test spinlock

lru_shard.go

@@ -3,7 +3,6 @@
 package lru
 
 import (
-	"sync"
 	"unsafe"
 )
 
@@ -22,7 +21,7 @@ type lrubucket struct {
 
 // lrushard is a LRU partition contains a list and a hash table.
 type lrushard[K comparable, V any] struct {
-	mu sync.Mutex
+	mu spinLock
 
 	// the hash table, with 20% extra space than the list for fewer conflicts.
 	table struct {

spinlock.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2023 Daniel Hu.
+
+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 lru
+
+import (
+	"runtime"
+	"sync/atomic"
+)
+
+// spinLock is a simple spin lock implementation with exponential backoff and adaptive spinning.
+type spinLock struct {
+	flag uint32
+}
+
+// Lock spins until it is able to acquire the lock.
+// It uses exponential backoff and adaptive spinning to reduce contention.
+func (sl *spinLock) Lock() {
+	backoff := 1
+	for !sl.TryLock() {
+		for i := 0; i < backoff; i++ {
+			runtime.Gosched()
+		}
+		if backoff < 128 { // Limit the maximum backoff time
+			backoff *= 2
+		}
+	}
+}
+
+// Unlock releases the lock.
+func (sl *spinLock) Unlock() {
+	atomic.StoreUint32(&sl.flag, 0)
+}
+
+// TryLock attempts to acquire the lock without blocking.
+// It returns true if the lock was successfully acquired, and false otherwise.
+func (sl *spinLock) TryLock() bool {
+	return atomic.CompareAndSwapUint32(&sl.flag, 0, 1)
+}

ttl_shard.go

@@ -3,7 +3,6 @@
 package lru
 
 import (
-	"sync"
 	"sync/atomic"
 	"time"
 	"unsafe"
@@ -26,7 +25,7 @@ type ttlbucket struct {
 
 // ttlshard is a LRU partition contains a list and a hash table.
 type ttlshard[K comparable, V any] struct {
-	mu sync.Mutex
+	mu spinLock
 
 	// the hash table, with 20% extra space than the list for fewer conflicts.
 	table struct {