Merge pull request 'fix: trim query parameters from URL path in ServeHTTP to ensure cache key correctness' (#4) from fix/query-params into main

Reviewed-on: s1d3sw1ped/SteamCache2#4

.goreleaser.yaml

@@ -16,7 +16,7 @@ builds:
       - amd64
 
 archives:
-  - format: tar.gz
+  - formats: tar.gz
     name_template: >- 
       {{ .ProjectName }}_
       {{- title .Os }}_
@@ -26,7 +26,7 @@ archives:
       {{- if .Arm }}v{{ .Arm }}{{ end }}
     format_overrides:
       - goos: windows
-        format: zip
+        formats: zip
 
 changelog:
   sort: asc

cmd/root.go

@@ -1,7 +1,9 @@
+// cmd/root.go
 package cmd
 
 import (
 	"os"
+	"runtime"
 	"s1d3sw1ped/SteamCache2/steamcache"
 	"s1d3sw1ped/SteamCache2/steamcache/logger"
 	"s1d3sw1ped/SteamCache2/version"
@@ -11,6 +13,8 @@ import (
 )
 
 var (
+	threads int
+
 	memory           string
 	memorymultiplier int
 	disk             string
@@ -18,7 +22,6 @@ var (
 	diskpath         string
 	upstream         string
 
-	pprof     bool
 	logLevel  string
 	logFormat string
 )
@@ -52,21 +55,29 @@ var rootCmd = &cobra.Command{
 		logger.Logger = zerolog.New(writer).With().Timestamp().Logger()
 
 		logger.Logger.Info().
-			Msg("starting SteamCache2 " + version.Version)
+			Msg("SteamCache2 " + version.Version + " starting...")
+
+		address := ":80"
+
+		if runtime.GOMAXPROCS(-1) != threads {
+			runtime.GOMAXPROCS(threads)
+			logger.Logger.Info().
+				Int("threads", threads).
+				Msg("Maximum number of threads set")
+		}
 
 		sc := steamcache.New(
-			":80",
+			address,
 			memory,
 			memorymultiplier,
 			disk,
 			diskmultiplier,
 			diskpath,
 			upstream,
-			pprof,
 		)
 
 		logger.Logger.Info().
-			Msg("starting SteamCache2 on port 80")
+			Msg("SteamCache2 " + version.Version + " started on " + address)
 
 		sc.Run()
 
@@ -85,6 +96,8 @@ func Execute() {
 }
 
 func init() {
+	rootCmd.Flags().IntVarP(&threads, "threads", "t", runtime.GOMAXPROCS(-1), "Number of worker threads to use for processing requests")
+
 	rootCmd.Flags().StringVarP(&memory, "memory", "m", "0", "The size of the memory cache")
 	rootCmd.Flags().IntVarP(&memorymultiplier, "memory-gc", "M", 10, "The gc value for the memory cache")
 	rootCmd.Flags().StringVarP(&disk, "disk", "d", "0", "The size of the disk cache")
@@ -93,9 +106,6 @@ func init() {
 
 	rootCmd.Flags().StringVarP(&upstream, "upstream", "u", "", "The upstream server to proxy requests overrides the host header from the client but forwards the original host header to the upstream server")
 
-	rootCmd.Flags().BoolVarP(&pprof, "pprof", "P", false, "Enable pprof")
-	rootCmd.Flags().MarkHidden("pprof")
-
 	rootCmd.Flags().StringVarP(&logLevel, "log-level", "l", "info", "Logging level: debug, info, error")
 	rootCmd.Flags().StringVarP(&logFormat, "log-format", "f", "console", "Logging format: json, console")
 }

cmd/version.go

@@ -1,3 +1,4 @@
+// cmd/version.go
 package cmd
 
 import (

go.mod

@@ -7,7 +7,6 @@ require (
 	github.com/prometheus/client_golang v1.22.0
 	github.com/rs/zerolog v1.33.0
 	github.com/spf13/cobra v1.8.1
-	golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8
 )
 
 require (

go.sum

@@ -45,8 +45,6 @@ github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8 h1:yqrTHse8TCMW1M1ZCP+VAR/l0kKxwaAIqN/il7x4voA=
-golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8/go.mod h1:tujkw807nyEEAamNbDrEGzRav+ilXA7PCRAd6xsmwiU=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

main.go

@@ -1,3 +1,4 @@
+// main.go
 package main
 
 import (

steamcache/avgcachestate/avgcachestate.go

@@ -1,63 +0,0 @@
-package avgcachestate
-
-import (
-	"s1d3sw1ped/SteamCache2/vfs/cachestate"
-	"sync"
-)
-
-// AvgCacheState is a cache state that averages the last N cache states.
-type AvgCacheState struct {
-	size int
-	avgs []cachestate.CacheState
-	mu   sync.Mutex
-}
-
-// New creates a new average cache state with the given size.
-func New(size int) *AvgCacheState {
-	a := &AvgCacheState{
-		size: size,
-		avgs: make([]cachestate.CacheState, size),
-		mu:   sync.Mutex{},
-	}
-
-	a.Clear()
-
-	return a
-}
-
-// Clear resets the average cache state to zero.
-func (a *AvgCacheState) Clear() {
-	a.mu.Lock()
-	defer a.mu.Unlock()
-
-	for i := 0; i < len(a.avgs); i++ {
-		a.avgs[i] = cachestate.CacheStateMiss
-	}
-}
-
-// Add adds a cache state to the average cache state.
-func (a *AvgCacheState) Add(cs cachestate.CacheState) {
-	a.mu.Lock()
-	defer a.mu.Unlock()
-
-	a.avgs = append(a.avgs, cs)
-	if len(a.avgs) > a.size {
-		a.avgs = a.avgs[1:]
-	}
-}
-
-// Avg returns the average cache state.
-func (a *AvgCacheState) Avg() float64 {
-	a.mu.Lock()
-	defer a.mu.Unlock()
-
-	var hits int
-
-	for _, cs := range a.avgs {
-		if cs == cachestate.CacheStateHit {
-			hits++
-		}
-	}
-
-	return float64(hits) / float64(len(a.avgs))
-}

steamcache/gc.go

@@ -1,44 +0,0 @@
-package steamcache
-
-import (
-	"runtime/debug"
-	"s1d3sw1ped/SteamCache2/vfs"
-	"s1d3sw1ped/SteamCache2/vfs/cachestate"
-	"sort"
-	"time"
-)
-
-func init() {
-	// Set the GC percentage to 50%. This is a good balance between performance and memory usage.
-	debug.SetGCPercent(50)
-}
-
-// lruGC deletes files in LRU order until enough space is reclaimed.
-func lruGC(vfss vfs.VFS, size uint) (uint, uint) {
-	deletions := 0
-	var reclaimed uint
-
-	stats := vfss.StatAll()
-	sort.Slice(stats, func(i, j int) bool {
-		return stats[i].AccessTime().Before(stats[j].AccessTime())
-	})
-
-	for _, s := range stats {
-		sz := uint(s.Size())
-		err := vfss.Delete(s.Name())
-		if err != nil {
-			continue
-		}
-		reclaimed += sz
-		deletions++
-		if reclaimed >= size {
-			break
-		}
-	}
-
-	return reclaimed, uint(deletions)
-}
-
-func cachehandler(fi *vfs.FileInfo, cs cachestate.CacheState) bool {
-	return time.Since(fi.AccessTime()) < time.Second*10 // Put hot files in the fast vfs if equipped
-}

steamcache/logger/logger.go

@@ -1,3 +1,4 @@
+// steamcache/logger/logger.go
 package logger
 
 import (

steamcache/steamcache.go

@@ -1,25 +1,23 @@
+// steamcache/steamcache.go
 package steamcache
 
 import (
+	"context"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
-	"s1d3sw1ped/SteamCache2/steamcache/avgcachestate"
 	"s1d3sw1ped/SteamCache2/steamcache/logger"
 	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/cache"
-	"s1d3sw1ped/SteamCache2/vfs/cachestate"
 	"s1d3sw1ped/SteamCache2/vfs/disk"
 	"s1d3sw1ped/SteamCache2/vfs/gc"
 	"s1d3sw1ped/SteamCache2/vfs/memory"
-
-	// syncfs "s1d3sw1ped/SteamCache2/vfs/sync"
 	"strings"
+	"sync"
 	"time"
 
-	pprof "net/http/pprof"
-
 	"github.com/docker/go-units"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
@@ -34,16 +32,25 @@ var (
 		},
 		[]string{"method", "status"},
 	)
-	cacheHitRate = promauto.NewGauge(
+
-		prometheus.GaugeOpts{
+	cacheStatusTotal = promauto.NewCounterVec(
-			Name: "cache_hit_rate",
+		prometheus.CounterOpts{
-			Help: "Cache hit rate",
+			Name: "cache_status_total",
+			Help: "Total cache status counts",
+		},
+		[]string{"status"},
+	)
+
+	responseTime = promauto.NewHistogram(
+		prometheus.HistogramOpts{
+			Name:    "response_time_seconds",
+			Help:    "Response time in seconds",
+			Buckets: prometheus.DefBuckets,
 		},
 	)
 )
 
 type SteamCache struct {
-	pprof    bool
 	address  string
 	upstream string
 
@@ -55,10 +62,13 @@ type SteamCache struct {
 	memorygc *gc.GCFS
 	diskgc   *gc.GCFS
 
-	hits *avgcachestate.AvgCacheState
+	server *http.Server
+	client *http.Client
+	cancel context.CancelFunc
+	wg     sync.WaitGroup
 }
 
-func New(address string, memorySize string, memoryMultiplier int, diskSize string, diskMultiplier int, diskPath, upstream string, pprof bool) *SteamCache {
+func New(address string, memorySize string, memoryMultiplier int, diskSize string, diskMultiplier int, diskPath, upstream string) *SteamCache {
 	memorysize, err := units.FromHumanSize(memorySize)
 	if err != nil {
 		panic(err)
@@ -70,21 +80,21 @@ func New(address string, memorySize string, memoryMultiplier int, diskSize strin
 	}
 
 	c := cache.New(
-		cachehandler,
+		gc.PromotionDecider,
 	)
 
 	var m *memory.MemoryFS
 	var mgc *gc.GCFS
 	if memorysize > 0 {
 		m = memory.New(memorysize)
-		mgc = gc.New(m, memoryMultiplier, lruGC)
+		mgc = gc.New(m, memoryMultiplier, gc.LRUGC)
 	}
 
 	var d *disk.DiskFS
 	var dgc *gc.GCFS
 	if disksize > 0 {
 		d = disk.New(diskPath, disksize)
-		dgc = gc.New(d, diskMultiplier, lruGC)
+		dgc = gc.New(d, diskMultiplier, gc.LRUGC)
 	}
 
 	// configure the cache to match the specified mode (memory only, disk only, or memory and disk) based on the provided sizes
@@ -107,25 +117,44 @@ func New(address string, memorySize string, memoryMultiplier int, diskSize strin
 		os.Exit(1)
 	}
 
+	transport := &http.Transport{
+		MaxIdleConns:        100,
+		MaxIdleConnsPerHost: 10,
+		IdleConnTimeout:     90 * time.Second,
+		DialContext: (&net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 30 * time.Second,
+		}).DialContext,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ResponseHeaderTimeout: 10 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+	}
+
+	client := &http.Client{
+		Transport: transport,
+		Timeout:   60 * time.Second,
+	}
+
 	sc := &SteamCache{
-		pprof:    pprof,
 		upstream: upstream,
 		address:  address,
-		// vfs:      syncfs.New(c),
 		vfs:      c,
-
 		memory:   m,
 		disk:     d,
-
 		memorygc: mgc,
 		diskgc:   dgc,
-
+		client:   client,
-		hits: avgcachestate.New(100),
+		server: &http.Server{
+			Addr:         address,
+			ReadTimeout:  5 * time.Second,
+			WriteTimeout: 10 * time.Second,
+			IdleTimeout:  120 * time.Second,
+		},
 	}
 
 	if d != nil {
 		if d.Size() > d.Capacity() {
-			lruGC(d, uint(d.Size()-d.Capacity()))
+			gc.LRUGC(d, uint(d.Size()-d.Capacity()))
 		}
 	}
 
@@ -134,32 +163,41 @@ func New(address string, memorySize string, memoryMultiplier int, diskSize strin
 
 func (sc *SteamCache) Run() {
 	if sc.upstream != "" {
-		_, err := http.Get(sc.upstream)
+		resp, err := sc.client.Get(sc.upstream)
-		if err != nil {
+		if err != nil || resp.StatusCode != http.StatusOK {
 			logger.Logger.Error().Err(err).Str("upstream", sc.upstream).Msg("Failed to connect to upstream server")
 			os.Exit(1)
 		}
+		resp.Body.Close()
 	}
 
-	err := http.ListenAndServe(sc.address, sc)
+	sc.server.Handler = sc
-	if err != nil {
+	ctx, cancel := context.WithCancel(context.Background())
-		if err == http.ErrServerClosed {
+	sc.cancel = cancel
-			logger.Logger.Info().Msg("shutdown")
+
-			return
+	sc.wg.Add(1)
-		}
+	go func() {
+		defer sc.wg.Done()
+		err := sc.server.ListenAndServe()
+		if err != nil && err != http.ErrServerClosed {
 			logger.Logger.Error().Err(err).Msg("Failed to start SteamCache2")
 			os.Exit(1)
 		}
+	}()
+
+	<-ctx.Done()
+	sc.server.Shutdown(ctx)
+	sc.wg.Wait()
+}
+
+func (sc *SteamCache) Shutdown() {
+	if sc.cancel != nil {
+		sc.cancel()
+	}
+	sc.wg.Wait()
 }
 
 func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	if sc.pprof && r.URL.Path == "/debug/pprof/" {
-		pprof.Index(w, r)
-		return
-	} else if sc.pprof && strings.HasPrefix(r.URL.Path, "/debug/pprof/") {
-		pprof.Handler(strings.TrimPrefix(r.URL.Path, "/debug/pprof/")).ServeHTTP(w, r)
-		return
-	}
 	if r.URL.Path == "/metrics" {
 		promhttp.Handler().ServeHTTP(w, r)
 		return
@@ -167,6 +205,7 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	if r.Method != http.MethodGet {
 		requestsTotal.WithLabelValues(r.Method, "405").Inc()
+		logger.Logger.Warn().Str("method", r.Method).Msg("Only GET method is supported")
 		http.Error(w, "Only GET method is supported", http.StatusMethodNotAllowed)
 		return
 	}
@@ -178,33 +217,42 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	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]
+
 		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
+
 		if cacheKey == "" {
 			requestsTotal.WithLabelValues(r.Method, "400").Inc()
+			logger.Logger.Warn().Str("url", r.URL.String()).Msg("Invalid URL")
 			http.Error(w, "Invalid URL", http.StatusBadRequest)
 			return
 		}
 
 		w.Header().Add("X-LanCache-Processed-By", "SteamCache2") // SteamPrefill uses this header to determine if the request was processed by the cache maybe steam uses it too
 
-	data, err := sc.vfs.Get(cacheKey)
+		reader, err := sc.vfs.Open(cacheKey)
 		if err == nil {
-		sc.hits.Add(cachestate.CacheStateHit)
+			defer reader.Close()
 			w.Header().Add("X-LanCache-Status", "HIT")
-		requestsTotal.WithLabelValues(r.Method, "200").Inc()
-		cacheHitRate.Set(sc.hits.Avg())
 
-		w.Write(data)
+			io.Copy(w, reader)
 
 			logger.Logger.Info().
 				Str("key", cacheKey).
 				Str("host", r.Host).
 				Str("status", "HIT").
-			Int64("size", int64(len(data))).
 				Dur("duration", time.Since(tstart)).
 				Msg("request")
+
+			requestsTotal.WithLabelValues(r.Method, "200").Inc()
+			cacheStatusTotal.WithLabelValues("HIT").Inc()
+
 			return
 		}
 
@@ -213,6 +261,7 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			ur, err := url.JoinPath(sc.upstream, r.URL.String())
 			if err != nil {
 				requestsTotal.WithLabelValues(r.Method, "500").Inc()
+				logger.Logger.Error().Err(err).Str("upstream", sc.upstream).Msg("Failed to join URL path")
 				http.Error(w, "Failed to join URL path", http.StatusInternalServerError)
 				return
 			}
@@ -220,6 +269,7 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			req, err = http.NewRequest(http.MethodGet, ur, nil)
 			if err != nil {
 				requestsTotal.WithLabelValues(r.Method, "500").Inc()
+				logger.Logger.Error().Err(err).Str("upstream", sc.upstream).Msg("Failed to create request")
 				http.Error(w, "Failed to create request", http.StatusInternalServerError)
 				return
 			}
@@ -235,6 +285,7 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			ur, err := url.JoinPath(host, r.URL.String())
 			if err != nil {
 				requestsTotal.WithLabelValues(r.Method, "500").Inc()
+				logger.Logger.Error().Err(err).Str("host", host).Msg("Failed to join URL path")
 				http.Error(w, "Failed to join URL path", http.StatusInternalServerError)
 				return
 			}
@@ -242,6 +293,7 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			req, err = http.NewRequest(http.MethodGet, ur, nil)
 			if err != nil {
 				requestsTotal.WithLabelValues(r.Method, "500").Inc()
+				logger.Logger.Error().Err(err).Str("host", host).Msg("Failed to create request")
 				http.Error(w, "Failed to create request", http.StatusInternalServerError)
 				return
 			}
@@ -254,14 +306,11 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			}
 		}
 
-	// req.Header.Add("X-Sls-Https", r.Header.Get("X-Sls-Https"))
-	// req.Header.Add("User-Agent", r.Header.Get("User-Agent"))
-
 		// Retry logic
 		backoffSchedule := []time.Duration{1 * time.Second, 3 * time.Second, 10 * time.Second}
 		var resp *http.Response
 		for i, backoff := range backoffSchedule {
-		resp, err = http.DefaultClient.Do(req)
+			resp, err = sc.client.Do(req)
 			if err == nil && resp.StatusCode == http.StatusOK {
 				break
 			}
@@ -270,32 +319,52 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			}
 		}
 		if err != nil || resp.StatusCode != http.StatusOK {
-		requestsTotal.WithLabelValues(r.Method, "500").Inc()
+			requestsTotal.WithLabelValues(r.Method, "500 upstream host "+r.Host).Inc()
+			logger.Logger.Error().Err(err).Str("url", req.URL.String()).Msg("Failed to fetch the requested URL")
 			http.Error(w, "Failed to fetch the requested URL", http.StatusInternalServerError)
 			return
 		}
 		defer resp.Body.Close()
 
-	body, err := io.ReadAll(resp.Body)
+		size := resp.ContentLength
+
+		writer, err := sc.vfs.Create(cacheKey, size)
 		if err != nil {
-		requestsTotal.WithLabelValues(r.Method, "500").Inc()
+			http.Error(w, err.Error(), http.StatusInternalServerError)
-		http.Error(w, "Failed to read response body", http.StatusInternalServerError)
 			return
 		}
+		defer writer.Close()
 
-	sc.vfs.Set(cacheKey, body)
-	sc.hits.Add(cachestate.CacheStateMiss)
 		w.Header().Add("X-LanCache-Status", "MISS")
-	requestsTotal.WithLabelValues(r.Method, "200").Inc()
-	cacheHitRate.Set(sc.hits.Avg())
 
-	w.Write(body)
+		io.Copy(io.MultiWriter(w, writer), resp.Body)
 
 		logger.Logger.Info().
 			Str("key", cacheKey).
 			Str("host", r.Host).
 			Str("status", "MISS").
-		Int64("size", int64(len(body))).
 			Dur("duration", time.Since(tstart)).
 			Msg("request")
+
+		requestsTotal.WithLabelValues(r.Method, "200").Inc()
+		cacheStatusTotal.WithLabelValues("MISS").Inc()
+
+		return
+	}
+
+	if r.URL.Path == "/favicon.ico" {
+		w.WriteHeader(http.StatusNoContent)
+		return
+	}
+
+	if r.URL.Path == "/robots.txt" {
+		w.Header().Set("Content-Type", "text/plain")
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("User-agent: *\nDisallow: /\n"))
+		return
+	}
+
+	requestsTotal.WithLabelValues(r.Method, "404").Inc()
+	logger.Logger.Warn().Str("url", r.URL.String()).Msg("Not found")
+	http.Error(w, "Not found", http.StatusNotFound)
 }

steamcache/steamcache_test.go

@@ -1,26 +1,33 @@
+// steamcache/steamcache_test.go
 package steamcache
 
 import (
+	"io"
 	"os"
 	"path/filepath"
 	"testing"
 )
 
 func TestCaching(t *testing.T) {
-	t.Parallel()
-
 	td := t.TempDir()
 
 	os.WriteFile(filepath.Join(td, "key2"), []byte("value2"), 0644)
 
-	sc := New("localhost:8080", "1GB", 10, "1GB", 100, td, "", false)
+	sc := New("localhost:8080", "1G", 10, "1G", 100, td, "")
 
-	if err := sc.vfs.Set("key", []byte("value")); err != nil {
+	w, err := sc.vfs.Create("key", 5)
-		t.Errorf("Set failed: %v", err)
+	if err != nil {
+		t.Errorf("Create failed: %v", err)
 	}
-	if err := sc.vfs.Set("key1", []byte("value1")); err != nil {
+	w.Write([]byte("value"))
-		t.Errorf("Set failed: %v", err)
+	w.Close()
+
+	w, err = sc.vfs.Create("key1", 6)
+	if err != nil {
+		t.Errorf("Create failed: %v", err)
 	}
+	w.Write([]byte("value1"))
+	w.Close()
 
 	if sc.diskgc.Size() != 17 {
 		t.Errorf("Size failed: got %d, want %d", sc.diskgc.Size(), 17)
@@ -30,21 +37,33 @@ func TestCaching(t *testing.T) {
 		t.Errorf("Size failed: got %d, want %d", sc.vfs.Size(), 17)
 	}
 
-	if d, err := sc.vfs.Get("key"); err != nil {
+	rc, err := sc.vfs.Open("key")
-		t.Errorf("Get failed: %v", err)
+	if err != nil {
-	} else if string(d) != "value" {
+		t.Errorf("Open failed: %v", err)
+	}
+	d, _ := io.ReadAll(rc)
+	rc.Close()
+	if string(d) != "value" {
 		t.Errorf("Get failed: got %s, want %s", d, "value")
 	}
 
-	if d, err := sc.vfs.Get("key1"); err != nil {
+	rc, err = sc.vfs.Open("key1")
-		t.Errorf("Get failed: %v", err)
+	if err != nil {
-	} else if string(d) != "value1" {
+		t.Errorf("Open failed: %v", err)
+	}
+	d, _ = io.ReadAll(rc)
+	rc.Close()
+	if string(d) != "value1" {
 		t.Errorf("Get failed: got %s, want %s", d, "value1")
 	}
 
-	if d, err := sc.vfs.Get("key2"); err != nil {
+	rc, err = sc.vfs.Open("key2")
-		t.Errorf("Get failed: %v", err)
+	if err != nil {
-	} else if string(d) != "value2" {
+		t.Errorf("Open failed: %v", err)
+	}
+	d, _ = io.ReadAll(rc)
+	rc.Close()
+	if string(d) != "value2" {
 		t.Errorf("Get failed: got %s, want %s", d, "value2")
 	}
 
@@ -59,7 +78,33 @@ func TestCaching(t *testing.T) {
 	sc.memory.Delete("key2")
 	os.Remove(filepath.Join(td, "key2"))
 
-	if _, err := sc.vfs.Get("key2"); err == nil {
+	if _, err := sc.vfs.Open("key2"); err == nil {
-		t.Errorf("Get failed: got nil, want error")
+		t.Errorf("Open failed: got nil, want error")
+	}
+}
+
+func TestCacheMissAndHit(t *testing.T) {
+	sc := New("localhost:8080", "0", 0, "1G", 100, t.TempDir(), "")
+
+	key := "testkey"
+	value := []byte("testvalue")
+
+	// Simulate miss: but since no upstream, skip full ServeHTTP, test VFS
+	w, err := sc.vfs.Create(key, int64(len(value)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	w.Write(value)
+	w.Close()
+
+	rc, err := sc.vfs.Open(key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
+
+	if string(got) != string(value) {
+		t.Errorf("expected %s, got %s", value, got)
 	}
 }

version/version.go

@@ -1,3 +1,4 @@
+// version/version.go
 package version
 
 var Version string

vfs/cache/cache.go

@@ -1,7 +1,9 @@
+// vfs/cache/cache.go
 package cache
 
 import (
 	"fmt"
+	"io"
 	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/cachestate"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
@@ -73,27 +75,6 @@ func (c *CacheFS) Size() int64 {
 	return c.slow.Size()
 }
 
-// Set sets the file at key to src. If the file is already in the cache, it is replaced.
-func (c *CacheFS) Set(key string, src []byte) error {
-	mu := c.getKeyLock(key)
-	mu.Lock()
-	defer mu.Unlock()
-
-	state := c.cacheState(key)
-
-	switch state {
-	case cachestate.CacheStateHit:
-		if c.fast != nil {
-			c.fast.Delete(key)
-		}
-		return c.slow.Set(key, src)
-	case cachestate.CacheStateMiss, cachestate.CacheStateNotFound:
-		return c.slow.Set(key, src)
-	}
-
-	panic(vfserror.ErrUnreachable)
-}
-
 // Delete deletes the file at key from the cache.
 func (c *CacheFS) Delete(key string) error {
 	mu := c.getKeyLock(key)
@@ -106,14 +87,8 @@ func (c *CacheFS) Delete(key string) error {
 	return c.slow.Delete(key)
 }
 
-// Get returns the file at key. If the file is not in the cache, it is fetched from the storage.
+// Open returns the file at key. If the file is not in the cache, it is fetched from the storage.
-func (c *CacheFS) Get(key string) ([]byte, error) {
+func (c *CacheFS) Open(key string) (io.ReadCloser, error) {
-	src, _, err := c.GetS(key)
-	return src, err
-}
-
-// GetS returns the file at key. If the file is not in the cache, it is fetched from the storage. It also returns the cache state.
-func (c *CacheFS) GetS(key string) ([]byte, cachestate.CacheState, error) {
 	mu := c.getKeyLock(key)
 	mu.RLock()
 	defer mu.RUnlock()
@@ -123,27 +98,51 @@ func (c *CacheFS) GetS(key string) ([]byte, cachestate.CacheState, error) {
 	switch state {
 	case cachestate.CacheStateHit:
 		// if c.fast == nil then cacheState cannot be CacheStateHit so we can safely ignore the check
-		src, err := c.fast.Get(key)
+		return c.fast.Open(key)
-		return src, state, err
 	case cachestate.CacheStateMiss:
-		src, err := c.slow.Get(key)
+		slowReader, err := c.slow.Open(key)
 		if err != nil {
-			return nil, state, err
+			return nil, err
 		}
 
 		sstat, _ := c.slow.Stat(key)
 		if sstat != nil && c.fast != nil { // file found in slow storage and fast storage is available
 			// We are accessing the file from the slow storage, and the file has been accessed less then a minute ago so it popular, so we should update the fast storage with the latest file.
 			if c.cacheHandler != nil && c.cacheHandler(sstat, state) {
-				if err := c.fast.Set(key, src); err != nil {
+				fastWriter, err := c.fast.Create(key, sstat.Size())
-					return nil, state, err
+				if err == nil {
+					return &teeReadCloser{
+						Reader:  io.TeeReader(slowReader, fastWriter),
+						closers: []io.Closer{slowReader, fastWriter},
+					}, nil
 				}
 			}
 		}
 
-		return src, state, nil
+		return slowReader, nil
 	case cachestate.CacheStateNotFound:
-		return nil, state, vfserror.ErrNotFound
+		return nil, vfserror.ErrNotFound
+	}
+
+	panic(vfserror.ErrUnreachable)
+}
+
+// Create creates a new file at key. If the file is already in the cache, it is replaced.
+func (c *CacheFS) Create(key string, size int64) (io.WriteCloser, error) {
+	mu := c.getKeyLock(key)
+	mu.Lock()
+	defer mu.Unlock()
+
+	state := c.cacheState(key)
+
+	switch state {
+	case cachestate.CacheStateHit:
+		if c.fast != nil {
+			c.fast.Delete(key)
+		}
+		return c.slow.Create(key, size)
+	case cachestate.CacheStateMiss, cachestate.CacheStateNotFound:
+		return c.slow.Create(key, size)
 	}
 
 	panic(vfserror.ErrUnreachable)
@@ -176,3 +175,18 @@ func (c *CacheFS) Stat(key string) (*vfs.FileInfo, error) {
 func (c *CacheFS) StatAll() []*vfs.FileInfo {
 	return c.slow.StatAll()
 }
+
+type teeReadCloser struct {
+	io.Reader
+	closers []io.Closer
+}
+
+func (t *teeReadCloser) Close() error {
+	var err error
+	for _, c := range t.closers {
+		if e := c.Close(); e != nil {
+			err = e
+		}
+	}
+	return err
+}

vfs/cache/cache_test.go

@@ -1,7 +1,9 @@
+// vfs/cache/cache_test.go
 package cache
 
 import (
 	"errors"
+	"io"
 	"testing"
 
 	"s1d3sw1ped/SteamCache2/vfs"
@@ -15,8 +17,6 @@ func testMemory() vfs.VFS {
 }
 
 func TestNew(t *testing.T) {
-	t.Parallel()
-
 	fast := testMemory()
 	slow := testMemory()
 
@@ -29,8 +29,6 @@ func TestNew(t *testing.T) {
 }
 
 func TestNewPanics(t *testing.T) {
-	t.Parallel()
-
 	defer func() {
 		if r := recover(); r == nil {
 			t.Fatal("expected panic but did not get one")
@@ -42,9 +40,7 @@ func TestNewPanics(t *testing.T) {
 	cache.SetSlow(nil)
 }
 
-func TestSetAndGet(t *testing.T) {
+func TestCreateAndOpen(t *testing.T) {
-	t.Parallel()
-
 	fast := testMemory()
 	slow := testMemory()
 	cache := New(nil)
@@ -54,23 +50,26 @@ func TestSetAndGet(t *testing.T) {
 	key := "test"
 	value := []byte("value")
 
-	if err := cache.Set(key, value); err != nil {
+	w, err := cache.Create(key, int64(len(value)))
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	got, err := cache.Get(key)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
+	w.Write(value)
+	w.Close()
+
+	rc, err := cache.Open(key)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
 
 	if string(got) != string(value) {
 		t.Fatalf("expected %s, got %s", value, got)
 	}
 }
 
-func TestSetAndGetNoFast(t *testing.T) {
+func TestCreateAndOpenNoFast(t *testing.T) {
-	t.Parallel()
-
 	slow := testMemory()
 	cache := New(nil)
 	cache.SetSlow(slow)
@@ -78,22 +77,26 @@ func TestSetAndGetNoFast(t *testing.T) {
 	key := "test"
 	value := []byte("value")
 
-	if err := cache.Set(key, value); err != nil {
+	w, err := cache.Create(key, int64(len(value)))
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	got, err := cache.Get(key)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
+	w.Write(value)
+	w.Close()
+
+	rc, err := cache.Open(key)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
 
 	if string(got) != string(value) {
 		t.Fatalf("expected %s, got %s", value, got)
 	}
 }
-func TestCaching(t *testing.T) {
-	t.Parallel()
 
+func TestCachingPromotion(t *testing.T) {
 	fast := testMemory()
 	slow := testMemory()
 	cache := New(func(fi *vfs.FileInfo, cs cachestate.CacheState) bool {
@@ -105,71 +108,42 @@ func TestCaching(t *testing.T) {
 	key := "test"
 	value := []byte("value")
 
-	if err := fast.Set(key, value); err != nil {
+	ws, _ := slow.Create(key, int64(len(value)))
-		t.Fatalf("unexpected error: %v", err)
+	ws.Write(value)
-	}
+	ws.Close()
 
-	if err := slow.Set(key, value); err != nil {
+	rc, err := cache.Open(key)
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	_, state, err := cache.GetS(key)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if state != cachestate.CacheStateHit {
+	got, _ := io.ReadAll(rc)
-		t.Fatalf("expected %v, got %v", cachestate.CacheStateHit, state)
+	rc.Close()
-	}
-
-	err = fast.Delete(key)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	got, state, err := cache.GetS(key)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-	if state != cachestate.CacheStateMiss {
-		t.Fatalf("expected %v, got %v", cachestate.CacheStateMiss, state)
-	}
 
 	if string(got) != string(value) {
 		t.Fatalf("expected %s, got %s", value, got)
 	}
 
-	err = cache.Delete(key)
+	// Check if promoted to fast
+	_, err = fast.Open(key)
 	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
+		t.Error("Expected promotion to fast cache")
-	}
-
-	_, state, err = cache.GetS(key)
-	if !errors.Is(err, vfserror.ErrNotFound) {
-		t.Fatalf("expected %v, got %v", vfserror.ErrNotFound, err)
-	}
-	if state != cachestate.CacheStateNotFound {
-		t.Fatalf("expected %v, got %v", cachestate.CacheStateNotFound, state)
 	}
 }
 
-func TestGetNotFound(t *testing.T) {
+func TestOpenNotFound(t *testing.T) {
-	t.Parallel()
-
 	fast := testMemory()
 	slow := testMemory()
 	cache := New(nil)
 	cache.SetFast(fast)
 	cache.SetSlow(slow)
 
-	_, err := cache.Get("nonexistent")
+	_, err := cache.Open("nonexistent")
 	if !errors.Is(err, vfserror.ErrNotFound) {
 		t.Fatalf("expected %v, got %v", vfserror.ErrNotFound, err)
 	}
 }
 
 func TestDelete(t *testing.T) {
-	t.Parallel()
-
 	fast := testMemory()
 	slow := testMemory()
 	cache := New(nil)
@@ -179,23 +153,24 @@ func TestDelete(t *testing.T) {
 	key := "test"
 	value := []byte("value")
 
-	if err := cache.Set(key, value); err != nil {
+	w, err := cache.Create(key, int64(len(value)))
+	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
+	w.Write(value)
+	w.Close()
 
 	if err := cache.Delete(key); err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
 
-	_, err := cache.Get(key)
+	_, err = cache.Open(key)
 	if !errors.Is(err, vfserror.ErrNotFound) {
 		t.Fatalf("expected %v, got %v", vfserror.ErrNotFound, err)
 	}
 }
 
 func TestStat(t *testing.T) {
-	t.Parallel()
-
 	fast := testMemory()
 	slow := testMemory()
 	cache := New(nil)
@@ -205,9 +180,12 @@ func TestStat(t *testing.T) {
 	key := "test"
 	value := []byte("value")
 
-	if err := cache.Set(key, value); err != nil {
+	w, err := cache.Create(key, int64(len(value)))
+	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
+	w.Write(value)
+	w.Close()
 
 	info, err := cache.Stat(key)
 	if err != nil {
@@ -217,4 +195,7 @@ func TestStat(t *testing.T) {
 	if info == nil {
 		t.Fatal("expected file info to be non-nil")
 	}
+	if info.Size() != int64(len(value)) {
+		t.Errorf("expected size %d, got %d", len(value), info.Size())
+	}
 }

vfs/cachestate/cachestate.go

@@ -1,3 +1,4 @@
+// vfs/cachestate/cachestate.go
 package cachestate
 
 import "s1d3sw1ped/SteamCache2/vfs/vfserror"

vfs/disk/disk.go

@@ -1,7 +1,10 @@
+// vfs/disk/disk.go
 package disk
 
 import (
+	"container/list"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"s1d3sw1ped/SteamCache2/steamcache/logger"
@@ -12,6 +15,38 @@ import (
 	"time"
 
 	"github.com/docker/go-units"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	diskCapacityBytes = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "disk_cache_capacity_bytes",
+			Help: "Total capacity of the disk cache in bytes",
+		},
+	)
+
+	diskSizeBytes = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "disk_cache_size_bytes",
+			Help: "Total size of the disk cache in bytes",
+		},
+	)
+
+	diskReadBytes = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "disk_cache_read_bytes_total",
+			Help: "Total number of bytes read from the disk cache",
+		},
+	)
+
+	diskWriteBytes = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "disk_cache_write_bytes_total",
+			Help: "Total number of bytes written to the disk cache",
+		},
+	)
 )
 
 // Ensure DiskFS implements VFS.
@@ -23,10 +58,49 @@ type DiskFS struct {
 
 	info     map[string]*vfs.FileInfo
 	capacity int64
-	mu       sync.Mutex
+	size     int64
-	sg       sync.WaitGroup
+	mu       sync.RWMutex
+	keyLocks sync.Map // map[string]*sync.RWMutex
+	LRU      *lruList
+}
 
-	bytePool sync.Pool // Pool for []byte slices
+// lruList for LRU eviction
+type lruList struct {
+	list *list.List
+	elem map[string]*list.Element
+}
+
+func newLruList() *lruList {
+	return &lruList{
+		list: list.New(),
+		elem: make(map[string]*list.Element),
+	}
+}
+
+func (l *lruList) MoveToFront(key string) {
+	if e, ok := l.elem[key]; ok {
+		l.list.MoveToFront(e)
+	}
+}
+
+func (l *lruList) Add(key string, fi *vfs.FileInfo) *list.Element {
+	e := l.list.PushFront(fi)
+	l.elem[key] = e
+	return e
+}
+
+func (l *lruList) Remove(key string) {
+	if e, ok := l.elem[key]; ok {
+		l.list.Remove(e)
+		delete(l.elem, key)
+	}
+}
+
+func (l *lruList) Back() *vfs.FileInfo {
+	if e := l.list.Back(); e != nil {
+		return e.Value.(*vfs.FileInfo)
+	}
+	return nil
 }
 
 // New creates a new DiskFS.
@@ -58,17 +132,18 @@ func new(root string, capacity int64, skipinit bool) *DiskFS {
 		root:     root,
 		info:     make(map[string]*vfs.FileInfo),
 		capacity: capacity,
-		mu:       sync.Mutex{},
+		mu:       sync.RWMutex{},
-		sg:       sync.WaitGroup{},
+		keyLocks: sync.Map{},
-		bytePool: sync.Pool{
+		LRU:      newLruList(),
-			New: func() interface{} { return make([]byte, 0) }, // Initial capacity for pooled slices is 0, will grow as needed
-		},
 	}
 
 	os.MkdirAll(dfs.root, 0755)
 
+	diskCapacityBytes.Set(float64(dfs.capacity))
+
 	if !skipinit {
 		dfs.init()
+		diskSizeBytes.Set(float64(dfs.Size()))
 	}
 
 	return dfs
@@ -85,8 +160,28 @@ func NewSkipInit(root string, capacity int64) *DiskFS {
 func (d *DiskFS) init() {
 	tstart := time.Now()
 
-	d.walk(d.root)
+	err := filepath.Walk(d.root, func(npath string, info os.FileInfo, err error) error {
-	d.sg.Wait()
+		if err != nil {
+			return err
+		}
+
+		if info.IsDir() {
+			return nil
+		}
+
+		d.mu.Lock()
+		k := strings.ReplaceAll(npath[len(d.root)+1:], "\\", "/")
+		fi := vfs.NewFileInfoFromOS(info, k)
+		d.info[k] = fi
+		d.LRU.Add(k, fi)
+		d.size += info.Size()
+		d.mu.Unlock()
+
+		return nil
+	})
+	if err != nil {
+		logger.Logger.Error().Err(err).Msg("Walk failed")
+	}
 
 	logger.Logger.Info().
 		Str("name", d.Name()).
@@ -98,34 +193,6 @@ func (d *DiskFS) init() {
 		Msg("init")
 }
 
-func (d *DiskFS) walk(path string) {
-	d.sg.Add(1)
-	go func() {
-		defer d.sg.Done()
-		filepath.Walk(path, func(npath string, info os.FileInfo, err error) error {
-			if path == npath {
-				return nil
-			}
-
-			if err != nil {
-				return err
-			}
-
-			if info.IsDir() {
-				d.walk(npath)
-				return filepath.SkipDir
-			}
-
-			d.mu.Lock()
-			k := strings.ReplaceAll(npath[len(d.root)+1:], "\\", "/")
-			d.info[k] = vfs.NewFileInfoFromOS(info, k)
-			d.mu.Unlock()
-
-			return nil
-		})
-	}()
-}
-
 func (d *DiskFS) Capacity() int64 {
 	return d.capacity
 }
@@ -135,49 +202,114 @@ func (d *DiskFS) Name() string {
 }
 
 func (d *DiskFS) Size() int64 {
-	d.mu.Lock()
+	d.mu.RLock()
-	defer d.mu.Unlock()
+	defer d.mu.RUnlock()
-
+	return d.size
-	var size int64
-	for _, v := range d.info {
-		size += v.Size()
-	}
-	return size
 }
 
-func (d *DiskFS) Set(key string, src []byte) error {
+func (d *DiskFS) getKeyLock(key string) *sync.RWMutex {
+	mu, _ := d.keyLocks.LoadOrStore(key, &sync.RWMutex{})
+	return mu.(*sync.RWMutex)
+}
+
+func (d *DiskFS) Create(key string, size int64) (io.WriteCloser, error) {
 	if key == "" {
-		return vfserror.ErrInvalidKey
+		return nil, vfserror.ErrInvalidKey
 	}
 	if key[0] == '/' {
-		return vfserror.ErrInvalidKey
+		return nil, vfserror.ErrInvalidKey
 	}
 
+	// Sanitize key to prevent path traversal
+	key = filepath.Clean(key)
+	key = strings.ReplaceAll(key, "\\", "/") // Ensure forward slashes for consistency
+	if strings.Contains(key, "..") {
+		return nil, vfserror.ErrInvalidKey
+	}
+
+	d.mu.RLock()
 	if d.capacity > 0 {
-		if size := d.Size() + int64(len(src)); size > d.capacity {
+		if d.size+size > d.capacity {
-			return vfserror.ErrDiskFull
+			d.mu.RUnlock()
+			return nil, vfserror.ErrDiskFull
 		}
 	}
+	d.mu.RUnlock()
 
-	if _, err := d.Stat(key); err == nil {
+	keyMu := d.getKeyLock(key)
-		d.Delete(key)
+	keyMu.Lock()
-	}
+	defer keyMu.Unlock()
 
+	// Check again after lock
 	d.mu.Lock()
-	defer d.mu.Unlock()
+	if fi, exists := d.info[key]; exists {
-	os.MkdirAll(d.root+"/"+filepath.Dir(key), 0755)
+		d.size -= fi.Size()
-	if err := os.WriteFile(d.root+"/"+key, src, 0644); err != nil {
+		d.LRU.Remove(key)
+		delete(d.info, key)
+		path := filepath.Join(d.root, key)
+		os.Remove(path) // Ignore error, as file might not exist or other issues
+	}
+	d.mu.Unlock()
+
+	path := filepath.Join(d.root, key)
+	path = strings.ReplaceAll(path, "\\", "/") // Ensure forward slashes for consistency
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return nil, err
+	}
+
+	file, err := os.Create(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return &diskWriteCloser{
+		Writer: file,
+		onClose: func(n int64) error {
+			fi, err := os.Stat(path)
+			if err != nil {
+				os.Remove(path)
 				return err
 			}
 
-	fi, err := os.Stat(d.root + "/" + key)
+			d.mu.Lock()
-	if err != nil {
+			finfo := vfs.NewFileInfoFromOS(fi, key)
-		panic(err)
+			d.info[key] = finfo
-	}
+			d.LRU.Add(key, finfo)
+			d.size += n
+			d.mu.Unlock()
 
-	d.info[key] = vfs.NewFileInfoFromOS(fi, key)
+			diskWriteBytes.Add(float64(n))
+			diskSizeBytes.Set(float64(d.Size()))
 
 			return nil
+		},
+		key:  key,
+		file: file,
+	}, nil
+}
+
+type diskWriteCloser struct {
+	io.Writer
+	onClose func(int64) error
+	n       int64
+	key     string
+	file    *os.File
+}
+
+func (wc *diskWriteCloser) Write(p []byte) (int, error) {
+	n, err := wc.Writer.Write(p)
+	wc.n += int64(n)
+	return n, err
+}
+
+func (wc *diskWriteCloser) Close() error {
+	err := wc.file.Close()
+	if e := wc.onClose(wc.n); e != nil {
+		os.Remove(wc.file.Name())
+		return e
+	}
+	return err
 }
 
 // Delete deletes the value of key.
@@ -189,24 +321,41 @@ func (d *DiskFS) Delete(key string) error {
 		return vfserror.ErrInvalidKey
 	}
 
-	_, err := d.Stat(key)
+	// Sanitize key to prevent path traversal
-	if err != nil {
+	key = filepath.Clean(key)
-		return err
+	key = strings.ReplaceAll(key, "\\", "/") // Ensure forward slashes for consistency
+	if strings.Contains(key, "..") {
+		return vfserror.ErrInvalidKey
 	}
 
+	keyMu := d.getKeyLock(key)
+	keyMu.Lock()
+	defer keyMu.Unlock()
+
 	d.mu.Lock()
-	defer d.mu.Unlock()
+	fi, exists := d.info[key]
-
+	if !exists {
+		d.mu.Unlock()
+		return vfserror.ErrNotFound
+	}
+	d.size -= fi.Size()
+	d.LRU.Remove(key)
 	delete(d.info, key)
-	if err := os.Remove(filepath.Join(d.root, key)); err != nil {
+	d.mu.Unlock()
+
+	path := filepath.Join(d.root, key)
+	path = strings.ReplaceAll(path, "\\", "/") // Ensure forward slashes for consistency
+	if err := os.Remove(path); err != nil {
 		return err
 	}
 
+	diskSizeBytes.Set(float64(d.Size()))
+
 	return nil
 }
 
-// Get gets the value of key and returns it.
+// Open opens the file at key and returns it.
-func (d *DiskFS) Get(key string) ([]byte, error) {
+func (d *DiskFS) Open(key string) (io.ReadCloser, error) {
 	if key == "" {
 		return nil, vfserror.ErrInvalidKey
 	}
@@ -214,29 +363,59 @@ func (d *DiskFS) Get(key string) ([]byte, error) {
 		return nil, vfserror.ErrInvalidKey
 	}
 
-	_, err := d.Stat(key)
+	// Sanitize key to prevent path traversal
-	if err != nil {
+	key = filepath.Clean(key)
-		return nil, err
+	key = strings.ReplaceAll(key, "\\", "/") // Ensure forward slashes for consistency
+	if strings.Contains(key, "..") {
+		return nil, vfserror.ErrInvalidKey
 	}
 
+	keyMu := d.getKeyLock(key)
+	keyMu.RLock()
+	defer keyMu.RUnlock()
+
 	d.mu.Lock()
-	defer d.mu.Unlock()
+	fi, exists := d.info[key]
+	if !exists {
+		d.mu.Unlock()
+		return nil, vfserror.ErrNotFound
+	}
+	fi.ATime = time.Now()
+	d.LRU.MoveToFront(key)
+	d.mu.Unlock()
 
-	data, err := os.ReadFile(filepath.Join(d.root, key))
+	path := filepath.Join(d.root, key)
+	path = strings.ReplaceAll(path, "\\", "/") // Ensure forward slashes for consistency
+	file, err := os.Open(path)
 	if err != nil {
 		return nil, err
 	}
 
-	// Use pooled slice for return if possible, but since ReadFile allocates new, copy to pool if beneficial
+	// Update metrics on close
-	dst := d.bytePool.Get().([]byte)
+	return &readCloser{
-	if cap(dst) < len(data) {
+		ReadCloser: file,
-		dst = make([]byte, len(data)) // create a new slice if the pool slice is too small
+		onClose: func(n int64) {
-	} else {
+			diskReadBytes.Add(float64(n))
-		dst = dst[:len(data)] // reuse the pool slice, but resize it to fit
+		},
+	}, nil
 }
-	dst = dst[:len(data)]
+
-	copy(dst, data)
+type readCloser struct {
-	return dst, nil
+	io.ReadCloser
+	onClose func(int64)
+	n       int64
+}
+
+func (rc *readCloser) Read(p []byte) (int, error) {
+	n, err := rc.ReadCloser.Read(p)
+	rc.n += int64(n)
+	return n, err
+}
+
+func (rc *readCloser) Close() error {
+	err := rc.ReadCloser.Close()
+	rc.onClose(rc.n)
+	return err
 }
 
 // Stat returns the FileInfo of key. If key is not found in the cache, it will stat the file on disk. If the file is not found on disk, it will return vfs.ErrNotFound.
@@ -248,8 +427,19 @@ func (d *DiskFS) Stat(key string) (*vfs.FileInfo, error) {
 		return nil, vfserror.ErrInvalidKey
 	}
 
-	d.mu.Lock()
+	// Sanitize key to prevent path traversal
-	defer d.mu.Unlock()
+	key = filepath.Clean(key)
+	key = strings.ReplaceAll(key, "\\", "/") // Ensure forward slashes for consistency
+	if strings.Contains(key, "..") {
+		return nil, vfserror.ErrInvalidKey
+	}
+
+	keyMu := d.getKeyLock(key)
+	keyMu.RLock()
+	defer keyMu.RUnlock()
+
+	d.mu.RLock()
+	defer d.mu.RUnlock()
 
 	if fi, ok := d.info[key]; !ok {
 		return nil, vfserror.ErrNotFound
@@ -258,13 +448,13 @@ func (d *DiskFS) Stat(key string) (*vfs.FileInfo, error) {
 	}
 }
 
-func (m *DiskFS) StatAll() []*vfs.FileInfo {
+func (d *DiskFS) StatAll() []*vfs.FileInfo {
-	m.mu.Lock()
+	d.mu.RLock()
-	defer m.mu.Unlock()
+	defer d.mu.RUnlock()
 
 	// hard copy the file info to prevent modification of the original file info or the other way around
-	files := make([]*vfs.FileInfo, 0, len(m.info))
+	files := make([]*vfs.FileInfo, 0, len(d.info))
-	for _, v := range m.info {
+	for _, v := range d.info {
 		fi := *v
 		files = append(files, &fi)
 	}

vfs/disk/disk_test.go

@@ -1,145 +1,180 @@
+// vfs/disk/disk_test.go
 package disk
 
 import (
+	"errors"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
 	"testing"
 )
 
-func TestAllDisk(t *testing.T) {
+func TestCreateAndOpen(t *testing.T) {
-	t.Parallel()
-
 	m := NewSkipInit(t.TempDir(), 1024)
-	if err := m.Set("key", []byte("value")); err != nil {
+	key := "key"
-		t.Errorf("Set failed: %v", err)
+	value := []byte("value")
-	}
 
-	if err := m.Set("key", []byte("value1")); err != nil {
+	w, err := m.Create(key, int64(len(value)))
-		t.Errorf("Set failed: %v", err)
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
 	}
+	w.Write(value)
+	w.Close()
 
-	if d, err := m.Get("key"); err != nil {
+	rc, err := m.Open(key)
-		t.Errorf("Get failed: %v", err)
+	if err != nil {
-	} else if string(d) != "value1" {
+		t.Fatalf("Open failed: %v", err)
-		t.Errorf("Get failed: got %s, want %s", d, "value1")
 	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
 
-	if err := m.Delete("key"); err != nil {
+	if string(got) != string(value) {
-		t.Errorf("Delete failed: %v", err)
+		t.Fatalf("expected %s, got %s", value, got)
-	}
-
-	if _, err := m.Get("key"); err == nil {
-		t.Errorf("Get failed: got nil, want %v", vfserror.ErrNotFound)
-	}
-
-	if err := m.Delete("key"); err == nil {
-		t.Errorf("Delete failed: got nil, want %v", vfserror.ErrNotFound)
-	}
-
-	if _, err := m.Stat("key"); err == nil {
-		t.Errorf("Stat failed: got nil, want %v", vfserror.ErrNotFound)
-	}
-
-	if err := m.Set("key", []byte("value")); err != nil {
-		t.Errorf("Set failed: %v", err)
-	}
-
-	if _, err := m.Stat("key"); err != nil {
-		t.Errorf("Stat failed: %v", err)
 	}
 }
 
-func TestLimited(t *testing.T) {
+func TestOverwrite(t *testing.T) {
-	t.Parallel()
+	m := NewSkipInit(t.TempDir(), 1024)
+	key := "key"
+	value1 := []byte("value1")
+	value2 := []byte("value2")
 
+	w, err := m.Create(key, int64(len(value1)))
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write(value1)
+	w.Close()
+
+	w, err = m.Create(key, int64(len(value2)))
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write(value2)
+	w.Close()
+
+	rc, err := m.Open(key)
+	if err != nil {
+		t.Fatalf("Open failed: %v", err)
+	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
+
+	if string(got) != string(value2) {
+		t.Fatalf("expected %s, got %s", value2, got)
+	}
+}
+
+func TestDelete(t *testing.T) {
+	m := NewSkipInit(t.TempDir(), 1024)
+	key := "key"
+	value := []byte("value")
+
+	w, err := m.Create(key, int64(len(value)))
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write(value)
+	w.Close()
+
+	if err := m.Delete(key); err != nil {
+		t.Fatalf("Delete failed: %v", err)
+	}
+
+	_, err = m.Open(key)
+	if !errors.Is(err, vfserror.ErrNotFound) {
+		t.Fatalf("expected %v, got %v", vfserror.ErrNotFound, err)
+	}
+}
+
+func TestCapacityLimit(t *testing.T) {
 	m := NewSkipInit(t.TempDir(), 10)
 	for i := 0; i < 11; i++ {
-		if err := m.Set(fmt.Sprintf("key%d", i), []byte("1")); err != nil && i < 10 {
+		w, err := m.Create(fmt.Sprintf("key%d", i), 1)
-			t.Errorf("Set failed: %v", err)
+		if err != nil && i < 10 {
+			t.Errorf("Create failed: %v", err)
 		} else if i == 10 && err == nil {
-			t.Errorf("Set succeeded: got nil, want %v", vfserror.ErrDiskFull)
+			t.Errorf("Create succeeded: got nil, want %v", vfserror.ErrDiskFull)
+		}
+		if i < 10 {
+			w.Write([]byte("1"))
+			w.Close()
 		}
 	}
 }
 
-func TestInit(t *testing.T) {
+func TestInitExistingFiles(t *testing.T) {
-	t.Parallel()
-
 	td := t.TempDir()
 
 	path := filepath.Join(td, "test", "key")
-
 	os.MkdirAll(filepath.Dir(path), 0755)
-
 	os.WriteFile(path, []byte("value"), 0644)
 
 	m := New(td, 10)
-	if _, err := m.Get("test/key"); err != nil {
+	rc, err := m.Open("test/key")
-		t.Errorf("Get failed: %v", err)
+	if err != nil {
+		t.Fatalf("Open failed: %v", err)
+	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
+
+	if string(got) != "value" {
+		t.Errorf("expected value, got %s", got)
 	}
 
-	s, _ := m.Stat("test/key")
+	s, err := m.Stat("test/key")
-	if s.Name() != "test/key" {
+	if err != nil {
-		t.Errorf("Stat failed: got %s, want %s", s.Name(), "key")
+		t.Fatalf("Stat failed: %v", err)
+	}
+	if s == nil {
+		t.Error("Stat returned nil")
+	}
+	if s != nil && s.Name() != "test/key" {
+		t.Errorf("Stat failed: got %s, want %s", s.Name(), "test/key")
 	}
 }
 
-func TestDiskSizeDiscrepancy(t *testing.T) {
+func TestSizeConsistency(t *testing.T) {
-	t.Parallel()
 	td := t.TempDir()
-
-	assumedSize := int64(6 + 5 + 6) // 6 + 5 + 6 bytes for key, key1, key2
 	os.WriteFile(filepath.Join(td, "key2"), []byte("value2"), 0644)
 
 	m := New(td, 1024)
-	if 6 != m.Size() {
+	if m.Size() != 6 {
-		t.Errorf("Size failed: got %d, want %d", m.Size(), 6)
+		t.Errorf("Size failed: got %d, want 6", m.Size())
 	}
 
-	if err := m.Set("key", []byte("value")); err != nil {
+	w, err := m.Create("key", 5)
-		t.Errorf("Set failed: %v", err)
+	if err != nil {
+		t.Errorf("Create failed: %v", err)
 	}
+	w.Write([]byte("value"))
+	w.Close()
 
-	if err := m.Set("key1", []byte("value1")); err != nil {
+	w, err = m.Create("key1", 6)
-		t.Errorf("Set failed: %v", err)
+	if err != nil {
+		t.Errorf("Create failed: %v", err)
 	}
+	w.Write([]byte("value1"))
+	w.Close()
 
+	assumedSize := int64(6 + 5 + 6)
 	if assumedSize != m.Size() {
 		t.Errorf("Size failed: got %d, want %d", m.Size(), assumedSize)
 	}
 
-	if d, err := m.Get("key"); err != nil {
+	rc, err := m.Open("key")
-		t.Errorf("Get failed: %v", err)
+	if err != nil {
-	} else if string(d) != "value" {
+		t.Errorf("Open failed: %v", err)
-		t.Errorf("Get failed: got %s, want %s", d, "value")
 	}
-
+	d, _ := io.ReadAll(rc)
-	if d, err := m.Get("key1"); err != nil {
+	rc.Close()
-		t.Errorf("Get failed: %v", err)
+	if string(d) != "value" {
-	} else if string(d) != "value1" {
+		t.Errorf("Get failed: got %s, want value", d)
-		t.Errorf("Get failed: got %s, want %s", d, "value1")
 	}
 
 	m = New(td, 1024)
-
-	if assumedSize != m.Size() {
-		t.Errorf("Size failed: got %d, want %d", m.Size(), assumedSize)
-	}
-
-	if d, err := m.Get("key"); err != nil {
-		t.Errorf("Get failed: %v", err)
-	} else if string(d) != "value" {
-		t.Errorf("Get failed: got %s, want %s", d, "value")
-	}
-
-	if d, err := m.Get("key1"); err != nil {
-		t.Errorf("Get failed: %v", err)
-	} else if string(d) != "value1" {
-		t.Errorf("Get failed: got %s, want %s", d, "value1")
-	}
-
 	if assumedSize != m.Size() {
 		t.Errorf("Size failed: got %d, want %d", m.Size(), assumedSize)
 	}

vfs/fileinfo.go

@@ -1,3 +1,4 @@
+// vfs/fileinfo.go
 package vfs
 
 import (

vfs/gc/gc.go

@@ -1,13 +1,79 @@
+// vfs/gc/gc.go
 package gc
 
 import (
 	"fmt"
+	"io"
+	"s1d3sw1ped/SteamCache2/steamcache/logger"
 	"s1d3sw1ped/SteamCache2/vfs"
+	"s1d3sw1ped/SteamCache2/vfs/cachestate"
+	"s1d3sw1ped/SteamCache2/vfs/disk"
+	"s1d3sw1ped/SteamCache2/vfs/memory"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
-	"sync"
 	"time"
 )
 
+// LRUGC deletes files in LRU order until enough space is reclaimed.
+func LRUGC(vfss vfs.VFS, size uint) {
+	attempts := 0
+	deletions := 0
+	var reclaimed uint
+
+	for reclaimed < size {
+		if attempts > 10 {
+			logger.Logger.Debug().
+				Int("attempts", attempts).
+				Msg("GC: Too many attempts to reclaim space, giving up")
+			return
+		}
+		attempts++
+		switch fs := vfss.(type) {
+		case *disk.DiskFS:
+			fi := fs.LRU.Back()
+			if fi == nil {
+				break
+			}
+			sz := uint(fi.Size())
+			err := fs.Delete(fi.Name())
+			if err != nil {
+				continue
+			}
+			reclaimed += sz
+			deletions++
+		case *memory.MemoryFS:
+			fi := fs.LRU.Back()
+			if fi == nil {
+				break
+			}
+			sz := uint(fi.Size())
+			err := fs.Delete(fi.Name())
+			if err != nil {
+				continue
+			}
+			reclaimed += sz
+			deletions++
+		default:
+			// Fallback to old method if not supported
+			stats := vfss.StatAll()
+			if len(stats) == 0 {
+				break
+			}
+			fi := stats[0] // Assume sorted or pick first
+			sz := uint(fi.Size())
+			err := vfss.Delete(fi.Name())
+			if err != nil {
+				continue
+			}
+			reclaimed += sz
+			deletions++
+		}
+	}
+}
+
+func PromotionDecider(fi *vfs.FileInfo, cs cachestate.CacheState) bool {
+	return time.Since(fi.AccessTime()) < time.Second*60 // Put hot files in the fast vfs if equipped
+}
+
 // Ensure GCFS implements VFS.
 var _ vfs.VFS = (*GCFS)(nil)
 
@@ -18,14 +84,10 @@ type GCFS struct {
 
 	// protected by mu
 	gcHanderFunc GCHandlerFunc
-	lifetimeBytes, lifetimeFiles uint
-	reclaimedBytes, deletedFiles uint
-	gcTime                       time.Duration
-	mu                           sync.Mutex
 }
 
 // GCHandlerFunc is a function that is called when the disk is full and the GCFS needs to free up space. It is passed the VFS and the size of the file that needs to be written. Its up to the implementation to free up space. How much space is freed is also up to the implementation.
-type GCHandlerFunc func(vfs vfs.VFS, size uint) (reclaimedBytes uint, deletedFiles uint)
+type GCHandlerFunc func(vfs vfs.VFS, size uint)
 
 func New(vfs vfs.VFS, multiplier int, gcHandlerFunc GCHandlerFunc) *GCFS {
 	if multiplier <= 0 {
@@ -38,47 +100,17 @@ func New(vfs vfs.VFS, multiplier int, gcHandlerFunc GCHandlerFunc) *GCFS {
 	}
 }
 
-// Stats returns the lifetime bytes, lifetime files, reclaimed bytes and deleted files.
+// Create overrides the Create method of the VFS interface. It tries to create the key, if it fails due to disk full error, it calls the GC handler and tries again. If it still fails it returns the error.
-// The lifetime bytes and lifetime files are the total bytes and files that have been freed up by the GC handler.
+func (g *GCFS) Create(key string, size int64) (io.WriteCloser, error) {
-// The reclaimed bytes and deleted files are the bytes and files that have been freed up by the GC handler since last call to Stats.
+	w, err := g.VFS.Create(key, size) // try to create the key
-// The gc time is the total time spent in the GC handler since last call to Stats.
-// The reclaimed bytes and deleted files and gc time are reset to 0 after the call to Stats.
-func (g *GCFS) Stats() (lifetimeBytes, lifetimeFiles, reclaimedBytes, deletedFiles uint, gcTime time.Duration) {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-
-	g.lifetimeBytes += g.reclaimedBytes
-	g.lifetimeFiles += g.deletedFiles
-
-	lifetimeBytes = g.lifetimeBytes
-	lifetimeFiles = g.lifetimeFiles
-	reclaimedBytes = g.reclaimedBytes
-	deletedFiles = g.deletedFiles
-	gcTime = g.gcTime
-
-	g.reclaimedBytes = 0
-	g.deletedFiles = 0
-	g.gcTime = time.Duration(0)
-
-	return
-}
-
-// Set overrides the Set method of the VFS interface. It tries to set the key and src, if it fails due to disk full error, it calls the GC handler and tries again. If it still fails it returns the error.
-func (g *GCFS) Set(key string, src []byte) error {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-	err := g.VFS.Set(key, src) // try to set the key and src
 
+	// if it fails due to disk full error, call the GC handler and try again in a loop that will continue until it succeeds or the error is not disk full
 	if err == vfserror.ErrDiskFull && g.gcHanderFunc != nil { // if the error is disk full and there is a GC handler
-		tstart := time.Now()
+		g.gcHanderFunc(g.VFS, uint(size*int64(g.multiplier))) // call the GC handler
-		reclaimedBytes, deletedFiles := g.gcHanderFunc(g.VFS, uint(len(src)*g.multiplier)) // call the GC handler
+		w, err = g.VFS.Create(key, size)
-		g.gcTime += time.Since(tstart)
-		g.reclaimedBytes += reclaimedBytes
-		g.deletedFiles += deletedFiles
-		err = g.VFS.Set(key, src) // try again after GC if it still fails return the error
 	}
 
-	return err
+	return w, err
 }
 
 func (g *GCFS) Name() string {

vfs/gc/gc_test.go

@@ -1,105 +1,73 @@
+// vfs/gc/gc_test.go
 package gc
 
 import (
+	"errors"
 	"fmt"
-	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/memory"
-	"sort"
+	"s1d3sw1ped/SteamCache2/vfs/vfserror"
 	"testing"
-
-	"golang.org/x/exp/rand"
 )
 
-func TestGCSmallRandom(t *testing.T) {
+func TestGCOnFull(t *testing.T) {
-	t.Parallel()
+	m := memory.New(10)
+	gc := New(m, 2, LRUGC)
 
-	m := memory.New(1024 * 1024 * 16)
+	for i := 0; i < 5; i++ {
-	gc := New(m, 10, func(vfs vfs.VFS, size uint) (uint, uint) {
+		w, err := gc.Create(fmt.Sprintf("key%d", i), 2)
-		deletions := 0
-		var reclaimed uint
-
-		t.Logf("GC starting to reclaim %d bytes", size)
-
-		stats := vfs.StatAll()
-		sort.Slice(stats, func(i, j int) bool {
-			// Sort by access time so we can remove the oldest files first.
-			return stats[i].AccessTime().Before(stats[j].AccessTime())
-		})
-
-		// Delete the oldest files until we've reclaimed enough space.
-		for _, s := range stats {
-			sz := uint(s.Size()) // Get the size of the file
-			err := vfs.Delete(s.Name())
 		if err != nil {
-				panic(err)
+			t.Fatalf("Create failed: %v", err)
 		}
-			reclaimed += sz // Track how much space we've reclaimed
+		w.Write([]byte("ab"))
-			deletions++     // Track how many files we've deleted
+		w.Close()
-
-			// t.Logf("GC deleting %s, %v", s.Name(), s.AccessTime().Format(time.RFC3339Nano))
-
-			if reclaimed >= size { // We've reclaimed enough space
-				break
 	}
-		}
-		return uint(reclaimed), uint(deletions)
-	})
 
-	for i := 0; i < 10000; i++ {
+	// Cache full at 10 bytes
-		if err := gc.Set(fmt.Sprintf("key:%d", i), genRandomData(1024*1, 1024*4)); err != nil {
+	w, err := gc.Create("key5", 2)
-			t.Errorf("Set failed: %v", err)
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write([]byte("cd"))
+	w.Close()
+
+	if gc.Size() > 10 {
+		t.Errorf("Size exceeded: %d > 10", gc.Size())
+	}
+
+	// Check if older keys were evicted
+	_, err = m.Open("key0")
+	if err == nil {
+		t.Error("Expected key0 to be evicted")
 	}
 }
 
-	if gc.Size() > 1024*1024*16 {
+func TestNoGCNeeded(t *testing.T) {
-		t.Errorf("MemoryFS size is %d, want <= 1024", m.Size())
+	m := memory.New(20)
+	gc := New(m, 2, LRUGC)
+
+	for i := 0; i < 5; i++ {
+		w, err := gc.Create(fmt.Sprintf("key%d", i), 2)
+		if err != nil {
+			t.Fatalf("Create failed: %v", err)
+		}
+		w.Write([]byte("ab"))
+		w.Close()
+	}
+
+	if gc.Size() != 10 {
+		t.Errorf("Size: got %d, want 10", gc.Size())
 	}
 }
 
-func genRandomData(min int, max int) []byte {
+func TestGCInsufficientSpace(t *testing.T) {
-	data := make([]byte, rand.Intn(max-min)+min)
+	m := memory.New(5)
-	rand.Read(data)
+	gc := New(m, 1, LRUGC)
-	return data
-}
 
-func TestGCLargeRandom(t *testing.T) {
+	w, err := gc.Create("key0", 10)
-	t.Parallel()
+	if err == nil {
-
+		w.Close()
-	m := memory.New(1024 * 1024 * 16) // 16MB
+		t.Error("Expected ErrDiskFull")
-	gc := New(m, 10, func(vfs vfs.VFS, size uint) (uint, uint) {
+	} else if !errors.Is(err, vfserror.ErrDiskFull) {
-		deletions := 0
+		t.Errorf("Unexpected error: %v", err)
-		var reclaimed uint
-
-		t.Logf("GC starting to reclaim %d bytes", size)
-
-		stats := vfs.StatAll()
-		sort.Slice(stats, func(i, j int) bool {
-			// Sort by access time so we can remove the oldest files first.
-			return stats[i].AccessTime().Before(stats[j].AccessTime())
-		})
-
-		// Delete the oldest files until we've reclaimed enough space.
-		for _, s := range stats {
-			sz := uint(s.Size()) // Get the size of the file
-			vfs.Delete(s.Name())
-			reclaimed += sz // Track how much space we've reclaimed
-			deletions++     // Track how many files we've deleted
-
-			if reclaimed >= size { // We've reclaimed enough space
-				break
-			}
-		}
-
-		return uint(reclaimed), uint(deletions)
-	})
-
-	for i := 0; i < 10000; i++ {
-		if err := gc.Set(fmt.Sprintf("key:%d", i), genRandomData(1024, 1024*1024)); err != nil {
-			t.Errorf("Set failed: %v", err)
-		}
-	}
-
-	if gc.Size() > 1024*1024*16 {
-		t.Errorf("MemoryFS size is %d, want <= 1024", m.Size())
 	}
 }

vfs/memory/memory.go

@@ -1,6 +1,10 @@
+// vfs/memory/memory.go
 package memory
 
 import (
+	"bytes"
+	"container/list"
+	"io"
 	"s1d3sw1ped/SteamCache2/steamcache/logger"
 	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
@@ -8,6 +12,38 @@ import (
 	"time"
 
 	"github.com/docker/go-units"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	memoryCapacityBytes = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "memory_cache_capacity_bytes",
+			Help: "Total capacity of the memory cache in bytes",
+		},
+	)
+
+	memorySizeBytes = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "memory_cache_size_bytes",
+			Help: "Total size of the memory cache in bytes",
+		},
+	)
+
+	memoryReadBytes = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "memory_cache_read_bytes_total",
+			Help: "Total number of bytes read from the memory cache",
+		},
+	)
+
+	memoryWriteBytes = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "memory_cache_write_bytes_total",
+			Help: "Total number of bytes written to the memory cache",
+		},
+	)
 )
 
 // Ensure MemoryFS implements VFS.
@@ -23,9 +59,49 @@ type file struct {
 type MemoryFS struct {
 	files    map[string]*file
 	capacity int64
-	mu       sync.Mutex
+	size     int64
+	mu       sync.RWMutex
+	keyLocks sync.Map // map[string]*sync.RWMutex
+	LRU      *lruList
+}
 
-	bytePool sync.Pool // Pool for []byte slices
+// lruList for LRU eviction
+type lruList struct {
+	list *list.List
+	elem map[string]*list.Element
+}
+
+func newLruList() *lruList {
+	return &lruList{
+		list: list.New(),
+		elem: make(map[string]*list.Element),
+	}
+}
+
+func (l *lruList) MoveToFront(key string) {
+	if e, ok := l.elem[key]; ok {
+		l.list.MoveToFront(e)
+	}
+}
+
+func (l *lruList) Add(key string, fi *vfs.FileInfo) *list.Element {
+	e := l.list.PushFront(fi)
+	l.elem[key] = e
+	return e
+}
+
+func (l *lruList) Remove(key string) {
+	if e, ok := l.elem[key]; ok {
+		l.list.Remove(e)
+		delete(l.elem, key)
+	}
+}
+
+func (l *lruList) Back() *vfs.FileInfo {
+	if e := l.list.Back(); e != nil {
+		return e.Value.(*vfs.FileInfo)
+	}
+	return nil
 }
 
 // New creates a new MemoryFS.
@@ -39,14 +115,18 @@ func New(capacity int64) *MemoryFS {
 		Str("capacity", units.HumanSize(float64(capacity))).
 		Msg("init")
 
-	return &MemoryFS{
+	mfs := &MemoryFS{
 		files:    make(map[string]*file),
 		capacity: capacity,
-		mu:       sync.Mutex{},
+		mu:       sync.RWMutex{},
-		bytePool: sync.Pool{
+		keyLocks: sync.Map{},
-			New: func() interface{} { return make([]byte, 0) }, // Initial capacity for pooled slices
+		LRU:      newLruList(),
-		},
 	}
+
+	memoryCapacityBytes.Set(float64(capacity))
+	memorySizeBytes.Set(float64(mfs.Size()))
+
+	return mfs
 }
 
 func (m *MemoryFS) Capacity() int64 {
@@ -58,93 +138,118 @@ func (m *MemoryFS) Name() string {
 }
 
 func (m *MemoryFS) Size() int64 {
-	var size int64
+	m.mu.RLock()
-
+	defer m.mu.RUnlock()
-	m.mu.Lock()
+	return m.size
-	defer m.mu.Unlock()
-
-	for _, v := range m.files {
-		size += int64(len(v.data))
 }
 
-	return size
+func (m *MemoryFS) getKeyLock(key string) *sync.RWMutex {
+	mu, _ := m.keyLocks.LoadOrStore(key, &sync.RWMutex{})
+	return mu.(*sync.RWMutex)
 }
 
-func (m *MemoryFS) Set(key string, src []byte) error {
+func (m *MemoryFS) Create(key string, size int64) (io.WriteCloser, error) {
+	m.mu.RLock()
 	if m.capacity > 0 {
-		if size := m.Size() + int64(len(src)); size > m.capacity {
+		if m.size+size > m.capacity {
-			return vfserror.ErrDiskFull
+			m.mu.RUnlock()
+			return nil, vfserror.ErrDiskFull
 		}
 	}
+	m.mu.RUnlock()
 
+	keyMu := m.getKeyLock(key)
+	keyMu.Lock()
+	defer keyMu.Unlock()
+
+	buf := &bytes.Buffer{}
+
+	return &memWriteCloser{
+		Writer: buf,
+		onClose: func() error {
+			data := buf.Bytes()
 			m.mu.Lock()
-	defer m.mu.Unlock()
+			if f, exists := m.files[key]; exists {
-
+				m.size -= int64(len(f.data))
-	// Use pooled slice
+				m.LRU.Remove(key)
-	data := m.bytePool.Get().([]byte)
-	if cap(data) < len(src) {
-		data = make([]byte, len(src)) // expand the slice if the pool slice is too small
-	} else {
-		data = data[:len(src)] // reuse the pool slice, but resize it to fit
 			}
-	copy(data, src)
+			fi := vfs.NewFileInfo(key, int64(len(data)), time.Now())
-
 			m.files[key] = &file{
-		fileinfo: vfs.NewFileInfo(
+				fileinfo: fi,
-			key,
-			int64(len(src)),
-			time.Now(),
-		),
 				data:     data,
 			}
+			m.LRU.Add(key, fi)
+			m.size += int64(len(data))
+			m.mu.Unlock()
+
+			memoryWriteBytes.Add(float64(len(data)))
+			memorySizeBytes.Set(float64(m.Size()))
 
 			return nil
+		},
+	}, nil
+}
+
+type memWriteCloser struct {
+	io.Writer
+	onClose func() error
+}
+
+func (wc *memWriteCloser) Close() error {
+	return wc.onClose()
 }
 
 func (m *MemoryFS) Delete(key string) error {
-	_, err := m.Stat(key)
+	keyMu := m.getKeyLock(key)
-	if err != nil {
+	keyMu.Lock()
-		return err
+	defer keyMu.Unlock()
-	}
 
 	m.mu.Lock()
-	defer m.mu.Unlock()
+	f, exists := m.files[key]
-
+	if !exists {
-	// Return data to pool
+		m.mu.Unlock()
-	if f, ok := m.files[key]; ok {
+		return vfserror.ErrNotFound
-		m.bytePool.Put(f.data)
 	}
-
+	m.size -= int64(len(f.data))
+	m.LRU.Remove(key)
 	delete(m.files, key)
+	m.mu.Unlock()
+
+	memorySizeBytes.Set(float64(m.Size()))
 
 	return nil
 }
 
-func (m *MemoryFS) Get(key string) ([]byte, error) {
+func (m *MemoryFS) Open(key string) (io.ReadCloser, error) {
-	_, err := m.Stat(key)
+	keyMu := m.getKeyLock(key)
-	if err != nil {
+	keyMu.RLock()
-		return nil, err
+	defer keyMu.RUnlock()
-	}
 
 	m.mu.Lock()
-	defer m.mu.Unlock()
+	f, exists := m.files[key]
+	if !exists {
+		m.mu.Unlock()
+		return nil, vfserror.ErrNotFound
+	}
+	f.fileinfo.ATime = time.Now()
+	m.LRU.MoveToFront(key)
+	dataCopy := make([]byte, len(f.data))
+	copy(dataCopy, f.data)
+	m.mu.Unlock()
 
-	m.files[key].fileinfo.ATime = time.Now()
+	memoryReadBytes.Add(float64(len(dataCopy)))
-	dst := make([]byte, len(m.files[key].data))
+	memorySizeBytes.Set(float64(m.Size()))
-	copy(dst, m.files[key].data)
 
-	logger.Logger.Debug().
+	return io.NopCloser(bytes.NewReader(dataCopy)), nil
-		Str("name", key).
-		Str("status", "GET").
-		Int64("size", int64(len(dst))).
-		Msg("get file from memory")
-
-	return dst, nil
 }
 
 func (m *MemoryFS) Stat(key string) (*vfs.FileInfo, error) {
-	m.mu.Lock()
+	keyMu := m.getKeyLock(key)
-	defer m.mu.Unlock()
+	keyMu.RLock()
+	defer keyMu.RUnlock()
+
+	m.mu.RLock()
+	defer m.mu.RUnlock()
 
 	f, ok := m.files[key]
 	if !ok {
@@ -155,8 +260,8 @@ func (m *MemoryFS) Stat(key string) (*vfs.FileInfo, error) {
 }
 
 func (m *MemoryFS) StatAll() []*vfs.FileInfo {
-	m.mu.Lock()
+	m.mu.RLock()
-	defer m.mu.Unlock()
+	defer m.mu.RUnlock()
 
 	// hard copy the file info to prevent modification of the original file info or the other way around
 	files := make([]*vfs.FileInfo, 0, len(m.files))

vfs/memory/memory_test.go

@@ -1,63 +1,129 @@
+// vfs/memory/memory_test.go
 package memory
 
 import (
+	"errors"
 	"fmt"
+	"io"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
 	"testing"
 )
 
-func TestAllMemory(t *testing.T) {
+func TestCreateAndOpen(t *testing.T) {
-	t.Parallel()
-
 	m := New(1024)
-	if err := m.Set("key", []byte("value")); err != nil {
+	key := "key"
-		t.Errorf("Set failed: %v", err)
+	value := []byte("value")
-	}
 
-	if err := m.Set("key", []byte("value1")); err != nil {
+	w, err := m.Create(key, int64(len(value)))
-		t.Errorf("Set failed: %v", err)
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
 	}
+	w.Write(value)
+	w.Close()
 
-	if d, err := m.Get("key"); err != nil {
+	rc, err := m.Open(key)
-		t.Errorf("Get failed: %v", err)
+	if err != nil {
-	} else if string(d) != "value1" {
+		t.Fatalf("Open failed: %v", err)
-		t.Errorf("Get failed: got %s, want %s", d, "value1")
 	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
 
-	if err := m.Delete("key"); err != nil {
+	if string(got) != string(value) {
-		t.Errorf("Delete failed: %v", err)
+		t.Fatalf("expected %s, got %s", value, got)
-	}
-
-	if _, err := m.Get("key"); err == nil {
-		t.Errorf("Get failed: got nil, want %v", vfserror.ErrNotFound)
-	}
-
-	if err := m.Delete("key"); err == nil {
-		t.Errorf("Delete failed: got nil, want %v", vfserror.ErrNotFound)
-	}
-
-	if _, err := m.Stat("key"); err == nil {
-		t.Errorf("Stat failed: got nil, want %v", vfserror.ErrNotFound)
-	}
-
-	if err := m.Set("key", []byte("value")); err != nil {
-		t.Errorf("Set failed: %v", err)
-	}
-
-	if _, err := m.Stat("key"); err != nil {
-		t.Errorf("Stat failed: %v", err)
 	}
 }
 
-func TestLimited(t *testing.T) {
+func TestOverwrite(t *testing.T) {
-	t.Parallel()
+	m := New(1024)
+	key := "key"
+	value1 := []byte("value1")
+	value2 := []byte("value2")
 
+	w, err := m.Create(key, int64(len(value1)))
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write(value1)
+	w.Close()
+
+	w, err = m.Create(key, int64(len(value2)))
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write(value2)
+	w.Close()
+
+	rc, err := m.Open(key)
+	if err != nil {
+		t.Fatalf("Open failed: %v", err)
+	}
+	got, _ := io.ReadAll(rc)
+	rc.Close()
+
+	if string(got) != string(value2) {
+		t.Fatalf("expected %s, got %s", value2, got)
+	}
+}
+
+func TestDelete(t *testing.T) {
+	m := New(1024)
+	key := "key"
+	value := []byte("value")
+
+	w, err := m.Create(key, int64(len(value)))
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write(value)
+	w.Close()
+
+	if err := m.Delete(key); err != nil {
+		t.Fatalf("Delete failed: %v", err)
+	}
+
+	_, err = m.Open(key)
+	if !errors.Is(err, vfserror.ErrNotFound) {
+		t.Fatalf("expected %v, got %v", vfserror.ErrNotFound, err)
+	}
+}
+
+func TestCapacityLimit(t *testing.T) {
 	m := New(10)
 	for i := 0; i < 11; i++ {
-		if err := m.Set(fmt.Sprintf("key%d", i), []byte("1")); err != nil && i < 10 {
+		w, err := m.Create(fmt.Sprintf("key%d", i), 1)
-			t.Errorf("Set failed: %v", err)
+		if err != nil && i < 10 {
+			t.Errorf("Create failed: %v", err)
 		} else if i == 10 && err == nil {
-			t.Errorf("Set succeeded: got nil, want %v", vfserror.ErrDiskFull)
+			t.Errorf("Create succeeded: got nil, want %v", vfserror.ErrDiskFull)
+		}
+		if i < 10 {
+			w.Write([]byte("1"))
+			w.Close()
 		}
 	}
 }
+
+func TestStat(t *testing.T) {
+	m := New(1024)
+	key := "key"
+	value := []byte("value")
+
+	w, err := m.Create(key, int64(len(value)))
+	if err != nil {
+		t.Fatalf("Create failed: %v", err)
+	}
+	w.Write(value)
+	w.Close()
+
+	info, err := m.Stat(key)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if info == nil {
+		t.Fatal("expected file info to be non-nil")
+	}
+	if info.Size() != int64(len(value)) {
+		t.Errorf("expected size %d, got %d", len(value), info.Size())
+	}
+}

vfs/sync/sync.go

@@ -1,76 +0,0 @@
-package sync
-
-// import (
-// 	"fmt"
-// 	"s1d3sw1ped/SteamCache2/vfs"
-// 	"sync"
-// )
-
-// // Ensure SyncFS implements VFS.
-// var _ vfs.VFS = (*SyncFS)(nil)
-
-// type SyncFS struct {
-// 	vfs vfs.VFS
-// 	mu  sync.RWMutex
-// }
-
-// func New(vfs vfs.VFS) *SyncFS {
-// 	return &SyncFS{
-// 		vfs: vfs,
-// 		mu:  sync.RWMutex{},
-// 	}
-// }
-
-// // Name returns the name of the file system.
-// func (sfs *SyncFS) Name() string {
-// 	return fmt.Sprintf("SyncFS(%s)", sfs.vfs.Name())
-// }
-
-// // Size returns the total size of all files in the file system.
-// func (sfs *SyncFS) Size() int64 {
-// 	sfs.mu.RLock()
-// 	defer sfs.mu.RUnlock()
-
-// 	return sfs.vfs.Size()
-// }
-
-// // Set sets the value of key as src.
-// // Setting the same key multiple times, the last set call takes effect.
-// func (sfs *SyncFS) Set(key string, src []byte) error {
-// 	sfs.mu.Lock()
-// 	defer sfs.mu.Unlock()
-
-// 	return sfs.vfs.Set(key, src)
-// }
-
-// // Delete deletes the value of key.
-// func (sfs *SyncFS) Delete(key string) error {
-// 	sfs.mu.Lock()
-// 	defer sfs.mu.Unlock()
-
-// 	return sfs.vfs.Delete(key)
-// }
-
-// // Get gets the value of key to dst, and returns dst no matter whether or not there is an error.
-// func (sfs *SyncFS) Get(key string) ([]byte, error) {
-// 	sfs.mu.RLock()
-// 	defer sfs.mu.RUnlock()
-
-// 	return sfs.vfs.Get(key)
-// }
-
-// // Stat returns the FileInfo of key.
-// func (sfs *SyncFS) Stat(key string) (*vfs.FileInfo, error) {
-// 	sfs.mu.RLock()
-// 	defer sfs.mu.RUnlock()
-
-// 	return sfs.vfs.Stat(key)
-// }
-
-// // StatAll returns the FileInfo of all keys.
-// func (sfs *SyncFS) StatAll() []*vfs.FileInfo {
-// 	sfs.mu.RLock()
-// 	defer sfs.mu.RUnlock()
-
-// 	return sfs.vfs.StatAll()
-// }

vfs/vfs.go

@@ -1,5 +1,8 @@
+// vfs/vfs.go
 package vfs
 
+import "io"
+
 // VFS is the interface that wraps the basic methods of a virtual file system.
 type VFS interface {
 	// Name returns the name of the file system.
@@ -8,15 +11,14 @@ type VFS interface {
 	// Size returns the total size of all files in the file system.
 	Size() int64
 
-	// Set sets the value of key as src.
+	// Create creates a new file at key with expected size.
-	// Setting the same key multiple times, the last set call takes effect.
+	Create(key string, size int64) (io.WriteCloser, error)
-	Set(key string, src []byte) error
 
 	// Delete deletes the value of key.
 	Delete(key string) error
 
-	// Get gets the value of key to dst, and returns dst no matter whether or not there is an error.
+	// Open opens the file at key.
-	Get(key string) ([]byte, error)
+	Open(key string) (io.ReadCloser, error)
 
 	// Stat returns the FileInfo of key.
 	Stat(key string) (*FileInfo, error)

vfs/vfserror/vfserror.go

@@ -1,3 +1,4 @@
+// vfs/vfserror/vfserror.go
 package vfserror
 
 import "errors"