code refactor for common package

pkg/common/bufpool/pool.go

@@ -0,0 +1,102 @@
+package bufpool
+
+import "sync"
+
+var (
+	pools = []struct {
+		size int
+		pool sync.Pool
+	}{
+		{
+			size: 128,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 128)
+				},
+			},
+		},
+		{
+			size: 512,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 512)
+				},
+			},
+		},
+		{
+			size: 1024,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 1024)
+				},
+			},
+		},
+		{
+			size: 4096,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 4096)
+				},
+			},
+		},
+		{
+			size: 8192,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 8192)
+				},
+			},
+		},
+		{
+			size: 16 * 1024,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 16*1024)
+				},
+			},
+		},
+		{
+			size: 32 * 1024,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 32*1024)
+				},
+			},
+		},
+		{
+			size: 64 * 1024,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 64*1024)
+				},
+			},
+		},
+		{
+			size: 65 * 1024,
+			pool: sync.Pool{
+				New: func() interface{} {
+					return make([]byte, 65*1024)
+				},
+			},
+		},
+	}
+)
+
+// Get returns a buffer size range from (0, 65]KB,
+// panic if size > 65KB.
+func Get(size int) []byte {
+	for i := range pools {
+		if size <= pools[i].size {
+			return pools[i].pool.Get().([]byte)
+		}
+	}
+	panic("size too large (max=65KB)")
+}
+
+func Put(b []byte) {
+	for i := range pools {
+		if cap(b) == pools[i].size {
+			pools[i].pool.Put(b[:cap(b)])
+		}
+	}
+}