Книга: Real-Time Concepts for Embedded Systems

7.6.1 Creating and Deleting Message Queues

7.6.1 Creating and Deleting Message Queues

Message queues can be created and deleted by using two simple calls, as shown in Table 7.1.

Table 7.1: Message queue creation and deletion operations.

Operation Description
Create Creates a message queue
Delete Deletes a message queue

When created, message queues are treated as global objects and are not owned by any particular task. Typically, the queue to be used by each group of tasks or ISRs is assigned in the design.

When creating a message queue, a developer needs to make some initial decisions about the length of the message queue, the maximum size of the messages it can handle, and the waiting order for tasks when they block on a message queue.

Deleting a message queue automatically unblocks waiting tasks. The blocking call in each of these tasks returns with an error. Messages that were queued are lost when the queue is deleted.

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