tag all events with a monotonic id in order to ignore outdated ones

4 files changed, 22 insertions, 28 deletions

diff --git a/TODO.md b/TODO.md
index 1361126..49f4a23 100644
--- a/TODO.md
+++ b/TODO.md
@@ -14,6 +14,7 @@
 - [X] escape HTML 
 - [X] support incremental search results
   - [X] distinguish different search queries
+- [ ] do not apply obsolete events
 
 ## Web Backend
 
@@ -21,7 +22,9 @@
 
 ## Backends
 
+- [ ] cancel old searches
 - [ ] make wrms thread safe
+  - [X] tag events with ids
 - [X] paralyze search
   - [X] report results incrementally
   - [X] distinguish different search queries
diff --git a/main.go b/main.go
index 8ff3a81..532cead 100644
--- a/main.go
+++ b/main.go
@@ -8,7 +8,6 @@ import (
 	"html/template"
 	"io"
 	"net/http"
-	"strconv"
 	"strings"
 	"time"
 
@@ -85,11 +84,7 @@ func searchHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	id, ok := strconv.Atoi(r.URL.Query().Get("id"))
-	if ok != err {
-		http.Error(w, "No or invalid search id provided", http.StatusBadRequest)
-		return
-	}
+	id := wrms.eventId.Add(1)
 
 	llog.Debug("Searching for %s", pattern)
 
@@ -99,7 +94,7 @@ func searchHandler(w http.ResponseWriter, r *http.Request) {
 	go func() {
 		for result := range resultsChan {
 			if len(result) > 0 {
-				conn.Send(newSearchResultEvent(id, result))
+				conn.Send(Event{Event: "search", Id: id, Songs: result})
 			}
 		}
 
@@ -235,7 +230,7 @@ func wsEndpoint(w http.ResponseWriter, r *http.Request) {
 		if currentSong := wrms.CurrentSong.Load(); currentSong != nil {
 			songs = []Song{*currentSong}
 		}
-		data, err := json.Marshal(newEvent("play", songs))
+		data, err := json.Marshal(wrms.newEvent("play", songs))
 		if err != nil {
 			llog.Error("Encoding the play event failed with %s", err)
 			return
@@ -246,7 +241,7 @@ func wsEndpoint(w http.ResponseWriter, r *http.Request) {
 	upvoted := []Song{}
 	downvoted := []Song{}
 	if len(wrms.Songs) > 0 {
-		data, err := json.Marshal(newEvent("add", wrms.Songs))
+		data, err := json.Marshal(wrms.newEvent("add", wrms.Songs))
 		if err != nil {
 			llog.Error("Encoding the add event failed with %s", err)
 			return
@@ -263,7 +258,7 @@ func wsEndpoint(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if len(upvoted) > 0 {
-		data, err := json.Marshal(newEvent("upvoted", upvoted))
+		data, err := json.Marshal(wrms.newEvent("upvoted", upvoted))
 		if err != nil {
 			llog.Error("Encoding the upvoted event failed with %s", err)
 			return
@@ -272,7 +267,7 @@ func wsEndpoint(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if len(downvoted) > 0 {
-		data, err := json.Marshal(newEvent("downvoted", downvoted))
+		data, err := json.Marshal(wrms.newEvent("downvoted", downvoted))
 		if err != nil {
 			llog.Error("Encoding the upvoted event failed with %s", err)
 			return
diff --git a/web/client.html b/web/client.html
index 8e0fa04..41e224f 100644
--- a/web/client.html
+++ b/web/client.html
@@ -291,7 +291,6 @@
 
         const form = new FormData(document.getElementById("searchForm"));
         const urlParams = new URLSearchParams(form);
-        urlParams.append("id", searchId);
         new HttpClient().get("/search?" + urlParams.toString(), console.log);
         return false;
       }
@@ -320,12 +319,12 @@
         searchingIndicator.style.display = "none";
         let searchResultsOverlay = document.getElementById("searchResultsOverlay");
         searchResultsOverlay['aria-busy'] = false;
-        searchId += 1;
       }
 
       function handleSearch(id, songs) {
         // Ignore stale search results
         if (id < searchId) { return; }
+        if (id > searchId) { searchId = id; }
 
         let searchResultsOverlay = document.getElementById("searchResultsOverlay");
         let searchResults = document.getElementById("searchResults");
diff --git a/wrms.go b/wrms.go
index 9409b49..c983eb5 100644
--- a/wrms.go
+++ b/wrms.go
@@ -42,20 +42,16 @@ func NewSongFromJson(data []byte) (Song, error) {
 
 type Event struct {
 	Event string `json:"cmd"`
-	Id    int    `json:"id"`
+	Id    uint64 `json:"id"`
 	Songs []Song `json:"songs"`
 }
 
-func newEvent(event string, songs []Song) Event {
-	return Event{Event: event, Songs: songs}
+func (wrms *Wrms) newEvent(event string, songs []Song) Event {
+	return Event{Event: event, Id: wrms.eventId.Add(1), Songs: songs}
 }
 
 func newNotification(notification string) Event {
-	return Event{Event: notification}
-}
-
-func newSearchResultEvent(id int, songs []Song) Event {
-	return Event{Event: "search", Id: id, Songs: songs}
+	return Event{Event: notification, Id: wrms.eventId.Add(1)}
 }
 
 type Connection struct {
@@ -116,6 +112,7 @@ type Wrms struct {
 	Player      Player
 	Playing     bool
 	Config      Config
+	eventId     atomic.Uint64
 }
 
 func NewWrms(config Config) *Wrms {
@@ -150,7 +147,7 @@ func (wrms *Wrms) Broadcast(ev Event) {
 
 func (wrms *Wrms) startPlaying() {
 	currentSong := wrms.CurrentSong.Load()
-	wrms.Broadcast(newEvent("play", []Song{*currentSong}))
+	wrms.Broadcast(wrms.newEvent("play", []Song{*currentSong}))
 }
 
 func (wrms *Wrms) AddSong(song Song) {
@@ -159,7 +156,7 @@ func (wrms *Wrms) AddSong(song Song) {
 	s := &wrms.Songs[len(wrms.Songs)-1]
 	wrms.queue.Add(s)
 	llog.Info("Added song %s (ptr=%p) to Songs", s.Uri, s)
-	wrms.Broadcast(newEvent("add", []Song{song}))
+	wrms.Broadcast(wrms.newEvent("add", []Song{song}))
 
 	if startPlayingAgain {
 		wrms.Next()
@@ -177,7 +174,7 @@ func (wrms *Wrms) DeleteSong(songUri string) {
 		wrms.Songs = wrms.Songs[:len(wrms.Songs)-1]
 
 		wrms.queue.RemoveSong(s)
-		wrms.Broadcast(newEvent("delete", []Song{*s}))
+		wrms.Broadcast(wrms.newEvent("delete", []Song{*s}))
 		break
 	}
 }
@@ -205,10 +202,10 @@ func (wrms *Wrms) Next() {
 	}
 
 	if wrms.Playing {
-		wrms.Broadcast(newEvent("play", []Song{*next}))
+		wrms.Broadcast(wrms.newEvent("play", []Song{*next}))
 		wrms.Player.Play(next)
 	} else if wrms.Player.mpv != nil {
-		wrms.Broadcast(newEvent("next", []Song{*next}))
+		wrms.Broadcast(wrms.newEvent("next", []Song{*next}))
 		wrms.Player.terminateMpv()
 	}
 }
@@ -222,7 +219,7 @@ func (wrms *Wrms) PlayPause() {
 			llog.Info("No song currently playing play the next")
 			wrms.Next()
 		} else {
-			wrms.Broadcast(newEvent("play", []Song{*currentSong}))
+			wrms.Broadcast(wrms.newEvent("play", []Song{*currentSong}))
 			if wrms.Player.mpv != nil {
 				wrms.Player.Continue()
 			} else {
@@ -293,7 +290,7 @@ func (wrms *Wrms) AdjustSongWeight(connId uuid.UUID, songUri string, vote string
 		}
 
 		wrms.queue.Adjust(s)
-		wrms.Broadcast(newEvent("update", []Song{*s}))
+		wrms.Broadcast(wrms.newEvent("update", []Song{*s}))
 		break
 	}
 }