Joseph Ferano
0837959140
The refusals: the arities, a pool of an owning element, ordering handles, free of a handle, and clone of a pool. Each names what it would cost — a cloned pool duplicates the generation counters with the slots, so one handle would resolve in both copies and name two different things. pool-stale-region.flan is the other failure, and the point of it is that it is not the first. A stale handle is an answer and resolve says None; a pool whose region was released has no slot array left to ask, so it traps. Same rule that keeps a Vec's generation word and its epoch word apart.
26 lines
1.1 KiB
Plaintext
26 lines
1.1 KiB
Plaintext
;;;; The epoch trap on the pool's side. spec-memory.md, "Dev builds detect a
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;;;; released region".
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;;;;
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;;;; This is deliberately the *other* failure from a stale handle, and the two
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;;;; must not be conflated — the same rule that keeps a Vec's generation word
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;;;; and its epoch word apart. A stale handle is an answer: the entity died,
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;;;; resolve says None, the program carries on. A released region is not an
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;;;; answer at all: the storage the pool sits in is gone, the slot array with
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;;;; it, and there is nothing left to ask. So one returns None and the other
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;;;; traps naming the site.
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(defn main [] i32
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(let [a (arena-new 4096)]
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(let [p (pool-new i32 a)]
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(let [h (insert p 7)]
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(match (resolve p h)
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(Some x) (println (deref x))
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None (println -1))
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;; The region goes. p is still in scope, still looks fine, and h is
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;; still a perfectly well-formed handle — which is exactly the case a
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;; static rule cannot see.
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(free-all a)
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(match (resolve p h)
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(Some x) (println (deref x))
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None (println -1)))))
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0)
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