A method for imposing a hierarchical call structure in asynchronous real time applications often goods

摘要

A kernel for enforcing a hierarchical invocation structure prevents upcalls by executing kernel operations during each invocation of code unit of application by another code unit. Kernel operations determine the priority of the invoking unit of code based on the hierarchy of the invocation structure. Only invocations by either lower priority units, or the unit itself are allowed. Once invoked, the kernel operates to establish a priority for the invoked task. The kernel provides various event mechanisms to provide for priority based preemption concurrently with the enforced invocation structure, thus allowing the handling of asynchronous events in a multitasking environment. The event mechanisms allow a unit of code to signal the occurrence of a condition, which may be captured by other code units. The kernel determines the proper code unit for responding to the condition, and employs scope rules to further define the handling operation. Scheduling and tasking mechanisms schedule the handling of the condition and dispatch the handling of the event on a prioritized basis.