github.com/wph95/goofys@v0.24.1-0.20200907140828-7bc615e8492e/internal/cgroup.go (about)

     1  // Copyright 2019 Ka-Hing Cheung
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package internal
    16  
    17  import (
    18  	"errors"
    19  	"io/ioutil"
    20  	"os"
    21  	"path/filepath"
    22  	"strconv"
    23  	"strings"
    24  )
    25  
    26  const CGROUP_PATH = "/proc/self/cgroup"
    27  const CGROUP_FOLDER_PREFIX = "/sys/fs/cgroup/memory"
    28  const MEM_LIMIT_FILE_SUFFIX = "/memory.limit_in_bytes"
    29  const MEM_USAGE_FILE_SUFFIX = "/memory.usage_in_bytes"
    30  
    31  func getCgroupAvailableMem() (retVal uint64, err error) {
    32  	//get the memory cgroup for self and send limit - usage for the cgroup
    33  
    34  	data, err := ioutil.ReadFile(CGROUP_PATH)
    35  	if err != nil {
    36  		log.Debugf("Unable to read file %s error: %s", CGROUP_PATH, err)
    37  		return 0, err
    38  	}
    39  
    40  	path, err := getMemoryCgroupPath(string(data))
    41  	if err != nil {
    42  		log.Debugf("Unable to get memory cgroup path")
    43  		return 0, err
    44  	}
    45  
    46  	// newer version of docker mounts the cgroup memory limit/usage files directly under
    47  	// /sys/fs/cgroup/memory/ rather than /sys/fs/cgroup/memory/docker/$container_id/
    48  	if _, err := os.Stat(filepath.Join(CGROUP_FOLDER_PREFIX, path)); os.IsExist(err) {
    49  		path = filepath.Join(CGROUP_FOLDER_PREFIX, path)
    50  	} else {
    51  		path = filepath.Join(CGROUP_FOLDER_PREFIX)
    52  	}
    53  
    54  	log.Debugf("the memory cgroup path for the current process is %v", path)
    55  
    56  	mem_limit, err := readFileAndGetValue(filepath.Join(path, MEM_LIMIT_FILE_SUFFIX))
    57  	if err != nil {
    58  		log.Debugf("Unable to get memory limit from cgroup error: %v", err)
    59  		return 0, err
    60  	}
    61  
    62  	mem_usage, err := readFileAndGetValue(filepath.Join(path, MEM_USAGE_FILE_SUFFIX))
    63  	if err != nil {
    64  		log.Debugf("Unable to get memory usage from cgroup error: %v", err)
    65  		return 0, err
    66  	}
    67  
    68  	return (mem_limit - mem_usage), nil
    69  }
    70  
    71  func getMemoryCgroupPath(data string) (string, error) {
    72  
    73  	/*
    74  	   Content of /proc/self/cgroup
    75  
    76  	   11:hugetlb:/
    77  	   10:memory:/user.slice
    78  	   9:cpuset:/
    79  	   8:blkio:/user.slice
    80  	   7:perf_event:/
    81  	   6:net_prio,net_cls:/
    82  	   5:cpuacct,cpu:/user.slice
    83  	   4:devices:/user.slice
    84  	   3:freezer:/
    85  	   2:pids:/
    86  	   1:name=systemd:/user.slice/user-1000.slice/session-1759.scope
    87  	*/
    88  
    89  	dataArray := strings.Split(data, "\n")
    90  	for index := range dataArray {
    91  		kvArray := strings.Split(dataArray[index], ":")
    92  		if len(kvArray) == 3 {
    93  			if kvArray[1] == "memory" {
    94  				return kvArray[2], nil
    95  			}
    96  		}
    97  	}
    98  
    99  	return "", errors.New("Unable to get memory cgroup path")
   100  }
   101  
   102  func readFileAndGetValue(path string) (uint64, error) {
   103  	data, err := ioutil.ReadFile(path)
   104  	if err != nil {
   105  		log.Debugf("Unable to read file %v error: %v", path, err)
   106  		return 0, err
   107  	}
   108  
   109  	return strconv.ParseUint(strings.TrimSpace(string(data)), 10, 64)
   110  }