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avoid some allocs

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This commit is contained in:
John Spray
2024-07-20 20:21:31 +01:00
parent 081161060e
commit 6a267cf9e3
2 changed files with 16 additions and 20 deletions
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10
pageserver/src/tenant/storage_layer/inmemory_layer.rs
View File

@@ -523,18 +523,16 @@ impl InMemoryLayer {
pub(crate) async fn put_values(
&self,
values: Vec<(Lsn, Key, smallvec::SmallVec<[u8; 256]>)>,
mut values: Vec<(Lsn, Key, smallvec::SmallVec<[u8; 256]>, u64)>,
ctx: &RequestContext,
) -> Result<()> {
let mut inner = self.inner.write().await;
self.assert_writable();
let mut index_updates = Vec::with_capacity(values.len());
for (lsn, key, buf) in values {
let off = self.put_value_locked2(&mut inner, &buf, ctx).await?;
index_updates.push((lsn, key, off));
for (_lsn, _key, buf, off) in &mut values {
*off = self.put_value_locked2(&mut inner, &buf, ctx).await?;
}
for (lsn, key, off) in index_updates {
for (lsn, key, _buf, off) in values.into_iter() {
let vec_map = inner.index.entry(key).or_default();
let old = vec_map.append_or_update_last(lsn, off).unwrap().0;
debug_assert!(old.is_none());

26
pageserver/src/tenant/timeline.rs
View File

@@ -5998,20 +5998,18 @@ impl<'a> TimelineWriter<'a> {
let last_lsn = batch.as_slice().last().unwrap().0;
let mut total_serialized_size = 0;
let serialized = batch
.into_iter()
.map(|(l, (k, v))| {
// Avoid doing allocations for "small" values.
// In the regression test suite, the limit of 256 avoided allocations in 95% of cases:
// https://github.com/neondatabase/neon/pull/5056#discussion_r1301975061
let mut buf = smallvec::SmallVec::<[u8; 256]>::new();
v.ser_into(&mut buf)
.expect("Serialization of Value is infallible");
let buf_size: u64 = buf.len().try_into().expect("oversized value buf");
total_serialized_size += buf_size;
(l, k, buf)
})
.collect::<Vec<_>>();
let mut serialized = Vec::with_capacity(batch.len());
for (l, (k, v)) in batch.into_iter() {
// Avoid doing allocations for "small" values.
// In the regression test suite, the limit of 256 avoided allocations in 95% of cases:
// https://github.com/neondatabase/neon/pull/5056#discussion_r1301975061
let mut buf = smallvec::SmallVec::<[u8; 256]>::new();
v.ser_into(&mut buf)
.expect("Serialization of Value is infallible");
let buf_size: u64 = buf.len().try_into().expect("oversized value buf");
total_serialized_size += buf_size;
serialized.push((l, k, buf, 0));
}
let action = self.get_open_layer_action(first_lsn, total_serialized_size);
let layer = self