fix: gc was being stupid allowing another thread to take the space it made before it could not anymore

steamcache/steamcache.go

@@ -68,7 +68,7 @@ type SteamCache struct {
 	wg     sync.WaitGroup
 }
 
-func New(address string, memorySize string, memoryMultiplier int, diskSize string, diskMultiplier int, diskPath, upstream string) *SteamCache {
+func New(address string, memorySize string, diskSize string, diskPath, upstream string) *SteamCache {
 	memorysize, err := units.FromHumanSize(memorySize)
 	if err != nil {
 		panic(err)
@@ -87,14 +87,14 @@ func New(address string, memorySize string, memoryMultiplier int, diskSize strin
 	var mgc *gc.GCFS
 	if memorysize > 0 {
 		m = memory.New(memorysize)
-		mgc = gc.New(m, memoryMultiplier, gc.LRUGC)
+		mgc = gc.New(m, gc.LRUGC)
 	}
 
 	var d *disk.DiskFS
 	var dgc *gc.GCFS
 	if disksize > 0 {
 		d = disk.New(diskPath, disksize)
-		dgc = gc.New(d, diskMultiplier, gc.LRUGC)
+		dgc = gc.New(d, gc.LRUGC)
 	}
 
 	// configure the cache to match the specified mode (memory only, disk only, or memory and disk) based on the provided sizes
@@ -220,16 +220,16 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	if strings.HasPrefix(r.URL.String(), "/depot/") {
 		// trim the query parameters from the URL path
 		// this is necessary because the cache key should not include query parameters
-		r.URL.Path = strings.Split(r.URL.Path, "?")[0]
+		path := strings.Split(r.URL.String(), "?")[0]
 
 		tstart := time.Now()
 		defer func() { responseTime.Observe(time.Since(tstart).Seconds()) }()
 
-		cacheKey := strings.ReplaceAll(r.URL.String()[1:], "\\", "/") // replace all backslashes with forward slashes shouldn't be necessary but just in case
+		cacheKey := strings.ReplaceAll(path[1:], "\\", "/") // replace all backslashes with forward slashes shouldn't be necessary but just in case
 
 		if cacheKey == "" {
 			requestsTotal.WithLabelValues(r.Method, "400").Inc()
-			logger.Logger.Warn().Str("url", r.URL.String()).Msg("Invalid URL")
+			logger.Logger.Warn().Str("url", path).Msg("Invalid URL")
 			http.Error(w, "Invalid URL", http.StatusBadRequest)
 			return
 		}
@@ -258,7 +258,7 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 		var req *http.Request
 		if sc.upstream != "" { // if an upstream server is configured, proxy the request to the upstream server
-			ur, err := url.JoinPath(sc.upstream, r.URL.String())
+			ur, err := url.JoinPath(sc.upstream, path)
 			if err != nil {
 				requestsTotal.WithLabelValues(r.Method, "500").Inc()
 				logger.Logger.Error().Err(err).Str("upstream", sc.upstream).Msg("Failed to join URL path")
@@ -282,7 +282,7 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				host = "http://" + host
 			}
 
-			ur, err := url.JoinPath(host, r.URL.String())
+			ur, err := url.JoinPath(host, path)
 			if err != nil {
 				requestsTotal.WithLabelValues(r.Method, "500").Inc()
 				logger.Logger.Error().Err(err).Str("host", host).Msg("Failed to join URL path")
@@ -328,16 +328,17 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 		size := resp.ContentLength
 
-		writer, err := sc.vfs.Create(cacheKey, size)
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
+		// this is sortof not needed as we should always be able to get a writer from the cache as long as the gc is able to reclaim enough space aka the file is not bigger than the disk can handle
+		ww := w.(io.Writer)                        // default writer to write to the response writer
+		writer, _ := sc.vfs.Create(cacheKey, size) // create a writer to write to the cache
+		if writer != nil {                         // if the writer is not nil, it means the cache is writable
+			defer writer.Close()           // close the writer when done
+			ww = io.MultiWriter(w, writer) // write to both the response writer and the cache writer
 		}
-		defer writer.Close()
 
 		w.Header().Add("X-LanCache-Status", "MISS")
 
-		io.Copy(io.MultiWriter(w, writer), resp.Body)
+		io.Copy(ww, resp.Body)
 
 		logger.Logger.Info().
 			Str("key", cacheKey).

steamcache/steamcache_test.go

@@ -13,7 +13,7 @@ func TestCaching(t *testing.T) {
 
 	os.WriteFile(filepath.Join(td, "key2"), []byte("value2"), 0644)
 
-	sc := New("localhost:8080", "1G", 10, "1G", 100, td, "")
+	sc := New("localhost:8080", "1G", "1G", td, "")
 
 	w, err := sc.vfs.Create("key", 5)
 	if err != nil {
@@ -84,7 +84,7 @@ func TestCaching(t *testing.T) {
 }
 
 func TestCacheMissAndHit(t *testing.T) {
-	sc := New("localhost:8080", "0", 0, "1G", 100, t.TempDir(), "")
+	sc := New("localhost:8080", "0", "1G", t.TempDir(), "")
 
 	key := "testkey"
 	value := []byte("testvalue")