Improve error handling by adding DISCARDED state for events

client/asink.go

@@ -109,15 +109,27 @@ func ProcessLocalEvent(globals AsinkGlobals, event *asink.Event) {
 		//copy to tmp
 		//TODO upload in chunks and check modification times to make sure it hasn't been changed instead of copying the whole thing off
 		tmpfilename, err := util.CopyToTmp(event.Path, globals.tmpDir)
-		if err != nil && !util.ErrorFileNotFound(err) {
+		if err != nil {
+			//bail out if the file we are trying to upload already got deleted
+			if util.ErrorFileNotFound(err) {
+				event.Status |= asink.DISCARDED
+				return
+			}
 			panic(err)
 		}
 
+		//try to collect the file's permissions
 		fileinfo, err := os.Stat(event.Path)
-		if err != nil && !util.ErrorFileNotFound(err) {
-			panic(err)
+		if err != nil {
+			//bail out if the file we are trying to upload already got deleted
+			if util.ErrorFileNotFound(err) {
+				event.Status |= asink.DISCARDED
+				return
 			}
+			panic(err)
+		} else {
 			event.Permissions = fileinfo.Mode()
+		}
 
 		//get the file's hash
 		hash, err := HashFile(tmpfilename)
@@ -129,6 +141,7 @@ func ProcessLocalEvent(globals AsinkGlobals, event *asink.Event) {
 		//If the file didn't actually change, squash this event
 		if latestLocal != nil && event.Hash == latestLocal.Hash {
 			os.Remove(tmpfilename)
+			event.Status |= asink.DISCARDED
 			return
 		}
 
@@ -148,6 +161,12 @@ func ProcessLocalEvent(globals AsinkGlobals, event *asink.Event) {
 		if err != nil {
 			panic(err)
 		}
+	} else {
+		//if we're trying to delete a file that we thought was already deleted, there's no need to delete it again
+		if latestLocal != nil && latestLocal.IsDelete() {
+			event.Status |= asink.DISCARDED
+			return
+		}
 	}
 
 	//finally, send it off to the server
@@ -155,16 +174,16 @@ func ProcessLocalEvent(globals AsinkGlobals, event *asink.Event) {
 	if err != nil {
 		panic(err) //TODO handle sensibly
 	}
-
 }
 
 func ProcessRemoteEvent(globals AsinkGlobals, event *asink.Event) {
 	latestLocal := LockPath(event.Path, true)
 	defer UnlockPath(event)
+
 	//if we already have this event, or if it is older than our most recent event, bail out
 	if latestLocal != nil {
 		if event.Timestamp < latestLocal.Timestamp || event.IsSameEvent(latestLocal) {
-			UnlockPath(event)
+			event.Status |= asink.DISCARDED
 			return
 		}
 
@@ -226,7 +245,6 @@ func ProcessRemoteEvent(globals AsinkGlobals, event *asink.Event) {
 		//TODO delete file hierarchy beneath this file if its the last one in its directory?
 	}
 
-	fmt.Println(event)
 	//TODO make sure file being overwritten is either unchanged or already copied off and hashed
 }
 

client/net.go

@@ -26,7 +26,6 @@ func SendEvent(globals AsinkGlobals, event *asink.Event) error {
 	if err != nil {
 		return err
 	}
-	fmt.Println(string(b))
 
 	//actually make the request
 	resp, err := http.Post(url, "application/json", bytes.NewReader(b))

client/path_map.go

@@ -32,6 +32,8 @@ func PathLocker(db *AsinkDB) {
 		select {
 		case event = <-pathUnlockerChan:
 			if v, ok = m[event.Path]; ok != false {
+				//only update status in data structures if the event hasn't been discarded
+				if event.Status&asink.DISCARDED == 0 {
 					if v.latestEvent == nil || !v.latestEvent.IsSameEvent(event) {
 						err := db.DatabaseAddEvent(event)
 						if err != nil {
@@ -40,14 +42,15 @@ func PathLocker(db *AsinkDB) {
 						//TODO batch database writes instead of doing one at a time
 					}
 					v.latestEvent = event
+				}
 				if len(v.localWaiters) > 0 {
 					c = v.localWaiters[0]
 					v.localWaiters = v.localWaiters[1:]
-					c <- event
+					c <- v.latestEvent
 				} else if len(v.remoteWaiters) > 0 {
 					c = v.remoteWaiters[0]
 					v.remoteWaiters = v.remoteWaiters[1:]
-					c <- event
+					c <- v.latestEvent
 				} else {
 					v.locked = false
 				}

client/watcher.go

@@ -47,7 +47,6 @@ func StartWatching(watchDir string, fileUpdates chan *asink.Event) {
 					panic("Unknown fsnotify event type")
 				}
 
-				event.Status = asink.NOTICED
 				event.Path = ev.Name
 				event.Timestamp = time.Now().UnixNano()
 

events.go

@@ -16,17 +16,8 @@ const (
 type EventStatus uint32
 
 const (
-	//the state of the event on the local asink instance on which it originated:
-	NOTICED       = 1 << iota //watcher.go has been notified that a file changed
-	COPIED_TO_TMP             //temporary version saved off
-	HASHED                    //hash taken of tmp file
-	CACHED                    //tmp file renamed to its hash
-	UPLOADED                  //tmp file has been successfully uploaded to storage
-	ON_SERVER                 //server has been successfully notified of event
-	//the state of the event on the asink instance notified that it occurred elsewhere
-	NOTIFIED   //we've been told a file has been changed remotely
-	DOWNLOADED //event has been downloaded and stored in the local file cache
-	SYNCED     //everything has been done to ensure the affected file is up-to-date
+	//Local event status flags
+	DISCARDED       = 1 << iota //event is to be discarded because it errored or is duplicate
 )
 
 type Event struct {