From 94d44b882ebebad55400b08eef23398e1a488ea8 Mon Sep 17 00:00:00 2001
From: roman <roman@osmosis.team>
Date: Fri, 19 Apr 2024 07:24:04 +0000
Subject: [PATCH] cache no candidate or ranked routes

---
 CHANGELOG.md                     | 4 ++++
 router/usecase/router_usecase.go | 9 ++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 32596ca2e..d265c7825 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 # Changelog
 
+## v0.17.4
+
+- Cache no candidate or ranked routes
+
 ## v0.17.3
 
 - Skip pool filtering if min osmo liquidity is zero
diff --git a/router/usecase/router_usecase.go b/router/usecase/router_usecase.go
index 2b1db0971..f93703779 100644
--- a/router/usecase/router_usecase.go
+++ b/router/usecase/router_usecase.go
@@ -71,7 +71,7 @@ var (
 	cacheWrite = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Name: "sqs_routes_cache_write_total",
-			Help: "Total number of cache misses",
+			Help: "Total number of cache writes",
 		},
 		[]string{"route", "cache_type", "token_in", "token_out", "token_in_order_of_magnitude"},
 	)
@@ -291,6 +291,13 @@ func (r *routerUseCaseImpl) computeAndRankRoutesByDirectQuote(ctx context.Contex
 		cacheWrite.WithLabelValues(requestURLPath, candidateRouteCacheLabel, tokenIn.Denom, tokenOutDenom, noOrderOfMagnitude).Inc()
 
 		r.candidateRouteCache.Set(formatCandidateRouteCacheKey(tokenIn.Denom, tokenOutDenom), candidateRoutes, time.Duration(routingOptions.CandidateRouteCacheExpirySeconds)*time.Second)
+	} else {
+		// If no candidate routes found, cache them for quarter of the duration
+		r.candidateRouteCache.Set(formatCandidateRouteCacheKey(tokenIn.Denom, tokenOutDenom), candidateRoutes, time.Duration(routingOptions.CandidateRouteCacheExpirySeconds/4)*time.Second)
+
+		r.rankedRouteCache.Set(formatRankedRouteCacheKey(tokenIn.Denom, tokenOutDenom, tokenInOrderOfMagnitude), candidateRoutes, time.Duration(routingOptions.RankedRouteCacheExpirySeconds/4)*time.Second)
+
+		return nil, nil, fmt.Errorf("no candidate routes found")
 	}
 
 	// Rank candidate routes by estimating direct quotes