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Merged
bjmeetsfo merged 1 commit into from
Sep 6, 2026
Merged

Avoid key clones in storage batch reads #73

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47 changes: 24 additions & 23 deletions src/runtime/storage_engines.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -545,31 +545,31 @@ pub struct CacheBuffer {

const STORAGE_BATCH_LINEAR_SCAN_MAX_KEYS: usize = 64;

fn coalesce_storage_batch_keys(keys: &[String]) -> (Vec<String>, Vec<usize>) {
fn coalesce_storage_batch_key_refs<'a>(keys: &[&'a str]) -> (Vec<&'a str>, Vec<usize>) {
if keys.len() <= STORAGE_BATCH_LINEAR_SCAN_MAX_KEYS {
let mut unique_keys = Vec::<String>::with_capacity(keys.len());
let mut unique_keys = Vec::<&'a str>::with_capacity(keys.len());
let mut output_positions = Vec::with_capacity(keys.len());
for key in keys {
if let Some(position) = unique_keys.iter().position(|existing| existing == key) {
output_positions.push(position);
} else {
output_positions.push(unique_keys.len());
unique_keys.push(key.clone());
unique_keys.push(*key);
}
}
return (unique_keys, output_positions);
}

let mut unique_keys = Vec::<String>::with_capacity(keys.len());
let mut unique_positions = HashMap::<String, usize>::with_capacity(keys.len());
let mut unique_keys = Vec::<&'a str>::with_capacity(keys.len());
let mut unique_positions = HashMap::<&'a str, usize>::with_capacity(keys.len());
let mut output_positions = Vec::with_capacity(keys.len());
for key in keys {
let position = if let Some(position) = unique_positions.get(key).copied() {
position
} else {
let position = unique_keys.len();
unique_positions.insert(key.clone(), position);
unique_keys.push(key.clone());
unique_positions.insert(*key, position);
unique_keys.push(*key);
position
};
output_positions.push(position);
Expand Down Expand Up @@ -2401,13 +2401,18 @@ impl StorageEngineRocksDb {
Ok(view)
}
pub fn get_batch(&self, keys: &[String]) -> Result<Vec<Option<Vec<u8>>>, CacheError> {
let key_refs = keys.iter().map(String::as_str).collect::<Vec<_>>();
self.get_batch_refs(&key_refs)
}

fn get_batch_refs(&self, keys: &[&str]) -> Result<Vec<Option<Vec<u8>>>, CacheError> {
if !self.initialized {
return Err(CacheError::Stopped);
}
if keys.is_empty() {
return Ok(Vec::new());
}
let (unique_keys, output_positions) = coalesce_storage_batch_keys(keys);
let (unique_keys, output_positions) = coalesce_storage_batch_key_refs(keys);
#[cfg(feature = "rocksdb-ssd")]
let unique_values = {
self.rocksdb()?
Expand All @@ -2417,12 +2422,10 @@ impl StorageEngineRocksDb {
.collect::<Result<Vec<_>, _>>()?
};
#[cfg(not(feature = "rocksdb-ssd"))]
let unique_values = {
unique_keys
.iter()
.map(|key| self.records.get(key).cloned())
.collect::<Vec<_>>()
};
let unique_values = unique_keys
.iter()
.map(|key| self.records.get(*key).cloned())
.collect::<Vec<_>>();
Ok(output_positions
.into_iter()
.map(|position| unique_values[position].clone())
Expand Down Expand Up @@ -3041,24 +3044,22 @@ impl StorageEngineMultiSsd {
return Ok(Vec::new());
}

let (unique_keys, output_positions) = coalesce_storage_batch_keys(keys);
let key_refs = keys.iter().map(String::as_str).collect::<Vec<_>>();
let (unique_keys, output_positions) = coalesce_storage_batch_key_refs(&key_refs);

let mut routed = vec![Vec::<(usize, String)>::new(); self.storages.len()];
let mut routed = vec![Vec::<(usize, &str)>::new(); self.storages.len()];
for (unique_index, key) in unique_keys.iter().enumerate() {
let storage_index = Self::hash(&key) as usize % self.storages.len();
routed[storage_index].push((unique_index, key.clone()));
let storage_index = Self::hash(key) as usize % self.storages.len();
routed[storage_index].push((unique_index, *key));
}

let mut unique_values = vec![None; unique_keys.len()];
for (storage_index, entries) in routed.into_iter().enumerate() {
if entries.is_empty() {
continue;
}
let storage_keys = entries
.iter()
.map(|(_, key)| key.clone())
.collect::<Vec<_>>();
let storage_values = self.storages[storage_index].get_batch(&storage_keys)?;
let storage_keys = entries.iter().map(|(_, key)| *key).collect::<Vec<_>>();
let storage_values = self.storages[storage_index].get_batch_refs(&storage_keys)?;
for ((unique_index, _), value) in entries.into_iter().zip(storage_values) {
unique_values[unique_index] = value;
}
Expand Down
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