kvdb: move channeldb/kvdb to top level

kvdb/etcd/bucket.go

@@ -0,0 +1,92 @@
+// +build kvdb_etcd
+
+package etcd
+
+import (
+	"crypto/sha256"
+)
+
+const (
+	bucketIDLength = 32
+)
+
+var (
+	valuePostfix   = []byte{0x00}
+	bucketPostfix  = []byte{0xFF}
+	sequencePrefix = []byte("$seq$")
+)
+
+// makeBucketID returns a deterministic key for the passed byte slice.
+// Currently it returns the sha256 hash of the slice.
+func makeBucketID(key []byte) [bucketIDLength]byte {
+	return sha256.Sum256(key)
+}
+
+// isValidBucketID checks if the passed slice is the required length to be a
+// valid bucket id.
+func isValidBucketID(s []byte) bool {
+	return len(s) == bucketIDLength
+}
+
+// makeKey concatenates parent, key and postfix into one byte slice.
+// The postfix indicates the use of this key (whether bucket or value), while
+// parent refers to the parent bucket.
+func makeKey(parent, key, postfix []byte) []byte {
+	keyBuf := make([]byte, len(parent)+len(key)+len(postfix))
+	copy(keyBuf, parent)
+	copy(keyBuf[len(parent):], key)
+	copy(keyBuf[len(parent)+len(key):], postfix)
+
+	return keyBuf
+}
+
+// makeBucketKey returns a bucket key from the passed parent bucket id and
+// the key.
+func makeBucketKey(parent []byte, key []byte) []byte {
+	return makeKey(parent, key, bucketPostfix)
+}
+
+// makeValueKey returns a value key from the passed parent bucket id and
+// the key.
+func makeValueKey(parent []byte, key []byte) []byte {
+	return makeKey(parent, key, valuePostfix)
+}
+
+// makeSequenceKey returns a sequence key of the passed parent bucket id.
+func makeSequenceKey(parent []byte) []byte {
+	keyBuf := make([]byte, len(sequencePrefix)+len(parent))
+	copy(keyBuf, sequencePrefix)
+	copy(keyBuf[len(sequencePrefix):], parent)
+	return keyBuf
+}
+
+// isBucketKey returns true if the passed key is a bucket key, meaning it
+// keys a bucket name.
+func isBucketKey(key string) bool {
+	if len(key) < bucketIDLength+1 {
+		return false
+	}
+
+	return key[len(key)-1] == bucketPostfix[0]
+}
+
+// getKey chops out the key from the raw key (by removing the bucket id
+// prefixing the key and the postfix indicating whether it is a bucket or
+// a value key)
+func getKey(rawKey string) []byte {
+	return []byte(rawKey[bucketIDLength : len(rawKey)-1])
+}
+
+// getKeyVal chops out the key from the raw key (by removing the bucket id
+// prefixing the key and the postfix indicating whether it is a bucket or
+// a value key) and also returns the appropriate value for the key, which is
+// nil in case of buckets (or the set value otherwise).
+func getKeyVal(kv *KV) ([]byte, []byte) {
+	var val []byte
+
+	if !isBucketKey(kv.key) {
+		val = []byte(kv.val)
+	}
+
+	return getKey(kv.key), val
+}