Merge pull request #132 from thaJeztah/optimize_ParsePortSpec

nat: ParsePortSpecs: reduce allocations and improve performance

Author: thaJeztah

nat/nat.go

@@ -198,42 +198,39 @@ func ParsePortSpec(rawPort string) ([]PortMapping, error) {
 		return nil, errors.New("invalid containerPort: " + containerPort)
 	}
 
-	var startHostPort, endHostPort uint64 = 0, 0
+	var startHostPort, endHostPort uint64
 	if hostPort != "" {
 		startHostPort, endHostPort, err = ParsePortRange(hostPort)
 		if err != nil {
 			return nil, errors.New("invalid hostPort: " + hostPort)
 		}
-	}
-
-	if hostPort != "" && (endPort-startPort) != (endHostPort-startHostPort) {
-		// Allow host port range iff containerPort is not a range.
-		// In this case, use the host port range as the dynamic
-		// host port range to allocate into.
-		if endPort != startPort {
-			return nil, fmt.Errorf("invalid ranges specified for container and host Ports: %s and %s", containerPort, hostPort)
+		if (endPort - startPort) != (endHostPort - startHostPort) {
+			// Allow host port range iff containerPort is not a range.
+			// In this case, use the host port range as the dynamic
+			// host port range to allocate into.
+			if endPort != startPort {
+				return nil, fmt.Errorf("invalid ranges specified for container and host Ports: %s and %s", containerPort, hostPort)
+			}
 		}
 	}
 
-	ports := []PortMapping{}
-	for i := uint64(0); i <= (endPort - startPort); i++ {
-		containerPort = strconv.FormatUint(startPort+i, 10)
+	count := endPort - startPort + 1
+	ports := make([]PortMapping, 0, count)
+
+	for i := uint64(0); i < count; i++ {
+		cPort := Port(strconv.FormatUint(startPort+i, 10) + "/" + proto)
+		hPort := ""
 		if hostPort != "" {
-			hostPort = strconv.FormatUint(startHostPort+i, 10)
-		}
-		// Set hostPort to a range only if there is a single container port
-		// and a dynamic host port.
-		if startPort == endPort && startHostPort != endHostPort {
-			hostPort = hostPort + "-" + strconv.FormatUint(endHostPort, 10)
-		}
-		port, err := NewPort(proto, containerPort)
-		if err != nil {
-			return nil, err
+			hPort = strconv.FormatUint(startHostPort+i, 10)
+			// Set hostPort to a range only if there is a single container port
+			// and a dynamic host port.
+			if count == 1 && startHostPort != endHostPort {
+				hPort += "-" + strconv.FormatUint(endHostPort, 10)
+			}
 		}
-
 		ports = append(ports, PortMapping{
-			Port:    port,
-			Binding: PortBinding{HostIP: ip, HostPort: hostPort},
+			Port:    cPort,
+			Binding: PortBinding{HostIP: ip, HostPort: hPort},
 		})
 	}
 	return ports, nil

nat/nat_test.go

@@ -841,3 +841,28 @@ func TestStringer(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkParsePortSpecs(b *testing.B) {
+	specs := [][]string{
+		{"1234/tcp", "2345/udp", "3456/sctp"},
+		{"1234:1234/tcp", "2345:2345/udp", "3456:3456/sctp"},
+		{"0.0.0.0:1234:1234/tcp", "0.0.0.0:2345:2345/udp", "0.0.0.0:3456:3456/sctp"},
+		{"1234-1236/tcp", "2345-2347/udp", "3456-3458/sctp"},
+		{"1234-1236:1234-1236/tcp", "2345-2347:2345-2347/udp", "3456-3458:3456-3458/sctp"},
+		{"0.0.0.0:1234-1236:1234-1236/tcp", "0.0.0.0:2345-2347:2345-2347/udp", "0.0.0.0:3456-3458:3456-3458/sctp"},
+		{"[2001:4860:0:2001::68]::333"},
+		{"[::1]:80:80"},
+		{"::1:80:80"},
+		{"::::80"},
+	}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for _, group := range specs {
+			if _, _, err := ParsePortSpecs(group); err != nil {
+				b.Fatalf("unexpected error: %v", err)
+			}
+		}
+	}
+}