telegraf/internal/internal.go

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package internal
import (
"bufio"
"bytes"
"compress/gzip"
"context"
"crypto/rand"
"errors"
"io"
"log"
"math/big"
"os"
"os/exec"
"strconv"
"strings"
"syscall"
"time"
"unicode"
"github.com/alecthomas/units"
)
const alphanum string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
var (
TimeoutErr = errors.New("Command timed out.")
NotImplementedError = errors.New("not implemented yet")
VersionAlreadySetError = errors.New("version has already been set")
)
// Set via the main module
var version string
// Duration just wraps time.Duration
type Duration struct {
Duration time.Duration
}
// Size just wraps an int64
type Size struct {
Size int64
}
// SetVersion sets the telegraf agent version
func SetVersion(v string) error {
if version != "" {
return VersionAlreadySetError
}
version = v
return nil
}
// Version returns the telegraf agent version
func Version() string {
return version
}
// UnmarshalTOML parses the duration from the TOML config file
func (d *Duration) UnmarshalTOML(b []byte) error {
var err error
b = bytes.Trim(b, `'`)
// see if we can directly convert it
d.Duration, err = time.ParseDuration(string(b))
if err == nil {
return nil
}
// Parse string duration, ie, "1s"
if uq, err := strconv.Unquote(string(b)); err == nil && len(uq) > 0 {
d.Duration, err = time.ParseDuration(uq)
if err == nil {
return nil
}
}
// First try parsing as integer seconds
sI, err := strconv.ParseInt(string(b), 10, 64)
if err == nil {
d.Duration = time.Second * time.Duration(sI)
return nil
}
// Second try parsing as float seconds
sF, err := strconv.ParseFloat(string(b), 64)
if err == nil {
d.Duration = time.Second * time.Duration(sF)
return nil
}
return nil
}
func (s *Size) UnmarshalTOML(b []byte) error {
var err error
b = bytes.Trim(b, `'`)
val, err := strconv.ParseInt(string(b), 10, 64)
if err == nil {
s.Size = val
return nil
}
uq, err := strconv.Unquote(string(b))
if err != nil {
return err
}
val, err = units.ParseStrictBytes(uq)
if err != nil {
return err
}
s.Size = val
return nil
}
// ReadLines reads contents from a file and splits them by new lines.
// A convenience wrapper to ReadLinesOffsetN(filename, 0, -1).
func ReadLines(filename string) ([]string, error) {
return ReadLinesOffsetN(filename, 0, -1)
}
// ReadLines reads contents from file and splits them by new line.
// The offset tells at which line number to start.
// The count determines the number of lines to read (starting from offset):
// n >= 0: at most n lines
// n < 0: whole file
func ReadLinesOffsetN(filename string, offset uint, n int) ([]string, error) {
f, err := os.Open(filename)
if err != nil {
return []string{""}, err
}
defer f.Close()
var ret []string
r := bufio.NewReader(f)
for i := 0; i < n+int(offset) || n < 0; i++ {
line, err := r.ReadString('\n')
if err != nil {
break
}
if i < int(offset) {
continue
}
ret = append(ret, strings.Trim(line, "\n"))
}
return ret, nil
}
// RandomString returns a random string of alpha-numeric characters
func RandomString(n int) string {
var bytes = make([]byte, n)
rand.Read(bytes)
for i, b := range bytes {
bytes[i] = alphanum[b%byte(len(alphanum))]
}
return string(bytes)
}
// SnakeCase converts the given string to snake case following the Golang format:
// acronyms are converted to lower-case and preceded by an underscore.
func SnakeCase(in string) string {
runes := []rune(in)
length := len(runes)
var out []rune
for i := 0; i < length; i++ {
if i > 0 && unicode.IsUpper(runes[i]) && ((i+1 < length && unicode.IsLower(runes[i+1])) || unicode.IsLower(runes[i-1])) {
out = append(out, '_')
}
out = append(out, unicode.ToLower(runes[i]))
}
return string(out)
}
// CombinedOutputTimeout runs the given command with the given timeout and
// returns the combined output of stdout and stderr.
// If the command times out, it attempts to kill the process.
func CombinedOutputTimeout(c *exec.Cmd, timeout time.Duration) ([]byte, error) {
var b bytes.Buffer
c.Stdout = &b
c.Stderr = &b
if err := c.Start(); err != nil {
return nil, err
}
err := WaitTimeout(c, timeout)
return b.Bytes(), err
}
// RunTimeout runs the given command with the given timeout.
// If the command times out, it attempts to kill the process.
func RunTimeout(c *exec.Cmd, timeout time.Duration) error {
if err := c.Start(); err != nil {
return err
}
return WaitTimeout(c, timeout)
}
// WaitTimeout waits for the given command to finish with a timeout.
// It assumes the command has already been started.
// If the command times out, it attempts to kill the process.
func WaitTimeout(c *exec.Cmd, timeout time.Duration) error {
timer := time.AfterFunc(timeout, func() {
err := c.Process.Kill()
if err != nil {
log.Printf("E! FATAL error killing process: %s", err)
return
}
})
err := c.Wait()
isTimeout := timer.Stop()
if err != nil {
return err
} else if isTimeout == false {
return TimeoutErr
}
return err
}
// RandomSleep will sleep for a random amount of time up to max.
// If the shutdown channel is closed, it will return before it has finished
// sleeping.
func RandomSleep(max time.Duration, shutdown chan struct{}) {
if max == 0 {
return
}
maxSleep := big.NewInt(max.Nanoseconds())
var sleepns int64
if j, err := rand.Int(rand.Reader, maxSleep); err == nil {
sleepns = j.Int64()
}
t := time.NewTimer(time.Nanosecond * time.Duration(sleepns))
select {
case <-t.C:
return
case <-shutdown:
t.Stop()
return
}
}
// RandomDuration returns a random duration between 0 and max.
func RandomDuration(max time.Duration) time.Duration {
if max == 0 {
return 0
}
var sleepns int64
maxSleep := big.NewInt(max.Nanoseconds())
if j, err := rand.Int(rand.Reader, maxSleep); err == nil {
sleepns = j.Int64()
}
return time.Duration(sleepns)
}
// SleepContext sleeps until the context is closed or the duration is reached.
func SleepContext(ctx context.Context, duration time.Duration) error {
if duration == 0 {
return nil
}
t := time.NewTimer(duration)
select {
case <-t.C:
return nil
case <-ctx.Done():
t.Stop()
return ctx.Err()
}
}
// AlignDuration returns the duration until next aligned interval.
func AlignDuration(tm time.Time, interval time.Duration) time.Duration {
return AlignTime(tm, interval).Sub(tm)
}
// AlignTime returns the time of the next aligned interval.
func AlignTime(tm time.Time, interval time.Duration) time.Time {
truncated := tm.Truncate(interval)
if truncated == tm {
return tm
}
return truncated.Add(interval)
}
// Exit status takes the error from exec.Command
// and returns the exit status and true
// if error is not exit status, will return 0 and false
func ExitStatus(err error) (int, bool) {
if exiterr, ok := err.(*exec.ExitError); ok {
if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
return status.ExitStatus(), true
}
}
return 0, false
}
// CompressWithGzip takes an io.Reader as input and pipes
// it through a gzip.Writer returning an io.Reader containing
// the gzipped data.
// An error is returned if passing data to the gzip.Writer fails
func CompressWithGzip(data io.Reader) (io.Reader, error) {
pipeReader, pipeWriter := io.Pipe()
gzipWriter := gzip.NewWriter(pipeWriter)
var err error
go func() {
_, err = io.Copy(gzipWriter, data)
gzipWriter.Close()
// subsequent reads from the read half of the pipe will
// return no bytes and the error err, or EOF if err is nil.
pipeWriter.CloseWithError(err)
}()
return pipeReader, err
}