perf(slice): make the IndexOf function thread-safe (#262)

slice/slice.go

@@ -10,6 +10,7 @@ import (
 	"reflect"
 	"sort"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/duke-git/lancet/v2/random"
@@ -21,6 +22,7 @@ import (
 var (
 	memoryHashMap     = make(map[string]map[any]int)
 	memoryHashCounter = make(map[string]int)
+	muForMemoryHash   sync.RWMutex
 )
 
 // Contain check if the target value is in the slice or not.
@@ -1174,23 +1176,46 @@ func IndexOf[T comparable](arr []T, val T) int {
 	limit := 10
 	// gets the hash value of the array as the key of the hash table.
 	key := fmt.Sprintf("%p", arr)
+
+	muForMemoryHash.RLock()
 	// determines whether the hash table is empty. If so, the hash table is created.
 	if memoryHashMap[key] == nil {
-		memoryHashMap[key] = make(map[any]int)
-		// iterate through the array, adding the value and index of each element to the hash table.
-		for i := len(arr) - 1; i >= 0; i-- {
-			memoryHashMap[key][arr[i]] = i
+
+		muForMemoryHash.RUnlock()
+		muForMemoryHash.Lock()
+
+		if memoryHashMap[key] == nil {
+			memoryHashMap[key] = make(map[any]int)
+			// iterate through the array, adding the value and index of each element to the hash table.
+			for i := len(arr) - 1; i >= 0; i-- {
+				memoryHashMap[key][arr[i]] = i
+			}
 		}
+
+		muForMemoryHash.Unlock()
+	} else {
+		muForMemoryHash.RUnlock()
 	}
+
+	muForMemoryHash.Lock()
 	// update the hash table counter.
 	memoryHashCounter[key]++
+	muForMemoryHash.Unlock()
 
 	// use the hash table to find the specified value. If found, the index is returned.
-	if index, ok := memoryHashMap[key][val]; ok {
+	muForMemoryHash.RLock()
+	index, ok := memoryHashMap[key][val]
+	muForMemoryHash.RUnlock()
+
+	if ok {
+		muForMemoryHash.RLock()
 		// calculate the memory usage of the hash table.
 		size := len(memoryHashMap)
+		muForMemoryHash.RUnlock()
+
 		// If the memory usage of the hash table exceeds the memory limit, the hash table with the lowest counter is cleared.
 		if size > limit {
+			muForMemoryHash.Lock()
 			var minKey string
 			var minVal int
 			for k, v := range memoryHashCounter {
@@ -1204,6 +1229,7 @@ func IndexOf[T comparable](arr []T, val T) int {
 			}
 			delete(memoryHashMap, minKey)
 			delete(memoryHashCounter, minKey)
+			muForMemoryHash.Unlock()
 		}
 		return index
 	}

slice/slice_concurrent.go

@@ -149,7 +149,7 @@ func FilterConcurrent[T any](slice []T, predicate func(index int, item T) bool,
 	return result
 }
 
-// UniqueByParallel removes duplicate elements from the slice by parallel
+// UniqueByConcurrent removes duplicate elements from the slice by parallel
 // The comparator function is used to compare the elements
 // The numThreads parameter specifies the number of threads to use
 // If numThreads is less than or equal to 0, it will be set to 1

slice/slice_test.go

@@ -6,6 +6,7 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
+	"sync"
 	"testing"
 
 	"github.com/duke-git/lancet/v2/internal"
@@ -1367,6 +1368,37 @@ func TestIndexOf(t *testing.T) {
 	assert.Equal(-1, IndexOf(arr3, "r"))
 	assert.Equal(2, memoryHashCounter[key3])
 	assert.Equal(0, memoryHashCounter[minKey])
+
+	arr4 := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+
+	const numGoroutines = 100
+	var wg sync.WaitGroup
+	wg.Add(numGoroutines)
+
+	for i := 0; i < numGoroutines; i++ {
+		go func(i int) {
+			defer wg.Done()
+			index := IndexOf(arr4, i%10+1)
+			assert.Equal(i%10, index)
+		}(i)
+	}
+	wg.Wait()
+}
+
+func BenchmarkIndexOfDifferentSizes(b *testing.B) {
+	sizes := []int{10, 100, 1000, 10000, 100000}
+	for _, size := range sizes {
+		arr := make([]int, size)
+		for i := 0; i < len(arr); i++ {
+			arr[i] = i
+		}
+
+		b.RunParallel(func(pb *testing.PB) {
+			for pb.Next() {
+				_ = IndexOf(arr, size/2) // 查找数组中间的元素
+			}
+		})
+	}
 }
 
 func TestLastIndexOf(t *testing.T) {