add a snowflake sequencer as more robust fid generator, but less compressable than small auto-inc id

weed/sequence/snowflake_sequencer.go

@@ -0,0 +1,43 @@
+package sequence
+
+import (
+	"fmt"
+	"hash/fnv"
+
+	"github.com/bwmarrin/snowflake"
+)
+
+// a simple snowflake Sequencer
+type SnowflakeSequencer struct {
+	node *snowflake.Node
+}
+
+func NewSnowflakeSequencer(nodeid string) (*SnowflakeSequencer, error) {
+	node, err := snowflake.NewNode(int64(hash(nodeid) & 0x3ff))
+	if err != nil {
+		fmt.Println(err)
+		return nil, err
+	}
+
+	sequencer := &SnowflakeSequencer{node: node}
+	return sequencer, nil
+}
+
+func hash(s string) uint32 {
+	h := fnv.New32a()
+	h.Write([]byte(s))
+	return h.Sum32()
+}
+
+func (m *SnowflakeSequencer) NextFileId(count uint64) uint64 {
+	return uint64(m.node.Generate().Int64())
+}
+
+// ignore setmax as we are snowflake
+func (m *SnowflakeSequencer) SetMax(seenValue uint64) {
+}
+
+// return a new id as no Peek is stored
+func (m *SnowflakeSequencer) Peek() uint64 {
+	return uint64(m.node.Generate().Int64())
+}