gossipd: use iterator helpers for iterating node channels.

Makes the next step easier.

MCP results from 5 runs, min-max(mean +/- stddev):
	store_load_msec:45791-46917(46330.4+/-3.6e+02)
	vsz_kb:2641316
	store_rewrite_sec:47.040000-48.720000(47.684+/-0.57)
	listnodes_sec:1.140000-1.340000(1.2+/-0.072)
	listchannels_sec:50.970000-54.250000(52.698+/-1.3)
	routing_sec:29.950000-31.010000(30.332+/-0.37)
	peer_write_all_sec:51.570000-52.970000(52.1+/-0.54)

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

gossipd/gossip_store.c

@@ -163,9 +163,7 @@ static bool add_local_unnannounced(int fd,
 	struct chan_map_iter i;
 	struct chan *c;
 
-	for (c = chan_map_first(&self->chans, &i);
+	for (c = first_chan(self, &i); c; c = next_chan(self, &i)) {
-	     c;
-	     c = chan_map_next(&self->chans, &i)) {
 		struct node *peer = other_node(self, c);
 		const u8 *msg;
 

gossipd/gossipd.c

@@ -178,9 +178,7 @@ static void peer_disable_channels(struct daemon *daemon, struct node *node)
 	struct chan_map_iter i;
 	struct chan *c;
 
-	for (c = chan_map_first(&node->chans, &i);
+	for (c = first_chan(node, &i); c; c = next_chan(node, &i)) {
-	     c;
-	     c = chan_map_next(&node->chans, &i)) {
 		if (pubkey_eq(&other_node(node, c)->id, &daemon->id))
 			c->local_disabled = true;
 	}
@@ -1805,9 +1803,7 @@ static void gossip_refresh_network(struct daemon *daemon)
 		struct chan_map_iter i;
 		struct chan *c;
 
-		for (c = chan_map_first(&n->chans, &i);
+		for (c = first_chan(n, &i); c; c = next_chan(n, &i)) {
-		     c;
-		     c = chan_map_next(&n->chans, &i)) {
 			struct half_chan *hc = half_chan_from(n, c);
 
 			if (!is_halfchan_defined(hc)) {
@@ -1847,9 +1843,7 @@ static void gossip_disable_local_channels(struct daemon *daemon)
 	if (!local_node)
 		return;
 
-	for (c = chan_map_first(&local_node->chans, &i);
+	for (c = first_chan(local_node, &i); c; c = next_chan(local_node, &i))
-	     c;
-	     c = chan_map_next(&local_node->chans, &i))
 		c->local_disabled = true;
 }
 
@@ -2035,9 +2029,7 @@ static struct io_plan *getchannels_req(struct io_conn *conn,
 			struct chan_map_iter i;
 			struct chan *c;
 
-			for (c = chan_map_first(&s->chans, &i);
+			for (c = first_chan(s, &i); c; c = next_chan(s, &i)) {
-			     c;
-			     c = chan_map_next(&s->chans, &i)) {
 				append_half_channel(&entries,
 						    c,
 						    !half_chan_to(s, c));
@@ -2179,9 +2171,7 @@ static bool node_has_public_channels(const struct node *peer,
 	struct chan_map_iter i;
 	struct chan *c;
 
-	for (c = chan_map_first(&peer->chans, &i);
+	for (c = first_chan(peer, &i); c; c = next_chan(peer, &i)) {
-	     c;
-	     c = chan_map_next(&peer->chans, &i)) {
 		if (c == exclude)
 			continue;
 		if (is_chan_public(c))
@@ -2232,9 +2222,7 @@ static struct io_plan *get_incoming_channels(struct io_conn *conn,
 		struct chan_map_iter i;
 		struct chan *c;
 
-		for (c = chan_map_first(&node->chans, &i);
+		for (c = first_chan(node, &i); c; c = next_chan(node, &i)) {
-		     c;
-		     c = chan_map_next(&node->chans, &i)) {
 			const struct half_chan *hc;
 			struct route_info ri;
 

gossipd/routing.c

@@ -79,6 +79,16 @@ static struct node_map *empty_node_map(const tal_t *ctx)
 	return map;
 }
 
+struct chan *first_chan(const struct node *node, struct chan_map_iter *i)
+{
+	return chan_map_first(&node->chans, i);
+}
+
+struct chan *next_chan(const struct node *node, struct chan_map_iter *i)
+{
+	return chan_map_next(&node->chans, i);
+}
+
 struct routing_state *new_routing_state(const tal_t *ctx,
 					const struct chainparams *chainparams,
 					const struct pubkey *local_id,
@@ -137,7 +147,7 @@ static void destroy_node(struct node *node, struct routing_state *rstate)
 	node_map_del(rstate->nodes, node);
 
 	/* These remove themselves from the map. */
-	while ((c = chan_map_first(&node->chans, &i)) != NULL)
+	while ((c = first_chan(node, &i)) != NULL)
 		tal_free(c);
 	chan_map_clear(&node->chans);
 }
@@ -174,9 +184,7 @@ static bool node_has_public_channels(struct node *node)
 	struct chan_map_iter i;
 	struct chan *c;
 
-	for (c = chan_map_first(&node->chans, &i);
+	for (c = first_chan(node, &i); c; c = next_chan(node, &i)) {
-	     c;
-	     c = chan_map_next(&node->chans, &i)) {
 		if (is_chan_public(c))
 			return true;
 	}
@@ -190,9 +198,7 @@ static bool node_has_broadcastable_channels(struct node *node)
 	struct chan_map_iter i;
 	struct chan *c;
 
-	for (c = chan_map_first(&node->chans, &i);
+	for (c = first_chan(node, &i); c; c = next_chan(node, &i)) {
-	     c;
-	     c = chan_map_next(&node->chans, &i)) {
 		if (!is_chan_public(c))
 			continue;
 		if (is_halfchan_defined(&c->half[0])
@@ -207,9 +213,7 @@ static bool node_announce_predates_channels(const struct node *node)
 	struct chan_map_iter i;
 	struct chan *c;
 
-	for (c = chan_map_first(&node->chans, &i);
+	for (c = first_chan(node, &i); c; c = next_chan(node, &i)) {
-	     c;
-	     c = chan_map_next(&node->chans, &i)) {
 		if (!is_chan_announced(c))
 			continue;
 
@@ -538,9 +542,9 @@ find_route(const tal_t *ctx, struct routing_state *rstate,
 			struct chan_map_iter i;
 			struct chan *chan;
 
-			for (chan = chan_map_first(&n->chans, &i);
+			for (chan = first_chan(n, &i);
 			     chan;
-			     chan = chan_map_next(&n->chans, &i)) {
+			     chan = next_chan(n, &i)) {
 				int idx = half_chan_to(n, chan);
 
 				SUPERVERBOSE("Node %s edge %s",
@@ -1710,9 +1714,7 @@ void routing_failure(struct routing_state *rstate,
 				     type_to_string(tmpctx,
 						    struct pubkey,
 						    &node->id));
-			for (c = chan_map_first(&node->chans, &i);
+			for (c = first_chan(node, &i); c; c = next_chan(node, &i)) {
-			     c;
-			     c = chan_map_next(&node->chans, &i)) {
 				/* Set it up to be pruned. */
 				tal_steal(tmpctx, c);
 			}

gossipd/routing.h

@@ -280,6 +280,10 @@ void handle_pending_cannouncement(struct routing_state *rstate,
 				  const struct amount_sat sat,
 				  const u8 *txscript);
 
+/* Iterate through channels in a node */
+struct chan *first_chan(const struct node *node, struct chan_map_iter *i);
+struct chan *next_chan(const struct node *node, struct chan_map_iter *i);
+
 /* Returns NULL if all OK, otherwise an error for the peer which sent. */
 u8 *handle_channel_update(struct routing_state *rstate, const u8 *update TAKES,
 			  const char *source);

gossipd/test/run-find_route.c

@@ -157,9 +157,7 @@ static struct chan *find_channel(struct routing_state *rstate UNUSED,
 
 	*idx = pubkey_idx(&from->id, &to->id);
 
-	for (c = chan_map_first(&to->chans, &i);
+	for (c = first_chan(to, &i); c; c = next_chan(to, &i)) {
-	     c;
-	     c = chan_map_next(&to->chans, &i)) {
 		if (c->nodes[*idx] == from)
 			return c;
 	}