Rename PlacementConfig to PlacementRequest for clarity

PlacementRequest better reflects that this is a request for placement
rather than a configuration object. This improves API semantics.

weed/storage/erasure_coding/placement/placement.go

@@ -39,8 +39,8 @@ type NodeCandidate struct {
 	Disks      []*DiskCandidate // All disks on this node
 }
 
-// PlacementConfig configures EC shard placement behavior
-type PlacementConfig struct {
+// PlacementRequest configures EC shard placement behavior
+type PlacementRequest struct {
 	// ShardsNeeded is the total number of shards to place
 	ShardsNeeded int
 
@@ -65,8 +65,8 @@ type PlacementConfig struct {
 }
 
 // DefaultConfig returns the default placement configuration
-func DefaultConfig() PlacementConfig {
-	return PlacementConfig{
+func DefaultConfig() PlacementRequest {
+	return PlacementRequest{
 		ShardsNeeded:           14,
 		MaxShardsPerServer:     0,
 		MaxShardsPerRack:       0,
@@ -98,7 +98,7 @@ type PlacementResult struct {
 // 1. First pass: Select one disk from each rack (maximize rack diversity)
 // 2. Second pass: Select one disk from each unused server in used racks (maximize server diversity)
 // 3. Third pass: Select additional disks from servers already used (maximize disk diversity)
-func SelectDestinations(disks []*DiskCandidate, config PlacementConfig) (*PlacementResult, error) {
+func SelectDestinations(disks []*DiskCandidate, config PlacementRequest) (*PlacementResult, error) {
 	if len(disks) == 0 {
 		return nil, fmt.Errorf("no disk candidates provided")
 	}
@@ -248,7 +248,7 @@ func SelectDestinations(disks []*DiskCandidate, config PlacementConfig) (*Placem
 }
 
 // filterSuitableDisks filters disks that are suitable for EC placement
-func filterSuitableDisks(disks []*DiskCandidate, config PlacementConfig) []*DiskCandidate {
+func filterSuitableDisks(disks []*DiskCandidate, config PlacementRequest) []*DiskCandidate {
 	var suitable []*DiskCandidate
 	for _, disk := range disks {
 		if disk.FreeSlots <= 0 {
@@ -323,7 +323,7 @@ func getSortedRackKeys(rackToDisks map[string][]*DiskCandidate) []string {
 
 // selectBestDiskFromRack selects the best disk from a rack for EC placement
 // It prefers servers that haven't been used yet
-func selectBestDiskFromRack(disks []*DiskCandidate, usedServers, usedDisks map[string]bool, config PlacementConfig) *DiskCandidate {
+func selectBestDiskFromRack(disks []*DiskCandidate, usedServers, usedDisks map[string]bool, config PlacementRequest) *DiskCandidate {
 	var bestDisk *DiskCandidate
 	bestScore := -1.0
 	bestIsFromUnusedServer := false

weed/storage/erasure_coding/placement/placement_test.go

@@ -31,7 +31,7 @@ func TestSelectDestinations_SingleRack(t *testing.T) {
 		makeDisk("server3", 1, "dc1", "rack1", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           6,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -77,7 +77,7 @@ func TestSelectDestinations_MultipleRacks(t *testing.T) {
 		makeDisk("server4", 1, "dc1", "rack2", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           8,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -125,7 +125,7 @@ func TestSelectDestinations_PrefersDifferentServers(t *testing.T) {
 		makeDisk("server4", 3, "dc1", "rack1", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           4,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -168,7 +168,7 @@ func TestSelectDestinations_SpilloverToMultipleDisksPerServer(t *testing.T) {
 		makeDisk("server2", 3, "dc1", "rack1", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           6,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -210,7 +210,7 @@ func TestSelectDestinations_MaxShardsPerServer(t *testing.T) {
 		makeDisk("server2", 3, "dc1", "rack1", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           6,
 		MaxShardsPerServer:     2,
 		PreferDifferentServers: true,
@@ -245,7 +245,7 @@ func TestSelectDestinations_14ShardsAcross7Servers(t *testing.T) {
 		disks = append(disks, makeDisk(serverID, 1, "dc1", "rack1", 10))
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           14,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -288,7 +288,7 @@ func TestSelectDestinations_FewerServersThanShards(t *testing.T) {
 		makeDisk("server3", 2, "dc1", "rack1", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           6,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -323,7 +323,7 @@ func TestSelectDestinations_NoSuitableDisks(t *testing.T) {
 		{NodeID: "server2", DiskID: 0, DataCenter: "dc1", Rack: "rack1", FreeSlots: 0},
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           4,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -351,7 +351,7 @@ func TestSelectDestinations_FiltersByLoad(t *testing.T) {
 		{NodeID: "server3", DiskID: 0, DataCenter: "dc1", Rack: "rack1", FreeSlots: 10, LoadCount: 1},
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           2,
 		MaxTaskLoad:            5,
 		PreferDifferentServers: true,
@@ -466,7 +466,7 @@ func TestSelectDestinations_MultiDC(t *testing.T) {
 		makeDisk("dc2-r2-s2", 1, "dc2", "rack2", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           8,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,
@@ -499,7 +499,7 @@ func TestSelectDestinations_SameRackDifferentDC(t *testing.T) {
 		makeDisk("dc2-s1", 0, "dc2", "rack1", 10),
 	}
 
-	config := PlacementConfig{
+	config := PlacementRequest{
 		ShardsNeeded:           2,
 		PreferDifferentServers: true,
 		PreferDifferentRacks:   true,

weed/worker/tasks/erasure_coding/detection.go

@@ -443,7 +443,7 @@ func selectBestECDestinations(disks []*topology.DiskInfo, sourceRack, sourceDC s
 	}
 
 	// Configure placement for EC shards
-	config := placement.PlacementConfig{
+	config := placement.PlacementRequest{
 		ShardsNeeded:           shardsNeeded,
 		MaxShardsPerServer:     0, // No hard limit, but prefer spreading
 		MaxShardsPerRack:       0, // No hard limit, but prefer spreading