[docker]: move String() to docker.go for all platforms.

docker/docker.go

@@ -1,6 +1,7 @@
 package docker
 
 import (
+	"encoding/json"
 	"errors"
 
 	"github.com/shirou/gopsutil/internal/common"
@@ -50,6 +51,11 @@ type CgroupMemStat struct {
 	MemFailCnt              uint64 `json:"memoryFailcnt"`
 }
 
+func (m CgroupMemStat) String() string {
+	s, _ := json.Marshal(m)
+	return string(s)
+}
+
 type CgroupDockerStat struct {
 	ContainerID string `json:"containerID"`
 	Name        string `json:"name"`
@@ -57,3 +63,8 @@ type CgroupDockerStat struct {
 	Status      string `json:"status"`
 	Running     bool   `json:"running"`
 }
+
+func (c CgroupDockerStat) String() string {
+	s, _ := json.Marshal(c)
+	return string(s)
+}

docker/docker_linux.go

@@ -3,7 +3,6 @@
 package docker
 
 import (
-	"encoding/json"
 	"fmt"
 	"os"
 	"os/exec"
@@ -52,11 +51,6 @@ func GetDockerStat() ([]CgroupDockerStat, error) {
 	return ret, nil
 }
 
-func (c CgroupDockerStat) String() string {
-	s, _ := json.Marshal(c)
-	return string(s)
-}
-
 // GetDockerIDList returnes a list of DockerID.
 // This requires certain permission.
 func GetDockerIDList() ([]string, error) {
@@ -220,11 +214,6 @@ func CgroupMemDocker(containerID string) (*CgroupMemStat, error) {
 	return CgroupMem(containerID, common.HostSys("fs/cgroup/memory/docker"))
 }
 
-func (m CgroupMemStat) String() string {
-	s, _ := json.Marshal(m)
-	return string(s)
-}
-
 // getCgroupFilePath constructs file path to get targetted stats file.
 func getCgroupFilePath(containerID, base, target, file string) string {
 	if len(base) == 0 {