mirrors/core-lightning
1
0
Fork 0
mirror of https://github.com/ElementsProject/lightning.git synced 2025-02-22 14:42:40 +01:00
Code Issues Projects Releases Wiki Activity

libplugin: cleanly separate apply and unapplying payment route.

Browse source 
They're close, but different.  In particular:
- Removal can't fail.
- Removal is much simpler.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2024-04-02 11:56:49 +10:30 • committed by Vincenzo Palazzo
parent aff8f0ff5e
commit 7d8c723018
1 changed files with 40 additions and 33 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

73
plugins/libplugin-pay.c
View file

@ -505,10 +505,9 @@ static struct channel_hint *payment_chanhints_get(struct payment *p,
* calls don't accidentally try to use those out-of-date estimates. We unapply
* if the payment failed, i.e., all HTLCs we might have added have been torn
* down again. Finally we leave the update in place if the payment went
* through, since the balances really changed in that case. The `remove`
* argument indicates whether we want to apply (`remove=false`), or clear a
* prior application (`remove=true`). */
static bool payment_chanhints_apply_route(struct payment *p, bool remove)
* through, since the balances really changed in that case.
*/
static bool payment_chanhints_apply_route(struct payment *p)
{
bool apply;
struct route_hop *curhop;
@ -516,11 +515,6 @@ static bool payment_chanhints_apply_route(struct payment *p, bool remove)
struct payment *root = payment_root(p);
assert(p->route != NULL);
/* No need to check for applicability if we increase
* capacity and budgets. */
if (remove)
goto apply_changes;
/* First round: make sure we can cleanly apply the update. */
for (size_t i = 0; i < tal_count(p->route); i++) {
curhop = &p->route[i];
@ -566,7 +560,6 @@ static bool payment_chanhints_apply_route(struct payment *p, bool remove)
}
}
apply_changes:
/* Second round: apply the changes, now that we know they'll succeed. */
for (size_t i = 0; i < tal_count(p->route); i++) {
curhop = &p->route[i];
@ -577,29 +570,12 @@ apply_changes:
/* Update the number of htlcs for any local
* channel in the route */
if (curhint->local) {
if (remove)
curhint->local->htlc_budget++;
else
curhint->local->htlc_budget--;
curhint->local->htlc_budget--;
}
/* Don't get fancy and replace this with remove && !amount_msat_add
* It won't work! */
if (remove) {
if (!amount_msat_add(
&curhint->estimated_capacity,
curhint->estimated_capacity,
curhop->amount)) {
/* This should never happen, it'd mean
* that we unapply a route that would
* result in a msatoshi
* wrap-around. */
abort();
}
} else if (!amount_msat_sub(
&curhint->estimated_capacity,
curhint->estimated_capacity,
curhop->amount)) {
if (!amount_msat_sub(&curhint->estimated_capacity,
curhint->estimated_capacity,
curhop->amount)) {
/* Given our preemptive test
* above, this should never
* happen either. */
@ -609,6 +585,37 @@ apply_changes:
return true;
}
/* Undo route changes above */
static void payment_chanhints_unapply_route(struct payment *p)
{
struct payment *root = payment_root(p);
for (size_t i = 0; i < tal_count(p->route); i++) {
struct route_hop *curhop;
struct channel_hint *curhint;
curhop = &p->route[i];
curhint = payment_chanhints_get(root, curhop);
if (!curhint)
continue;
/* Update the number of htlcs for any local
* channel in the route */
if (curhint->local)
curhint->local->htlc_budget++;
if (!amount_msat_add(&curhint->estimated_capacity,
curhint->estimated_capacity,
curhop->amount)) {
/* This should never happen, it'd mean
* that we unapply a route that would
* result in a msatoshi
* wrap-around. */
abort();
}
}
}
static const struct short_channel_id_dir *
payment_get_excluded_channels(const tal_t *ctx, struct payment *p)
{
@ -1585,7 +1592,7 @@ payment_waitsendpay_finished(struct command *cmd, const char *buffer,
return command_still_pending(cmd);
}
payment_chanhints_apply_route(p, true);
payment_chanhints_unapply_route(p);
/* Tell gossipd, if we received an update */
update = channel_update_from_onion_error(tmpctx, p->result->raw_message);
@ -1780,7 +1787,7 @@ static void payment_compute_onion_payloads(struct payment *p)
/* Now that we are about to fix the route parameters by
* encoding them in an onion is the right time to update the
* channel hints. */
if (!payment_chanhints_apply_route(p, false)) {
if (!payment_chanhints_apply_route(p)) {
/* We can still end up with a failed channel_hints
* update, either because a plugin changed the route,
* or because a modifier was not synchronous, allowing