Performance improvement with string matcher#2
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This PR introduces a performance enhancement for matching user agents to crawler patterns. In the current version all matching is performed using regex Pattern.matcher. Since there are currently over 1,400 patterns this creates over 1,400 Matcher objects per crawler check. On a busy website, this generates a lot of pressure on the GC.
In this PR, crawler patterns are analyzed to detect if they can be matched using simple string operations (equals, contains, starts with and ends with) otherwise regex matching is used. This approach generates fewer Matcher objects and improves execution speed since string matching is faster than regex matching. Matching is done in new Matcher class which has corresponding new JUnit test.
All existing tests pass with this approach.