Reply To: Inter-process Communication

Yes, you can do a read-only persistent grant to data outside the frame, such as global or heap, when returning a large result. However, it will be difficult and complex to revert that grant at some future time; it’s not like returning an integer by copy. Having the caller transiently grant a return space to the callee removes this issue, but requires the caller to know how much space to grant.

Language runtime systems can use the underlying hardware to provide copy semantics, but they must be able to track ownership. A single-owner language such as Rust could do this by creating an Ownership Manager that is the actual grantee of a new creation and which handles change of access and ownership. The performance would be similar to using a shares arena, but would have less need of trust between caller and callee.