P1478 Byte-wise atomic memcpy

[wg21bot]

P1478R0 Byte-wise atomic memcpy (Hans-J. Boehm)

SG1 in Kona

[wg21bot]

P1478R1 Byte-wise atomic memcpy (Hans-J. Boehm)

[ogiroux]

We want another name composed from some combination of {atomic, byte-wise,
race-free, read/write}_memcpy with a veto if it's bad.
-Unanimous consent.

[wg21bot]

P1478R2 Byte-wise atomic memcpy (Hans Boehm)

[ogiroux]

SG1 in Belfast.

With changes to the wording requested in the minutes,
we forward P1478R2 to LEWG for Concurrency TS 2:
SF F N A SA
3 10 0 0 0
Unanimous consent

[wg21bot]

P1478R3 Byte-wise atomic memcpy (Hans Boehm)

[brycelelbach]

P1478R3: Byte-wise atomic memcpy

2020-06-01 Library Evolution Telecon Minutes

Chair: Billy Baker

Champion: Hans Boehm

Minute Taker: Inbal Levi

Start: 2020-06-01 08:02

POLL: P1478 (Byte-wise atomic memcpy) should include a type-safe (std::copy analog) version

SF	F	N	A	SA
1	3	8	2	1

Attendance: 24

That has no consensus.

POLL: The design of P1478 (Byte-wise atomic memcpy) is acceptable for continued Library Evolution time.

SF	F	N	A	SA
5	11	0	0	0

Attendance: 24

We have unanimous consent for that.

End: 2020-06-01 09:03

SUMMARY: This paper proposes a byte-wise atomic memcpy interface. Library Evolution feels this is a useful feature worth pursuing. Much of our discussion centered around whether the interface should be std::memcpy-like (e.g. byte-centric) or std::copy like (which provides better type safety). There was a related discussion about possible C compatibility, which would need a std::memcpy-like interface. In the end, we did not have consensus for adding a std::copy-like interface to the proposal, because this is a lower-level feature. We need to see and review a version of the proposal with wording before this can proceed further.

OUTCOME: Bring a revision of P1478R3 (Byte-wise atomic memcpy), with the guidance below, to Library Evolution for further design review.

• Add wording including a synopsis.
• Clarify that this feature should live in <atomic>
• Clarify atomic_(load|store)_per_byte_memcpy should return void.
• Make the source parameters pointers-to-const.
• Explore C compatibility with the Standard C committee.