snowflake sequencer need an unique id

fix https://github.com/chrislusf/seaweedfs/issues/2213

weed/command/scaffold/master.toml

@@ -26,6 +26,8 @@ type = "raft"     # Choose [raft|etcd|snowflake] type for storing the file id se
 # when sequencer.type = etcd, set listen client urls of etcd cluster that store file id sequence
 # example : http://127.0.0.1:2379,http://127.0.0.1:2389
 sequencer_etcd_urls = "http://127.0.0.1:2379"
+# when sequencer.type = snowflake, the snowflake id must be different from other masters
+sequencer_snowflake_id = 0     # any number between 1~1023
 
 
 # configurations for tiered cloud storage

weed/sequence/snowflake_sequencer.go

@@ -13,8 +13,11 @@ type SnowflakeSequencer struct {
 	node *snowflake.Node
 }
 
-func NewSnowflakeSequencer(nodeid string) (*SnowflakeSequencer, error) {
+func NewSnowflakeSequencer(nodeid string, snowflakeId int) (*SnowflakeSequencer, error) {
 	nodeid_hash := hash(nodeid) & 0x3ff
+	if snowflakeId != 0 {
+		nodeid_hash = uint32(snowflakeId)
+	}
 	glog.V(0).Infof("use snowflake seq id generator, nodeid:%s hex_of_nodeid: %x", nodeid, nodeid_hash)
 	node, err := snowflake.NewNode(int64(nodeid_hash))
 	if err != nil {

weed/server/master_server.go

@@ -28,6 +28,7 @@ import (
 const (
 	SequencerType     = "master.sequencer.type"
 	SequencerEtcdUrls = "master.sequencer.sequencer_etcd_urls"
+	SequencerSnowflakeId = "master.sequencer.sequencer_snowflake_id"
 )
 
 type MasterOption struct {
@@ -293,7 +294,8 @@ func (ms *MasterServer) createSequencer(option *MasterOption) sequence.Sequencer
 		}
 	case "snowflake":
 		var err error
-		seq, err = sequence.NewSnowflakeSequencer(fmt.Sprintf("%s:%d", option.Host, option.Port))
+		snowflakeId := v.GetInt(SequencerSnowflakeId)
+		seq, err = sequence.NewSnowflakeSequencer(fmt.Sprintf("%s:%d", option.Host, option.Port), snowflakeId)
 		if err != nil {
 			glog.Error(err)
 			seq = nil