Deserialize Optimizations #82
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Call Vec::with_capacity(...) when we know what the expected length will be.
When parsing FeatureCollection and Feature JSON objects, avoid a .clone() call.
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Thanks @jwass! |
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bors r+ |
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🔒 Permission denied Existing reviewers: click here to make KodrAus a reviewer |
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@frewsxcv looks like bors says no :( @jwass Thanks again for doing this! Historically we've had two serialisation frameworks to support, so optimisation for any particular one took a backseat. That's not the case anymore so we can freely make the |
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bors r+ |
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82: Deserialize Optimizations r=frewsxcv a=jwass Hello, this PR has a couple of parsing optimizations in two commits: - When creating `Vec`s for GeoJSON objects, initialize with `Vec::with_capacity(...)` since we know what size to expect. - Avoid a couple of critical `clone()` calls. Currently, when parsing from a string, the entire JSON value is cloned after it's parsed, then each Feature is cloned again when parsing a FeatureCollection. I believe this is due to serde_json's `as_array()` and `as_object()` functions returning borrowed references. I avoid those calls by doing the `match` directly (by adding the `_owned` macros), which allows moving those objects without cloning. I tested this on a release target on a ~330MB GeoJSON file (all Polygons), current master parses in about 18 seconds. After these changes, it takes under 10s. Parsing using just serde_json is about 8.2 s. I'm pretty new to Rust so feel free to let me know if these changes are a bad idea -- or any other suggestions.
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Hello, this PR has a couple of parsing optimizations in two commits:
Vecs for GeoJSON objects, initialize withVec::with_capacity(...)since we know what size to expect.clone()calls.Currently, when parsing from a string, the entire JSON value is cloned after it's parsed, then each Feature is cloned again when parsing a FeatureCollection. I believe this is due to serde_json's
as_array()andas_object()functions returning borrowed references. I avoid those calls by doing thematchdirectly (by adding the_ownedmacros), which allows moving those objects without cloning.I tested this on a release target on a ~330MB GeoJSON file (all Polygons), current master parses in about 18 seconds. After these changes, it takes under 10s. Parsing using just serde_json is about 8.2 s.
I'm pretty new to Rust so feel free to let me know if these changes are a bad idea -- or any other suggestions.