wallet: Cache the max_index for bip32 and bip86 address indices
What the developer wrote
Authored by Christian Decker
wallet: Cache the max_index for bip32 and bip86 address indices
We were looking up the index for the addresses to scan, twice, for
every single output, for every single TX for every block. No wonder
that was being slow.
Changelog-Fixed: wallet: Addressed a performance regression during blockchain scans
What changed, and why it matters
This commit is a straightforward performance optimization. It caches two address-index values in memory instead of reading them from the database twice for every transaction output in every scanned block. The change fixes a slowdown during blockchain scans and does not alter security behavior.
No security action required. Treat as a normal performance fix.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The patch adds bip32_max_index and bip86_max_index fields to the struct wallet and initializes them once from database intvars in wallet_new(). wallet_can_spend() now reads these cached values instead of calling db_get_intvar() twice per invocation, and updates both the in-memory cache and the persisted intvar when a larger address index is discovered. The logic and security checks remain identical; only redundant database lookups are removed.
Changed components
wallet/wallet.cwallet/wallet.hInspect captured patch +15 / −5
diff --git a/wallet/wallet.c b/wallet/wallet.c
index 91eb507..7c54ad1 100644
--- a/wallet/wallet.c
+++ b/wallet/wallet.c
@@ -231,6 +231,9 @@ struct wallet *wallet_new(struct lightningd *ld, struct timers *timers)
our_addresses_init(wallet);
trace_span_end(wallet);
+ wallet->bip32_max_index = db_get_intvar(wallet->db, "bip32_max_index", 0);
+ wallet->bip86_max_index = db_get_intvar(wallet->db, "bip86_max_index", 0);
+
db_commit_transaction(wallet->db);
return wallet;
}
@@ -1030,9 +1033,8 @@ bool wallet_can_spend(struct wallet *w, const u8 *script, size_t script_len,
const struct wallet_address *waddr;
struct script_with_len scriptwl = {script, script_len};
- /* Update hash table if we need to */
- bip32_max_index = db_get_intvar(w->db, "bip32_max_index", 0);
- bip86_max_index = db_get_intvar(w->db, "bip86_max_index", 0);
+ bip32_max_index = w->bip32_max_index;
+ bip86_max_index = w->bip86_max_index;
/* Scan both BIP32 and BIP86 addresses */
u64 max_index = (bip32_max_index > bip86_max_index) ? bip32_max_index : bip86_max_index;
@@ -1047,12 +1049,16 @@ bool wallet_can_spend(struct wallet *w, const u8 *script, size_t script_len,
* remember that. */
if (w->ld->bip86_base) {
/* BIP86-based wallet: all addresses use BIP86 derivation */
- if (waddr->index > bip86_max_index)
+ if (waddr->index > bip86_max_index) {
+ w->bip86_max_index = waddr->index;
db_set_intvar(w->db, "bip86_max_index", waddr->index);
+ }
} else {
/* Legacy wallet: all addresses use BIP32 derivation */
- if (waddr->index > bip32_max_index)
+ if (waddr->index > bip32_max_index) {
db_set_intvar(w->db, "bip32_max_index", waddr->index);
+ w->bip32_max_index = waddr->index;
+ }
}
*index = waddr->index;
diff --git a/wallet/wallet.h b/wallet/wallet.h
index 504e49a..c110b8b 100644
--- a/wallet/wallet.h
+++ b/wallet/wallet.h
@@ -56,6 +56,10 @@ struct wallet {
/* How many keys should we look ahead at most? */
u64 keyscan_gap;
+
+ /* Address lookahead max index. */
+ u64 bip32_max_index;
+ u64 bip86_max_index;
};
static inline enum output_status output_status_in_db(enum output_status s)
Why this scored 15/100
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