From 2fd4030cb8935582b47216bee2c3af714db855c1 Mon Sep 17 00:00:00 2001
From: Daniel Liu <139250065@qq.com>
Date: Sat, 1 Nov 2025 14:35:24 +0800
Subject: [PATCH] eth/gasprice: ensure cache purging goroutine terminates with
 subscription #31025, close XFN-89 (#1687)

---
 eth/gasprice/gasprice.go | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/eth/gasprice/gasprice.go b/eth/gasprice/gasprice.go
index 900455fa71..0cdffce31f 100644
--- a/eth/gasprice/gasprice.go
+++ b/eth/gasprice/gasprice.go
@@ -119,16 +119,23 @@ func NewOracle(backend OracleBackend, params Config, startPrice *big.Int) *Oracl
 
 	cache := lru.NewCache[cacheKey, processedFees](2048)
 	headEvent := make(chan core.ChainHeadEvent, 1)
-	backend.SubscribeChainHeadEvent(headEvent)
-	go func() {
-		var lastHead common.Hash
-		for ev := range headEvent {
-			if ev.Block.ParentHash() != lastHead {
-				cache.Purge()
+	sub := backend.SubscribeChainHeadEvent(headEvent)
+	if sub != nil { // the gasprice testBackend doesn't support subscribing to head events
+		go func() {
+			var lastHead common.Hash
+			for {
+				select {
+				case ev := <-headEvent:
+					if ev.Block.ParentHash() != lastHead {
+						cache.Purge()
+					}
+					lastHead = ev.Block.Hash()
+				case <-sub.Err():
+					return
+				}
 			}
-			lastHead = ev.Block.Hash()
-		}
-	}()
+		}()
+	}
 
 	return &Oracle{
 		backend:          backend,