最近在拆分一个旧服务，需要从几十万行代码中，按业务功能拆分出对应代码，并部署新服务；然而，面对这种巨型服务，代码调用错综复杂，纯人力拆分需要耗费很多时间；基于此，这里借助golang自带callgraph调用图能力，帮我们找到需要拆出的代码；

package mainimport ("fmt""io/ioutil""path/filepath""sort""strings""github.com/pkg/errors""golang.org/x/tools/go/packages""golang.org/x/tools/go/ssa/ssautil""golang.org/x/tools/go/callgraph""golang.org/x/tools/go/pointer"
)// getProjectUsedCall 获取项目使用中的调用方法
func getProjectUsedCall(projectPath string) ([]string, error) {projectModule, err := parseProjectModule(projectPath)if err != nil {return nil, errors.Wrap(err, "parseProjectModule fail")}log.Debugf("projectModule: %+v", projectModule)callMap, err := parseProjectCallMap(projectPath)if err != nil {return nil, errors.Wrap(err, "parseProjectCallMap fail")}log.Debugf("callMap: %+v", callMap)srcCall := fmt.Sprintf("%v.main", projectModule)isDeleteEdgeFunc := func(caller, callee string) bool {// 非本项目调用if !strings.Contains(caller, projectModule) || !strings.Contains(callee, projectModule) {return true}// 非初始化调用if isInitCall(caller) || isInitCall(callee) {return true}// 非自我调用if caller == callee {return true}return false}// 过滤不需要的边for caller, callees := range callMap {for callee := range callees {if isDeleteEdgeFunc(caller, callee) {delete(callees, callee)}}if len(callees) == 0 {delete(callMap, caller)}}// 广度搜索图for {srcCallees := callMap[srcCall]srcSize := len(srcCallees)for srcCallee := range srcCallees {for nextCallee := range callMap[srcCallee] {callMap[srcCall][nextCallee] = true}}if srcSize == len(callMap[srcCall]) {break}}// 调用源涉及到的所有方法var callees []stringfor c := range callMap[srcCall] {callees = append(callees, c)}sort.Strings(callees)return callees, nil
}// parseProjectCallMap 解析项目调用图
func parseProjectCallMap(projectPath string) (map[string]map[string]bool, error) {projectModule, err := parseProjectModule(projectPath)if err != nil {return nil, errors.Wrap(err, "parseProjectModule fail")}log.Debugf("projectModule: %+v", projectModule)result, err := analyzeProject(projectPath)if err != nil {return nil, errors.Wrap(err, "analyzeProject fail")}log.Debugf("analyzeProject: %+v", result)// 遍历调用链路var callMap = make(map[string]map[string]bool)visitFunc := func(edge *callgraph.Edge) error {if edge == nil {return nil}// 解析调用者和被调用者caller, callee, err := parseCallEdge(edge)if err != nil {return errors.Wrap(err, "parseCallEdge fail")}// 记录调用关系if callMap[caller] == nil {callMap[caller] = make(map[string]bool)}callMap[caller][callee] = truereturn nil}err = callgraph.GraphVisitEdges(result.CallGraph, visitFunc)if err != nil {return nil, errors.Wrap(err, "GraphVisitEdges fail")}return callMap, nil
}func parseProjectModule(projectPath string) (string, error) {modFilename := filepath.Join(projectPath, "go.mod")content, err := ioutil.ReadFile(modFilename)if err != nil {return "", errors.Wrap(err, "ioutil.ReadFile fail")}lines := strings.Split(string(content), "\n")module := strings.TrimPrefix(lines[0], "module ")module = strings.TrimSpace(module)return module, nil
}func analyzeProject(projectPath string) (*pointer.Result, error) {// 生成Go Packagespkgs, err := packages.Load(&packages.Config{Mode: packages.LoadAllSyntax,Dir:  projectPath,})if err != nil {return nil, errors.Wrap(err, "packages.Load fail")}log.Debugf("pkgs: %+v", pkgs)// 生成ssa 构建编译prog, ssaPkgs := ssautil.AllPackages(pkgs, 0)prog.Build()log.Debugf("ssaPkgs: %+v", ssaPkgs)// 使用pointer生成调用链路return pointer.Analyze(&pointer.Config{Mains:          ssaPkgs,BuildCallGraph: true,})
}func parseCallEdge(edge *callgraph.Edge) (string, string, error) {const callArrow = "-->"edgeStr := fmt.Sprintf("%+v", edge)strArray := strings.Split(edgeStr, callArrow)if len(strArray) != 2 {return "", "", fmt.Errorf("invalid format: %v", edgeStr)}callerNodeStr, calleeNodeStr := strArray[0], strArray[1]caller, callee := getCallRoute(callerNodeStr), getCallRoute(calleeNodeStr)return caller, callee, nil
}func getCallRoute(nodeStr string) string {nodeStr = strings.TrimSpace(nodeStr)if strings.Contains(nodeStr, ":") {nodeStr = nodeStr[strings.Index(nodeStr, ":")+1:]}nodeStr = strings.ReplaceAll(nodeStr, "*", "")nodeStr = strings.ReplaceAll(nodeStr, "(", "")nodeStr = strings.ReplaceAll(nodeStr, ")", "")nodeStr = strings.ReplaceAll(nodeStr, "<", "")nodeStr = strings.ReplaceAll(nodeStr, ">", "")if strings.Contains(nodeStr, "$") {nodeStr = nodeStr[:strings.Index(nodeStr, "$")]}if strings.Contains(nodeStr, "#") {nodeStr = nodeStr[:strings.Index(nodeStr, "#")]}return strings.TrimSpace(nodeStr)
}func isInitCall(call string) bool {return strings.HasSuffix(call, ".init")
}