This patch adds new callbacks in evhttp: connection start, connection end, request start, request end and error callback.
Patch for this issue
In the medium term, I'm hoping that Mark Ellzey's "libevhtp" will replace evhttp; it's faster, more maintainable, and better designed. Since it aims (eventually) for backward compatibility with evhttp, I'd like to make sure that any new features added to evhttp be compatible with the way that libevhtp does things. Can you check with Mark to see what he thinks of this interface?