From 3fbd9567c90e88262090863638c5d9acd2c772f6 Mon Sep 17 00:00:00 2001
From: Andy Pan <panjf2000@gmail.com>
Date: Sun, 11 Dec 2022 19:40:00 +0800
Subject: [PATCH] opt: leverage binary-search algorithm to speed up
 PoolWithFunc.purgeStaleWorkers()

---
 .github/workflows/test.yml |  2 +-
 pool_func.go               | 16 ++++++++++++----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b7f531f..b31e475 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -40,7 +40,7 @@ jobs:
         uses: golangci/golangci-lint-action@v3
         with:
           version: v1.50.1
-          args: -v -E gofumpt -E gocritic -E misspell -E revive -E godot
+          args: --timeout 5m -v -E gofumpt -E gocritic -E misspell -E revive -E godot
   test:
     needs: lint
     strategy:
diff --git a/pool_func.go b/pool_func.go
index 6bca66e..a3cf224 100644
--- a/pool_func.go
+++ b/pool_func.go
@@ -89,17 +89,25 @@ func (p *PoolWithFunc) purgeStaleWorkers(ctx context.Context) {
 			break
 		}
 
-		currentTime := time.Now()
+		criticalTime := time.Now().Add(-p.options.ExpiryDuration)
+
 		p.lock.Lock()
 		idleWorkers := p.workers
 		n := len(idleWorkers)
-		var i int
-		for i = 0; i < n && currentTime.Sub(idleWorkers[i].recycleTime) > p.options.ExpiryDuration; i++ {
+		l, r, mid := 0, n-1, 0
+		for l <= r {
+			mid = (l + r) / 2
+			if criticalTime.Before(idleWorkers[mid].recycleTime) {
+				r = mid - 1
+			} else {
+				l = mid + 1
+			}
 		}
+		i := r + 1
 		expiredWorkers = append(expiredWorkers[:0], idleWorkers[:i]...)
 		if i > 0 {
 			m := copy(idleWorkers, idleWorkers[i:])
-			for i = m; i < n; i++ {
+			for i := m; i < n; i++ {
 				idleWorkers[i] = nil
 			}
 			p.workers = idleWorkers[:m]