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tombstone.go
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tombstone.go
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package tombstone
import (
"context"
"encoding/json"
"fmt"
"io/ioutil"
"log"
"os"
"path/filepath"
"sync"
"time"
"github.com/fsnotify/fsnotify"
"sigs.k8s.io/yaml"
)
type Tombstone struct {
Born *time.Time `json:",omitempty"`
Died *time.Time `json:",omitempty"`
ExitCode *int `json:",omitempty"`
Graveyard string `json:"-"`
Name string `json:"-"`
fileLock sync.Mutex `json:"-"`
}
func (t *Tombstone) Path() string {
return filepath.Join(t.Graveyard, t.Name)
}
// Write a tombstone file, truncating before writing.
// If the FilePath directories do not exist, they will be created.
func (t *Tombstone) Write() error {
// one write at a time
t.fileLock.Lock()
defer t.fileLock.Unlock()
err := os.MkdirAll(t.Graveyard, os.ModePerm)
if err != nil {
return err
}
// does not exit
file, err := os.Create(t.Path())
if err != nil {
return fmt.Errorf("failed to create tombstone file: %v", err)
}
defer file.Close()
pretty, err := yaml.Marshal(t)
if err != nil {
return fmt.Errorf("failed to marshal tombstone yaml: %v", err)
}
file.Write(pretty)
return nil
}
func (t *Tombstone) RecordBirth() error {
born := time.Now()
t.Born = &born
log.Printf("Creating tombstone: %s\n", t.Path())
err := t.Write()
if err != nil {
return fmt.Errorf("failed to create tombstone: ", err)
}
return nil
}
func (t *Tombstone) RecordDeath(exitCode int) error {
code := exitCode
died := time.Now()
t.Died = &died
t.ExitCode = &code
log.Printf("Updating tombstone: %s\n", t.Path())
err := t.Write()
if err != nil {
return fmt.Errorf("failed to update tombstone: ", err)
}
return nil
}
func (t *Tombstone) String() string {
inline, err := json.Marshal(t)
if err != nil {
return fmt.Sprintf("%+v", t)
}
return string(inline)
}
// Read a tombstone from a graveyard.
func Read(graveyard, name string) (*Tombstone, error) {
t := Tombstone{
Graveyard: graveyard,
Name: name,
}
bytes, err := ioutil.ReadFile(t.Path())
if err != nil {
return nil, fmt.Errorf("failed to read tombstone file: %v", err)
}
err = yaml.Unmarshal(bytes, &t)
if err != nil {
return nil, fmt.Errorf("failed to unmarshal tombstone yaml: %v", err)
}
return &t, nil
}
type EventHandler func(fsnotify.Event)
// LoggingEventHandler is an example EventHandler that logs fsnotify events
func LoggingEventHandler(event fsnotify.Event) {
if event.Op&fsnotify.Create == fsnotify.Create {
log.Printf("Tombstone Watch: file created: %s\n", event.Name)
}
if event.Op&fsnotify.Remove == fsnotify.Remove {
log.Printf("Tombstone Watch: file removed: %s\n", event.Name)
}
if event.Op&fsnotify.Write == fsnotify.Write {
log.Printf("Tombstone Watch: file modified: %s\n", event.Name)
}
if event.Op&fsnotify.Rename == fsnotify.Rename {
log.Printf("Tombstone Watch: file renamed: %s\n", event.Name)
}
if event.Op&fsnotify.Chmod == fsnotify.Chmod {
log.Printf("Tombstone Watch: file chmoded: %s\n", event.Name)
}
}
// Watch a graveyard and call the eventHandler (asyncronously) when an
// event happens. When the supplied context is canceled, watching will stop.
func Watch(ctx context.Context, graveyard string, eventHandler EventHandler) error {
watcher, err := fsnotify.NewWatcher()
if err != nil {
return fmt.Errorf("failed to create watcher: %v", err)
}
go func() {
defer watcher.Close()
for {
select {
case <-ctx.Done():
log.Printf("Tombstone Watch(%s): done\n", graveyard)
return
case event, ok := <-watcher.Events:
if !ok {
return
}
eventHandler(event)
case err, ok := <-watcher.Errors:
if !ok {
return
}
log.Printf("Tombstone Watch(%s): error: %v\n", graveyard, err)
// TODO: wrap ctx with WithCancel and cancel on terminal errors, if any
}
}
}()
err = watcher.Add(graveyard)
if err != nil {
return fmt.Errorf("failed to add watcher: %v", err)
}
return nil
}