MQX Lite manages the way tasks share the processor runtime (context switching) by using the Scheduler. Only one task is active (owns the processor) at any given time. The only scheduling policy that MQX Lite offers is FIFO, which is the priority based pre-emptive scheduler. The active task is the highest-priority task that is in "ready state". The active task runs until any of the following occurs:
- The active task voluntarily relinquishes the processor because it calls a blocking MQX Lite function.
- An interrupt occurs that has higher priority than the active task.
- A task that has priority higher than the active task becomes ready.
Scheduling is controlled by the task state and the position of the task in the ready queue. Each task is in one of the following logical states:
- Blocked - task is not ready to become active because it is waiting for a condition to occur; when the condition occurs, the task becomes ready.
- Ready - task is ready to become active, but it is not active because it is of the same priority as, or lower priority than, the active task.
- Active - task is running.
- Terminated - task has been destroyed/aborted.
Each task priority level has a ready queue. The active task is the first in the highest-priority ready queue. Tasks in each ready queue are in the FIFO order.
The list of MQX Lite Scheduler component API functions (_sched_ prefix) is provided together with detailed description of each function in the MQX Lite Reference Manual ( MQXLITERM).
