Transmission")
+            else:
+                logger.error("Transmission authorization required")
+            return
+        elif response.status_code == 409:
+            _session_id = response.headers['x-transmission-session-id']
+            if _session_id is None:
+                logger.error("Expected a Session ID from Transmission, got None")
+                return
+            # retry request with new session id
+            logger.debug("Retrying Transmission request with new session id")
+            continue
 
-    response = request.request_json(host, method="POST", data=json.dumps(data),
-                                    headers=headers, auth=auth)
-
-    print response
-
-    if not response:
-        logger.error("Error sending torrent to Transmission")
-        return
-
-    return response
+        resp_json = response.json()
+        print resp_json
+        return resp_json