Implemented database LISTEN via db_wait_notification()

This introduces async waiting for report parsing. Commit
2584a3c36c97c757dc80108b898eede52b91dc44 introduced sending
a NOTIFY whenever an INSERT is done into the submissionqueue table.
With the db_wait_notification() the process_submission_queue() function
will sleep until a a notification is received.

The LISTEN, UNLISTEN and NOTIFY SQL commands are PostgreSQL dependent.
Other database implementations may use what that database supports, or
just simply do a sleep() to change the behaviour to a polling model.

0 files changed, 0 insertions, 0 deletions