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perf(db): cache db handles using OnceLock #6750

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merged 2 commits into from Feb 26, 2024
Merged

perf(db): cache db handles using OnceLock #6750

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653348e
perf(db): cache db handles using OnceLock
DaniPopes Feb 23, 2024
f769c53
chore: clippy
DaniPopes Feb 23, 2024
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35 changes: 25 additions & 10 deletions crates/storage/db/src/implementation/mdbx/tx.rs
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Expand Up @@ -8,7 +8,6 @@ use crate::{
transaction::{DbTx, DbTxMut},
DatabaseError,
};
use parking_lot::Mutex;
use reth_interfaces::db::{DatabaseWriteError, DatabaseWriteOperation};
use reth_libmdbx::{ffi::DBI, CommitLatency, Transaction, TransactionKind, WriteFlags, RW};
use reth_tracing::tracing::{debug, trace, warn};
Expand All @@ -17,7 +16,7 @@ use std::{
marker::PhantomData,
sync::{
atomic::{AtomicBool, Ordering},
Arc,
Arc, OnceLock,
},
time::{Duration, Instant},
};
Expand All @@ -38,7 +37,7 @@ pub struct Tx<K: TransactionKind> {
metrics_handler: Option<MetricsHandler<K>>,

/// Database table handle cache.
db_handles: Mutex<[Option<DBI>; Tables::COUNT]>,
db_handles: [OnceLock<DBI>; Tables::COUNT],
}

impl<K: TransactionKind> Tx<K> {
Expand Down Expand Up @@ -66,7 +65,14 @@ impl<K: TransactionKind> Tx<K> {

#[inline]
fn new_inner(inner: Transaction<K>, metrics_handler: Option<MetricsHandler<K>>) -> Self {
Self { inner, db_handles: Mutex::new([None; Tables::COUNT]), metrics_handler }
// NOTE: These constants are needed to initialize `OnceLock` at compile-time, as array
// initialization is not allowed with non-Copy types, and `const { }` blocks are not stable
// yet.
#[allow(clippy::declare_interior_mutable_const)]
const ONCELOCK_DBI_NEW: OnceLock<DBI> = OnceLock::new();
#[allow(clippy::declare_interior_mutable_const)]
const DB_HANDLES: [OnceLock<DBI>; Tables::COUNT] = [ONCELOCK_DBI_NEW; Tables::COUNT];
Self { inner, db_handles: DB_HANDLES, metrics_handler }
}

/// Gets this transaction ID.
Expand All @@ -76,13 +82,22 @@ impl<K: TransactionKind> Tx<K> {

/// Gets a table database handle if it exists, otherwise creates it.
pub fn get_dbi<T: Table>(&self) -> Result<DBI, DatabaseError> {
match self.db_handles.lock()[T::TABLE as usize] {
Some(handle) => Ok(handle),
ref mut handle @ None => {
let db =
self.inner.open_db(Some(T::NAME)).map_err(|e| DatabaseError::Open(e.into()))?;
Ok(*handle.insert(db.dbi()))
// TODO: Use `OnceLock::get_or_try_init` once it's stable.
let slot = &self.db_handles[T::TABLE as usize];
match slot.get() {
Some(handle) => Ok(*handle),
None => self.open_and_store_db::<T>(slot),
}
}

#[cold]
fn open_and_store_db<T: Table>(&self, slot: &OnceLock<DBI>) -> Result<DBI, DatabaseError> {
match self.inner.open_db(Some(T::NAME)) {
Ok(db) => {
slot.set(db.dbi()).unwrap();
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can we map_err

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@DaniPopes DaniPopes Feb 26, 2024 •
edited

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Already tried, this ends up as map(|db| db.dbi()).map_err(|| ..).inspect(|| slot.set().unwrap()), it's not any better

Ok(db.dbi())
}
Err(e) => Err(DatabaseError::Open(e.into())),
}
}

Expand Down