Update compressed domain tree format in control plane

Signed-off-by: Kris Jacque <[email protected]>

src/control/server/mgmt_pool_test.go

@@ -1356,7 +1356,7 @@ func TestServer_MgmtSvc_PoolExtend(t *testing.T) {
 	missingSB.harness.instances[0].(*EngineInstance)._superblock = nil
 	notAP := newTestMgmtSvc(t, log)
 	mockRanks := []uint32{1}
-	mockFaultDomains := []uint32{1, 1, 1, 1}
+	mockFaultDomains := []uint32{0, 1, 1, 1, 1}
 
 	for name, tc := range map[string]struct {
 		nilReq      bool

src/control/system/membership.go

@@ -1,5 +1,6 @@
 //
 // (C) Copyright 2020-2024 Intel Corporation.
+// (C) Copyright 2025 Hewlett Packard Enterprise Development LP
 //
 // SPDX-License-Identifier: BSD-2-Clause-Patent
 //
@@ -611,6 +612,7 @@ func (m *Membership) OnEvent(_ context.Context, evt *events.RASEvent) {
 
 // CompressedFaultDomainTree returns the tree of fault domains of joined
 // members in a compressed format.
+// The first uint32 is a bitmask providing metadata about the tree.
 // Each domain is represented as a tuple: (level, ID, number of children)
 // Except for the rank, which is represented as: (rank)
 // The order of items is a breadth-first traversal of the tree.
@@ -625,7 +627,26 @@ func (m *Membership) CompressedFaultDomainTree(ranks ...uint32) ([]uint32, error
 		return nil, err
 	}
 
-	return compressTree(subtree), nil
+	md := getCompressedTreeMetadata(tree)
+	return append([]uint32{md}, compressTree(subtree)...), nil
+}
+
+const (
+	DomTreeMetadataHasFaultDom uint32 = (1 << iota)
+	DomTreeMetadataHasPerfDom
+)
+
+func getCompressedTreeMetadata(tree *FaultDomainTree) uint32 {
+	var md uint32
+
+	// TODO DAOS-6353: Properly detect when fault and perf domain are requested.
+	// Currently any depth greater than the minimum must indicate a performance domain.
+	minDepth := 2 // domain + rank
+	if tree.Depth() > minDepth {
+		md |= DomTreeMetadataHasPerfDom
+	}
+
+	return md
 }
 
 func getFaultDomainSubtree(tree *FaultDomainTree, ranks ...uint32) (*FaultDomainTree, error) {

src/control/system/membership_test.go

@@ -1,5 +1,6 @@
 //
 // (C) Copyright 2020-2024 Intel Corporation.
+// (C) Copyright 2025 Hewlett Packard Enterprise Development LP
 //
 // SPDX-License-Identifier: BSD-2-Clause-Patent
 //
@@ -1075,6 +1076,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 		"root only": {
 			tree: NewFaultDomainTree(),
 			expResult: []uint32{
+				0, // metadata
 				0,
 				ExpFaultDomainID(0),
 				0,
@@ -1085,6 +1087,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				MustCreateFaultDomain("one", "two", "three"),
 			),
 			expResult: []uint32{
+				DomTreeMetadataHasPerfDom, // metadata
 				3,
 				ExpFaultDomainID(0),
 				1,
@@ -1108,6 +1111,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				MustCreateFaultDomainFromString("/rack2/pdu4"),
 			),
 			expResult: []uint32{
+				0, // metadata
 				2, // root
 				ExpFaultDomainID(0),
 				3,
@@ -1142,6 +1146,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				rankDomain("/one/two/three", 5),
 			),
 			expResult: []uint32{
+				DomTreeMetadataHasPerfDom, // metadata
 				4,
 				ExpFaultDomainID(0),
 				1,
@@ -1167,6 +1172,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				rankDomain("/rack2/pdu4", 5),
 			),
 			expResult: []uint32{
+				DomTreeMetadataHasPerfDom, // metadata
 				3,
 				ExpFaultDomainID(0), // root
 				3,
@@ -1208,6 +1214,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				rankDomain(fmt.Sprintf("/top/%s2/bottom", RankFaultDomainPrefix), 1),
 			),
 			expResult: []uint32{
+				DomTreeMetadataHasPerfDom, // metadata
 				4,
 				ExpFaultDomainID(0), // root
 				1,
@@ -1223,6 +1230,28 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				1, // rank
 			},
 		},
+		"request one rank with node only": {
+			tree: NewFaultDomainTree(
+				rankDomain("/node0", 0),
+				rankDomain("/node1", 1),
+				rankDomain("/node2", 2),
+				rankDomain("/node3", 3),
+				rankDomain("/node3", 4),
+				rankDomain("/node4", 5),
+			),
+			inputRanks: []uint32{4},
+			expResult: []uint32{
+				0, // metadata
+				2,
+				ExpFaultDomainID(0), // root
+				1,
+				1,
+				ExpFaultDomainID(7), // node3
+				1,
+				// ranks
+				4,
+			},
+		},
 		"request one rank": {
 			tree: NewFaultDomainTree(
 				rankDomain("/rack0/pdu0", 0),
@@ -1234,6 +1263,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 			),
 			inputRanks: []uint32{4},
 			expResult: []uint32{
+				DomTreeMetadataHasPerfDom, // metadata
 				3,
 				ExpFaultDomainID(0), // root
 				1,
@@ -1258,6 +1288,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 			),
 			inputRanks: []uint32{4, 0, 5, 3},
 			expResult: []uint32{
+				DomTreeMetadataHasPerfDom, // metadata
 				3,
 				ExpFaultDomainID(0), // root
 				3,