This module provides protection against a user calling a runmode too
frequently. A typical use-case might be a contact form that sends email.
You'd like to allow your users to send you messages, but thousands of
messages from a single user would be a problem.

This module works by maintaining a database of hits to protected runmodes.
It then checks this database to determine if a new hit should be allowed
based on past activity by the user. The user's identity is, by default,
tied to login (via REMOTE_USER) or IP address (via REMOTE_IP) if login info
is not available. You may provide your own identity function via the
identity_callback() method.

To use this module you must create a table in your database with the
following schema (using MySQL-syntax, although other DBs may work as well
with minor alterations):