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31 lines
1.3 KiB
Rust
31 lines
1.3 KiB
Rust
// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
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use std::collections::HashMap;
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// KeyCache stores a pool struct keys mapped to v8,
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// to minimize allocs and speed up decoding/encoding `v8::Object`s
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// TODO: experiment with in from_v8/to_v8
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pub struct KeyCache(HashMap<&'static str, v8::Global<v8::String>>);
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// creates an optimized v8::String for a struct field
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// TODO: experiment with external strings
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// TODO: evaluate if own KeyCache is better than v8's dedupe
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pub fn v8_struct_key<'s>(
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scope: &mut v8::HandleScope<'s>,
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field: &'static str,
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) -> v8::Local<'s, v8::String> {
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// Internalized v8 strings are significantly faster than "normal" v8 strings
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// since v8 deduplicates re-used strings minimizing new allocations
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// see: https://github.com/v8/v8/blob/14ac92e02cc3db38131a57e75e2392529f405f2f/include/v8.h#L3165-L3171
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v8::String::new_from_utf8(
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scope,
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field.as_ref(),
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v8::NewStringType::Internalized,
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)
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.unwrap()
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// TODO: consider external strings later
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// right now non-deduped external strings (without KeyCache)
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// are slower than the deduped internalized strings by ~2.5x
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// since they're a new string in v8's eyes and needs to be hashed, etc...
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// v8::String::new_external_onebyte_static(scope, field).unwrap()
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}
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