From e4eab01148653bb0400d00a0ce60bad8de718694 Mon Sep 17 00:00:00 2001
From: Andy Walker <andy@andy.dev>
Date: Fri, 25 Apr 2025 14:06:33 -0400
Subject: [PATCH 1/2] demonstrate that bits.Len64 passes tests

---
 log.go | 22 ++++------------------
 1 file changed, 4 insertions(+), 18 deletions(-)

diff --git a/log.go b/log.go
index b21b946..9a3ce6d 100644
--- a/log.go
+++ b/log.go
@@ -1,6 +1,8 @@
 package puddle
 
-import "unsafe"
+import (
+	"math/bits"
+)
 
 type ints interface {
 	int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64
@@ -12,21 +14,5 @@ func log2Int[T ints](val T) uint8 {
 	if val <= 0 {
 		panic("log2 of non-positive number does not exist")
 	}
-
-	return log2IntRange(val, 0, uint8(8*unsafe.Sizeof(val)))
-}
-
-func log2IntRange[T ints](val T, begin, end uint8) uint8 {
-	length := end - begin
-	if length == 1 {
-		return begin
-	}
-
-	delim := begin + length/2
-	mask := T(1) << delim
-	if mask > val {
-		return log2IntRange(val, begin, delim)
-	} else {
-		return log2IntRange(val, delim, end)
-	}
+	return uint8(bits.Len64(uint64(val)) - 1)
 }

From 3f8c490739d3df345b61f9b353779faf0c4160f7 Mon Sep 17 00:00:00 2001
From: Andy Walker <andy@andy.dev>
Date: Fri, 25 Apr 2025 14:07:26 -0400
Subject: [PATCH 2/2] replace custom log2 impl with bits.Len64

---
 log.go      | 18 ------------------
 log_test.go | 49 -------------------------------------------------
 pool.go     |  7 +++++--
 3 files changed, 5 insertions(+), 69 deletions(-)
 delete mode 100644 log.go
 delete mode 100644 log_test.go

diff --git a/log.go b/log.go
deleted file mode 100644
index 9a3ce6d..0000000
--- a/log.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package puddle
-
-import (
-	"math/bits"
-)
-
-type ints interface {
-	int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64
-}
-
-// log2Int returns log2 of an integer. This function panics if val < 0. For val
-// == 0, returns 0.
-func log2Int[T ints](val T) uint8 {
-	if val <= 0 {
-		panic("log2 of non-positive number does not exist")
-	}
-	return uint8(bits.Len64(uint64(val)) - 1)
-}
diff --git a/log_test.go b/log_test.go
deleted file mode 100644
index d425313..0000000
--- a/log_test.go
+++ /dev/null
@@ -1,49 +0,0 @@
-package puddle
-
-import (
-	"math"
-	"math/rand"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestLog2Uint(t *testing.T) {
-	r := require.New(t)
-
-	r.Equal(uint8(0), log2Int(1))
-	r.Equal(uint8(0), log2Int[uint64](1))
-	r.Equal(uint8(1), log2Int[uint32](2))
-	r.Equal(uint8(7), log2Int[uint8](math.MaxUint8))
-	r.Equal(uint8(15), log2Int[uint16](math.MaxUint16))
-	r.Equal(uint8(31), log2Int[uint32](math.MaxUint32))
-	r.Equal(uint8(63), log2Int[uint64](math.MaxUint64))
-
-	r.Panics(func() { log2Int[uint64](0) })
-	r.Panics(func() { log2Int[int64](-1) })
-}
-
-func FuzzLog2Uint(f *testing.F) {
-	const cnt = 1000
-
-	rand := rand.New(rand.NewSource(time.Now().UnixNano()))
-	for i := 0; i < cnt; i++ {
-		val := uint64(rand.Int63())
-		// val + 1 not to test val == 0.
-		f.Add(val + 1)
-	}
-
-	f.Fuzz(func(t *testing.T, val uint64) {
-		var mx uint8
-		for i := 63; i >= 0; i-- {
-			mask := uint64(1) << i
-			if mask&val != 0 {
-				mx = uint8(i)
-				break
-			}
-		}
-
-		require.Equal(t, mx, log2Int(val))
-	})
-}
diff --git a/pool.go b/pool.go
index c411d2f..4b8c361 100644
--- a/pool.go
+++ b/pool.go
@@ -3,6 +3,7 @@ package puddle
 import (
 	"context"
 	"errors"
+	"math/bits"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -543,12 +544,14 @@ func (p *Pool[T]) TryAcquire(ctx context.Context) (*Resource[T], error) {
 // TODO: Replace this with acquireSem.TryAcquireAll() if it gets to
 // upstream. https://github.com/golang/sync/pull/19
 func acquireSemAll(sem *semaphore.Weighted, num int) int {
+	if num <= 0 {
+		panic("aquireSemAll: num <= 0")
+	}
 	if sem.TryAcquire(int64(num)) {
 		return num
 	}
-
 	var acquired int
-	for i := int(log2Int(num)); i >= 0; i-- {
+	for i := bits.Len64(uint64(num)) - 1; i >= 0; i-- {
 		val := 1 << i
 		if sem.TryAcquire(int64(val)) {
 			acquired += val