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Every asynchronous agent has an associated allocator. An agent's allocator is an interface used by the agent's asynchronous operations to obtain per-operation stable memory resources (POSMs). This name reflects the fact that the memory is per-operation because the memory is only retained for the lifetime of that operation, and stable, because the memory is guaranteed to be available at that location throughout the operation.

Asynchronous operations may utilise POSMs in a number of different ways:

Associated allocators allow users to treat POSM optimisation as a cross-cutting concern to the composition of asynchronous operations. Furthermore, using allocators as the interface to obtain POSMs grant substantial flexibility to both the implementers and users of asynchronous operations:

As noted previously, all resources must be released prior to calling the completion handler. This enables memory to be recycled for subsequent asynchronous operations within an agent. This allows applications with long-lived asynchronous agents to have no hot-path memory allocations, even though the user code is unaware of associated allocators.

See Also

Custom Memory Allocation.