From 5ea5d20d4bd72de0419d4fdb370ca531195f0bc9 Mon Sep 17 00:00:00 2001
From: Mohamed Hamza <mhamza15@github.com>
Date: Thu, 23 Jan 2025 11:39:13 -0500
Subject: [PATCH] Revert "[release-19.0] VTTablet: smartconnpool: notify all
 expired waiters (#16897) (#16901)"

This reverts commit 805d607ecbb7acc3eff312d742dca5ac9605f5b2.
---
 go/pools/smartconnpool/waitlist.go      |  5 +-
 go/pools/smartconnpool/waitlist_test.go | 68 -------------------------
 2 files changed, 1 insertion(+), 72 deletions(-)
 delete mode 100644 go/pools/smartconnpool/waitlist_test.go

diff --git a/go/pools/smartconnpool/waitlist.go b/go/pools/smartconnpool/waitlist.go
index f16215f4b14..d4abeade0ac 100644
--- a/go/pools/smartconnpool/waitlist.go
+++ b/go/pools/smartconnpool/waitlist.go
@@ -88,14 +88,11 @@ func (wl *waitlist[C]) expire(force bool) {
 	// or remove everything if force is true
 	for e := wl.list.Front(); e != nil; e = e.Next() {
 		if force || e.Value.ctx.Err() != nil {
+			wl.list.Remove(e)
 			expired = append(expired, e)
 			continue
 		}
 	}
-	// remove the expired waiters from the waitlist after traversing it
-	for _, e := range expired {
-		wl.list.Remove(e)
-	}
 	wl.mu.Unlock()
 
 	// once all the expired waiters have been removed from the waitlist, wake them up one by one
diff --git a/go/pools/smartconnpool/waitlist_test.go b/go/pools/smartconnpool/waitlist_test.go
deleted file mode 100644
index 1486aa989b6..00000000000
--- a/go/pools/smartconnpool/waitlist_test.go
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
-Copyright 2024 The Vitess Authors.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-package smartconnpool
-
-import (
-	"context"
-	"sync/atomic"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-func TestWaitlistExpireWithMultipleWaiters(t *testing.T) {
-	wait := waitlist[*TestConn]{}
-	wait.init()
-
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
-	defer cancel()
-
-	waiterCount := 2
-	expireCount := atomic.Int32{}
-
-	for i := 0; i < waiterCount; i++ {
-		go func() {
-			_, err := wait.waitForConn(ctx, nil)
-			if err != nil {
-				expireCount.Add(1)
-			}
-		}()
-	}
-
-	// Wait for the context to expire
-	<-ctx.Done()
-
-	// Expire the waiters
-	wait.expire(false)
-
-	// Wait for the notified goroutines to finish
-	timeout := time.After(1 * time.Second)
-	ticker := time.NewTicker(10 * time.Millisecond)
-	defer ticker.Stop()
-	for expireCount.Load() != int32(waiterCount) {
-		select {
-		case <-timeout:
-			require.Failf(t, "Timed out waiting for all waiters to expire", "Wanted %d, got %d", waiterCount, expireCount.Load())
-		case <-ticker.C:
-			// try again
-		}
-	}
-
-	assert.Equal(t, int32(waiterCount), expireCount.Load())
-}