From aadf187094bbb7f131e681a03df58bcdbdd193a6 Mon Sep 17 00:00:00 2001
From: Daniel Nephin <dnephin@hashicorp.com>
Date: Wed, 10 Mar 2021 13:37:17 -0500
Subject: [PATCH] state: remove config-entries namespace index

Use a prefix of the ID index instead.
---
 agent/consul/state/config_entry_oss.go         |  4 ++--
 agent/consul/state/config_entry_schema.go      |  7 ++++---
 agent/consul/state/indexer.go                  | 18 ++++++++++++++++++
 .../state/testdata/TestStateStoreSchema.golden |  2 +-
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/agent/consul/state/config_entry_oss.go b/agent/consul/state/config_entry_oss.go
index 9ef1d374b2..e265d09058 100644
--- a/agent/consul/state/config_entry_oss.go
+++ b/agent/consul/state/config_entry_oss.go
@@ -44,11 +44,11 @@ func validateConfigEntryEnterprise(_ ReadTxn, _ structs.ConfigEntry) error {
 }
 
 func getAllConfigEntriesWithTxn(tx ReadTxn, _ *structs.EnterpriseMeta) (memdb.ResultIterator, error) {
-	return tx.Get(tableConfigEntries, "id")
+	return tx.Get(tableConfigEntries, indexID)
 }
 
 func getConfigEntryKindsWithTxn(tx ReadTxn, kind string, _ *structs.EnterpriseMeta) (memdb.ResultIterator, error) {
-	return tx.Get(tableConfigEntries, "kind", kind)
+	return tx.Get(tableConfigEntries, indexKind, kind)
 }
 
 func configIntentionsConvertToList(iter memdb.ResultIterator, _ *structs.EnterpriseMeta) structs.Intentions {
diff --git a/agent/consul/state/config_entry_schema.go b/agent/consul/state/config_entry_schema.go
index 11ad01e4d1..746b659f3e 100644
--- a/agent/consul/state/config_entry_schema.go
+++ b/agent/consul/state/config_entry_schema.go
@@ -22,9 +22,10 @@ func configTableSchema() *memdb.TableSchema {
 				Name:         indexID,
 				AllowMissing: false,
 				Unique:       true,
-				Indexer: indexerSingle{
-					readIndex:  readIndex(indexFromConfigEntryKindName),
-					writeIndex: writeIndex(indexFromConfigEntry),
+				Indexer: indexerSingleWithPrefix{
+					readIndex:   readIndex(indexFromConfigEntryKindName),
+					writeIndex:  writeIndex(indexFromConfigEntry),
+					prefixIndex: prefixIndex(indexFromConfigEntryKindName),
 				},
 			},
 			indexKind: {
diff --git a/agent/consul/state/indexer.go b/agent/consul/state/indexer.go
index dc91e2af8d..22474fc82f 100644
--- a/agent/consul/state/indexer.go
+++ b/agent/consul/state/indexer.go
@@ -30,6 +30,13 @@ type indexerMulti struct {
 	writeIndexMulti
 }
 
+// indexerSingleWithPrefix is a indexerSingle which also supports prefix queries.
+type indexerSingleWithPrefix struct {
+	readIndex
+	writeIndex
+	prefixIndex
+}
+
 // readIndex implements memdb.Indexer. It exists so that a function can be used
 // to provide the interface.
 //
@@ -78,6 +85,17 @@ func (f writeIndexMulti) FromObject(raw interface{}) (bool, [][]byte, error) {
 	return err == nil, v, err
 }
 
+// prefixIndex implements memdb.PrefixIndexer. It exists so that a function
+// can be used to provide this interface.
+type prefixIndex func(args interface{}) ([]byte, error)
+
+func (f prefixIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
+	if len(args) != 1 {
+		return nil, fmt.Errorf("index supports only a single arg")
+	}
+	return f(args[0])
+}
+
 const null = "\x00"
 
 // indexBuilder is a buffer used to construct memdb index values.
diff --git a/agent/consul/state/testdata/TestStateStoreSchema.golden b/agent/consul/state/testdata/TestStateStoreSchema.golden
index 83f59d8b61..2ef93dfcf7 100644
--- a/agent/consul/state/testdata/TestStateStoreSchema.golden
+++ b/agent/consul/state/testdata/TestStateStoreSchema.golden
@@ -60,7 +60,7 @@ table=checks
 
 table=config-entries
   index=id unique
-    indexer=github.com/hashicorp/consul/agent/consul/state.indexerSingle readIndex=github.com/hashicorp/consul/agent/consul/state.indexFromConfigEntryKindName writeIndex=github.com/hashicorp/consul/agent/consul/state.indexFromConfigEntry
+    indexer=github.com/hashicorp/consul/agent/consul/state.indexerSingleWithPrefix readIndex=github.com/hashicorp/consul/agent/consul/state.indexFromConfigEntryKindName writeIndex=github.com/hashicorp/consul/agent/consul/state.indexFromConfigEntry prefixIndex=github.com/hashicorp/consul/agent/consul/state.indexFromConfigEntryKindName
   index=intention-legacy-id unique allow-missing
     indexer=github.com/hashicorp/consul/agent/consul/state.ServiceIntentionLegacyIDIndex uuidFieldIndex={}
   index=intention-source allow-missing