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watcher.go
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watcher.go
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package main
import (
"os"
"path"
"sync"
"syscall"
"time"
"github.com/ataul443/log"
)
const (
CREATE_EVENT = "CREATE"
MODIFY_EVENT = "MODIFY"
DELETE_EVENT = "DELETE"
)
type fileStat struct {
scanID uint
absPath string
baseName string
creationTime time.Time
modificationTime time.Time
}
type watcherOptn func(*Watcher)
type Watcher struct {
scanInterval time.Duration
rootPath string
logger log.Logger
excludeDir []string
rules []Rule
stopCh chan struct{}
fileStats map[string]fileStat
scanID uint
}
func WithLogger(logger log.Logger) watcherOptn {
return func(w *Watcher) {
w.logger = logger
}
}
func WithExcludeDir(excludeDir []string) watcherOptn {
return func(w *Watcher) {
w.excludeDir = excludeDir
}
}
func WithScanInterval(timeInterval int) watcherOptn {
return func(w *Watcher) {
w.scanInterval = time.Second * time.Duration(timeInterval)
}
}
func NewWatcher(rootPath string, rules []Rule, optns ...watcherOptn) *Watcher {
w := new(Watcher)
w.rootPath = rootPath
w.rules = rules
w.fileStats = make(map[string]fileStat)
w.scanID = 0
for _, optn := range optns {
optn(w)
}
return w
}
func (w *Watcher) Stop() {
// It might give panic if already closed
w.stopCh <- struct{}{}
}
func (w *Watcher) Watch() chan Event {
eventCh := make(chan Event, 10)
// ticker := time.NewTicker(w.scanInterval)
go func() {
w.logger.Infof("Started watching `%s` ...", w.rootPath)
ticker := time.NewTicker(w.scanInterval)
for {
select {
case <-ticker.C:
// Now its time for scan
w.scan(w.rootPath, eventCh)
w.scanID += 1
case <-w.stopCh:
return
}
}
}()
return eventCh
}
func (w *Watcher) scan(fullDirPath string, eventCh chan<- Event) {
fileInfoCollector := func() chan fileStat {
ch := make(chan fileStat)
go func() {
defer close(ch)
w.extractFileInfoFromDir(fullDirPath, ch)
}()
return ch
}
fileCh := fileInfoCollector()
w.detectEvents(fileCh, eventCh)
}
func (w *Watcher) eventDispatcher(f fileStat, eventName string, rules []Rule, eventCh chan<- Event) {
rule, err := searchPattern(f, eventName, w.rules)
if err != nil {
w.logger.Debugf("%s", err)
} else {
w.logger.Infof(`Matched pattern "%s" on "%s"`, rule.Pattern, f.baseName)
e := event{
fullFilePath: f.absPath,
baseFilePath: f.baseName,
rule: rule,
}
eventCh <- e
}
}
func (w *Watcher) detectEvents(fileCh chan fileStat, eventCh chan<- Event) {
for {
select {
case f, ok := <-fileCh:
if !ok {
// All scan done
// Check for deleted files
for k, v := range w.fileStats {
if v.scanID < w.scanID {
w.logger.Infof(`Detected "%s" on "%s"`, DELETE_EVENT, v.baseName)
// "DELETE" event detected
w.eventDispatcher(v, DELETE_EVENT, w.rules, eventCh)
delete(w.fileStats, k)
}
}
return
}
if w.scanID != uint(0) {
// Check if it is an event
oldFileInfo, ok := w.fileStats[f.absPath]
if !ok {
// New file found, "CREATE" event
w.logger.Infof(`Detected "%s" on "%s"`, CREATE_EVENT, f.baseName)
w.eventDispatcher(f, CREATE_EVENT, w.rules, eventCh)
} else {
isModified := oldFileInfo.modificationTime.Before(f.modificationTime)
if isModified {
// File modified, do something
w.logger.Infof(`Detected "%s" on "%s"`, MODIFY_EVENT, f.baseName)
w.eventDispatcher(f, MODIFY_EVENT, w.rules, eventCh)
}
}
}
w.fileStats[f.absPath] = f
}
}
}
func (w *Watcher) extractFileInfoFromDir(fullDirPath string, fileInfoCollector chan fileStat) {
d, err := os.Open(fullDirPath)
if err != nil {
log.Errorf("Failed to open `%s`: %s", fullDirPath, err)
return
}
// Be careful, this directory might contains millions of files
nodesInfo, err := d.Readdir(-1)
if err != nil {
log.Errorf("Failed to scan `%s`: %s", fullDirPath, err)
return
}
wg := &sync.WaitGroup{}
for _, n := range nodesInfo {
nextNode := path.Join(fullDirPath, n.Name())
if n.IsDir() {
// Check if directory needed to be excluded
if shouldDirExclude(n.Name(), w.excludeDir) {
log.Debugf("excluding %s", nextNode)
continue
}
// Node is a dir, do something about it
wg.Add(1)
go func() {
defer wg.Done()
w.extractFileInfoFromDir(nextNode, fileInfoCollector)
}()
} else {
// Node is a file, dispatch it to fileInfoCollector
stat_t := n.Sys().(*syscall.Stat_t)
fileInfoCollector <- fileStat{
scanID: w.scanID,
baseName: n.Name(),
absPath: nextNode,
creationTime: timespecToTime(stat_t.Ctim),
modificationTime: timespecToTime(stat_t.Mtim),
}
}
}
wg.Wait()
}