minimal-copy deserialize for InternedString
#7310
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r? @ehuss (rust_highfive has picked a reviewer for you, use r? to override) |
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Seems reasonable, even if there isn't a big performance win. Looks like resolver-tests needs to be updated, though? |
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oops, taken care of! |
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CI failure is spurious and unrelated. |
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@bors: r+ 👍 |
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📌 Commit c14bb6e has been approved by |
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minimal-copy `deserialize` for `InternedString` I just learnt that `serde::Deserialize` for `Cow<'a, str>` allocates by default! Thus negating the intended benefit of ea957da, and this is in the hot loop for no-op builds #6908. The docs https://serde.rs/lifetimes.html#borrowing-data-in-a-derived-impl say you can fix this with a `#[serde(borrow)]`, but in practice this does not work on `Option<Cow<'a, str>>`. Some of these are just going to be turned into `InternedString`s, so we can tell serde to do that directly saving an allocation while we are at it! So is this faster, or just reducing the number of `InternedString` <-> `&str` conversions? I ran the benchmark script developed for #7168 (comment). Looks like no change for Cargo's lockfile and a ~7% improvement for the 2000 crate stress test.
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☀️ Test successful - checks-azure |
This was referenced Sep 3, 2019
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Update cargo, books ## cargo 8 commits in 22f7dd0495cd72ce2082d318d5a9b4dccb9c5b8c..fe0e5a48b75da2b405c8ce1ba2674e174ae11d5d 2019-08-27 16:10:51 +0000 to 2019-09-04 00:51:27 +0000 - Rename `--all` to `--workspace` (rust-lang/cargo#7241) - Basic standard library support. (rust-lang/cargo#7216) - Allow using 'config.toml' instead of just 'config' files. (rust-lang/cargo#7295) - Retry on SSL Connect Error. (rust-lang/cargo#7318) - minimal-copy `deserialize` for `InternedString` (rust-lang/cargo#7310) - Fix typo in cargo vendor examples (rust-lang/cargo#7320) - Fixes around multiple `[patch]` per crate (rust-lang/cargo#7303) - Improve error messages on mkdir failure (rust-lang/cargo#7306) ## reference 7 commits in d191a0c..090c015 2019-08-15 08:42:23 +0200 to 2019-09-03 13:59:28 -0700 - Fix rust-lang/reference#664: Review Oxford comma usage. (rust-lang/reference#668) - Fix some links. (rust-lang/reference#667) - Remove trait object warning. (rust-lang/reference#666) - Specify pattern types in `let` statements and `for` expressions (rust-lang/reference#663) - Fix loop expression link. (rust-lang/reference#662) - async-await initial reference material (rust-lang/reference#635) - Correct errors in the reference of extern functions definitions and declarations (rust-lang/reference#652) ## rust-by-example 1 commits in 580839d90aacd537f0293697096fa8355bc4e673..e76be6b2dc84c6a992e186157efe29d625e29b94 2019-08-17 23:17:50 -0300 to 2019-09-03 07:42:26 -0300 - Change link to russian translation repository (rust-lang/rust-by-example#1245) ## embedded-book 1 commits in 432ca26686c11d396eed6a59499f93ce1bf2433c..5ca585c4a7552efb546e7681c3de0712f4ae4fdc 2019-08-09 23:20:22 +0000 to 2019-08-27 13:39:14 +0000 - Fixup book CI (rust-embedded/book#205)
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I just learnt that
serde::DeserializeforCow<'a, str>allocates by default! Thus negating the intended benefit of ea957da, and this is in the hot loop for no-op builds #6908. The docs https://serde.rs/lifetimes.html#borrowing-data-in-a-derived-impl say you can fix this with a#[serde(borrow)], but in practice this does not work onOption<Cow<'a, str>>. Some of these are just going to be turned intoInternedStrings, so we can tell serde to do that directly saving an allocation while we are at it!So is this faster, or just reducing the number of
InternedString<->&strconversions?I ran the benchmark script developed for #7168 (comment). Looks like no change for Cargo's lockfile and a ~7% improvement for the 2000 crate stress test.