Process.read_timer

You're seeing just the function read_timer, go back to Process module for more information.

Specs

read_timer(reference()) :: non_neg_integer() | false

Reads a timer created by send_after/3.

When the result is an integer, it represents the time in milliseconds left until the timer will expire.

When the result is false, a timer corresponding to timer_ref could not be found. This can be either because the timer expired, because it has already been canceled, or because timer_ref never corresponded to a timer.

Even if the timer had expired and the message was sent, this function does not tell you if the timeout message has arrived at its destination yet.

Inlined by the compiler.