AVreentrant

AVreentrant is a term that appears in the context of Apple's Core Audio framework, specifically related to audio processing units and their threading behavior. It indicates whether an audio processing unit can be reentered by the audio system while it is already executing. This concept is crucial for managing audio data flow and preventing audio glitches or crashes in real-time audio applications.

When an audio processing unit is marked as reentrant, it means that the audio system can safely call its processing function multiple times concurrently or in rapid succession without corrupting its internal state or causing unexpected behavior. This is typically achieved through careful design of the unit's internal data structures and algorithms, ensuring thread safety. Non-reentrant units, on the other hand, require exclusive access to their resources, and the audio system must ensure that their processing function is not called again until the previous call has fully completed.

The reentrancy property of an audio processing unit influences how the Core Audio framework schedules and executes audio processing tasks. For reentrant units, the system has more flexibility in dispatching tasks, potentially allowing for more efficient use of system resources. For non-reentrant units, the system must implement stricter synchronization mechanisms, which can introduce overhead. Developers working with Core Audio need to be aware of the reentrancy characteristics of the audio units they are using to ensure stable and high-performance audio playback and processing. This information is often provided in the documentation for specific audio unit types or when querying their properties.