from_stack.go

Documentation: k8s.io/apimachinery/pkg/util/naming

     1  /*
     2  Copyright 2018 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package naming
    18  
    19  import (
    20  	"fmt"
    21  	"regexp"
    22  	goruntime "runtime"
    23  	"runtime/debug"
    24  	"strconv"
    25  	"strings"
    26  )
    27  
    28  // GetNameFromCallsite walks back through the call stack until we find a caller from outside of the ignoredPackages
    29  // it returns back a shortpath/filename:line to aid in identification of this reflector when it starts logging
    30  func GetNameFromCallsite(ignoredPackages ...string) string {
    31  	name := "????"
    32  	const maxStack = 10
    33  	for i := 1; i < maxStack; i++ {
    34  		_, file, line, ok := goruntime.Caller(i)
    35  		if !ok {
    36  			file, line, ok = extractStackCreator()
    37  			if !ok {
    38  				break
    39  			}
    40  			i += maxStack
    41  		}
    42  		if hasPackage(file, append(ignoredPackages, "/runtime/asm_")) {
    43  			continue
    44  		}
    45  
    46  		file = trimPackagePrefix(file)
    47  		name = fmt.Sprintf("%s:%d", file, line)
    48  		break
    49  	}
    50  	return name
    51  }
    52  
    53  // hasPackage returns true if the file is in one of the ignored packages.
    54  func hasPackage(file string, ignoredPackages []string) bool {
    55  	for _, ignoredPackage := range ignoredPackages {
    56  		if strings.Contains(file, ignoredPackage) {
    57  			return true
    58  		}
    59  	}
    60  	return false
    61  }
    62  
    63  // trimPackagePrefix reduces duplicate values off the front of a package name.
    64  func trimPackagePrefix(file string) string {
    65  	if l := strings.LastIndex(file, "/vendor/"); l >= 0 {
    66  		return file[l+len("/vendor/"):]
    67  	}
    68  	if l := strings.LastIndex(file, "/src/"); l >= 0 {
    69  		return file[l+5:]
    70  	}
    71  	if l := strings.LastIndex(file, "/pkg/"); l >= 0 {
    72  		return file[l+1:]
    73  	}
    74  	return file
    75  }
    76  
    77  var stackCreator = regexp.MustCompile(`(?m)^created by (.*)\n\s+(.*):(\d+) \+0x[[:xdigit:]]+$`)
    78  
    79  // extractStackCreator retrieves the goroutine file and line that launched this stack. Returns false
    80  // if the creator cannot be located.
    81  // TODO: Go does not expose this via runtime https://github.com/golang/go/issues/11440
    82  func extractStackCreator() (string, int, bool) {
    83  	stack := debug.Stack()
    84  	matches := stackCreator.FindStringSubmatch(string(stack))
    85  	if len(matches) != 4 {
    86  		return "", 0, false
    87  	}
    88  	line, err := strconv.Atoi(matches[3])
    89  	if err != nil {
    90  		return "", 0, false
    91  	}
    92  	return matches[2], line, true
    93  }
    94
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