Memory Leak and Niagara

We used Valgrind to check the original code. One memory leak is found so far. We have fixed it. We will keep checking other possible problems.

As to Niagara, we run the original code without multi-threading and the rulecahce update time of one trace file is cut to half. It looks Niagara already did some optimization. We will try other trace files. The results from multi-threaded code is not very good. We will keep looking for fixes and other potential optimizations.