This consists of a single method that is used to update the expiration time of a given key. It is passed two arguments, a key and an expiration time. If the expiration time is greater than zero, the key receives the new expiration time.
The expiration time can be expressed as either an offset in
seconds or a Unix time stamp. If the value of the expiration
time is smaller than
60*60*24*30 (that is,
one month in seconds) it is considered to be an offset in
seconds. Larger values are considered to be Unix time stamps.
If the expiration time is zero, then any existing expiration time is cleared and the value remains stored indefinitely unless explicitly deleted or updated with expiration at a later time.
This is a lightweight means by which to ensure entities "stay alive" without the overhead of having to reset their value or fetch them.
Updates the given key with the specified