path: root/metrics/disk_linux.go

// Contains the Linux implementation of process disk IO counter retrieval.

package metrics

import (
    "bufio"
    "fmt"
    "io"
    "os"
    "strconv"
    "strings"
)

// ReadDiskStats retrieves the disk IO stats belonging to the current process.
func ReadDiskStats(stats *DiskStats) error {
    // Open the process disk IO counter file
    inf, err := os.Open(fmt.Sprintf("/proc/%d/io", os.Getpid()))
    if err != nil {
        return err
    }
    in := bufio.NewReader(inf)

    // Iterate over the IO counter, and extract what we need
    for {
        // Read the next line and split to key and value
        line, err := in.ReadString('\n')
        if err != nil {
            if err == io.EOF {
                return nil
            }
            return err
        }
        key, value := "", int64(0)
        if parts := strings.Split(line, ":"); len(parts) != 2 {
            continue
        } else {
            key = strings.TrimSpace(parts[0])
            if value, err = strconv.ParseInt(strings.TrimSpace(parts[1]), 10, 64); err != nil {
                return err
            }
        }
        // Update the counter based on the key
        switch key {
        case "syscr":
            stats.ReadCount = value
        case "syscw":
            stats.WriteCount = value
        case "rchar":
            stats.ReadBytes = value
        case "wchar":
            stats.WriteBytes = value
        }
    }
    return nil
}