swaps.go

Documentation: github.com/prometheus/procfs

     1  // Copyright 2019 The Prometheus Authors
     2  // Licensed under the Apache License, Version 2.0 (the "License");
     3  // you may not use this file except in compliance with the License.
     4  // You may obtain a copy of the License at
     5  //
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package procfs
    15  
    16  import (
    17  	"bufio"
    18  	"bytes"
    19  	"fmt"
    20  	"strconv"
    21  	"strings"
    22  
    23  	"github.com/prometheus/procfs/internal/util"
    24  )
    25  
    26  // Swap represents an entry in /proc/swaps.
    27  type Swap struct {
    28  	Filename string
    29  	Type     string
    30  	Size     int
    31  	Used     int
    32  	Priority int
    33  }
    34  
    35  // Swaps returns a slice of all configured swap devices on the system.
    36  func (fs FS) Swaps() ([]*Swap, error) {
    37  	data, err := util.ReadFileNoStat(fs.proc.Path("swaps"))
    38  	if err != nil {
    39  		return nil, err
    40  	}
    41  	return parseSwaps(data)
    42  }
    43  
    44  func parseSwaps(info []byte) ([]*Swap, error) {
    45  	swaps := []*Swap{}
    46  	scanner := bufio.NewScanner(bytes.NewReader(info))
    47  	scanner.Scan() // ignore header line
    48  	for scanner.Scan() {
    49  		swapString := scanner.Text()
    50  		parsedSwap, err := parseSwapString(swapString)
    51  		if err != nil {
    52  			return nil, err
    53  		}
    54  		swaps = append(swaps, parsedSwap)
    55  	}
    56  
    57  	err := scanner.Err()
    58  	return swaps, err
    59  }
    60  
    61  func parseSwapString(swapString string) (*Swap, error) {
    62  	var err error
    63  
    64  	swapFields := strings.Fields(swapString)
    65  	swapLength := len(swapFields)
    66  	if swapLength < 5 {
    67  		return nil, fmt.Errorf("%w: too few fields in swap string: %s", ErrFileParse, swapString)
    68  	}
    69  
    70  	swap := &Swap{
    71  		Filename: swapFields[0],
    72  		Type:     swapFields[1],
    73  	}
    74  
    75  	swap.Size, err = strconv.Atoi(swapFields[2])
    76  	if err != nil {
    77  		return nil, fmt.Errorf("%s: invalid swap size: %s: %w", ErrFileParse, swapFields[2], err)
    78  	}
    79  	swap.Used, err = strconv.Atoi(swapFields[3])
    80  	if err != nil {
    81  		return nil, fmt.Errorf("%s: invalid swap used: %s: %w", ErrFileParse, swapFields[3], err)
    82  	}
    83  	swap.Priority, err = strconv.Atoi(swapFields[4])
    84  	if err != nil {
    85  		return nil, fmt.Errorf("%s: invalid swap priority: %s: %w", ErrFileParse, swapFields[4], err)
    86  	}
    87  
    88  	return swap, nil
    89  }
    90
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