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⚡ Optimize DeflateEncoder flush buffer allocation #373

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Merged
404Setup merged 1 commit into from
Feb 24, 2026
Merged

⚡ Optimize DeflateEncoder flush buffer allocation #373

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18 changes: 15 additions & 3 deletions src/stream.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -67,7 +67,11 @@ impl<W: Write + Send> DeflateEncoder<W> {
output
.try_reserve(bound - output.len())
.map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
output.resize(bound, 0);
// SAFETY: We just reserved sufficient capacity. The compressor writes to
// the buffer using `MaybeUninit` pointers, so uninitialized memory is fine.
unsafe {
output.set_len(bound);
}
}

let mode = if final_block {
Expand Down Expand Up @@ -101,7 +105,11 @@ impl<W: Write + Send> DeflateEncoder<W> {
output
.try_reserve(bound - output.len())
.map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
output.resize(bound, 0);
// SAFETY: We just reserved sufficient capacity. The compressor writes to
// the buffer using `MaybeUninit` pointers, so uninitialized memory is fine.
unsafe {
output.set_len(bound);
}
}

let mode = if final_block && i == num_chunks - 1 {
Expand Down Expand Up @@ -146,7 +154,11 @@ impl<W: Write + Send> DeflateEncoder<W> {
output
.try_reserve(bound - output.len())
.map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
output.resize(bound, 0);
// SAFETY: We just reserved sufficient capacity. The compressor writes to
// the buffer using `MaybeUninit` pointers, so uninitialized memory is fine.
unsafe {
output.set_len(bound);
}
}

let mode = if final_block {
Expand Down