How to achieve execution agent local variable?

Sometimes we need some variables to be execution agent local. Taking a use-case of parallel random number generation. If I want random number generator to be non-blocking for multiple threads, then each thread should have a separate copy of random generator.

For example, in case of a thread pool scheduler a thread_local random generator can be used. But that's not a generic solution.

I don't know how to handle the same with P2300. Is there some way to handle this kind of use-case?

I feel the use-case can be solved if I have 2 queries:

• Maximum number of tasks that can be executed concurrently at any moment of time. (can be unbounded too)
• Let's say the above query returns n. Then a query like current_execution_id that returns [0, n) representing on which execution agent task is currently at.

Start by reviewing P2300's execution-agent model and how stdexec represents scheduler or execution context. Compare the proposed concurrency-count and current-execution-id queries with the per-thread random-generator use case. Done would require a maintainer decision or documented supported design; this remains an unanswered design question.