Add keyPrefix support for TiKV store (#7756)

* Add keyPrefix support for TiKV store

Similar to the Redis keyPrefix feature (#7299), this adds keyPrefix support
for TiKV stores to enable sharing a single TiKV cluster as metadata store
for multitenant SeaweedFS clusters.

Changes:
- Add keyPrefix field to TikvStore struct
- Update Initialize function to read keyPrefix from config
- Add getKey method to prepend prefix to all keys
- Update generateKey, getNameFromKey, and genDirectoryKeyPrefix methods
  to be store receiver methods and handle key prefixing
- Update filer.toml scaffold with keyPrefix configuration option

Fixes #7752

* Fix potential slice corruption in getKey method

Use a new slice with proper capacity to avoid modifying the
underlying array of store.keyPrefix when appending.

* Add keyPrefix validation and defensive bounds check

- Add validation in Initialize to reject keyPrefix longer than 256 bytes
- Add bounds check in getNameFromKey to prevent panic on malformed keys

* Update weed/filer/tikv/tikv_store.go

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update weed/command/scaffold/filer.toml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

weed/command/scaffold/filer.toml

@@ -399,6 +399,8 @@ enabled = false
 # If you have many pd address, use ',' split then:
 #   pdaddrs = "pdhost1:2379, pdhost2:2379, pdhost3:2379"
 pdaddrs = "localhost:2379"
+# prefix for filer TiKV keys, useful for sharing a TiKV cluster with multiple seaweedfs clusters
+keyPrefix = ""
 # Enable 1PC
 enable_1pc = false
 # batch delete count, default 10000 in code

weed/filer/tikv/tikv_store.go

@@ -34,6 +34,7 @@ type TikvStore struct {
 	client          *txnkv.Client
 	onePC           bool
 	batchCommitSize int
+	keyPrefix       []byte
 }
 
 // Basic APIs
@@ -47,6 +48,7 @@ func (store *TikvStore) Initialize(config util.Configuration, prefix string) err
 	key := config.GetString(prefix + "key_path")
 	verify_cn := strings.Split(config.GetString(prefix+"verify_cn"), ",")
 	pdAddrs := strings.Split(config.GetString(prefix+"pdaddrs"), ",")
+	keyPrefix := config.GetString(prefix + "keyPrefix")
 
 	bdc := config.GetInt(prefix + "batchdelete_count")
 	if bdc <= 0 {
@@ -55,6 +57,7 @@ func (store *TikvStore) Initialize(config util.Configuration, prefix string) err
 
 	store.onePC = config.GetBool(prefix + "enable_1pc")
 	store.batchCommitSize = bdc
+	store.keyPrefix = []byte(keyPrefix)
 	return store.initialize(ca, cert, key, verify_cn, pdAddrs)
 }
 
@@ -79,7 +82,7 @@ func (store *TikvStore) Shutdown() {
 // Entry APIs
 func (store *TikvStore) InsertEntry(ctx context.Context, entry *filer.Entry) error {
 	dir, name := entry.DirAndName()
-	key := generateKey(dir, name)
+	key := store.generateKey(dir, name)
 
 	value, err := entry.EncodeAttributesAndChunks()
 	if err != nil {
@@ -104,7 +107,7 @@ func (store *TikvStore) UpdateEntry(ctx context.Context, entry *filer.Entry) err
 
 func (store *TikvStore) FindEntry(ctx context.Context, path util.FullPath) (*filer.Entry, error) {
 	dir, name := path.DirAndName()
-	key := generateKey(dir, name)
+	key := store.generateKey(dir, name)
 
 	txn, err := store.getTxn(ctx)
 	if err != nil {
@@ -139,7 +142,7 @@ func (store *TikvStore) FindEntry(ctx context.Context, path util.FullPath) (*fil
 
 func (store *TikvStore) DeleteEntry(ctx context.Context, path util.FullPath) error {
 	dir, name := path.DirAndName()
-	key := generateKey(dir, name)
+	key := store.generateKey(dir, name)
 
 	txn, err := store.getTxn(ctx)
 	if err != nil {
@@ -159,7 +162,7 @@ func (store *TikvStore) DeleteEntry(ctx context.Context, path util.FullPath) err
 
 // Directory APIs
 func (store *TikvStore) DeleteFolderChildren(ctx context.Context, path util.FullPath) error {
-	directoryPrefix := genDirectoryKeyPrefix(path, "")
+	directoryPrefix := store.genDirectoryKeyPrefix(path, "")
 
 	iterTxn, err := store.getTxn(ctx)
 	if err != nil {
@@ -242,10 +245,10 @@ func (store *TikvStore) ListDirectoryEntries(ctx context.Context, dirPath util.F
 
 func (store *TikvStore) ListDirectoryPrefixedEntries(ctx context.Context, dirPath util.FullPath, startFileName string, includeStartFile bool, limit int64, prefix string, eachEntryFunc filer.ListEachEntryFunc) (string, error) {
 	lastFileName := ""
-	directoryPrefix := genDirectoryKeyPrefix(dirPath, prefix)
+	directoryPrefix := store.genDirectoryKeyPrefix(dirPath, prefix)
 	lastFileStart := directoryPrefix
 	if startFileName != "" {
-		lastFileStart = genDirectoryKeyPrefix(dirPath, startFileName)
+		lastFileStart = store.genDirectoryKeyPrefix(dirPath, startFileName)
 	}
 
 	txn, err := store.getTxn(ctx)
@@ -265,7 +268,7 @@ func (store *TikvStore) ListDirectoryPrefixedEntries(ctx context.Context, dirPat
 			if !bytes.HasPrefix(key, directoryPrefix) {
 				break
 			}
-			fileName := getNameFromKey(key)
+			fileName := store.getNameFromKey(key)
 			if fileName == "" {
 				if err := iter.Next(); err != nil {
 					break
@@ -418,22 +421,37 @@ func hashToBytes(dir string) []byte {
 	return b
 }
 
-func generateKey(dirPath, fileName string) []byte {
+func (store *TikvStore) getKey(key []byte) []byte {
+	if len(store.keyPrefix) == 0 {
+		return key
+	}
+	result := make([]byte, len(store.keyPrefix)+len(key))
+	copy(result, store.keyPrefix)
+	copy(result[len(store.keyPrefix):], key)
+	return result
+}
+
+func (store *TikvStore) generateKey(dirPath, fileName string) []byte {
 	key := hashToBytes(dirPath)
 	key = append(key, []byte(fileName)...)
-	return key
+	return store.getKey(key)
 }
 
-func getNameFromKey(key []byte) string {
-	return string(key[sha1.Size:])
+func (store *TikvStore) getNameFromKey(key []byte) string {
+	minKeyLen := len(store.keyPrefix) + sha1.Size
+	if len(key) < minKeyLen {
+		glog.Warningf("malformed key: length %d is less than minimum %d", len(key), minKeyLen)
+		return ""
+	}
+	return string(key[minKeyLen:])
 }
 
-func genDirectoryKeyPrefix(fullpath util.FullPath, startFileName string) (keyPrefix []byte) {
+func (store *TikvStore) genDirectoryKeyPrefix(fullpath util.FullPath, startFileName string) (keyPrefix []byte) {
 	keyPrefix = hashToBytes(string(fullpath))
 	if len(startFileName) > 0 {
 		keyPrefix = append(keyPrefix, []byte(startFileName)...)
 	}
-	return keyPrefix
+	return store.getKey(keyPrefix)
 }
 
 func isNotExists(err error) bool {