Rework parameters passing for functions within `ec.rebuild` (#7445)

* Rework parameters passing for functions within `ec.rebuild`

This simplifies the overall codebase and allows to cleanly handle parallelization via waitgroups.

* fix copy source

* add tests

* remove tests not useful

* fmt

* nil check

---------

Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>
Co-authored-by: chrislu <chris.lu@gmail.com>

2 files changed, 380 insertions, 31 deletions

diff --git a/weed/shell/command_ec_rebuild.go b/weed/shell/command_ec_rebuild.go
index bef56d191..3b2c63cc7 100644
--- a/weed/shell/command_ec_rebuild.go
+++ b/weed/shell/command_ec_rebuild.go
@@ -11,13 +11,21 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb"
 	"github.com/seaweedfs/seaweedfs/weed/storage/erasure_coding"
 	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
-	"google.golang.org/grpc"
 )
 
 func init() {
 	Commands = append(Commands, &commandEcRebuild{})
 }
 
+type ecRebuilder struct {
+	// TODO: add ErrorWaitGroup for parallelization
+	commandEnv   *CommandEnv
+	ecNodes      []*EcNode
+	writer       io.Writer
+	applyChanges bool
+	collections  []string
+}
+
 type commandEcRebuild struct {
 }
 
@@ -93,10 +101,18 @@ func (c *commandEcRebuild) Do(args []string, commandEnv *CommandEnv, writer io.W
 		collections = []string{*collection}
 	}
 
+	erb := &ecRebuilder{
+		commandEnv:   commandEnv,
+		ecNodes:      allEcNodes,
+		writer:       writer,
+		applyChanges: *applyChanges,
+		collections:  collections,
+	}
+
 	fmt.Printf("rebuildEcVolumes for %d collection(s)\n", len(collections))
 	for _, c := range collections {
 		fmt.Printf("rebuildEcVolumes collection %s\n", c)
-		if err = rebuildEcVolumes(commandEnv, allEcNodes, c, writer, *applyChanges); err != nil {
+		if err = erb.rebuildEcVolumes(c); err != nil {
 			return err
 		}
 	}
@@ -104,13 +120,36 @@ func (c *commandEcRebuild) Do(args []string, commandEnv *CommandEnv, writer io.W
 	return nil
 }
 
-func rebuildEcVolumes(commandEnv *CommandEnv, allEcNodes []*EcNode, collection string, writer io.Writer, applyChanges bool) error {
+func (erb *ecRebuilder) write(format string, a ...any) {
+	fmt.Fprintf(erb.writer, format, a...)
+}
+
+func (erb *ecRebuilder) isLocked() bool {
+	return erb.commandEnv.isLocked()
+}
+
+// ecNodeWithMoreFreeSlots returns the EC node with higher free slot count, from all nodes visible to the rebuilder.
+func (erb *ecRebuilder) ecNodeWithMoreFreeSlots() *EcNode {
+	if len(erb.ecNodes) == 0 {
+		return nil
+	}
 
+	res := erb.ecNodes[0]
+	for i := 1; i < len(erb.ecNodes); i++ {
+		if erb.ecNodes[i].freeEcSlot > res.freeEcSlot {
+			res = erb.ecNodes[i]
+		}
+	}
+
+	return res
+}
+
+func (erb *ecRebuilder) rebuildEcVolumes(collection string) error {
 	fmt.Printf("rebuildEcVolumes %s\n", collection)
 
 	// collect vid => each shard locations, similar to ecShardMap in topology.go
 	ecShardMap := make(EcShardMap)
-	for _, ecNode := range allEcNodes {
+	for _, ecNode := range erb.ecNodes {
 		ecShardMap.registerEcNode(ecNode, collection)
 	}
 
@@ -120,16 +159,10 @@ func rebuildEcVolumes(commandEnv *CommandEnv, allEcNodes []*EcNode, collection s
 			continue
 		}
 		if shardCount < erasure_coding.DataShardsCount {
-			return fmt.Errorf("ec volume %d is unrepairable with %d shards\n", vid, shardCount)
-		}
-
-		sortEcNodesByFreeslotsDescending(allEcNodes)
-
-		if allEcNodes[0].freeEcSlot < erasure_coding.TotalShardsCount {
-			return fmt.Errorf("disk space is not enough")
+			return fmt.Errorf("ec volume %d is unrepairable with %d shards", vid, shardCount)
 		}
 
-		if err := rebuildOneEcVolume(commandEnv, allEcNodes[0], collection, vid, locations, writer, applyChanges); err != nil {
+		if err := erb.rebuildOneEcVolume(collection, vid, locations); err != nil {
 			return err
 		}
 	}
@@ -137,17 +170,25 @@ func rebuildEcVolumes(commandEnv *CommandEnv, allEcNodes []*EcNode, collection s
 	return nil
 }
 
-func rebuildOneEcVolume(commandEnv *CommandEnv, rebuilder *EcNode, collection string, volumeId needle.VolumeId, locations EcShardLocations, writer io.Writer, applyChanges bool) error {
-
-	if !commandEnv.isLocked() {
+func (erb *ecRebuilder) rebuildOneEcVolume(collection string, volumeId needle.VolumeId, locations EcShardLocations) error {
+	if !erb.isLocked() {
 		return fmt.Errorf("lock is lost")
 	}
 
+	// TODO: fix this logic so it supports concurrent executions
+	rebuilder := erb.ecNodeWithMoreFreeSlots()
+	if rebuilder == nil {
+		return fmt.Errorf("no EC nodes available for rebuild")
+	}
+	if rebuilder.freeEcSlot < erasure_coding.TotalShardsCount {
+		return fmt.Errorf("disk space is not enough")
+	}
+
 	fmt.Printf("rebuildOneEcVolume %s %d\n", collection, volumeId)
 
 	// collect shard files to rebuilder local disk
 	var generatedShardIds []uint32
-	copiedShardIds, _, err := prepareDataToRecover(commandEnv, rebuilder, collection, volumeId, locations, writer, applyChanges)
+	copiedShardIds, _, err := erb.prepareDataToRecover(rebuilder, collection, volumeId, locations)
 	if err != nil {
 		return err
 	}
@@ -155,25 +196,25 @@ func rebuildOneEcVolume(commandEnv *CommandEnv, rebuilder *EcNode, collection st
 		// clean up working files
 
 		// ask the rebuilder to delete the copied shards
-		err = sourceServerDeleteEcShards(commandEnv.option.GrpcDialOption, collection, volumeId, pb.NewServerAddressFromDataNode(rebuilder.info), copiedShardIds)
+		err = sourceServerDeleteEcShards(erb.commandEnv.option.GrpcDialOption, collection, volumeId, pb.NewServerAddressFromDataNode(rebuilder.info), copiedShardIds)
 		if err != nil {
-			fmt.Fprintf(writer, "%s delete copied ec shards %s %d.%v\n", rebuilder.info.Id, collection, volumeId, copiedShardIds)
+			erb.write("%s delete copied ec shards %s %d.%v\n", rebuilder.info.Id, collection, volumeId, copiedShardIds)
 		}
 
 	}()
 
-	if !applyChanges {
+	if !erb.applyChanges {
 		return nil
 	}
 
 	// generate ec shards, and maybe ecx file
-	generatedShardIds, err = generateMissingShards(commandEnv.option.GrpcDialOption, collection, volumeId, pb.NewServerAddressFromDataNode(rebuilder.info))
+	generatedShardIds, err = erb.generateMissingShards(collection, volumeId, pb.NewServerAddressFromDataNode(rebuilder.info))
 	if err != nil {
 		return err
 	}
 
 	// mount the generated shards
-	err = mountEcShards(commandEnv.option.GrpcDialOption, collection, volumeId, pb.NewServerAddressFromDataNode(rebuilder.info), generatedShardIds)
+	err = mountEcShards(erb.commandEnv.option.GrpcDialOption, collection, volumeId, pb.NewServerAddressFromDataNode(rebuilder.info), generatedShardIds)
 	if err != nil {
 		return err
 	}
@@ -183,9 +224,9 @@ func rebuildOneEcVolume(commandEnv *CommandEnv, rebuilder *EcNode, collection st
 	return nil
 }
 
-func generateMissingShards(grpcDialOption grpc.DialOption, collection string, volumeId needle.VolumeId, sourceLocation pb.ServerAddress) (rebuiltShardIds []uint32, err error) {
+func (erb *ecRebuilder) generateMissingShards(collection string, volumeId needle.VolumeId, sourceLocation pb.ServerAddress) (rebuiltShardIds []uint32, err error) {
 
-	err = operation.WithVolumeServerClient(false, sourceLocation, grpcDialOption, func(volumeServerClient volume_server_pb.VolumeServerClient) error {
+	err = operation.WithVolumeServerClient(false, sourceLocation, erb.commandEnv.option.GrpcDialOption, func(volumeServerClient volume_server_pb.VolumeServerClient) error {
 		resp, rebuildErr := volumeServerClient.VolumeEcShardsRebuild(context.Background(), &volume_server_pb.VolumeEcShardsRebuildRequest{
 			VolumeId:   uint32(volumeId),
 			Collection: collection,
@@ -198,7 +239,7 @@ func generateMissingShards(grpcDialOption grpc.DialOption, collection string, vo
 	return
 }
 
-func prepareDataToRecover(commandEnv *CommandEnv, rebuilder *EcNode, collection string, volumeId needle.VolumeId, locations EcShardLocations, writer io.Writer, applyBalancing bool) (copiedShardIds []uint32, localShardIds []uint32, err error) {
+func (erb *ecRebuilder) prepareDataToRecover(rebuilder *EcNode, collection string, volumeId needle.VolumeId, locations EcShardLocations) (copiedShardIds []uint32, localShardIds []uint32, err error) {
 
 	needEcxFile := true
 	var localShardBits erasure_coding.ShardBits
@@ -212,21 +253,20 @@ func prepareDataToRecover(commandEnv *CommandEnv, rebuilder *EcNode, collection
 	}
 
 	for shardId, ecNodes := range locations {
-
 		if len(ecNodes) == 0 {
-			fmt.Fprintf(writer, "missing shard %d.%d\n", volumeId, shardId)
+			erb.write("missing shard %d.%d\n", volumeId, shardId)
 			continue
 		}
 
 		if localShardBits.HasShardId(erasure_coding.ShardId(shardId)) {
 			localShardIds = append(localShardIds, uint32(shardId))
-			fmt.Fprintf(writer, "use existing shard %d.%d\n", volumeId, shardId)
+			erb.write("use existing shard %d.%d\n", volumeId, shardId)
 			continue
 		}
 
 		var copyErr error
-		if applyBalancing {
-			copyErr = operation.WithVolumeServerClient(false, pb.NewServerAddressFromDataNode(rebuilder.info), commandEnv.option.GrpcDialOption, func(volumeServerClient volume_server_pb.VolumeServerClient) error {
+		if erb.applyChanges {
+			copyErr = operation.WithVolumeServerClient(false, pb.NewServerAddressFromDataNode(rebuilder.info), erb.commandEnv.option.GrpcDialOption, func(volumeServerClient volume_server_pb.VolumeServerClient) error {
 				_, copyErr := volumeServerClient.VolumeEcShardsCopy(context.Background(), &volume_server_pb.VolumeEcShardsCopyRequest{
 					VolumeId:       uint32(volumeId),
 					Collection:     collection,
@@ -243,9 +283,9 @@ func prepareDataToRecover(commandEnv *CommandEnv, rebuilder *EcNode, collection
 			}
 		}
 		if copyErr != nil {
-			fmt.Fprintf(writer, "%s failed to copy %d.%d from %s: %v\n", rebuilder.info.Id, volumeId, shardId, ecNodes[0].info.Id, copyErr)
+			erb.write("%s failed to copy %d.%d from %s: %v\n", rebuilder.info.Id, volumeId, shardId, ecNodes[0].info.Id, copyErr)
 		} else {
-			fmt.Fprintf(writer, "%s copied %d.%d from %s\n", rebuilder.info.Id, volumeId, shardId, ecNodes[0].info.Id)
+			erb.write("%s copied %d.%d from %s\n", rebuilder.info.Id, volumeId, shardId, ecNodes[0].info.Id)
 			copiedShardIds = append(copiedShardIds, uint32(shardId))
 		}
 
diff --git a/weed/shell/command_ec_rebuild_test.go b/weed/shell/command_ec_rebuild_test.go
new file mode 100644
index 000000000..5ab431137
--- /dev/null
+++ b/weed/shell/command_ec_rebuild_test.go
@@ -0,0 +1,309 @@
+package shell
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/storage/erasure_coding"
+	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
+)
+
+// TestEcShardMapRegister tests that EC shards are properly registered
+func TestEcShardMapRegister(t *testing.T) {
+	ecShardMap := make(EcShardMap)
+
+	// Create test nodes with EC shards
+	node1 := newEcNode("dc1", "rack1", "node1", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{0, 1, 2, 3, 4, 5, 6})
+	node2 := newEcNode("dc1", "rack1", "node2", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{7, 8, 9, 10, 11, 12, 13})
+
+	ecShardMap.registerEcNode(node1, "c1")
+	ecShardMap.registerEcNode(node2, "c1")
+
+	// Verify volume 1 is registered
+	locations, found := ecShardMap[needle.VolumeId(1)]
+	if !found {
+		t.Fatal("Expected volume 1 to be registered")
+	}
+
+	// Check shard count
+	count := locations.shardCount()
+	if count != erasure_coding.TotalShardsCount {
+		t.Errorf("Expected %d shards, got %d", erasure_coding.TotalShardsCount, count)
+	}
+
+	// Verify shard distribution
+	for i := 0; i < 7; i++ {
+		if len(locations[i]) != 1 || locations[i][0].info.Id != "node1" {
+			t.Errorf("Shard %d should be on node1", i)
+		}
+	}
+	for i := 7; i < erasure_coding.TotalShardsCount; i++ {
+		if len(locations[i]) != 1 || locations[i][0].info.Id != "node2" {
+			t.Errorf("Shard %d should be on node2", i)
+		}
+	}
+}
+
+// TestEcShardMapShardCount tests shard counting
+func TestEcShardMapShardCount(t *testing.T) {
+	testCases := []struct {
+		name          string
+		shardIds      []uint32
+		expectedCount int
+	}{
+		{"all shards", []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13}, 14},
+		{"data shards only", []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, 10},
+		{"parity shards only", []uint32{10, 11, 12, 13}, 4},
+		{"missing some shards", []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8}, 9},
+		{"single shard", []uint32{0}, 1},
+		{"no shards", []uint32{}, 0},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			locations := make(EcShardLocations, erasure_coding.MaxShardCount)
+			for _, shardId := range tc.shardIds {
+				locations[shardId] = []*EcNode{
+					newEcNode("dc1", "rack1", "node1", 100),
+				}
+			}
+
+			count := locations.shardCount()
+			if count != tc.expectedCount {
+				t.Errorf("Expected %d shards, got %d", tc.expectedCount, count)
+			}
+		})
+	}
+}
+
+// TestEcRebuilderEcNodeWithMoreFreeSlots tests the free slot selection
+func TestEcRebuilderEcNodeWithMoreFreeSlots(t *testing.T) {
+	testCases := []struct {
+		name         string
+		nodes        []*EcNode
+		expectedNode string
+	}{
+		{
+			name: "single node",
+			nodes: []*EcNode{
+				newEcNode("dc1", "rack1", "node1", 100),
+			},
+			expectedNode: "node1",
+		},
+		{
+			name: "multiple nodes - select highest",
+			nodes: []*EcNode{
+				newEcNode("dc1", "rack1", "node1", 50),
+				newEcNode("dc1", "rack1", "node2", 150),
+				newEcNode("dc1", "rack1", "node3", 100),
+			},
+			expectedNode: "node2",
+		},
+		{
+			name: "multiple nodes - same slots",
+			nodes: []*EcNode{
+				newEcNode("dc1", "rack1", "node1", 100),
+				newEcNode("dc1", "rack1", "node2", 100),
+			},
+			expectedNode: "node1", // Should return first one
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			erb := &ecRebuilder{
+				ecNodes: tc.nodes,
+			}
+
+			node := erb.ecNodeWithMoreFreeSlots()
+			if node == nil {
+				t.Fatal("Expected a node, got nil")
+			}
+
+			if node.info.Id != tc.expectedNode {
+				t.Errorf("Expected node %s, got %s", tc.expectedNode, node.info.Id)
+			}
+		})
+	}
+}
+
+// TestEcRebuilderEcNodeWithMoreFreeSlotsEmpty tests empty node list
+func TestEcRebuilderEcNodeWithMoreFreeSlotsEmpty(t *testing.T) {
+	erb := &ecRebuilder{
+		ecNodes: []*EcNode{},
+	}
+
+	node := erb.ecNodeWithMoreFreeSlots()
+	if node != nil {
+		t.Errorf("Expected nil for empty node list, got %v", node)
+	}
+}
+
+// TestRebuildEcVolumesInsufficientShards tests error handling for unrepairable volumes
+func TestRebuildEcVolumesInsufficientShards(t *testing.T) {
+	var logBuffer bytes.Buffer
+
+	// Create a volume with insufficient shards (less than DataShardsCount)
+	node1 := newEcNode("dc1", "rack1", "node1", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{0, 1, 2, 3, 4}) // Only 5 shards
+
+	erb := &ecRebuilder{
+		commandEnv: &CommandEnv{
+			env:    make(map[string]string),
+			noLock: true, // Bypass lock check for unit test
+		},
+		ecNodes: []*EcNode{node1},
+		writer:  &logBuffer,
+	}
+
+	err := erb.rebuildEcVolumes("c1")
+	if err == nil {
+		t.Fatal("Expected error for insufficient shards, got nil")
+	}
+
+	if !strings.Contains(err.Error(), "unrepairable") {
+		t.Errorf("Expected 'unrepairable' in error message, got: %s", err.Error())
+	}
+}
+
+// TestRebuildEcVolumesCompleteVolume tests that complete volumes are skipped
+func TestRebuildEcVolumesCompleteVolume(t *testing.T) {
+	var logBuffer bytes.Buffer
+
+	// Create a volume with all shards
+	node1 := newEcNode("dc1", "rack1", "node1", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13})
+
+	erb := &ecRebuilder{
+		commandEnv: &CommandEnv{
+			env:    make(map[string]string),
+			noLock: true, // Bypass lock check for unit test
+		},
+		ecNodes:      []*EcNode{node1},
+		writer:       &logBuffer,
+		applyChanges: false,
+	}
+
+	err := erb.rebuildEcVolumes("c1")
+	if err != nil {
+		t.Fatalf("Expected no error for complete volume, got: %v", err)
+	}
+
+	// The function should return quickly without attempting rebuild
+	// since the volume is already complete
+}
+
+// TestRebuildEcVolumesInsufficientSpace tests error handling for insufficient disk space
+func TestRebuildEcVolumesInsufficientSpace(t *testing.T) {
+	var logBuffer bytes.Buffer
+
+	// Create a volume with missing shards but insufficient free slots
+	node1 := newEcNode("dc1", "rack1", "node1", 5). // Only 5 free slots, need 14
+							addEcVolumeAndShardsForTest(1, "c1", []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9})
+
+	erb := &ecRebuilder{
+		commandEnv: &CommandEnv{
+			env:    make(map[string]string),
+			noLock: true, // Bypass lock check for unit test
+		},
+		ecNodes:      []*EcNode{node1},
+		writer:       &logBuffer,
+		applyChanges: false,
+	}
+
+	err := erb.rebuildEcVolumes("c1")
+	if err == nil {
+		t.Fatal("Expected error for insufficient disk space, got nil")
+	}
+
+	if !strings.Contains(err.Error(), "disk space is not enough") {
+		t.Errorf("Expected 'disk space' in error message, got: %s", err.Error())
+	}
+}
+
+// TestMultipleNodesWithShards tests rebuild with shards distributed across multiple nodes
+func TestMultipleNodesWithShards(t *testing.T) {
+	ecShardMap := make(EcShardMap)
+
+	// Create 3 nodes with different shards
+	node1 := newEcNode("dc1", "rack1", "node1", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{0, 1, 2, 3})
+	node2 := newEcNode("dc1", "rack1", "node2", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{4, 5, 6, 7})
+	node3 := newEcNode("dc1", "rack1", "node3", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{8, 9})
+
+	ecShardMap.registerEcNode(node1, "c1")
+	ecShardMap.registerEcNode(node2, "c1")
+	ecShardMap.registerEcNode(node3, "c1")
+
+	locations := ecShardMap[needle.VolumeId(1)]
+	count := locations.shardCount()
+
+	// We have 10 shards total, which is enough for data shards
+	if count != 10 {
+		t.Errorf("Expected 10 shards, got %d", count)
+	}
+
+	// Verify each shard is on the correct node
+	for i := 0; i < 4; i++ {
+		if len(locations[i]) != 1 || locations[i][0].info.Id != "node1" {
+			t.Errorf("Shard %d should be on node1", i)
+		}
+	}
+	for i := 4; i < 8; i++ {
+		if len(locations[i]) != 1 || locations[i][0].info.Id != "node2" {
+			t.Errorf("Shard %d should be on node2", i)
+		}
+	}
+	for i := 8; i < 10; i++ {
+		if len(locations[i]) != 1 || locations[i][0].info.Id != "node3" {
+			t.Errorf("Shard %d should be on node3", i)
+		}
+	}
+}
+
+// TestDuplicateShards tests handling of duplicate shards on multiple nodes
+func TestDuplicateShards(t *testing.T) {
+	ecShardMap := make(EcShardMap)
+
+	// Create 2 nodes with overlapping shards (both have shard 0)
+	node1 := newEcNode("dc1", "rack1", "node1", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{0, 1, 2, 3})
+	node2 := newEcNode("dc1", "rack1", "node2", 100).
+		addEcVolumeAndShardsForTest(1, "c1", []uint32{0, 4, 5, 6}) // Duplicate shard 0
+
+	ecShardMap.registerEcNode(node1, "c1")
+	ecShardMap.registerEcNode(node2, "c1")
+
+	locations := ecShardMap[needle.VolumeId(1)]
+
+	// Shard 0 should be on both nodes
+	if len(locations[0]) != 2 {
+		t.Errorf("Expected shard 0 on 2 nodes, got %d", len(locations[0]))
+	}
+
+	// Verify both nodes are registered for shard 0
+	foundNode1 := false
+	foundNode2 := false
+	for _, node := range locations[0] {
+		if node.info.Id == "node1" {
+			foundNode1 = true
+		}
+		if node.info.Id == "node2" {
+			foundNode2 = true
+		}
+	}
+	if !foundNode1 || !foundNode2 {
+		t.Error("Both nodes should have shard 0")
+	}
+
+	// Shard count should be 7 (unique shards: 0, 1, 2, 3, 4, 5, 6)
+	count := locations.shardCount()
+	if count != 7 {
+		t.Errorf("Expected 7 unique shards, got %d", count)
+	}
+}