feat(cold): increase LRU cache from 128 to 2048 entries (#55)

* feat(cold): increase LRU cache from 128 to 2048 entries per map

128 entries is too small for RPC workloads where the same recent
blocks, transactions, and receipts are queried repeatedly by
different concurrent callers, causing unnecessary cold storage
round-trips.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: revert added comment, bump version to 0.7.2

Removes the explanatory comment on DEFAULT_CACHE_CAPACITY per review
feedback. Bumps workspace version from 0.7.1 to 0.7.2.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: rswanson

Cargo.toml

@@ -3,7 +3,7 @@ members = ["crates/*"]
 resolver = "2"
 
 [workspace.package]
-version = "0.7.1"
+version = "0.7.2"
 edition = "2024"
 rust-version = "1.92"
 authors = ["init4"]
@@ -35,13 +35,13 @@ incremental = false
 
 [workspace.dependencies]
 # internal
-signet-hot = { version = "0.7.1", path = "./crates/hot" }
-signet-hot-mdbx = { version = "0.7.1", path = "./crates/hot-mdbx" }
-signet-cold = { version = "0.7.1", path = "./crates/cold" }
-signet-cold-mdbx = { version = "0.7.1", path = "./crates/cold-mdbx" }
-signet-cold-sql = { version = "0.7.1", path = "./crates/cold-sql" }
-signet-storage = { version = "0.7.1", path = "./crates/storage" }
-signet-storage-types = { version = "0.7.1", path = "./crates/types" }
+signet-hot = { version = "0.7.2", path = "./crates/hot" }
+signet-hot-mdbx = { version = "0.7.2", path = "./crates/hot-mdbx" }
+signet-cold = { version = "0.7.2", path = "./crates/cold" }
+signet-cold-mdbx = { version = "0.7.2", path = "./crates/cold-mdbx" }
+signet-cold-sql = { version = "0.7.2", path = "./crates/cold-sql" }
+signet-storage = { version = "0.7.2", path = "./crates/storage" }
+signet-storage-types = { version = "0.7.2", path = "./crates/types" }
 
 # External, in-house
 signet-libmdbx = { version = "0.8.0" }

crates/cold/src/task/cache.rs

@@ -10,7 +10,7 @@ use signet_storage_types::{RecoveredTx, SealedHeader};
 use std::num::NonZeroUsize;
 
 /// Default capacity for each LRU cache map.
-const DEFAULT_CACHE_CAPACITY: usize = 128;
+const DEFAULT_CACHE_CAPACITY: usize = 2048;
 
 /// Evict all entries from an LRU cache whose keys satisfy the predicate.
 fn evict_where<K: Copy + Eq + std::hash::Hash, V>(
@@ -34,7 +34,7 @@ pub(crate) struct ColdCache {
 }
 
 impl ColdCache {
-    /// Create a new cache with the default capacity (128 per map).
+    /// Create a new cache with the default capacity (2048 per map).
     pub(crate) fn new() -> Self {
         Self::new_with_cap(DEFAULT_CACHE_CAPACITY)
     }