From d9a672ab02faf0eef3d388c00e5230800b84b87b Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Thu, 14 Jun 2018 14:20:47 +0930
Subject: [PATCH] listinvoice: speed up single-invoice case.

satoshis.place was slowing to a crawl, c-lightning was unresponsive.
Logs revealed charged doing many, many listinvoice <label> RPCs.

We were iterating the entire db every time: stop that!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 lightningd/invoice.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/lightningd/invoice.c b/lightningd/invoice.c
index 227a10031..63d3b2909 100644
--- a/lightningd/invoice.c
+++ b/lightningd/invoice.c
@@ -384,11 +384,20 @@ static void json_add_invoices(struct json_result *response,
 	struct invoice_iterator it;
 	struct invoice_details details;
 
+	/* Don't iterate entire db if we're just after one. */
+	if (label) {
+		struct invoice invoice;
+		if (wallet_invoice_find_by_label(wallet, &invoice, label)) {
+			wallet_invoice_details(response, wallet, invoice,
+					       &details);
+			json_add_invoice(response, &details, modern);
+		}
+		return;
+	}
+
 	memset(&it, 0, sizeof(it));
 	while (wallet_invoice_iterate(wallet, &it)) {
 		wallet_invoice_iterator_deref(response, wallet, &it, &details);
-		if (label && !json_escaped_eq(details.label, label))
-			continue;
 		json_add_invoice(response, &details, modern);
 	}
 }