Reuse phf hash and remove phf::OrderedSet indirection #103
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This allows us to bypass the indirection of `phf::OrderedSet`: we don’t care about the order, only about getting numeric indices. This will also allow us to re-use the phf hash for the dynamic table, to avoid hashing strings twice.
SimonSapin
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In https://github.com/servo/string-cache, we currently use a `phf::OrderedSet` with its `get_index` method to get an identified stored in an `Atom`, and `index` to get a string back from that identifier. However, the extra inderection of `OrderedSet` of `Set` is not necessary. We don’t care about the order, only about getting numeric identifiers. Additionally, when `get_index` returns `None`, we hash the input string again to find it in table of dynamic atoms. With this chang, we can reuse the phf hash instead: servo/string-cache#103 At first I tried adding hash and index access to `phf::Map`, but the API got messy quickly.
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@pcwalton, would this help servo/servo#6906 ? |
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I suspect it will, yes. |
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r? @glennw |
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@bors-servo r+ |
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📌 Commit 573161f has been approved by |
bors-servo
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Sep 1, 2015
Reuse phf hash and remove phf::OrderedSet indirection <s>Do not merge yet.</s> This depends on rust-phf/rust-phf#62 Use the `phf_shared` and `phf_generator` crates directly instead of `phf`. This allows us to re-use the phf hash in the dynamic table and avoid hashing the same string again. Also remove the indirection of `phf::OrderedSet` compared to `phf::Set`: we don’t care about the order, only about getting numeric indices. (The optimization mentioned in a comment of using a bit map of the first 64 atoms in the html5ever tree builder was never implemented. If we want it, the indirection and order preservation can be added back while preserving the hash reuse.) Fixes #38. <!-- Reviewable:start --> [<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/string-cache/103) <!-- Reviewable:end -->
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☀️ Test successful - travis |
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Do not merge yet.This depends on rust-phf/rust-phf#62Use the
phf_sharedandphf_generatorcrates directly instead ofphf. This allows us to re-use the phf hash in the dynamic table and avoid hashing the same string again.Also remove the indirection of
phf::OrderedSetcompared tophf::Set: we don’t care about the order, only about getting numeric indices. (The optimization mentioned in a comment of using a bit map of the first 64 atoms in the html5ever tree builder was never implemented. If we want it, the indirection and order preservation can be added back while preserving the hash reuse.)Fixes #38.