Add expiry date to cal solution hashes in Redis to save space.

Need to decide how to handle the zset index entries.

coordinator/telstate_interface.py

@@ -211,6 +211,8 @@ def format_cals(self, product_id, cal_K, cal_G, cal_B, cal_all, nants, ants, nch
                     "nants":nants, "antenna_list":str(ants), "nchan":nchans,
                     "refant":refant, "script_ts":timestamp, "retrieval_ts":r_t}
         self.red.hmset(hash_key, hash_dict)
+        # Expire after 30 days to save space
+        self.red.expire(hash_key, 2592000)
         # Save to index (zset)
         index_name = "{}:cal_solutions:index".format(product_id)
         log.info("Saving into Redis zset index: {}".format(index_name))