Scheduled and Periodic Functions

Scheduled and Periodic Functions

GBBopen provides two forms of time-scheduled functions: scheduled functions and periodic functions, both built using Portable Threads. These time-scheduled-function entities are provided by the :portable-threads module.

Scheduled Functions

A scheduled function is an object that contains a function to be run at a specified time. When that specified time arrives, the function is invoked with a single argument: the scheduled function object. A repeat interval (in seconds) can also be specified for the scheduled function. This value is used whenever the scheduled function is invoked to schedule itself again at a new time relative to the current invocation. Scheduled functions can be scheduled to a resolution of one second.

Scheduled functions are scheduled and invoked by a separate "Scheduled-Function Scheduler" thread. Unless the run time of the invoked function is brief, the invoked function should spawn a new thread in which to perform its activities so as to avoid delaying the invocation of a subsequent scheduled function.

Periodic Functions

A periodic function is a function to be run repeatedly at a specified interval. Unlike scheduled functions, which can be scheduled only to a resolution of one second, a periodic function can be repeated at intervals as brief as is supported by the sleep function of the Common Lisp implementation. A periodic function is scheduled and executed in its own thread. As with scheduled functions, the invoked function should spawn a new thread in which to perform its activities, unless its run time is brief.

Entities

• *periodic-function-verbose*
• *schedule-function-verbose*
• all-scheduled-functions
• kill-periodic-function
• make-scheduled-function
• pause-scheduled-function-scheduler
• restart-scheduled-function-scheduler
• resume-scheduled-function-scheduler
• schedule-function
• schedule-function-relative
• scheduled-function-context
• scheduled-function-invocation-time
• scheduled-function-marker
• scheduled-function-marker-test
• scheduled-function-name
• scheduled-function-name-test
• scheduled-function-repeat-interval
• scheduled-function-scheduler-paused-p
• scheduled-function-scheduler-running-p
• spawn-periodic-function
• unschedule-function

Scheduled and Periodic Functions