Merge pull request 'fix: gc was being stupid allowing another thread to take the space it made before it could not anymore' (#5) from fix/gc-breaking-downloads into main

Reviewed-on: s1d3sw1ped/SteamCache2#5

.gitea/workflows/release-tag.yaml

@@ -8,14 +8,14 @@ jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@main
         with:
           fetch-depth: 0
       - run: git fetch --force --tags
-      - uses: actions/setup-go@v5
+      - uses: actions/setup-go@main
         with:
           go-version-file: 'go.mod'
-      - uses: goreleaser/goreleaser-action@v6
+      - uses: goreleaser/goreleaser-action@master
         with:
           distribution: goreleaser
           version: 'latest'

.gitea/workflows/test-pr.yaml

@@ -6,14 +6,10 @@ jobs:
   check-and-test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@main
-      - uses: actions/setup-go@v5
+      - uses: actions/setup-go@main
         with:
           go-version-file: 'go.mod'
       - run: go mod tidy  
-      - uses: golangci/golangci-lint-action@v3
-        with:
-          args: -D errcheck
-          version: latest
       - run: go build ./...
       - run: go test -race -v -shuffle=on ./...

.gitignore

@@ -1,3 +1,5 @@
 dist/
 tmp/
 __*.exe
+.smashed.txt
+.smashignore

.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

.vscode/launch.json

@@ -17,9 +17,8 @@
                 "10G",
                 "--disk-path",
                 "tmp/disk",
-                "--upstream",
+                "--log-level",
-                "http://192.168.2.88:80",
+                "debug",
-                "--verbose",
             ],
         },
         {
@@ -33,9 +32,8 @@
                 "10G",
                 "--disk-path",
                 "tmp/disk",
-                "--upstream",
+                "--log-level",
-                "http://192.168.2.88:80",
+                "debug",
-                "--verbose",
             ],
         },
         {
@@ -47,9 +45,8 @@
             "args": [
                 "--memory",
                 "1G",
-                "--upstream",
+                "--log-level",
-                "http://192.168.2.88:80",
+                "debug",
-                "--verbose",
             ],
         }
     ]

cmd/root.go

@@ -1,23 +1,27 @@
+// cmd/root.go
 package cmd
 
 import (
 	"os"
+	"runtime"
 	"s1d3sw1ped/SteamCache2/steamcache"
+	"s1d3sw1ped/SteamCache2/steamcache/logger"
+	"s1d3sw1ped/SteamCache2/version"
 
 	"github.com/rs/zerolog"
 	"github.com/spf13/cobra"
 )
 
 var (
+	threads int
+
 	memory   string
-	memorymultiplier int
 	disk     string
-	diskmultiplier   int
 	diskpath string
 	upstream string
 
-	pprof   bool
+	logLevel  string
-	verbose bool
+	logFormat string
 )
 
 var rootCmd = &cobra.Command{
@@ -29,21 +33,52 @@ var rootCmd = &cobra.Command{
 	By caching game files, SteamCache2 ensures that subsequent downloads of the same files are served from the local cache, 
 	significantly improving download times and reducing the load on the internet connection.`,
 	Run: func(cmd *cobra.Command, args []string) {
-		if verbose {
+		// Configure logging
+		switch logLevel {
+		case "debug":
 			zerolog.SetGlobalLevel(zerolog.DebugLevel)
+		case "error":
+			zerolog.SetGlobalLevel(zerolog.ErrorLevel)
+		case "info":
+			zerolog.SetGlobalLevel(zerolog.InfoLevel)
+		default:
+			zerolog.SetGlobalLevel(zerolog.InfoLevel) // Default to info level if not specified
+		}
+		var writer zerolog.ConsoleWriter
+		if logFormat == "json" {
+			writer = zerolog.ConsoleWriter{Out: os.Stderr, NoColor: true}
+		} else {
+			writer = zerolog.ConsoleWriter{Out: os.Stderr}
+		}
+		logger.Logger = zerolog.New(writer).With().Timestamp().Logger()
+
+		logger.Logger.Info().
+			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("SteamCache2 " + version.Version + " started on " + address)
+
 		sc.Run()
+
+		logger.Logger.Info().Msg("SteamCache2 stopped")
+		os.Exit(0)
 	},
 }
 
@@ -57,15 +92,14 @@ 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")
-	rootCmd.Flags().IntVarP(&diskmultiplier, "disk-gc", "D", 100, "The gc value for the disk cache")
 	rootCmd.Flags().StringVarP(&diskpath, "disk-path", "p", "", "The path to the disk cache")
 
 	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().StringVarP(&logLevel, "log-level", "l", "info", "Logging level: debug, info, error")
-	rootCmd.Flags().MarkHidden("pprof")
+	rootCmd.Flags().StringVarP(&logFormat, "log-format", "f", "console", "Logging format: json, console")
-	rootCmd.Flags().BoolVarP(&verbose, "verbose", "v", false, "Enable verbose logging")
 }

cmd/version.go

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

go.mod

@@ -4,15 +4,22 @@ go 1.23.0
 
 require (
 	github.com/docker/go-units v0.5.0
+	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 (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.19 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/prometheus/client_model v0.6.1 // indirect
+	github.com/prometheus/common v0.62.0 // indirect
+	github.com/prometheus/procfs v0.15.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	golang.org/x/sys v0.12.0 // indirect
+	golang.org/x/sys v0.30.0 // indirect
+	google.golang.org/protobuf v1.36.5 // indirect
 )

go.sum

@@ -1,16 +1,40 @@
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
 github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
 github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
+github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
+github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
+github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
 github.com/mattn/go-isatty v0.0.19 h1:JITubQf0MOLdlGRuRq+jtsDlekdYPia9ZFsB8h/APPA=
 github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_golang v1.22.0 h1:rb93p9lokFEsctTys46VnV1kLCDpVZ0a/Y92Vm0Zc6Q=
+github.com/prometheus/client_golang v1.22.0/go.mod h1:R7ljNsLXhuQXYZYtw6GAE9AZg8Y7vEW5scdCXrWRXC0=
+github.com/prometheus/client_model v0.6.1 h1:ZKSh/rekM+n3CeS952MLRAdFwIKqeY8b62p8ais2e9E=
+github.com/prometheus/client_model v0.6.1/go.mod h1:OrxVMOVHjw3lKMa8+x6HeMGkHMQyHDk9E3jmP2AmGiY=
+github.com/prometheus/common v0.62.0 h1:xasJaQlnWAeyHdUBeGjXmutelfJHWMRr+Fg4QszZ2Io=
+github.com/prometheus/common v0.62.0/go.mod h1:vyBcEuLSvWos9B1+CyL7JZ2up+uFzXhkqml0W5zIY1I=
+github.com/prometheus/procfs v0.15.1 h1:YagwOFzUgYfKKHX6Dr+sHT7km/hxC76UB0learggepc=
+github.com/prometheus/procfs v0.15.1/go.mod h1:fB45yRUv8NstnjriLhBQLuOUt+WW4BsoGhij/e3PBqk=
 github.com/rs/xid v1.5.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
 github.com/rs/zerolog v1.33.0 h1:1cU2KZkvPxNyfgEmhHAz/1A9Bz+llsdYzklWFzgp0r8=
 github.com/rs/zerolog v1.33.0/go.mod h1:/7mN4D5sKwJLZQ2b/znpjC3/GQWY/xaDXUM0kKWRHss=
@@ -19,11 +43,15 @@ github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
 github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
-golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8 h1:yqrTHse8TCMW1M1ZCP+VAR/l0kKxwaAIqN/il7x4voA=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
-golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8/go.mod h1:tujkw807nyEEAamNbDrEGzRav+ilXA7PCRAd6xsmwiU=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 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 h1:CM0HF96J0hcLAwsHPJZjfdNzs0gftsLfgKt57wWHJ0o=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
+golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+google.golang.org/protobuf v1.36.5 h1:tPhr+woSbjfYvY6/GPufUoYizxw1cF/yFoxJ2fmpwlM=
+google.golang.org/protobuf v1.36.5/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

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

@@ -1,49 +0,0 @@
-package steamcache
-
-import (
-	"runtime/debug"
-	"s1d3sw1ped/SteamCache2/vfs"
-	"s1d3sw1ped/SteamCache2/vfs/cachestate"
-	"time"
-
-	"golang.org/x/exp/rand"
-)
-
-func init() {
-	// Set the GC percentage to 50%. This is a good balance between performance and memory usage.
-	debug.SetGCPercent(50)
-}
-
-// RandomGC randomly deletes files until we've reclaimed enough space.
-func randomgc(vfss vfs.VFS, size uint) (uint, uint) {
-	// Randomly delete files until we've reclaimed enough space.
-	random := func(vfss vfs.VFS, stats []*vfs.FileInfo) int64 {
-		randfile := stats[rand.Intn(len(stats))]
-		sz := randfile.Size()
-		err := vfss.Delete(randfile.Name())
-		if err != nil {
-			return 0
-		}
-
-		return sz
-	}
-
-	deletions := 0
-	targetreclaim := int64(size)
-	var reclaimed int64
-
-	stats := vfss.StatAll()
-	for {
-		if reclaimed >= targetreclaim {
-			break
-		}
-		reclaimed += random(vfss, stats)
-		deletions++
-	}
-
-	return uint(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

@@ -1,13 +1,8 @@
+// steamcache/logger/logger.go
 package logger
 
 import (
-	"os"
-
 	"github.com/rs/zerolog"
 )
 
-func init() {
+var Logger zerolog.Logger
-	zerolog.SetGlobalLevel(zerolog.InfoLevel)
-}
-
-var Logger = zerolog.New(zerolog.ConsoleWriter{Out: os.Stderr}).With().Timestamp().Logger()

steamcache/steamcache.go

@@ -1,33 +1,56 @@
+// steamcache/steamcache.go
 package steamcache
 
 import (
-	"fmt"
+	"context"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
-	"runtime"
-	"s1d3sw1ped/SteamCache2/steamcache/avgcachestate"
 	"s1d3sw1ped/SteamCache2/steamcache/logger"
-	"s1d3sw1ped/SteamCache2/version"
 	"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"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var (
+	requestsTotal = promauto.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "http_requests_total",
+			Help: "Total number of HTTP requests",
+		},
+		[]string{"method", "status"},
+	)
+
+	cacheStatusTotal = promauto.NewCounterVec(
+		prometheus.CounterOpts{
+			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
 
@@ -39,13 +62,13 @@ type SteamCache struct {
 	memorygc *gc.GCFS
 	diskgc   *gc.GCFS
 
-	hits *avgcachestate.AvgCacheState
+	server *http.Server
-
+	client *http.Client
-	dirty bool
+	cancel context.CancelFunc
-	mu    sync.Mutex
+	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, diskSize string, diskPath, upstream string) *SteamCache {
 	memorysize, err := units.FromHumanSize(memorySize)
 	if err != nil {
 		panic(err)
@@ -57,21 +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, randomgc)
+		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, randomgc)
+		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
@@ -94,24 +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() {
-			randomgc(d, uint(d.Size()-d.Capacity()))
+			gc.LRUGC(d, uint(d.Size()-d.Capacity()))
 		}
 	}
 
@@ -120,106 +163,49 @@ 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()
 	}
 
-	sc.mu.Lock()
+	sc.server.Handler = sc
-	sc.dirty = true
+	ctx, cancel := context.WithCancel(context.Background())
-	sc.mu.Unlock()
+	sc.cancel = cancel
 
-	sc.LogStats()
+	sc.wg.Add(1)
-	t := time.NewTicker(1 * time.Second)
 	go func() {
-		for range t.C {
+		defer sc.wg.Done()
-			sc.LogStats()
+		err := sc.server.ListenAndServe()
-		}
+		if err != nil && err != http.ErrServerClosed {
-	}()
-
-	err := http.ListenAndServe(sc.address, sc)
-	if err != nil {
-		if err == http.ErrServerClosed {
-			logger.Logger.Info().Msg("shutdown")
-			return
-		}
 			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) LogStats() {
+func (sc *SteamCache) Shutdown() {
-	sc.mu.Lock()
+	if sc.cancel != nil {
-	defer sc.mu.Unlock()
+		sc.cancel()
-	if sc.dirty {
-
-		logger.Logger.Info().Str("address", sc.address).Str("version", version.Version).Str("upstream", sc.upstream).Msg("listening")
-		if sc.memory != nil { // only log memory if memory is enabled
-			lifetimeBytes, lifetimeFiles, reclaimedBytes, deletedFiles, gcTime := sc.memorygc.Stats()
-
-			logger.Logger.Info().
-				Str("size", units.HumanSize(float64(sc.memory.Size()))).
-				Str("capacity", units.HumanSize(float64(sc.memory.Capacity()))).
-				Str("files", fmt.Sprintf("%d", len(sc.memory.StatAll()))).
-				Msg("memory")
-
-			logger.Logger.Info().
-				Str("data_total", units.HumanSize(float64(lifetimeBytes))).
-				Uint("files_total", lifetimeFiles).
-				Str("data", units.HumanSize(float64(reclaimedBytes))).
-				Uint("files", deletedFiles).
-				Str("gc_time", gcTime.String()).
-				Msg("memory_gc")
-		}
-
-		if sc.disk != nil { // only log disk if disk is enabled
-			lifetimeBytes, lifetimeFiles, reclaimedBytes, deletedFiles, gcTime := sc.diskgc.Stats()
-
-			logger.Logger.Info().
-				Str("size", units.HumanSize(float64(sc.disk.Size()))).
-				Str("capacity", units.HumanSize(float64(sc.disk.Capacity()))).
-				Str("files", fmt.Sprintf("%d", len(sc.disk.StatAll()))).
-				Msg("disk")
-
-			logger.Logger.Info().
-				Str("data_total", units.HumanSize(float64(lifetimeBytes))).
-				Uint("files_total", lifetimeFiles).
-				Str("data", units.HumanSize(float64(reclaimedBytes))).
-				Uint("files", deletedFiles).
-				Str("gc_time", gcTime.String()).
-				Msg("disk_gc")
-		}
-
-		// log golang Garbage Collection stats
-		var m runtime.MemStats
-		runtime.ReadMemStats(&m)
-
-		logger.Logger.Info().
-			Str("alloc", units.HumanSize(float64(m.Alloc))).
-			Str("sys", units.HumanSize(float64(m.Sys))).
-			Msg("app_gc")
-
-		logger.Logger.Info().
-			Str("hitrate", fmt.Sprintf("%.2f%%", sc.hits.Avg()*100)).
-			Msg("cache")
-
-		logger.Logger.Info().Msg("") // empty line to separate log entries for better readability
-		sc.dirty = false
 	}
+	sc.wg.Wait()
 }
 
 func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	if sc.pprof && r.URL.Path == "/debug/pprof/" {
+	if r.URL.Path == "/metrics" {
-		pprof.Index(w, r)
+		promhttp.Handler().ServeHTTP(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.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
 	}
@@ -231,42 +217,63 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	sc.mu.Lock()
+	if strings.HasPrefix(r.URL.String(), "/depot/") {
-	sc.dirty = true
+		// trim the query parameters from the URL path
-	sc.mu.Unlock()
+		// this is necessary because the cache key should not include query parameters
+		path := strings.Split(r.URL.String(), "?")[0]
 
-	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
+		tstart := time.Now()
+		defer func() { responseTime.Observe(time.Since(tstart).Seconds()) }()
+
+		cacheKey := strings.ReplaceAll(path[1:], "\\", "/") // replace all backslashes with forward slashes shouldn't be necessary but just in case
 
-	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", path).Msg("Invalid URL")
 			http.Error(w, "Invalid URL", http.StatusBadRequest)
 			return
 		}
 
-	data, err := sc.vfs.Get(cacheKey)
+		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
+
+		reader, err := sc.vfs.Open(cacheKey)
 		if err == nil {
-		sc.hits.Add(cachestate.CacheStateHit)
+			defer reader.Close()
 			w.Header().Add("X-LanCache-Status", "HIT")
-		w.Write(data)
+
-		logger.Logger.Debug().Str("key", r.URL.String()).Msg("cache")
+			io.Copy(w, reader)
+
+			logger.Logger.Info().
+				Str("key", cacheKey).
+				Str("host", r.Host).
+				Str("status", "HIT").
+				Dur("duration", time.Since(tstart)).
+				Msg("request")
+
+			requestsTotal.WithLabelValues(r.Method, "200").Inc()
+			cacheStatusTotal.WithLabelValues("HIT").Inc()
+
 			return
 		}
 
 		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")
 				http.Error(w, "Failed to join URL path", http.StatusInternalServerError)
 				return
 			}
 
 			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
 			}
 			req.Host = r.Host
-		logger.Logger.Debug().Str("key", cacheKey).Str("host", sc.upstream).Msg("upstream")
 		} else { // if no upstream server is configured, proxy the request to the host specified in the request
 			host := r.Host
 			if r.Header.Get("X-Sls-Https") == "enable" {
@@ -275,43 +282,90 @@ 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")
 				http.Error(w, "Failed to join URL path", http.StatusInternalServerError)
 				return
 			}
 
 			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
 			}
-
-		logger.Logger.Debug().Str("key", cacheKey).Str("host", host).Msg("forward")
 		}
 
-	req.Header.Add("X-Sls-Https", r.Header.Get("X-Sls-Https"))
+		// Copy headers from the original request to the new request
-	req.Header.Add("User-Agent", r.Header.Get("User-Agent"))
+		for key, values := range r.Header {
-	resp, err := http.DefaultClient.Do(req)
+			for _, value := range values {
-	if err != nil {
+				req.Header.Add(key, value)
+			}
+		}
+
+		// 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 = sc.client.Do(req)
+			if err == nil && resp.StatusCode == http.StatusOK {
+				break
+			}
+			if i < len(backoffSchedule)-1 {
+				time.Sleep(backoff)
+			}
+		}
+		if err != nil || resp.StatusCode != http.StatusOK {
+			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()
 
-	if resp.StatusCode != http.StatusOK {
+		size := resp.ContentLength
-		http.Error(w, "Failed to fetch the requested URL", resp.StatusCode)
+
-		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
 		}
 
-	body, err := io.ReadAll(resp.Body)
-	if err != nil {
-		http.Error(w, "Failed to read response body", http.StatusInternalServerError)
-		return
-	}
-
-	sc.vfs.Set(cacheKey, body)
-	sc.hits.Add(cachestate.CacheStateMiss)
 		w.Header().Add("X-LanCache-Status", "MISS")
-	w.Write(body)
+
+		io.Copy(ww, resp.Body)
+
+		logger.Logger.Info().
+			Str("key", cacheKey).
+			Str("host", r.Host).
+			Str("status", "MISS").
+			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

@@ -1,32 +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", "1G", td, "")
 
-	sc.dirty = true
+	w, err := sc.vfs.Create("key", 5)
-	sc.LogStats()
+	if err != nil {
-
+		t.Errorf("Create failed: %v", err)
-	if err := sc.vfs.Set("key", []byte("value")); err != nil {
-		t.Errorf("Set failed: %v", err)
-	}
-	if err := sc.vfs.Set("key1", []byte("value1")); err != nil {
-		t.Errorf("Set failed: %v", err)
 	}
+	w.Write([]byte("value"))
+	w.Close()
 
-	sc.dirty = true
+	w, err = sc.vfs.Create("key1", 6)
-	sc.LogStats()
+	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)
@@ -36,21 +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")
 	}
 
@@ -65,7 +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", "1G", 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 +1,10 @@
+// version/version.go
 package version
 
 var Version string
+
+func init() {
+	if Version == "" {
+		Version = "0.0.0-dev"
+	}
+}

vfs/cache/cache.go

@@ -1,10 +1,13 @@
+// vfs/cache/cache.go
 package cache
 
 import (
 	"fmt"
+	"io"
 	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/cachestate"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
+	"sync"
 )
 
 // Ensure CacheFS implements VFS.
@@ -16,6 +19,8 @@ type CacheFS struct {
 	slow vfs.VFS
 
 	cacheHandler CacheHandler
+
+	keyLocks sync.Map // map[string]*sync.RWMutex for per-key locks
 }
 
 type CacheHandler func(*vfs.FileInfo, cachestate.CacheState) bool
@@ -24,6 +29,7 @@ type CacheHandler func(*vfs.FileInfo, cachestate.CacheState) bool
 func New(cacheHandler CacheHandler) *CacheFS {
 	return &CacheFS{
 		cacheHandler: cacheHandler,
+		keyLocks:     sync.Map{},
 	}
 }
 
@@ -39,6 +45,12 @@ func (c *CacheFS) SetFast(vfs vfs.VFS) {
 	c.fast = vfs
 }
 
+// getKeyLock returns a RWMutex for the given key, creating it if necessary.
+func (c *CacheFS) getKeyLock(key string) *sync.RWMutex {
+	mu, _ := c.keyLocks.LoadOrStore(key, &sync.RWMutex{})
+	return mu.(*sync.RWMutex)
+}
+
 // cacheState returns the state of the file at key.
 func (c *CacheFS) cacheState(key string) cachestate.CacheState {
 	if c.fast != nil {
@@ -63,65 +75,74 @@ 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 {
-	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)
+	mu.Lock()
+	defer mu.Unlock()
+
 	if c.fast != nil {
 		c.fast.Delete(key)
 	}
 	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)
+	mu := c.getKeyLock(key)
-	return src, err
+	mu.RLock()
-}
+	defer mu.RUnlock()
 
-// 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) {
 	state := c.cacheState(key)
 
 	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)
@@ -130,6 +151,10 @@ func (c *CacheFS) GetS(key string) ([]byte, cachestate.CacheState, error) {
 // Stat returns information about the file at key.
 // Warning: This will return information about the file in the fastest storage its in.
 func (c *CacheFS) Stat(key string) (*vfs.FileInfo, error) {
+	mu := c.getKeyLock(key)
+	mu.RLock()
+	defer mu.RUnlock()
+
 	state := c.cacheState(key)
 
 	switch state {
@@ -150,3 +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.
@@ -23,8 +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
+}
+
+// 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.
@@ -42,6 +118,11 @@ func new(root string, capacity int64, skipinit bool) *DiskFS {
 		if !os.IsNotExist(err) {
 			panic(err) // panic if the error is something other than not found
 		}
+		os.Mkdir(root, 0755)    // create the root directory if it does not exist
+		fi, err = os.Stat(root) // re-stat to get the file info
+		if err != nil {
+			panic(err) // panic if the re-stat fails
+		}
 	}
 	if !fi.IsDir() {
 		panic("disk root must be a directory") // panic if the root is not a directory
@@ -51,14 +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{},
+		LRU:      newLruList(),
 	}
 
 	os.MkdirAll(dfs.root, 0755)
 
+	diskCapacityBytes.Set(float64(dfs.capacity))
+
 	if !skipinit {
 		dfs.init()
+		diskSizeBytes.Set(float64(dfs.Size()))
 	}
 
 	return dfs
@@ -73,12 +158,30 @@ func NewSkipInit(root string, capacity int64) *DiskFS {
 }
 
 func (d *DiskFS) init() {
-	// logger.Logger.Info().Str("name", d.Name()).Str("root", d.root).Str("capacity", units.HumanSize(float64(d.capacity))).Msg("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()).
@@ -90,36 +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:], "\\", "/")
-			logger.Logger.Debug().Str("name", k).Str("root", d.root).Msg("walk")
-			d.info[k] = vfs.NewFileInfoFromOS(info, k)
-			d.mu.Unlock()
-
-			// logger.Logger.Debug().Str("name", d.Name()).Str("root", d.root).Str("capacity", units.HumanSize(float64(d.capacity))).Str("path", npath).Msg("init")
-			return nil
-		})
-	}()
-}
-
 func (d *DiskFS) Capacity() int64 {
 	return d.capacity
 }
@@ -129,52 +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()
 
-	logger.Logger.Debug().Str("name", key).Str("root", d.root).Msg("set")
+	keyMu := d.getKeyLock(key)
-
+	keyMu.Lock()
-	if _, err := d.Stat(key); err == nil {
+	defer keyMu.Unlock()
-		logger.Logger.Debug().Str("name", key).Str("root", d.root).Msg("delete")
-		d.Delete(key)
-	}
 
+	// 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.
@@ -186,24 +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
 	}
@@ -211,20 +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
 	}
 
-	return data, nil
+	// Update metrics on close
+	return &readCloser{
+		ReadCloser: file,
+		onClose: func(n int64) {
+			diskReadBytes.Add(float64(n))
+		},
+	}, nil
+}
+
+type readCloser struct {
+	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.
@@ -236,10 +427,19 @@ func (d *DiskFS) Stat(key string) (*vfs.FileInfo, error) {
 		return nil, vfserror.ErrInvalidKey
 	}
 
-	logger.Logger.Debug().Str("name", key).Str("root", d.root).Msg("stat")
+	// 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.Lock()
+	keyMu := d.getKeyLock(key)
-	defer d.mu.Unlock()
+	keyMu.RLock()
+	defer keyMu.RUnlock()
+
+	d.mu.RLock()
+	defer d.mu.RUnlock()
 
 	if fi, ok := d.info[key]; !ok {
 		return nil, vfserror.ErrNotFound
@@ -248,13 +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

@@ -1,84 +1,108 @@
+// 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"
 )
 
+var (
+	// ErrInsufficientSpace is returned when there are no files to delete in the VFS.
+	ErrInsufficientSpace = fmt.Errorf("no files to delete")
+)
+
+// LRUGC deletes files in LRU order until enough space is reclaimed.
+func LRUGC(vfss vfs.VFS, size uint) error {
+	logger.Logger.Debug().Uint("target", size).Msg("Attempting to reclaim space using LRU GC")
+
+	var reclaimed uint // reclaimed space in bytes
+
+	for {
+		switch fs := vfss.(type) {
+		case *disk.DiskFS:
+			fi := fs.LRU.Back()
+			if fi == nil {
+				return ErrInsufficientSpace // No files to delete
+			}
+			sz := uint(fi.Size())
+			err := fs.Delete(fi.Name())
+			if err != nil {
+				continue // If delete fails, try the next file
+			}
+			reclaimed += sz
+		case *memory.MemoryFS:
+			fi := fs.LRU.Back()
+			if fi == nil {
+				return ErrInsufficientSpace // No files to delete
+			}
+			sz := uint(fi.Size())
+			err := fs.Delete(fi.Name())
+			if err != nil {
+				continue // If delete fails, try the next file
+			}
+			reclaimed += sz
+		default:
+			panic("unreachable: unsupported VFS type for LRU GC") // panic if the VFS is not disk or memory
+		}
+
+		if reclaimed >= size {
+			logger.Logger.Debug().Uint("target", size).Uint("achieved", reclaimed).Msg("Reclaimed enough space using LRU GC")
+			return nil // stop if enough space is reclaimed
+		}
+	}
+}
+
+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)
 
 // GCFS is a virtual file system that calls a GC handler when the disk is full. The GC handler is responsible for freeing up space on the disk. The GCFS is a wrapper around another VFS.
 type GCFS struct {
 	vfs.VFS
-	multiplier int
 
-	// 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) error
 
-func New(vfs vfs.VFS, multiplier int, gcHandlerFunc GCHandlerFunc) *GCFS {
+func New(vfs vfs.VFS, gcHandlerFunc GCHandlerFunc) *GCFS {
-	if multiplier <= 0 {
-		multiplier = 1 // if the multiplier is less than or equal to 0 set it to 1 will be slow but the user can set it to a higher value if they want
-	}
 	return &GCFS{
 		VFS:          vfs,
-		multiplier:   multiplier,
 		gcHanderFunc: gcHandlerFunc,
 	}
 }
 
-// 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.
+	for err == vfserror.ErrDiskFull && g.gcHanderFunc != nil { // if the error is disk full and there is a GC handler
-// The reclaimed bytes and deleted files and gc time are reset to 0 after the call to Stats.
+		errr := g.gcHanderFunc(g.VFS, uint(size)) // call the GC handler
-func (g *GCFS) Stats() (lifetimeBytes, lifetimeFiles, reclaimedBytes, deletedFiles uint, gcTime time.Duration) {
+		if errr == ErrInsufficientSpace {
-	g.mu.Lock()
+			return nil, errr // if the GC handler returns no files to delete, return the error
-	defer g.mu.Unlock()
+		}
-
+		w, err = g.VFS.Create(key, size)
-	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.
+	if err != nil {
-func (g *GCFS) Set(key string, src []byte) error {
+		if err == vfserror.ErrDiskFull {
-	g.mu.Lock()
+			logger.Logger.Error().Str("key", key).Int64("size", size).Msg("Failed to create file due to disk full, even after GC")
-	defer g.mu.Unlock()
+		} else {
-	err := g.VFS.Set(key, src) // try to set the key and src
+			logger.Logger.Error().Str("key", key).Int64("size", size).Err(err).Msg("Failed to create file")
-
+		}
-	if err == vfserror.ErrDiskFull && g.gcHanderFunc != nil { // if the error is disk full and there is a GC handler
-		tstart := time.Now()
-		reclaimedBytes, deletedFiles := g.gcHanderFunc(g.VFS, uint(len(src)*g.multiplier)) // call the GC handler
-		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 +1,72 @@
+// vfs/gc/gc_test.go
 package gc
 
 import (
+	"errors"
 	"fmt"
-	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/memory"
-	"sort"
 	"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, 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, 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, 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, ErrInsufficientSpace) {
-		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

@@ -1,10 +1,49 @@
+// vfs/memory/memory.go
 package memory
 
 import (
+	"bytes"
+	"container/list"
+	"io"
+	"s1d3sw1ped/SteamCache2/steamcache/logger"
 	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
 	"sync"
 	"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.
@@ -20,7 +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
+}
+
+// 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.
@@ -29,11 +110,23 @@ func New(capacity int64) *MemoryFS {
 		panic("memory capacity must be greater than 0") // panic if the capacity is less than or equal to 0
 	}
 
-	return &MemoryFS{
+	logger.Logger.Info().
+		Str("name", "MemoryFS").
+		Str("capacity", units.HumanSize(float64(capacity))).
+		Msg("init")
+
+	mfs := &MemoryFS{
 		files:    make(map[string]*file),
 		capacity: capacity,
-		mu:       sync.Mutex{},
+		mu:       sync.RWMutex{},
+		keyLocks: sync.Map{},
+		LRU:      newLruList(),
 	}
+
+	memoryCapacityBytes.Set(float64(capacity))
+	memorySizeBytes.Set(float64(mfs.Size()))
+
+	return mfs
 }
 
 func (m *MemoryFS) Capacity() int64 {
@@ -45,73 +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))
-	m.files[key] = &file{
+				m.LRU.Remove(key)
-		fileinfo: vfs.NewFileInfo(
-			key,
-			int64(len(src)),
-			time.Now(),
-		),
-		data: src,
 			}
+			fi := vfs.NewFileInfo(key, int64(len(data)), time.Now())
+			m.files[key] = &file{
+				fileinfo: fi,
+				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 {
+		m.mu.Unlock()
+		return vfserror.ErrNotFound
+	}
+	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)
 
-	return dst, nil
+	return io.NopCloser(bytes.NewReader(dataCopy)), 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 {
@@ -122,8 +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"