From c5497ba4758c55cfb7be120c882a811f187d7513 Mon Sep 17 00:00:00 2001
From: Nathan VanBenschoten <nvanbenschoten@gmail.com>
Date: Mon, 6 Jun 2022 14:54:33 -0400
Subject: [PATCH] keys: move Raft log suffix parsing into pkg/keys

This did not belong in stateloader.go.
---
 pkg/keys/keys.go                           |  9 ++++++++-
 pkg/kv/kvserver/stateloader/BUILD.bazel    |  1 -
 pkg/kv/kvserver/stateloader/stateloader.go | 13 ++++++++-----
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/pkg/keys/keys.go b/pkg/keys/keys.go
index 5ab51a93c6e1..1d39b9c0e700 100644
--- a/pkg/keys/keys.go
+++ b/pkg/keys/keys.go
@@ -337,6 +337,13 @@ func RaftLogKeyFromPrefix(raftLogPrefix []byte, logIndex uint64) roachpb.Key {
 	return encoding.EncodeUint64Ascending(raftLogPrefix, logIndex)
 }
 
+// DecodeRaftLogKeyFromSuffix parses the suffix of a system-local key for a Raft
+// log entry and returns the entry's log index.
+func DecodeRaftLogKeyFromSuffix(raftLogSuffix []byte) (uint64, error) {
+	_, logIndex, err := encoding.DecodeUint64Ascending(raftLogSuffix)
+	return logIndex, err
+}
+
 // RaftReplicaIDKey returns a system-local key for a RaftReplicaID.
 func RaftReplicaIDKey(rangeID roachpb.RangeID) roachpb.Key {
 	return MakeRangeIDPrefixBuf(rangeID).RaftReplicaIDKey()
@@ -453,7 +460,7 @@ func LockTableSingleKey(key roachpb.Key, buf []byte) (roachpb.Key, []byte) {
 }
 
 // DecodeLockTableSingleKey decodes the single-key lock table key to return the key
-// that was locked..
+// that was locked.
 func DecodeLockTableSingleKey(key roachpb.Key) (lockedKey roachpb.Key, err error) {
 	if !bytes.HasPrefix(key, LocalRangeLockTablePrefix) {
 		return nil, errors.Errorf("key %q does not have %q prefix",
diff --git a/pkg/kv/kvserver/stateloader/BUILD.bazel b/pkg/kv/kvserver/stateloader/BUILD.bazel
index 56f558fb6afb..89250e5f4926 100644
--- a/pkg/kv/kvserver/stateloader/BUILD.bazel
+++ b/pkg/kv/kvserver/stateloader/BUILD.bazel
@@ -15,7 +15,6 @@ go_library(
         "//pkg/roachpb",
         "//pkg/storage",
         "//pkg/storage/enginepb",
-        "//pkg/util/encoding",
         "//pkg/util/hlc",
         "//pkg/util/log",
         "//pkg/util/protoutil",
diff --git a/pkg/kv/kvserver/stateloader/stateloader.go b/pkg/kv/kvserver/stateloader/stateloader.go
index 6c9eb30c91e5..575c3e7117b0 100644
--- a/pkg/kv/kvserver/stateloader/stateloader.go
+++ b/pkg/kv/kvserver/stateloader/stateloader.go
@@ -19,7 +19,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
 	"github.com/cockroachdb/cockroach/pkg/storage"
 	"github.com/cockroachdb/cockroach/pkg/storage/enginepb"
-	"github.com/cockroachdb/cockroach/pkg/util/encoding"
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
@@ -45,7 +44,7 @@ type StateLoader struct {
 	keys.RangeIDPrefixBuf
 }
 
-// Make creates a a StateLoader.
+// Make creates a StateLoader.
 func Make(rangeID roachpb.RangeID) StateLoader {
 	rsl := StateLoader{
 		RangeIDPrefixBuf: keys.MakeRangeIDPrefixBuf(rangeID),
@@ -302,11 +301,15 @@ func (rsl StateLoader) LoadLastIndex(ctx context.Context, reader storage.Reader)
 	var lastIndex uint64
 	iter.SeekLT(storage.MakeMVCCMetadataKey(keys.RaftLogKeyFromPrefix(prefix, math.MaxUint64)))
 	if ok, _ := iter.Valid(); ok {
-		key := iter.Key()
+		key := iter.UnsafeKey().Key
+		if len(key) < len(prefix) {
+			log.Fatalf(ctx, "unable to decode Raft log index key: len(%s) < len(%s)", key.String(), prefix.String())
+		}
+		suffix := key[len(prefix):]
 		var err error
-		_, lastIndex, err = encoding.DecodeUint64Ascending(key.Key[len(prefix):])
+		lastIndex, err = keys.DecodeRaftLogKeyFromSuffix(suffix)
 		if err != nil {
-			log.Fatalf(ctx, "unable to decode Raft log index key: %s", key)
+			log.Fatalf(ctx, "unable to decode Raft log index key: %s; %v", key.String(), err)
 		}
 	}