83fa93ccaf
The replace_headers method had to be moved since the async_impl module is not compiled while compiling to wasm. This caused the replace_headers method to be unavailable. fast_random had to be excluded from the wasm build to prevent dead code warnings in the wasm target.
66 lines
1.8 KiB
Rust
66 lines
1.8 KiB
Rust
use crate::header::HeaderMap;
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// xor-shift
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#[cfg(not(target_arch = "wasm32"))]
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pub(crate) fn fast_random() -> u64 {
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use std::cell::Cell;
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use std::collections::hash_map::RandomState;
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use std::hash::{BuildHasher, Hasher};
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use std::num::Wrapping;
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thread_local! {
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static RNG: Cell<Wrapping<u64>> = Cell::new(Wrapping(seed()));
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}
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fn seed() -> u64 {
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let seed = RandomState::new();
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let mut out = 0;
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let mut cnt = 0;
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while out == 0 {
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cnt += 1;
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let mut hasher = seed.build_hasher();
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hasher.write_usize(cnt);
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out = hasher.finish();
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}
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out
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}
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RNG.with(|rng| {
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let mut n = rng.get();
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debug_assert_ne!(n.0, 0);
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n ^= n >> 12;
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n ^= n << 25;
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n ^= n >> 27;
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rng.set(n);
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n.0.wrapping_mul(0x2545_f491_4f6c_dd1d)
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})
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}
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pub(crate) fn replace_headers(dst: &mut HeaderMap, src: HeaderMap) {
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// IntoIter of HeaderMap yields (Option<HeaderName>, HeaderValue).
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// The first time a name is yielded, it will be Some(name), and if
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// there are more values with the same name, the next yield will be
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// None.
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//
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// TODO: a complex exercise would be to optimize this to only
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// require 1 hash/lookup of the key, but doing something fancy
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// with header::Entry...
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let mut prev_name = None;
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for (key, value) in src {
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match key {
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Some(key) => {
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dst.insert(key.clone(), value);
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prev_name = Some(key);
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}
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None => match prev_name {
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Some(ref key) => {
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dst.append(key.clone(), value);
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}
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None => unreachable!("HeaderMap::into_iter yielded None first"),
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},
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}
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}
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}
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