lightningd: use a hash table for peer->dbid.

Otherwise, loading up when we have 100k peers is *painful*!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/lightningd.c

@@ -181,6 +181,9 @@ static struct lightningd *new_lightningd(const tal_t *ctx)
 	 *  linked-list as part of the 100k-peers project! */
 	ld->peers = tal(ld, struct peer_node_id_map);
 	peer_node_id_map_init(ld->peers);
+	/*~ And this was done at the same time, for db lookups at startup */
+	ld->peers_by_dbid = tal(ld, struct peer_dbid_map);
+	peer_dbid_map_init(ld->peers_by_dbid);
 
 	/*~ For multi-part payments, we need to keep some incoming payments
 	 * in limbo until we get all the parts, or we time them out. */

lightningd/lightningd.h

@@ -181,6 +181,8 @@ struct lightningd {
 
 	/* All peers we're tracking (by node_id) */
 	struct peer_node_id_map *peers;
+	/* And those in database by dbid */
+	struct peer_dbid_map *peers_by_dbid;
 
 	/* Outstanding connect commands. */
 	struct list_head connects;

lightningd/memdump.c

@@ -156,6 +156,7 @@ static void finish_report(const struct leak_detect *leaks)
 	memleak_scan_htable(memtable, &ld->htlcs_out->raw);
 	memleak_scan_htable(memtable, &ld->htlc_sets->raw);
 	memleak_scan_htable(memtable, &ld->peers->raw);
+	memleak_scan_htable(memtable, &ld->peers_by_dbid->raw);
 
 	/* Now delete ld and those which it has pointers to. */
 	memleak_scan_obj(memtable, ld);

lightningd/peer_control.c

@@ -72,6 +72,8 @@
 static void destroy_peer(struct peer *peer)
 {
 	peer_node_id_map_del(peer->ld->peers, peer);
+	if (peer->dbid)
+		peer_dbid_map_del(peer->ld->peers_by_dbid, peer);
 }
 
 static void peer_update_features(struct peer *peer,
@@ -81,6 +83,14 @@ static void peer_update_features(struct peer *peer,
 	peer->their_features = tal_dup_talarr(peer, u8, their_features);
 }
 
+void peer_set_dbid(struct peer *peer, u64 dbid)
+{
+	assert(!peer->dbid);
+	assert(dbid);
+	peer->dbid = dbid;
+	peer_dbid_map_add(peer->ld->peers_by_dbid, peer);
+}
+
 struct peer *new_peer(struct lightningd *ld, u64 dbid,
 		      const struct node_id *id,
 		      const struct wireaddr_internal *addr,
@@ -107,6 +117,8 @@ struct peer *new_peer(struct lightningd *ld, u64 dbid,
 #endif
 
 	peer_node_id_map_add(ld->peers, peer);
+	if (dbid)
+		peer_dbid_map_add(ld->peers_by_dbid, peer);
 	tal_add_destructor(peer, destroy_peer);
 	return peer;
 }
@@ -131,6 +143,7 @@ void maybe_delete_peer(struct peer *peer)
 		/* This isn't sufficient to keep it in db! */
 		if (peer->dbid != 0) {
 			wallet_peer_delete(peer->ld->wallet, peer->dbid);
+			peer_dbid_map_del(peer->ld->peers_by_dbid, peer);
 			peer->dbid = 0;
 		}
 		return;
@@ -177,17 +190,7 @@ static void peer_channels_cleanup(struct lightningd *ld,
 
 struct peer *find_peer_by_dbid(struct lightningd *ld, u64 dbid)
 {
-	struct peer *p;
-	struct peer_node_id_map_iter it;
-
-	/* FIXME: Support lookup by dbid directly! */
-	for (p = peer_node_id_map_first(ld->peers, &it);
-	     p;
-	     p = peer_node_id_map_next(ld->peers, &it)) {
-		if (p->dbid == dbid)
-			return p;
-	}
-	return NULL;
+	return peer_dbid_map_get(ld->peers_by_dbid, dbid);
 }
 
 struct peer *peer_by_id(struct lightningd *ld, const struct node_id *id)

lightningd/peer_control.h

@@ -102,6 +102,9 @@ u8 *p2wpkh_for_keyidx(const tal_t *ctx, struct lightningd *ld, u64 keyidx);
 /* We've loaded peers from database, set them going. */
 void setup_peers(struct lightningd *ld);
 
+/* When database first writes peer into db, it sets the dbid */
+void peer_set_dbid(struct peer *peer, u64 dbid);
+
 /* At startup, re-send any transactions we want bitcoind to have */
 void resend_closing_transactions(struct lightningd *ld);
 
@@ -156,4 +159,24 @@ HTABLE_DEFINE_TYPE(struct peer,
 		   peer_node_id, node_id_hash, peer_node_id_eq,
 		   peer_node_id_map);
 
+static inline size_t dbid_hash(u64 dbid)
+{
+	return siphash24(siphash_seed(), &dbid, sizeof(dbid));
+}
+
+static u64 peer_dbid(const struct peer *peer)
+{
+	assert(peer->dbid);
+	return peer->dbid;
+}
+
+static bool peer_dbid_eq(const struct peer *peer, u64 dbid)
+{
+	return peer->dbid == dbid;
+}
+/* Defines struct peer_dbid_map */
+HTABLE_DEFINE_TYPE(struct peer,
+		   peer_dbid, dbid_hash, peer_dbid_eq,
+		   peer_dbid_map);
+
 #endif /* LIGHTNING_LIGHTNINGD_PEER_CONTROL_H */

wallet/test/run-wallet.c

@@ -1934,6 +1934,8 @@ int main(int argc, const char *argv[])
 	/* Only elements in ld we should access */
 	ld->peers = tal(ld, struct peer_node_id_map);
 	peer_node_id_map_init(ld->peers);
+	ld->peers_by_dbid = tal(ld, struct peer_dbid_map);
+	peer_dbid_map_init(ld->peers_by_dbid);
 	ld->rr_counter = 0;
 	node_id_from_hexstr("02a1633cafcc01ebfb6d78e39f687a1f0995c62fc95f51ead10a02ee0be551b5dc", 66, &ld->id);
 	/* Accessed in peer destructor sanity check */

wallet/wallet.c

@@ -2155,7 +2155,7 @@ static void wallet_peer_save(struct wallet *w, struct peer *peer)
 
 	if (db_step(stmt)) {
 		/* So we already knew this peer, just return its dbid */
-		peer->dbid = db_col_u64(stmt, "id");
+		peer_set_dbid(peer, db_col_u64(stmt, "id"));
 		tal_free(stmt);
 
 		/* Since we're at it update the wireaddr */
@@ -2174,7 +2174,7 @@ static void wallet_peer_save(struct wallet *w, struct peer *peer)
 		db_bind_node_id(stmt, 0, &peer->id);
 		db_bind_text(stmt, 1,addr);
 		db_exec_prepared_v2(stmt);
-		peer->dbid = db_last_insert_id_v2(take(stmt));
+		peer_set_dbid(peer, db_last_insert_id_v2(take(stmt)));
 	}
 }