feat: add configurations for memory only, disk only, and memory & disk modes

vfs/cache/cache.go

@@ -21,23 +21,24 @@ type CacheFS struct {
 type CacheHandler func(*vfs.FileInfo, cachestate.CacheState) bool
 
 // New creates a new CacheFS. fast is used for caching, and slow is used for storage. fast should obviously be faster than slow.
-func New(fast, slow vfs.VFS, cacheHandler CacheHandler) *CacheFS {
-	if slow == nil {
-		panic("slow is nil")
-	}
-
-	if fast == slow {
-		panic("fast and slow are the same")
-	}
-
+func New(cacheHandler CacheHandler) *CacheFS {
 	return &CacheFS{
-		fast: fast,
-		slow: slow,
-
 		cacheHandler: cacheHandler,
 	}
 }
 
+func (c *CacheFS) SetSlow(vfs vfs.VFS) {
+	if vfs == nil {
+		panic("vfs is nil") // panic if the vfs is nil
+	}
+
+	c.slow = vfs
+}
+
+func (c *CacheFS) SetFast(vfs vfs.VFS) {
+	c.fast = vfs
+}
+
 // cacheState returns the state of the file at key.
 func (c *CacheFS) cacheState(key string) cachestate.CacheState {
 	if c.fast != nil {

vfs/cache/cache_test.go

@@ -20,7 +20,9 @@ func TestNew(t *testing.T) {
 	fast := testMemory()
 	slow := testMemory()
 
-	cache := New(fast, slow, nil)
+	cache := New(nil)
+	cache.SetFast(fast)
+	cache.SetSlow(slow)
 	if cache == nil {
 		t.Fatal("expected cache to be non-nil")
 	}
@@ -35,7 +37,9 @@ func TestNewPanics(t *testing.T) {
 		}
 	}()
 
-	New(nil, nil, nil)
+	cache := New(nil)
+	cache.SetFast(nil)
+	cache.SetSlow(nil)
 }
 
 func TestSetAndGet(t *testing.T) {
@@ -43,7 +47,9 @@ func TestSetAndGet(t *testing.T) {
 
 	fast := testMemory()
 	slow := testMemory()
-	cache := New(fast, slow, nil)
+	cache := New(nil)
+	cache.SetFast(fast)
+	cache.SetSlow(slow)
 
 	key := "test"
 	value := []byte("value")
@@ -66,7 +72,8 @@ func TestSetAndGetNoFast(t *testing.T) {
 	t.Parallel()
 
 	slow := testMemory()
-	cache := New(nil, slow, nil)
+	cache := New(nil)
+	cache.SetSlow(slow)
 
 	key := "test"
 	value := []byte("value")
@@ -89,9 +96,11 @@ func TestCaching(t *testing.T) {
 
 	fast := testMemory()
 	slow := testMemory()
-	cache := New(fast, slow, func(fi *vfs.FileInfo, cs cachestate.CacheState) bool {
+	cache := New(func(fi *vfs.FileInfo, cs cachestate.CacheState) bool {
 		return true
 	})
+	cache.SetFast(fast)
+	cache.SetSlow(slow)
 
 	key := "test"
 	value := []byte("value")
@@ -148,7 +157,9 @@ func TestGetNotFound(t *testing.T) {
 
 	fast := testMemory()
 	slow := testMemory()
-	cache := New(fast, slow, nil)
+	cache := New(nil)
+	cache.SetFast(fast)
+	cache.SetSlow(slow)
 
 	_, err := cache.Get("nonexistent")
 	if !errors.Is(err, vfserror.ErrNotFound) {
@@ -161,7 +172,9 @@ func TestDelete(t *testing.T) {
 
 	fast := testMemory()
 	slow := testMemory()
-	cache := New(fast, slow, nil)
+	cache := New(nil)
+	cache.SetFast(fast)
+	cache.SetSlow(slow)
 
 	key := "test"
 	value := []byte("value")
@@ -185,7 +198,9 @@ func TestStat(t *testing.T) {
 
 	fast := testMemory()
 	slow := testMemory()
-	cache := New(fast, slow, nil)
+	cache := New(nil)
+	cache.SetFast(fast)
+	cache.SetSlow(slow)
 
 	key := "test"
 	value := []byte("value")

vfs/disk/disk.go

@@ -27,6 +27,24 @@ type DiskFS struct {
 
 // New creates a new DiskFS.
 func new(root string, capacity int64, skipinit bool) *DiskFS {
+	if capacity <= 0 {
+		panic("disk capacity must be greater than 0") // panic if the capacity is less than or equal to 0
+	}
+
+	if root == "" {
+		panic("disk root must not be empty") // panic if the root is empty
+	}
+
+	fi, err := os.Stat(root)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			panic(err) // panic if the error is something other than not found
+		}
+	}
+	if !fi.IsDir() {
+		panic("disk root must be a directory") // panic if the root is not a directory
+	}
+
 	dfs := &DiskFS{
 		root:     root,
 		info:     make(map[string]*vfs.FileInfo),

vfs/gc/gc.go

@@ -20,6 +20,9 @@ type GCFS struct {
 type GCHandlerFunc func(vfs vfs.VFS, size int)
 
 func New(vfs vfs.VFS, multiplier int, 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,

vfs/memory/memory.go

@@ -25,6 +25,10 @@ type MemoryFS struct {
 
 // New creates a new MemoryFS.
 func New(capacity int64) *MemoryFS {
+	if capacity <= 0 {
+		panic("memory capacity must be greater than 0") // panic if the capacity is less than or equal to 0
+	}
+
 	return &MemoryFS{
 		files:    make(map[string]*file),
 		capacity: capacity,