From 1cdcfb826029873149b02783ec9c6a6e37285154 Mon Sep 17 00:00:00 2001
From: Daniel Nephin <dnephin@hashicorp.com>
Date: Fri, 12 Feb 2021 18:06:56 -0500
Subject: [PATCH 1/3] state: convert checks.ID index to new pattern

---
 agent/consul/state/catalog.go                 | 23 ++++++++----
 agent/consul/state/catalog_oss.go             | 36 ++++++++++++++++---
 agent/consul/state/catalog_schema.go          | 22 ++++++------
 agent/consul/state/catalog_test.go            |  4 +--
 agent/consul/state/operations_oss.go          |  8 ++---
 agent/consul/state/session_oss.go             |  5 +--
 agent/consul/state/state_store_test.go        |  2 +-
 .../testdata/TestStateStoreSchema.golden      |  2 +-
 8 files changed, 68 insertions(+), 34 deletions(-)

diff --git a/agent/consul/state/catalog.go b/agent/consul/state/catalog.go
index 0171d6b247..c93e87d9fb 100644
--- a/agent/consul/state/catalog.go
+++ b/agent/consul/state/catalog.go
@@ -194,7 +194,7 @@ func ensureNoNodeWithSimilarNameTxn(tx ReadTxn, node *structs.Node, allowClashWi
 		if strings.EqualFold(node.Node, enode.Node) && node.ID != enode.ID {
 			// Look up the existing node's Serf health check to see if it's failed.
 			// If it is, the node can be renamed.
-			_, enodeCheck, err := firstWatchCompoundWithTxn(tx, "checks", "id", structs.DefaultEnterpriseMeta(), enode.Node, string(structs.SerfCheckID))
+			_, enodeCheck, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *structs.DefaultEnterpriseMeta(), Node: enode.Node, CheckID: string(structs.SerfCheckID)})
 			if err != nil {
 				return fmt.Errorf("Cannot get status of node %s: %s", enode.Node, err)
 			}
@@ -1471,7 +1471,7 @@ func (s *Store) ensureCheckCASTxn(tx WriteTxn, idx uint64, hc *structs.HealthChe
 // checks with no matching node or service.
 func (s *Store) ensureCheckTxn(tx WriteTxn, idx uint64, preserveIndexes bool, hc *structs.HealthCheck) error {
 	// Check if we have an existing health check
-	_, existing, err := firstWatchCompoundWithTxn(tx, "checks", "id", &hc.EnterpriseMeta, hc.Node, string(hc.CheckID))
+	_, existing, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: hc.EnterpriseMeta, Node: hc.Node, CheckID: string(hc.CheckID)})
 	if err != nil {
 		return fmt.Errorf("failed health check lookup: %s", err)
 	}
@@ -1578,8 +1578,13 @@ func getNodeCheckTxn(tx ReadTxn, nodeName string, checkID types.CheckID, entMeta
 	// Get the table index.
 	idx := catalogChecksMaxIndex(tx, entMeta)
 
+	// TODO: accept non-pointer value
+	if entMeta == nil {
+		entMeta = structs.DefaultEnterpriseMeta()
+	}
+
 	// Return the check.
-	_, check, err := firstWatchCompoundWithTxn(tx, "checks", "id", entMeta, nodeName, string(checkID))
+	_, check, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: nodeName, CheckID: string(checkID)})
 	if err != nil {
 		return 0, nil, fmt.Errorf("failed check lookup: %s", err)
 	}
@@ -1702,7 +1707,7 @@ func checksInStateTxn(tx ReadTxn, ws memdb.WatchSet, state string, entMeta *stru
 	var iter memdb.ResultIterator
 	var err error
 	if state == api.HealthAny {
-		iter, err = catalogListChecks(tx, entMeta)
+		iter, err = tx.Get(tableChecks, indexID+"_prefix", entMeta)
 	} else {
 		iter, err = catalogListChecksInState(tx, state, entMeta)
 	}
@@ -1800,8 +1805,12 @@ type NodeServiceQuery struct {
 // deleteCheckTxn is the inner method used to call a health
 // check deletion within an existing transaction.
 func (s *Store) deleteCheckTxn(tx WriteTxn, idx uint64, node string, checkID types.CheckID, entMeta *structs.EnterpriseMeta) error {
+	if entMeta == nil {
+		entMeta = structs.DefaultEnterpriseMeta()
+	}
+
 	// Try to retrieve the existing health check.
-	_, hc, err := firstWatchCompoundWithTxn(tx, "checks", "id", entMeta, node, string(checkID))
+	_, hc, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: node, CheckID: string(checkID)})
 	if err != nil {
 		return fmt.Errorf("check lookup failed: %s", err)
 	}
@@ -2149,7 +2158,7 @@ func parseCheckServiceNodes(
 	// We need a similar fallback for checks. Since services need the
 	// status of node + service-specific checks, we pull in a top-level
 	// watch over all checks.
-	allChecks, err := tx.Get("checks", "id")
+	allChecks, err := tx.Get(tableChecks, indexID)
 	if err != nil {
 		return 0, nil, fmt.Errorf("failed checks lookup: %s", err)
 	}
@@ -2310,7 +2319,7 @@ func parseNodes(tx ReadTxn, ws memdb.WatchSet, idx uint64,
 	allServicesCh := allServices.WatchCh()
 
 	// We need a similar fallback for checks.
-	allChecks, err := tx.Get("checks", "id")
+	allChecks, err := tx.Get(tableChecks, indexID)
 	if err != nil {
 		return 0, nil, fmt.Errorf("failed checks lookup: %s", err)
 	}
diff --git a/agent/consul/state/catalog_oss.go b/agent/consul/state/catalog_oss.go
index 090422603c..8a187066c0 100644
--- a/agent/consul/state/catalog_oss.go
+++ b/agent/consul/state/catalog_oss.go
@@ -103,6 +103,38 @@ func indexFromServiceNode(raw interface{}) ([]byte, error) {
 	return b.Bytes(), nil
 }
 
+func indexFromHealthCheck(raw interface{}) ([]byte, error) {
+	hc, ok := raw.(*structs.HealthCheck)
+	if !ok {
+		return nil, fmt.Errorf("unexpected type %T for structs.HealthCheck index", raw)
+	}
+
+	if hc.Node == "" || hc.CheckID == "" {
+		return nil, errMissingValueForIndex
+	}
+
+	var b indexBuilder
+	b.String(strings.ToLower(hc.Node))
+	b.String(strings.ToLower(string(hc.CheckID)))
+	return b.Bytes(), nil
+}
+
+func indexFromNodeCheckID(raw interface{}) ([]byte, error) {
+	hc, ok := raw.(NodeCheckID)
+	if !ok {
+		return nil, fmt.Errorf("unexpected type %T for NodeCheckID index", raw)
+	}
+
+	if hc.Node == "" || hc.CheckID == "" {
+		return nil, errMissingValueForIndex
+	}
+
+	var b indexBuilder
+	b.String(strings.ToLower(hc.Node))
+	b.String(strings.ToLower(hc.CheckID))
+	return b.Bytes(), nil
+}
+
 func serviceIndexName(name string, _ *structs.EnterpriseMeta) string {
 	return fmt.Sprintf("service.%s", name)
 }
@@ -243,10 +275,6 @@ func catalogListChecksInState(tx ReadTxn, state string, _ *structs.EnterpriseMet
 	return tx.Get("checks", "status", state)
 }
 
-func catalogListChecks(tx ReadTxn, _ *structs.EnterpriseMeta) (memdb.ResultIterator, error) {
-	return tx.Get("checks", "id")
-}
-
 func catalogInsertCheck(tx WriteTxn, chk *structs.HealthCheck, idx uint64) error {
 	// Insert the check
 	if err := tx.Insert("checks", chk); err != nil {
diff --git a/agent/consul/state/catalog_schema.go b/agent/consul/state/catalog_schema.go
index 506da6f5aa..eef6c6d2a3 100644
--- a/agent/consul/state/catalog_schema.go
+++ b/agent/consul/state/catalog_schema.go
@@ -123,17 +123,10 @@ func checksTableSchema() *memdb.TableSchema {
 				Name:         indexID,
 				AllowMissing: false,
 				Unique:       true,
-				Indexer: &memdb.CompoundIndex{
-					Indexes: []memdb.Indexer{
-						&memdb.StringFieldIndex{
-							Field:     "Node",
-							Lowercase: true,
-						},
-						&memdb.StringFieldIndex{
-							Field:     "CheckID",
-							Lowercase: true,
-						},
-					},
+				Indexer: indexerSingleWithPrefix{
+					readIndex:   readIndex(indexFromNodeCheckID),
+					prefixIndex: prefixIndex(prefixIndexFromQuery),
+					writeIndex:  writeIndex(indexFromHealthCheck),
 				},
 			},
 			indexStatus: {
@@ -331,3 +324,10 @@ type upstreamDownstream struct {
 
 	structs.RaftIndex
 }
+
+// NodeCheckID is used to query the ID index of the checks table.
+type NodeCheckID struct {
+	Node    string
+	CheckID string
+	structs.EnterpriseMeta
+}
diff --git a/agent/consul/state/catalog_test.go b/agent/consul/state/catalog_test.go
index 1f22948d96..44f82e295a 100644
--- a/agent/consul/state/catalog_test.go
+++ b/agent/consul/state/catalog_test.go
@@ -1307,7 +1307,7 @@ func TestStateStore_DeleteNode(t *testing.T) {
 	}
 
 	// Associated health check was removed.
-	checks, err := getCompoundWithTxn(tx, "checks", "id", nil, "node1", "check1")
+	checks, err := tx.Get(tableChecks, indexID, NodeCheckID{Node: "node1", CheckID: "check1"})
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
@@ -2067,7 +2067,7 @@ func TestStateStore_DeleteService(t *testing.T) {
 	// that it actually is removed in the state store.
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	_, check, err := firstWatchCompoundWithTxn(tx, "checks", "id", nil, "node1", "check1")
+	_, check, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{Node: "node1", CheckID: "check1"})
 	if err != nil || check != nil {
 		t.Fatalf("bad: %#v (err: %s)", check, err)
 	}
diff --git a/agent/consul/state/operations_oss.go b/agent/consul/state/operations_oss.go
index 30deb70683..a3a8f396d4 100644
--- a/agent/consul/state/operations_oss.go
+++ b/agent/consul/state/operations_oss.go
@@ -3,8 +3,9 @@
 package state
 
 import (
-	"github.com/hashicorp/consul/agent/structs"
 	"github.com/hashicorp/go-memdb"
+
+	"github.com/hashicorp/consul/agent/structs"
 )
 
 func firstWithTxn(tx ReadTxn,
@@ -19,11 +20,6 @@ func firstWatchWithTxn(tx ReadTxn,
 	return tx.FirstWatch(table, index, idxVal)
 }
 
-func firstWatchCompoundWithTxn(tx ReadTxn,
-	table, index string, _ *structs.EnterpriseMeta, idxVals ...interface{}) (<-chan struct{}, interface{}, error) {
-	return tx.FirstWatch(table, index, idxVals...)
-}
-
 func getWithTxn(tx ReadTxn,
 	table, index, idxVal string, entMeta *structs.EnterpriseMeta) (memdb.ResultIterator, error) {
 
diff --git a/agent/consul/state/session_oss.go b/agent/consul/state/session_oss.go
index b76deb5009..cd4cad3ade 100644
--- a/agent/consul/state/session_oss.go
+++ b/agent/consul/state/session_oss.go
@@ -5,9 +5,10 @@ package state
 import (
 	"fmt"
 
+	"github.com/hashicorp/go-memdb"
+
 	"github.com/hashicorp/consul/agent/structs"
 	"github.com/hashicorp/consul/api"
-	"github.com/hashicorp/go-memdb"
 )
 
 func sessionIndexer() *memdb.UUIDFieldIndex {
@@ -107,7 +108,7 @@ func sessionMaxIndex(tx ReadTxn, entMeta *structs.EnterpriseMeta) uint64 {
 func validateSessionChecksTxn(tx *txn, session *structs.Session) error {
 	// Go over the session checks and ensure they exist.
 	for _, checkID := range session.CheckIDs() {
-		check, err := tx.First("checks", "id", session.Node, string(checkID))
+		check, err := tx.First(tableChecks, indexID, NodeCheckID{Node: session.Node, CheckID: string(checkID)})
 		if err != nil {
 			return fmt.Errorf("failed check lookup: %s", err)
 		}
diff --git a/agent/consul/state/state_store_test.go b/agent/consul/state/state_store_test.go
index bc87eda27b..938804c907 100644
--- a/agent/consul/state/state_store_test.go
+++ b/agent/consul/state/state_store_test.go
@@ -163,7 +163,7 @@ func testRegisterCheck(t *testing.T, s *Store, idx uint64,
 
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	_, c, err := firstWatchCompoundWithTxn(tx, "checks", "id", nil, nodeID, string(checkID))
+	_, c, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{Node: nodeID, CheckID: string(checkID)})
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
diff --git a/agent/consul/state/testdata/TestStateStoreSchema.golden b/agent/consul/state/testdata/TestStateStoreSchema.golden
index 4a6b752557..72bb71e3c3 100644
--- a/agent/consul/state/testdata/TestStateStoreSchema.golden
+++ b/agent/consul/state/testdata/TestStateStoreSchema.golden
@@ -48,7 +48,7 @@ table=autopilot-config
 
 table=checks
   index=id unique
-    indexer=github.com/hashicorp/go-memdb.CompoundIndex Indexes=[github.com/hashicorp/go-memdb.StringFieldIndex Field=Node Lowercase=true, github.com/hashicorp/go-memdb.StringFieldIndex Field=CheckID Lowercase=true] AllowMissing=false
+    indexer=github.com/hashicorp/consul/agent/consul/state.indexerSingleWithPrefix readIndex=github.com/hashicorp/consul/agent/consul/state.indexFromNodeCheckID writeIndex=github.com/hashicorp/consul/agent/consul/state.indexFromHealthCheck prefixIndex=github.com/hashicorp/consul/agent/consul/state.prefixIndexFromQuery
   index=node allow-missing
     indexer=github.com/hashicorp/consul/agent/consul/state.indexerSingle readIndex=github.com/hashicorp/consul/agent/consul/state.indexFromNodeQuery writeIndex=github.com/hashicorp/consul/agent/consul/state.indexFromNodeIdentity
   index=node_service allow-missing

From 30281a533273fa62d9cb18dc2f43ac31ba34c05f Mon Sep 17 00:00:00 2001
From: Daniel Nephin <dnephin@hashicorp.com>
Date: Mon, 22 Mar 2021 17:09:22 -0400
Subject: [PATCH 2/3] state: use tx.First instead of tx.FirstWatch

Where appropriate. After removing the helper function a bunch of  these calls can
be changed to tx.First.
---
 agent/consul/state/catalog.go          | 23 +++++++++++------------
 agent/consul/state/catalog_test.go     |  2 +-
 agent/consul/state/state_store_test.go |  6 +++---
 3 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/agent/consul/state/catalog.go b/agent/consul/state/catalog.go
index c93e87d9fb..aa80345067 100644
--- a/agent/consul/state/catalog.go
+++ b/agent/consul/state/catalog.go
@@ -141,7 +141,7 @@ func (s *Store) ensureRegistrationTxn(tx WriteTxn, idx uint64, preserveIndexes b
 	// node info above to make sure we actually need to update the service
 	// definition in order to prevent useless churn if nothing has changed.
 	if req.Service != nil {
-		_, existing, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: req.Service.EnterpriseMeta, Node: req.Node, Service: req.Service.ID})
+		existing, err := tx.First(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: req.Service.EnterpriseMeta, Node: req.Node, Service: req.Service.ID})
 		if err != nil {
 			return fmt.Errorf("failed service lookup: %s", err)
 		}
@@ -194,7 +194,7 @@ func ensureNoNodeWithSimilarNameTxn(tx ReadTxn, node *structs.Node, allowClashWi
 		if strings.EqualFold(node.Node, enode.Node) && node.ID != enode.ID {
 			// Look up the existing node's Serf health check to see if it's failed.
 			// If it is, the node can be renamed.
-			_, enodeCheck, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *structs.DefaultEnterpriseMeta(), Node: enode.Node, CheckID: string(structs.SerfCheckID)})
+			enodeCheck, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *structs.DefaultEnterpriseMeta(), Node: enode.Node, CheckID: string(structs.SerfCheckID)})
 			if err != nil {
 				return fmt.Errorf("Cannot get status of node %s: %s", enode.Node, err)
 			}
@@ -602,7 +602,7 @@ var errCASCompareFailed = errors.New("compare-and-set: comparison failed")
 // Returns an error if the write didn't happen and nil if write was successful.
 func ensureServiceCASTxn(tx WriteTxn, idx uint64, node string, svc *structs.NodeService) error {
 	// Retrieve the existing service.
-	_, existing, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: svc.EnterpriseMeta, Node: node, Service: svc.ID})
+	existing, err := tx.First(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: svc.EnterpriseMeta, Node: node, Service: svc.ID})
 	if err != nil {
 		return fmt.Errorf("failed service lookup: %s", err)
 	}
@@ -627,7 +627,7 @@ func ensureServiceCASTxn(tx WriteTxn, idx uint64, node string, svc *structs.Node
 // existing memdb transaction.
 func ensureServiceTxn(tx WriteTxn, idx uint64, node string, preserveIndexes bool, svc *structs.NodeService) error {
 	// Check for existing service
-	_, existing, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: svc.EnterpriseMeta, Node: node, Service: svc.ID})
+	existing, err := tx.First(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: svc.EnterpriseMeta, Node: node, Service: svc.ID})
 	if err != nil {
 		return fmt.Errorf("failed service lookup: %s", err)
 	}
@@ -1148,7 +1148,7 @@ func getNodeServiceTxn(tx ReadTxn, nodeName, serviceID string, entMeta *structs.
 	}
 
 	// Query the service
-	_, service, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: *entMeta, Node: nodeName, Service: serviceID})
+	service, err := tx.First(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: *entMeta, Node: nodeName, Service: serviceID})
 	if err != nil {
 		return nil, fmt.Errorf("failed querying service for node %q: %s", nodeName, err)
 	}
@@ -1321,8 +1321,7 @@ func (s *Store) deleteServiceTxn(tx WriteTxn, idx uint64, nodeName, serviceID st
 		entMeta = structs.DefaultEnterpriseMeta()
 	}
 
-	// Look up the service.
-	_, service, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: *entMeta, Node: nodeName, Service: serviceID})
+	service, err := tx.First(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: *entMeta, Node: nodeName, Service: serviceID})
 	if err != nil {
 		return fmt.Errorf("failed service lookup: %s", err)
 	}
@@ -1471,7 +1470,7 @@ func (s *Store) ensureCheckCASTxn(tx WriteTxn, idx uint64, hc *structs.HealthChe
 // checks with no matching node or service.
 func (s *Store) ensureCheckTxn(tx WriteTxn, idx uint64, preserveIndexes bool, hc *structs.HealthCheck) error {
 	// Check if we have an existing health check
-	_, existing, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: hc.EnterpriseMeta, Node: hc.Node, CheckID: string(hc.CheckID)})
+	existing, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: hc.EnterpriseMeta, Node: hc.Node, CheckID: string(hc.CheckID)})
 	if err != nil {
 		return fmt.Errorf("failed health check lookup: %s", err)
 	}
@@ -1503,7 +1502,7 @@ func (s *Store) ensureCheckTxn(tx WriteTxn, idx uint64, preserveIndexes bool, hc
 	// If the check is associated with a service, check that we have
 	// a registration for the service.
 	if hc.ServiceID != "" {
-		_, service, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: hc.EnterpriseMeta, Node: hc.Node, Service: hc.ServiceID})
+		service, err := tx.First(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: hc.EnterpriseMeta, Node: hc.Node, Service: hc.ServiceID})
 		if err != nil {
 			return fmt.Errorf("failed service lookup: %s", err)
 		}
@@ -1584,7 +1583,7 @@ func getNodeCheckTxn(tx ReadTxn, nodeName string, checkID types.CheckID, entMeta
 	}
 
 	// Return the check.
-	_, check, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: nodeName, CheckID: string(checkID)})
+	check, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: nodeName, CheckID: string(checkID)})
 	if err != nil {
 		return 0, nil, fmt.Errorf("failed check lookup: %s", err)
 	}
@@ -1810,7 +1809,7 @@ func (s *Store) deleteCheckTxn(tx WriteTxn, idx uint64, node string, checkID typ
 	}
 
 	// Try to retrieve the existing health check.
-	_, hc, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: node, CheckID: string(checkID)})
+	hc, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: node, CheckID: string(checkID)})
 	if err != nil {
 		return fmt.Errorf("check lookup failed: %s", err)
 	}
@@ -1825,7 +1824,7 @@ func (s *Store) deleteCheckTxn(tx WriteTxn, idx uint64, node string, checkID typ
 				return err
 			}
 
-			_, svcRaw, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: existing.EnterpriseMeta, Node: existing.Node, Service: existing.ServiceID})
+			svcRaw, err := tx.First(tableServices, indexID, NodeServiceQuery{EnterpriseMeta: existing.EnterpriseMeta, Node: existing.Node, Service: existing.ServiceID})
 			if err != nil {
 				return fmt.Errorf("failed retrieving service from state store: %v", err)
 			}
diff --git a/agent/consul/state/catalog_test.go b/agent/consul/state/catalog_test.go
index 44f82e295a..3302ffa8ed 100644
--- a/agent/consul/state/catalog_test.go
+++ b/agent/consul/state/catalog_test.go
@@ -2067,7 +2067,7 @@ func TestStateStore_DeleteService(t *testing.T) {
 	// that it actually is removed in the state store.
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	_, check, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{Node: "node1", CheckID: "check1"})
+	check, err := tx.First(tableChecks, indexID, NodeCheckID{Node: "node1", CheckID: "check1"})
 	if err != nil || check != nil {
 		t.Fatalf("bad: %#v (err: %s)", check, err)
 	}
diff --git a/agent/consul/state/state_store_test.go b/agent/consul/state/state_store_test.go
index 938804c907..0e0db1f2b3 100644
--- a/agent/consul/state/state_store_test.go
+++ b/agent/consul/state/state_store_test.go
@@ -105,7 +105,7 @@ func testRegisterServiceWithChange(t *testing.T, s *Store, idx uint64, nodeID, s
 
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	_, service, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{Node: nodeID, Service: serviceID})
+	service, err := tx.First(tableServices, indexID, NodeServiceQuery{Node: nodeID, Service: serviceID})
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
@@ -138,7 +138,7 @@ func testRegisterIngressService(t *testing.T, s *Store, idx uint64, nodeID, serv
 
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	_, service, err := tx.FirstWatch(tableServices, indexID, NodeServiceQuery{Node: nodeID, Service: serviceID})
+	service, err := tx.First(tableServices, indexID, NodeServiceQuery{Node: nodeID, Service: serviceID})
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
@@ -163,7 +163,7 @@ func testRegisterCheck(t *testing.T, s *Store, idx uint64,
 
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	_, c, err := tx.FirstWatch(tableChecks, indexID, NodeCheckID{Node: nodeID, CheckID: string(checkID)})
+	c, err := tx.First(tableChecks, indexID, NodeCheckID{Node: nodeID, CheckID: string(checkID)})
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}

From 8743e925d5a72bc83d3316171ee7fd8af73ccb36 Mon Sep 17 00:00:00 2001
From: Daniel Nephin <dnephin@hashicorp.com>
Date: Mon, 22 Mar 2021 17:29:58 -0400
Subject: [PATCH 3/3] state: add tests for checks.ID indexer

---
 agent/consul/state/catalog.go          |  8 ++---
 agent/consul/state/catalog_oss.go      |  4 +--
 agent/consul/state/catalog_oss_test.go | 42 ++++++++++++++++++++------
 agent/consul/state/catalog_schema.go   |  4 +--
 agent/consul/state/catalog_test.go     |  4 +--
 agent/consul/state/session_oss.go      |  2 +-
 agent/consul/state/state_store_test.go |  2 +-
 7 files changed, 45 insertions(+), 21 deletions(-)

diff --git a/agent/consul/state/catalog.go b/agent/consul/state/catalog.go
index aa80345067..d8d1b5a21f 100644
--- a/agent/consul/state/catalog.go
+++ b/agent/consul/state/catalog.go
@@ -194,7 +194,7 @@ func ensureNoNodeWithSimilarNameTxn(tx ReadTxn, node *structs.Node, allowClashWi
 		if strings.EqualFold(node.Node, enode.Node) && node.ID != enode.ID {
 			// Look up the existing node's Serf health check to see if it's failed.
 			// If it is, the node can be renamed.
-			enodeCheck, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *structs.DefaultEnterpriseMeta(), Node: enode.Node, CheckID: string(structs.SerfCheckID)})
+			enodeCheck, err := tx.First(tableChecks, indexID, NodeCheckQuery{EnterpriseMeta: *structs.DefaultEnterpriseMeta(), Node: enode.Node, CheckID: string(structs.SerfCheckID)})
 			if err != nil {
 				return fmt.Errorf("Cannot get status of node %s: %s", enode.Node, err)
 			}
@@ -1470,7 +1470,7 @@ func (s *Store) ensureCheckCASTxn(tx WriteTxn, idx uint64, hc *structs.HealthChe
 // checks with no matching node or service.
 func (s *Store) ensureCheckTxn(tx WriteTxn, idx uint64, preserveIndexes bool, hc *structs.HealthCheck) error {
 	// Check if we have an existing health check
-	existing, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: hc.EnterpriseMeta, Node: hc.Node, CheckID: string(hc.CheckID)})
+	existing, err := tx.First(tableChecks, indexID, NodeCheckQuery{EnterpriseMeta: hc.EnterpriseMeta, Node: hc.Node, CheckID: string(hc.CheckID)})
 	if err != nil {
 		return fmt.Errorf("failed health check lookup: %s", err)
 	}
@@ -1583,7 +1583,7 @@ func getNodeCheckTxn(tx ReadTxn, nodeName string, checkID types.CheckID, entMeta
 	}
 
 	// Return the check.
-	check, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: nodeName, CheckID: string(checkID)})
+	check, err := tx.First(tableChecks, indexID, NodeCheckQuery{EnterpriseMeta: *entMeta, Node: nodeName, CheckID: string(checkID)})
 	if err != nil {
 		return 0, nil, fmt.Errorf("failed check lookup: %s", err)
 	}
@@ -1809,7 +1809,7 @@ func (s *Store) deleteCheckTxn(tx WriteTxn, idx uint64, node string, checkID typ
 	}
 
 	// Try to retrieve the existing health check.
-	hc, err := tx.First(tableChecks, indexID, NodeCheckID{EnterpriseMeta: *entMeta, Node: node, CheckID: string(checkID)})
+	hc, err := tx.First(tableChecks, indexID, NodeCheckQuery{EnterpriseMeta: *entMeta, Node: node, CheckID: string(checkID)})
 	if err != nil {
 		return fmt.Errorf("check lookup failed: %s", err)
 	}
diff --git a/agent/consul/state/catalog_oss.go b/agent/consul/state/catalog_oss.go
index 8a187066c0..ab2d87bf3d 100644
--- a/agent/consul/state/catalog_oss.go
+++ b/agent/consul/state/catalog_oss.go
@@ -120,9 +120,9 @@ func indexFromHealthCheck(raw interface{}) ([]byte, error) {
 }
 
 func indexFromNodeCheckID(raw interface{}) ([]byte, error) {
-	hc, ok := raw.(NodeCheckID)
+	hc, ok := raw.(NodeCheckQuery)
 	if !ok {
-		return nil, fmt.Errorf("unexpected type %T for NodeCheckID index", raw)
+		return nil, fmt.Errorf("unexpected type %T for NodeCheckQuery index", raw)
 	}
 
 	if hc.Node == "" || hc.CheckID == "" {
diff --git a/agent/consul/state/catalog_oss_test.go b/agent/consul/state/catalog_oss_test.go
index 39d61ac10f..925c130c4b 100644
--- a/agent/consul/state/catalog_oss_test.go
+++ b/agent/consul/state/catalog_oss_test.go
@@ -2,10 +2,40 @@
 
 package state
 
-import "github.com/hashicorp/consul/agent/structs"
+import (
+	"github.com/hashicorp/consul/agent/structs"
+)
 
 func testIndexerTableChecks() map[string]indexerTestCase {
+	obj := &structs.HealthCheck{
+		Node:      "NoDe",
+		ServiceID: "SeRvIcE",
+		CheckID:   "CheckID",
+	}
 	return map[string]indexerTestCase{
+		indexID: {
+			read: indexValue{
+				source: NodeCheckQuery{
+					Node:    "NoDe",
+					CheckID: "CheckId",
+				},
+				expected: []byte("node\x00checkid\x00"),
+			},
+			write: indexValue{
+				source:   obj,
+				expected: []byte("node\x00checkid\x00"),
+			},
+			prefix: []indexValue{
+				{
+					source:   structs.EnterpriseMeta{},
+					expected: nil,
+				},
+				{
+					source:   Query{Value: "nOdE"},
+					expected: []byte("node\x00"),
+				},
+			},
+		},
 		indexNodeService: {
 			read: indexValue{
 				source: NodeServiceQuery{
@@ -15,10 +45,7 @@ func testIndexerTableChecks() map[string]indexerTestCase {
 				expected: []byte("node\x00service\x00"),
 			},
 			write: indexValue{
-				source: &structs.HealthCheck{
-					Node:      "NoDe",
-					ServiceID: "SeRvIcE",
-				},
+				source:   obj,
 				expected: []byte("node\x00service\x00"),
 			},
 		},
@@ -30,10 +57,7 @@ func testIndexerTableChecks() map[string]indexerTestCase {
 				expected: []byte("node\x00"),
 			},
 			write: indexValue{
-				source: &structs.HealthCheck{
-					Node:      "NoDe",
-					ServiceID: "SeRvIcE",
-				},
+				source:   obj,
 				expected: []byte("node\x00"),
 			},
 		},
diff --git a/agent/consul/state/catalog_schema.go b/agent/consul/state/catalog_schema.go
index eef6c6d2a3..5c10c8e349 100644
--- a/agent/consul/state/catalog_schema.go
+++ b/agent/consul/state/catalog_schema.go
@@ -325,8 +325,8 @@ type upstreamDownstream struct {
 	structs.RaftIndex
 }
 
-// NodeCheckID is used to query the ID index of the checks table.
-type NodeCheckID struct {
+// NodeCheckQuery is used to query the ID index of the checks table.
+type NodeCheckQuery struct {
 	Node    string
 	CheckID string
 	structs.EnterpriseMeta
diff --git a/agent/consul/state/catalog_test.go b/agent/consul/state/catalog_test.go
index 3302ffa8ed..b68a76aca2 100644
--- a/agent/consul/state/catalog_test.go
+++ b/agent/consul/state/catalog_test.go
@@ -1307,7 +1307,7 @@ func TestStateStore_DeleteNode(t *testing.T) {
 	}
 
 	// Associated health check was removed.
-	checks, err := tx.Get(tableChecks, indexID, NodeCheckID{Node: "node1", CheckID: "check1"})
+	checks, err := tx.Get(tableChecks, indexID, NodeCheckQuery{Node: "node1", CheckID: "check1"})
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
@@ -2067,7 +2067,7 @@ func TestStateStore_DeleteService(t *testing.T) {
 	// that it actually is removed in the state store.
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	check, err := tx.First(tableChecks, indexID, NodeCheckID{Node: "node1", CheckID: "check1"})
+	check, err := tx.First(tableChecks, indexID, NodeCheckQuery{Node: "node1", CheckID: "check1"})
 	if err != nil || check != nil {
 		t.Fatalf("bad: %#v (err: %s)", check, err)
 	}
diff --git a/agent/consul/state/session_oss.go b/agent/consul/state/session_oss.go
index cd4cad3ade..483ff840d6 100644
--- a/agent/consul/state/session_oss.go
+++ b/agent/consul/state/session_oss.go
@@ -108,7 +108,7 @@ func sessionMaxIndex(tx ReadTxn, entMeta *structs.EnterpriseMeta) uint64 {
 func validateSessionChecksTxn(tx *txn, session *structs.Session) error {
 	// Go over the session checks and ensure they exist.
 	for _, checkID := range session.CheckIDs() {
-		check, err := tx.First(tableChecks, indexID, NodeCheckID{Node: session.Node, CheckID: string(checkID)})
+		check, err := tx.First(tableChecks, indexID, NodeCheckQuery{Node: session.Node, CheckID: string(checkID)})
 		if err != nil {
 			return fmt.Errorf("failed check lookup: %s", err)
 		}
diff --git a/agent/consul/state/state_store_test.go b/agent/consul/state/state_store_test.go
index 0e0db1f2b3..985e7540ba 100644
--- a/agent/consul/state/state_store_test.go
+++ b/agent/consul/state/state_store_test.go
@@ -163,7 +163,7 @@ func testRegisterCheck(t *testing.T, s *Store, idx uint64,
 
 	tx := s.db.Txn(false)
 	defer tx.Abort()
-	c, err := tx.First(tableChecks, indexID, NodeCheckID{Node: nodeID, CheckID: string(checkID)})
+	c, err := tx.First(tableChecks, indexID, NodeCheckQuery{Node: nodeID, CheckID: string(checkID)})
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}