更新vim torque

go/map 和 slice 索引速度比较.md

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+# golang 中map 和slice 索引速度比较
+
+## 主文件
+
+```go
+package main
+
+var max = 100
+var Slice = make([]int, max+10)
+var Map = make(map[int]int)
+
+func init() {
+    for i := 0; i < max; i++ {
+        Slice[i] = i
+        Map[i] = i 
+    }
+}
+
+// 查找算法可以优化，本文对于常用无序查找做比较
+func SearchSlice(i int) int {
+    for _, v := range Slice {
+        if v == i {
+            return v
+        }
+    }
+    return -1
+}
+
+func SearchMap(i int) int {
+    return Map[i]
+}
+```
+
+## 测试文件
+
+```go
+package main
+
+import "testing"
+
+func BenchmarkSearchMap(b *testing.B) {
+    for i := 0; i < b.N; i++ {
+        _ = SearchMap(i % max)
+    }
+}
+
+func BenchmarkSearchSlice(b *testing.B) {
+    for i := 0; i < b.N; i++ {
+        _ = SearchSlice(i % max)
+    }
+}
+
+func BenchmarkSlice(b *testing.B) {
+    for i := 0; i < b.N; i++ {
+        _ = Slice[i%max]
+    }
+}
+```
+
+## 测试结果
+
+max = 100 
+
+```bash
+BenchmarkSearchMap-16           94148293                12.7 ns/op             0 B/op          0 allocs/op
+BenchmarkSearchSlice-16         49473447                23.6 ns/op             0 B/op          0 allocs/op
+BenchmarkSlice-16               187461336                6.46 ns/op            0 B/op          0 allocs/op
+```
+
+max = 10000
+
+```bash
+BenchmarkSearchMap-16           43147364                27.6 ns/op             0 B/op          0 allocs/op
+BenchmarkSearchSlice-16           968623              1159 ns/op               0 B/op          0 allocs/op
+BenchmarkSlice-16               187649472                6.42 ns/op            0 B/op          0 allocs/op
+```
+
+Max = 1000000
+
+```bash
+BenchmarkSearchMap-16                   15015690                90.1 ns/op             0 B/op          0 allocs/op
+BenchmarkSearchSlice-16                   441436            104242 ns/op               0 B/op          0 allocs/op
+BenchmarkSlice-16                       182620702                6.58 ns/op            0 B/op          0 allocs/op
+```
+
+
+
+在一些特定优化条件下，可以尝试用slice，效果会比map好，比如把10^6^级的查找优化成3级10^2^查找, 对于一些结构体，可以根据某些特征分类或预先根据特征值排序