Revision 920686

cpp: Prevent TFileTransport from throwing uncaught exceptions

FilleTransport::writerThread throws exceptions. This function is run
inside the writer thread, so these exceptions are not caught. When these
exceptions happen, the system aborts.

The fix is to first eliminate all the throw commands inside this function. In
addition, add some error recovery logic into the code: whenever an IO error
happens, we enter into an error recovery mode. Go to sleep for a few seconds
then try to reopen the file.

Note: Currently, when errors happen, we drop events.