ec shard info can be queried via VolumeList()

weed/storage/erasure_coding/ec_volume.go

@@ -10,9 +10,11 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/storage/needle"
 )
 
+type ShardId uint8
+
 type EcVolumeShard struct {
 	VolumeId   needle.VolumeId
-	ShardId    uint8
+	ShardId    ShardId
 	Collection string
 	dir        string
 	ecdFile    *os.File
@@ -22,7 +24,7 @@ type EcVolumeShards []*EcVolumeShard
 
 func NewEcVolumeShard(dirname string, collection string, id needle.VolumeId, shardId int) (v *EcVolumeShard, e error) {
 
-	v = &EcVolumeShard{dir: dirname, Collection: collection, VolumeId: id, ShardId: uint8(shardId)}
+	v = &EcVolumeShard{dir: dirname, Collection: collection, VolumeId: id, ShardId: ShardId(shardId)}
 
 	baseFileName := v.FileName()
 	if v.ecxFile, e = os.OpenFile(baseFileName+".ecx", os.O_RDONLY, 0644); e != nil {

weed/storage/erasure_coding/ec_volume_info.go

@@ -0,0 +1,46 @@
+package erasure_coding
+
+import (
+	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
+	"github.com/chrislusf/seaweedfs/weed/storage/needle"
+)
+
+// data structure used in master
+type EcVolumeInfo struct {
+	VolumeId   needle.VolumeId
+	Collection string
+	shardIds   uint16 // use bits to indicate the shard id
+}
+
+func (ecInfo *EcVolumeInfo) AddShardId(id ShardId) {
+	ecInfo.shardIds |= (1 << id)
+}
+
+func (ecInfo *EcVolumeInfo) RemoveShardId(id ShardId) {
+	ecInfo.shardIds &^= (1 << id)
+}
+
+func (ecInfo *EcVolumeInfo) HasShardId(id ShardId) bool {
+	return ecInfo.shardIds&(1<<id) > 0
+}
+
+func (ecInfo *EcVolumeInfo) ShardIds() (ret []ShardId) {
+	for i := ShardId(0); i < DataShardsCount+ParityShardsCount; i++ {
+		if ecInfo.HasShardId(i) {
+			ret = append(ret, i)
+		}
+	}
+	return
+}
+
+func (ecInfo *EcVolumeInfo) ToVolumeEcShardInformationMessage() (ret []*master_pb.VolumeEcShardInformationMessage) {
+	for _, shard := range ecInfo.ShardIds() {
+		ret = append(ret, &master_pb.VolumeEcShardInformationMessage{
+			Id:         uint32(ecInfo.VolumeId),
+			EcIndex:    uint32(shard),
+			Collection: ecInfo.Collection,
+		})
+
+	}
+	return
+}