cgroup.go (2367B)
1 // Copyright (c) 2017 Uber Technologies, Inc. 2 // 3 // Permission is hereby granted, free of charge, to any person obtaining a copy 4 // of this software and associated documentation files (the "Software"), to deal 5 // in the Software without restriction, including without limitation the rights 6 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 7 // copies of the Software, and to permit persons to whom the Software is 8 // furnished to do so, subject to the following conditions: 9 // 10 // The above copyright notice and this permission notice shall be included in 11 // all copies or substantial portions of the Software. 12 // 13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 18 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 19 // THE SOFTWARE. 20 21 //go:build linux 22 // +build linux 23 24 package cgroups 25 26 import ( 27 "bufio" 28 "io" 29 "os" 30 "path/filepath" 31 "strconv" 32 ) 33 34 // CGroup represents the data structure for a Linux control group. 35 type CGroup struct { 36 path string 37 } 38 39 // NewCGroup returns a new *CGroup from a given path. 40 func NewCGroup(path string) *CGroup { 41 return &CGroup{path: path} 42 } 43 44 // Path returns the path of the CGroup*. 45 func (cg *CGroup) Path() string { 46 return cg.path 47 } 48 49 // ParamPath returns the path of the given cgroup param under itself. 50 func (cg *CGroup) ParamPath(param string) string { 51 return filepath.Join(cg.path, param) 52 } 53 54 // readFirstLine reads the first line from a cgroup param file. 55 func (cg *CGroup) readFirstLine(param string) (string, error) { 56 paramFile, err := os.Open(cg.ParamPath(param)) 57 if err != nil { 58 return "", err 59 } 60 defer paramFile.Close() 61 62 scanner := bufio.NewScanner(paramFile) 63 if scanner.Scan() { 64 return scanner.Text(), nil 65 } 66 if err := scanner.Err(); err != nil { 67 return "", err 68 } 69 return "", io.ErrUnexpectedEOF 70 } 71 72 // readInt parses the first line from a cgroup param file as int. 73 func (cg *CGroup) readInt(param string) (int, error) { 74 text, err := cg.readFirstLine(param) 75 if err != nil { 76 return 0, err 77 } 78 return strconv.Atoi(text) 79 }