From 7e210bcc259b2f7bf57598260aaee072a0f7ced8 Mon Sep 17 00:00:00 2001
From: ucwong <ucwong@126.com>
Date: Fri, 5 Jan 2024 12:49:31 +0000
Subject: [PATCH] eth/downloader, eth/filters: use defer to call Unsubscribe
 (#28762)

---
 eth/downloader/api.go |  3 +--
 eth/filters/api.go    | 10 ++++------
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/eth/downloader/api.go b/eth/downloader/api.go
index b3f7113bcde9..606c6d4e7ec1 100644
--- a/eth/downloader/api.go
+++ b/eth/downloader/api.go
@@ -101,16 +101,15 @@ func (api *DownloaderAPI) Syncing(ctx context.Context) (*rpc.Subscription, error
 	go func() {
 		statuses := make(chan interface{})
 		sub := api.SubscribeSyncStatus(statuses)
+		defer sub.Unsubscribe()
 
 		for {
 			select {
 			case status := <-statuses:
 				notifier.Notify(rpcSub.ID, status)
 			case <-rpcSub.Err():
-				sub.Unsubscribe()
 				return
 			case <-notifier.Closed():
-				sub.Unsubscribe()
 				return
 			}
 		}
diff --git a/eth/filters/api.go b/eth/filters/api.go
index a4eaa9cec805..5dc59d01cd71 100644
--- a/eth/filters/api.go
+++ b/eth/filters/api.go
@@ -159,6 +159,8 @@ func (api *FilterAPI) NewPendingTransactions(ctx context.Context, fullTx *bool)
 	go func() {
 		txs := make(chan []*types.Transaction, 128)
 		pendingTxSub := api.events.SubscribePendingTxs(txs)
+		defer pendingTxSub.Unsubscribe()
+
 		chainConfig := api.sys.backend.ChainConfig()
 
 		for {
@@ -176,10 +178,8 @@ func (api *FilterAPI) NewPendingTransactions(ctx context.Context, fullTx *bool)
 					}
 				}
 			case <-rpcSub.Err():
-				pendingTxSub.Unsubscribe()
 				return
 			case <-notifier.Closed():
-				pendingTxSub.Unsubscribe()
 				return
 			}
 		}
@@ -233,16 +233,15 @@ func (api *FilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, error) {
 	go func() {
 		headers := make(chan *types.Header)
 		headersSub := api.events.SubscribeNewHeads(headers)
+		defer headersSub.Unsubscribe()
 
 		for {
 			select {
 			case h := <-headers:
 				notifier.Notify(rpcSub.ID, h)
 			case <-rpcSub.Err():
-				headersSub.Unsubscribe()
 				return
 			case <-notifier.Closed():
-				headersSub.Unsubscribe()
 				return
 			}
 		}
@@ -267,6 +266,7 @@ func (api *FilterAPI) Logs(ctx context.Context, crit FilterCriteria) (*rpc.Subsc
 	if err != nil {
 		return nil, err
 	}
+	defer logsSub.Unsubscribe()
 
 	go func() {
 		for {
@@ -277,10 +277,8 @@ func (api *FilterAPI) Logs(ctx context.Context, crit FilterCriteria) (*rpc.Subsc
 					notifier.Notify(rpcSub.ID, &log)
 				}
 			case <-rpcSub.Err(): // client send an unsubscribe request
-				logsSub.Unsubscribe()
 				return
 			case <-notifier.Closed(): // connection dropped
-				logsSub.Unsubscribe()
 				return
 			}
 		}