state: remove duplicate index on the checks table

By using a new pattern for more specific indexes. This allows us to use
the same index for both service checks and node checks. It removes the
abstraction around memdb.Txn operations, and isolates all of the
enterprise differences in a single place (the indexer).

agent/consul/state/catalog.go

@@ -1315,9 +1315,14 @@ func (s *Store) deleteServiceTxn(tx WriteTxn, idx uint64, nodeName, serviceID st
 		return nil
 	}
 
+	// TODO: accept a non-pointer value for EnterpriseMeta
+	if entMeta == nil {
+		entMeta = structs.DefaultEnterpriseMeta()
+	}
 	// Delete any checks associated with the service. This will invalidate
 	// sessions as necessary.
-	checks, err := catalogListServiceChecks(tx, nodeName, serviceID, entMeta)
+	q := NodeServiceQuery{Node: nodeName, Service: serviceID, EnterpriseMeta: *entMeta}
+	checks, err := tx.Get(tableChecks, indexNodeService, q)
 	if err != nil {
 		return fmt.Errorf("failed service check lookup: %s", err)
 	}
@@ -1766,6 +1771,13 @@ func (s *Store) deleteCheckCASTxn(tx WriteTxn, idx, cidx uint64, node string, ch
 	return true, nil
 }
 
+// NodeServiceQuery is a type used to query the checks table.
+type NodeServiceQuery struct {
+	Node    string
+	Service string
+	structs.EnterpriseMeta
+}
+
 // 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 {
@@ -2137,7 +2149,8 @@ func parseCheckServiceNodes(
 		// First add the node-level checks. These always apply to any
 		// service on the node.
 		var checks structs.HealthChecks
-		iter, err := catalogListNodeChecks(tx, sn.Node)
+		q := NodeServiceQuery{Node: sn.Node, EnterpriseMeta: *structs.DefaultEnterpriseMeta()}
+		iter, err := tx.Get(tableChecks, indexNodeService, q)
 		if err != nil {
 			return 0, nil, err
 		}
@@ -2147,7 +2160,8 @@ func parseCheckServiceNodes(
 		}
 
 		// Now add the service-specific checks.
-		iter, err = catalogListServiceChecks(tx, sn.Node, sn.ServiceID, &sn.EnterpriseMeta)
+		q = NodeServiceQuery{Node: sn.Node, Service: sn.ServiceID, EnterpriseMeta: sn.EnterpriseMeta}
+		iter, err = tx.Get(tableChecks, indexNodeService, q)
 		if err != nil {
 			return 0, nil, err
 		}

agent/consul/state/catalog_oss.go

@@ -4,6 +4,7 @@ package state
 
 import (
 	"fmt"
+	"strings"
 
 	memdb "github.com/hashicorp/go-memdb"
 
@@ -12,6 +13,34 @@ import (
 
 func withEnterpriseSchema(_ *memdb.DBSchema) {}
 
+func indexNodeServiceFromHealthCheck(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 == "" {
+		return nil, errMissingValueForIndex
+	}
+
+	var b indexBuilder
+	b.String(strings.ToLower(hc.Node))
+	b.String(strings.ToLower(hc.ServiceID))
+	return b.Bytes(), nil
+}
+
+func indexFromNodeServiceQuery(arg interface{}) ([]byte, error) {
+	hc, ok := arg.(NodeServiceQuery)
+	if !ok {
+		return nil, fmt.Errorf("unexpected type %T for NodeServiceQuery index", arg)
+	}
+
+	var b indexBuilder
+	b.String(strings.ToLower(hc.Node))
+	b.String(strings.ToLower(hc.Service))
+	return b.Bytes(), nil
+}
+
 func serviceIndexName(name string, _ *structs.EnterpriseMeta) string {
 	return fmt.Sprintf("service.%s", name)
 }
@@ -156,14 +185,6 @@ func catalogListChecks(tx ReadTxn, _ *structs.EnterpriseMeta) (memdb.ResultItera
 	return tx.Get("checks", "id")
 }
 
-func catalogListNodeChecks(tx ReadTxn, node string) (memdb.ResultIterator, error) {
-	return tx.Get("checks", indexNodeServiceCheck, node, false)
-}
-
-func catalogListServiceChecks(tx ReadTxn, node string, service string, _ *structs.EnterpriseMeta) (memdb.ResultIterator, error) {
-	return tx.Get("checks", indexNodeService, node, service)
-}
-
 func catalogInsertCheck(tx WriteTxn, chk *structs.HealthCheck, idx uint64) error {
 	// Insert the check
 	if err := tx.Insert("checks", chk); err != nil {

agent/consul/state/catalog_schema.go

@@ -22,7 +22,6 @@ const (
 	indexConnect     = "connect"
 	indexKind        = "kind"
 	indexStatus      = "status"
-	indexNodeServiceCheck = "node_service_check"
 	indexNodeService = "node_service"
 )
 
@@ -170,37 +169,13 @@ func checksTableSchema() *memdb.TableSchema {
 					Lowercase: true,
 				},
 			},
-			indexNodeServiceCheck: {
-				Name:         indexNodeServiceCheck,
-				AllowMissing: true,
-				Unique:       false,
-				Indexer: &memdb.CompoundIndex{
-					Indexes: []memdb.Indexer{
-						&memdb.StringFieldIndex{
-							Field:     "Node",
-							Lowercase: true,
-						},
-						&memdb.FieldSetIndex{
-							Field: "ServiceID",
-						},
-					},
-				},
-			},
 			indexNodeService: {
 				Name:         indexNodeService,
 				AllowMissing: true,
 				Unique:       false,
-				Indexer: &memdb.CompoundIndex{
-					Indexes: []memdb.Indexer{
-						&memdb.StringFieldIndex{
-							Field:     "Node",
-							Lowercase: true,
-						},
-						&memdb.StringFieldIndex{
-							Field:     "ServiceID",
-							Lowercase: true,
-						},
-					},
+				Indexer: indexerSingle{
+					fromArgsIndexer:   indexFromSingleArg(indexFromNodeServiceQuery),
+					fromObjectIndexer: indexFromObject(indexNodeServiceFromHealthCheck),
 				},
 			},
 		},

agent/consul/state/testdata/TestStateStoreSchema.golden

@@ -52,9 +52,7 @@ table=checks
   index=node allow-missing
     indexer=github.com/hashicorp/go-memdb.StringFieldIndex Field=Node Lowercase=true
   index=node_service allow-missing
-    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=ServiceID Lowercase=true] AllowMissing=false
-  index=node_service_check allow-missing
-    indexer=github.com/hashicorp/go-memdb.CompoundIndex Indexes=[github.com/hashicorp/go-memdb.StringFieldIndex Field=Node Lowercase=true, github.com/hashicorp/go-memdb.FieldSetIndex Field=ServiceID] AllowMissing=false
+    indexer=github.com/hashicorp/consul/agent/consul/state.indexerSingle fromArgsIndexer=github.com/hashicorp/consul/agent/consul/state.indexFromSingleArg.func1 fromObjectIndexer=github.com/hashicorp/consul/agent/consul/state.indexNodeServiceFromHealthCheck
   index=service allow-missing
     indexer=github.com/hashicorp/go-memdb.StringFieldIndex Field=ServiceName Lowercase=true
   index=status