SNIP_CLASSIC_PWM_SECTION_2_2_6_Concurrency_safe_implementation_of_modules

2.2.6 Concurrency safe implementation of modules Concurrency safety of BSW modules respectively the functions implemented by these modules may be achieved by different mechanisms. Generally, the following levels of reentrancy can be distinguished according to [TPS_ BSWMDT_04103]. The concrete level of a BswModuleEntity is defined in the optional attribute "reentrancyLevel". • Multi-core reentrant: Unlimited concurrent execution of an interface is possible, including preemption and parallel execution on multi-core systems. This level can be either achieved by mutual exclusion when entering critical regions, or by the absence of such regions, for example if there are no shared resources (including hardware and memory). • Single-core reentrant: Pseudo-concurrent execution (i.e. preemption) of an interface is possible on single core systems. This is the highest level of reentrancy defined by AUTOSAR 4.0.3. Because it does not explicitly cover multi-core systems, "concurrency safe" has been introduced additionally. This level can generally be ensured by the same mechanisms as "concurrency safe", but they must be ensured to work across core boundaries. • Non-reentrant: Concurrent execution of this interface is not possible. If a module that is not concurrency safe is invoked in different partitions, there is no warranty that the module will uphold its desired behavior. In this case, correct behavior shall be ensured by the usage of the module, for example if the caller(s) prevent parallel execution by using exclusive areas.