pay: Switch to msat for total_capacity

This minimizes the need to convert back and forth from and to sat
values, and it also removes a new instance of sats in the public
interface (`channel_hints`).

Suggested-By: Rusty Russell <@rustyrussell>

common/route.c

@@ -81,7 +81,7 @@ static bool dijkstra_to_hops(struct route_hop **hops,
 	const struct gossmap_node *next;
 	size_t num_hops = tal_count(*hops);
 	const struct half_chan *h;
-	struct amount_sat total;
+	struct amount_msat total_msat;
 
 	if (dist == 0)
 		return true;
@@ -105,8 +105,8 @@ static bool dijkstra_to_hops(struct route_hop **hops,
 	if (!dijkstra_to_hops(hops, gossmap, dij, next, amount, cltv))
 		return false;
 
-	gossmap_chan_get_capacity(gossmap, c, &total);
-	(*hops)[num_hops].capacity = total;
+	total_msat = gossmap_chan_get_capacity(gossmap, c);
+	(*hops)[num_hops].capacity = total_msat;
 	(*hops)[num_hops].amount = *amount;
 	(*hops)[num_hops].delay = *cltv;
 

common/route.h

@@ -26,7 +26,7 @@ struct route_hop {
 	int direction;
 	struct node_id node_id;
 	struct amount_msat amount;
-	struct amount_sat capacity;
+	struct amount_msat capacity;
 	u32 delay;
 };
 

plugins/channel_hint.c

@@ -9,7 +9,7 @@ void channel_hint_to_json(const char *name, const struct channel_hint *hint,
 	json_add_short_channel_id_dir(dest, "scid", hint->scid);
 	json_add_amount_msat(dest, "estimated_capacity_msat",
 			     hint->estimated_capacity);
-	json_add_amount_sat(dest, "capacity_sat", hint->capacity);
+	json_add_amount_msat(dest, "total_capacity_msat", hint->capacity);
 	json_add_bool(dest, "enabled", hint->enabled);
 	json_object_end(dest);
 }
@@ -55,9 +55,7 @@ bool channel_hint_update(const struct timeabs now, struct channel_hint *hint)
 	 * overall / refill_rate`.
 	 */
 	struct amount_msat refill;
-	struct amount_msat capacity;
-	if (!amount_sat_to_msat(&capacity, hint->capacity))
-		abort();
+	struct amount_msat capacity = hint->capacity;
 
 	if (now.ts.tv_sec < hint->timestamp + PAY_REFILL_HYSTERESIS)
 		return true;
@@ -109,7 +107,7 @@ struct channel_hint *
 channel_hint_set_add(struct channel_hint_set *self, u32 timestamp,
 		     const struct short_channel_id_dir *scidd, bool enabled,
 		     const struct amount_msat *estimated_capacity,
-		     const struct amount_sat capacity, u16 *htlc_budget)
+		     const struct amount_msat capacity, u16 *htlc_budget)
 {
 	struct channel_hint *copy, *old, *newhint;
 
@@ -143,7 +141,7 @@ channel_hint_set_add(struct channel_hint_set *self, u32 timestamp,
 		 * being told. This is because in some cases, such as
 		 * routehints, we're not actually being told the total
 		 * capacity, just lower values. */
-		if (amount_sat_greater(capacity, old->capacity))
+		if (amount_msat_greater(capacity, old->capacity))
 			old->capacity = capacity;
 
 		return copy;
@@ -169,11 +167,11 @@ struct channel_hint *channel_hint_from_json(const tal_t *ctx,
 	struct channel_hint *hint = tal(ctx, struct channel_hint);
 
 	ret = json_scan(ctx, buffer, jhint,
-			"{timestamp:%,scid:%,estimated_capacity_msat:%,capacity_sat:%,enabled:%}",
+			"{timestamp:%,scid:%,estimated_capacity_msat:%,total_capacity_msat:%,enabled:%}",
 			JSON_SCAN(json_to_u32, &hint->timestamp),
 			JSON_SCAN(json_to_short_channel_id_dir, &hint->scid),
 			JSON_SCAN(json_to_msat, &hint->estimated_capacity),
-			JSON_SCAN(json_to_sat, &hint->capacity),
+			JSON_SCAN(json_to_msat, &hint->capacity),
 			JSON_SCAN(json_to_bool, &hint->enabled));
 
 	if (ret != NULL)

plugins/channel_hint.h

@@ -39,10 +39,10 @@ struct channel_hint {
 	/* Non-null if we are one endpoint of this channel */
 	struct local_hint *local;
 
-	/* The total `amount_sat` that were used to fund the
-	 * channel. This is always smaller gte the
-	 * estimated_capacity (after normalization) */
-	struct amount_sat capacity;
+	/* The total `amount_msat` that were used to fund the
+	 * channel. This is always smaller gte the estimated_capacity
+	 * (after normalization) */
+	struct amount_msat capacity;
 };
 
 /* A collection of channel_hint instances, allowing us to handle and
@@ -84,7 +84,7 @@ struct channel_hint *channel_hint_set_add(struct channel_hint_set *self,
 					  const struct short_channel_id_dir *scidd,
 					  bool enabled,
 					  const struct amount_msat *estimated_capacity,
-					  const struct amount_sat overall_capacity,
+					  const struct amount_msat overall_capacity,
 					  u16 *htlc_budget);
 
 /**

plugins/libplugin-pay.c

@@ -411,7 +411,7 @@ static void channel_hints_update(struct payment *p,
 				 const struct short_channel_id scid,
 				 int direction, bool enabled, bool local,
 				 const struct amount_msat *estimated_capacity,
-				 const struct amount_sat overall_capacity,
+				 const struct amount_msat overall_capacity,
 				 u16 *htlc_budget)
 {
 	struct payment *root = payment_root(p);
@@ -2553,7 +2553,7 @@ local_channel_hints_listpeerchannels(struct command *cmd, const char *buffer,
 				     const jsmntok_t *toks, struct payment *p)
 {
 	struct listpeers_channel **chans;
-	struct amount_sat capacity;
+	struct amount_msat capacity;
 
 	chans = json_to_listpeers_channels(tmpctx, buffer, toks);
 
@@ -2578,8 +2578,7 @@ local_channel_hints_listpeerchannels(struct command *cmd, const char *buffer,
 		else
 			htlc_budget = chans[i]->max_accepted_htlcs - chans[i]->num_htlcs;
 
-		if(!amount_msat_to_sat(&capacity, chans[i]->total_msat))
-			abort();
+		capacity = chans[i]->total_msat;
 
 		/* If we have both a scid and a local alias we want to
 		 * use the scid, and mark the alias as
@@ -3096,7 +3095,7 @@ static void routehint_step_cb(struct routehints_data *d, struct payment *p)
 			hop.amount = dest_amount;
 			hop.delay = route_cltv(d->final_cltv, routehint + i + 1,
 					       tal_count(routehint) - i - 1);
-			hop.capacity = amount_msat_to_sat_round_down(estimate);
+			hop.capacity = estimate;
 
 			/* Should we get a failure inside the routehint we'll
 			 * need the direction so we can exclude it. Luckily
@@ -3866,7 +3865,7 @@ static void route_exclusions_step_cb(struct route_exclusions_data *d,
 		struct route_exclusion *e = exclusions[i];
 
 		/* We don't need the details if we skip anyway. */
-		struct amount_sat total = AMOUNT_SAT(0);
+		struct amount_msat total = AMOUNT_MSAT(0);
 
 		if (e->type == EXCLUDE_CHANNEL) {
 			channel_hints_update(p, e->u.chan_id.scid,

plugins/pay.c

@@ -1487,7 +1487,7 @@ static struct command_result *handle_channel_hint_update(struct command *cmd,
 		   ".estimate = %s, .capacity = %s }",
 		   fmt_short_channel_id_dir(tmpctx, &hint->scid), hint->enabled,
 		   fmt_amount_msat(tmpctx, hint->estimated_capacity),
-		   fmt_amount_sat(tmpctx, hint->capacity)
+		   fmt_amount_msat(tmpctx, hint->capacity)
 	);
 	channel_hint_set_add(global_hints, time_now().ts.tv_sec, &hint->scid,
 			     hint->enabled, &hint->estimated_capacity,