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file.go
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file.go
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package file
import (
"context"
"io/ioutil"
"os"
"sync"
"time"
"github.com/fsnotify/fsnotify"
logger "github.com/gokits/stdlogger"
"github.com/gokits/stdlogger/nooplogger"
)
type File struct {
filename string
watcher *fsnotify.Watcher
rw sync.RWMutex
logger logger.LeveledLogger
content []byte
ver int64
c chan struct{}
ignoreEvents map[fsnotify.Op]struct{}
}
type Option func(*File)
func WithLogger(log logger.LeveledLogger) Option {
return func(f *File) {
f.logger = log
}
}
func WithIgnoreEvents(ops []fsnotify.Op) Option {
return func(f *File) {
for _, op := range ops {
f.ignoreEvents[op] = struct{}{}
}
}
}
func NewFileSource(filename string, opts ...Option) (fs *File, err error) {
fs = &File{
filename: filename,
logger: nooplogger.Default(),
ignoreEvents: make(map[fsnotify.Op]struct{}),
}
for _, opt := range opts {
opt(fs)
}
if fs.watcher, err = fsnotify.NewWatcher(); err != nil {
return
}
defer func() {
if err != nil {
fs.watcher.Close()
}
}()
fs.c = make(chan struct{})
go fs.run()
return
}
func (f *File) readfile() error {
fh, err := os.OpenFile(f.filename, os.O_RDONLY, 0444)
if err != nil {
return err
}
defer fh.Close()
ct, err := ioutil.ReadAll(fh)
if err != nil {
return err
}
f.rw.Lock()
close(f.c)
f.c = make(chan struct{})
f.content = ct
f.ver += 1
f.rw.Unlock()
return nil
}
func (f *File) run() {
var err error
watched := false
for {
for !watched {
select {
case e, ok := <-f.watcher.Events:
if !ok {
f.Close()
f.logger.Info("watcher.Events closed")
return
}
f.logger.Warnf("unexpected watched event %v", e)
case err, ok := <-f.watcher.Errors:
f.Close()
if ok {
f.logger.Warnf("watched error %v", err)
} else {
f.logger.Info("watcher.Errors closed")
}
return
default:
}
if err = f.watcher.Add(f.filename); err != nil {
f.logger.Infof("watcher.Add %s failed: %v", f.filename, err)
time.Sleep(time.Second)
continue
}
watched = true
if err = f.readfile(); err != nil {
f.logger.Warnf("readfile of %s failed: %v", f.filename, err)
}
}
select {
case ev, ok := <-f.watcher.Events:
if !ok {
f.Close()
f.logger.Info("watcher.Events closed")
return
}
f.logger.Debugf("watched event: %v", ev)
watched = f.handleEvent(ev)
case err, ok := <-f.watcher.Errors:
f.Close()
if ok {
f.logger.Errorf("watched error %v of %s", err, f.filename)
} else {
f.logger.Info("watcher.Errors closed")
}
return
}
}
}
func (f *File) Next(ctx context.Context, preversion int64) (content []byte, curversion int64, ok bool) {
f.rw.RLock()
if f.ver != preversion {
defer f.rw.RUnlock()
content, curversion, ok = f.content, f.ver, true
return
}
copyc := f.c
f.rw.RUnlock()
select {
case <-ctx.Done():
return
case <-copyc:
f.rw.RLock()
content, curversion, ok = f.content, f.ver, true
f.rw.RUnlock()
return
}
}
func (f *File) Close() {
f.watcher.Close()
f.rw.Lock()
defer f.rw.Unlock()
select {
case <-f.c:
return
default:
close(f.c)
}
}