Checking whether an array is a statically allocated

Question

Checking whether an array is a statically allocated

Shinmera opened this issue 7 years ago · comments

Is there a way to check whether an array is one that was allocated by static-vectors? I'd like to know this so that I can optimise functions to take a fast-path instead of having to conservatively copy the array to a foreign buffer first.

Stelian Ionescu · Answer 1 · Wed Jun 14 2017 19:50:54 GMT+0800 (China Standard Time)

Is there a way to check whether an array is one that was allocated by static-vectors so that one can know whether it's necessary to call free-static- vector on it?

Unfortunately not.

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-- Stelian Ionescu a.k.a. fe[nl]ix Quidquid latine dictum sit, altum videtur.

Yukari Hafner · Answer 2 · Wed Jun 14 2017 20:27:32 GMT+0800 (China Standard Time)

Alright, will have to hack a way around that, then.

Stelian Ionescu · Answer 3 · Wed Jun 14 2017 20:34:13 GMT+0800 (China Standard Time)

I can emulate the test using a key-weak hash table, but I'm unsure about the performance effects. I'll have to do some checks.

Yukari Hafner · Answer 4 · Wed Jun 14 2017 20:35:13 GMT+0800 (China Standard Time)

That's what I'm doing internally where I'm using static-vectors now, since performance on de/allocation is not that big of a deal to me. I'd be very happy to see the feature in the mainline library though.

Ryan Pavlik · Answer 5 · Wed Jun 14 2017 21:58:16 GMT+0800 (China Standard Time)

Is it safe to call static-vector-pointer on any vector (without using the result)? Performance might be better keeping an index of allocated pointers than weak refs.

Stelian Ionescu · Answer 6 · Wed Jun 14 2017 22:06:50 GMT+0800 (China Standard Time)

No, it's not safe.