From e90504fe6211eca08472e71243513dc6e08b51fc Mon Sep 17 00:00:00 2001
From: Piotr Tabor <ptab@google.com>
Date: Thu, 29 Apr 2021 09:34:54 +0200
Subject: [PATCH] Unify shared code (and constants) with cindex package.

---
 etcdctl/ctlv3/command/migrate_command.go |  3 ++-
 server/etcdserver/cindex/cindex.go       | 25 +++++++++++++++++++-----
 server/mvcc/kvstore.go                   |  7 +++----
 server/mvcc/util.go                      | 21 --------------------
 4 files changed, 25 insertions(+), 31 deletions(-)

diff --git a/etcdctl/ctlv3/command/migrate_command.go b/etcdctl/ctlv3/command/migrate_command.go
index 33e87c09e..deba3c2ff 100644
--- a/etcdctl/ctlv3/command/migrate_command.go
+++ b/etcdctl/ctlv3/command/migrate_command.go
@@ -36,6 +36,7 @@ import (
 	"go.etcd.io/etcd/server/v3/etcdserver/api/snap"
 	"go.etcd.io/etcd/server/v3/etcdserver/api/v2error"
 	"go.etcd.io/etcd/server/v3/etcdserver/api/v2store"
+	"go.etcd.io/etcd/server/v3/etcdserver/cindex"
 	"go.etcd.io/etcd/server/v3/mvcc"
 	"go.etcd.io/etcd/server/v3/mvcc/backend"
 	"go.etcd.io/etcd/server/v3/wal"
@@ -91,7 +92,7 @@ func migrateCommandFunc(cmd *cobra.Command, args []string) {
 	}()
 
 	readKeys(reader, be)
-	mvcc.UpdateConsistentIndex(be, index)
+	cindex.UpdateConsistentIndex(be.BatchTx(), index)
 	err := <-errc
 	if err != nil {
 		fmt.Println("failed to transform keys")
diff --git a/server/etcdserver/cindex/cindex.go b/server/etcdserver/cindex/cindex.go
index ed5c14b56..25bbeb872 100644
--- a/server/etcdserver/cindex/cindex.go
+++ b/server/etcdserver/cindex/cindex.go
@@ -80,11 +80,7 @@ func (ci *consistentIndex) UnsafeSave(tx backend.BatchTx) {
 		// Never save 0 as it means that we didn't loaded the real index yet.
 		return
 	}
-	bs := make([]byte, 8) // this is kept on stack (not heap) so its quick.
-	binary.BigEndian.PutUint64(bs, index)
-	// put the index into the underlying backend
-	// tx has been locked in TxnBegin, so there is no need to lock it again
-	tx.UnsafePut(MetaBucketName, ConsistentIndexKeyName, bs)
+	unsafeUpdateConsistentIndex(tx, index)
 }
 
 func (ci *consistentIndex) SetBatchTx(tx backend.BatchTx) {
@@ -130,3 +126,22 @@ func ReadConsistentIndex(tx backend.ReadTx) uint64 {
 	defer tx.Unlock()
 	return unsafeReadConsistentIndex(tx)
 }
+
+func unsafeUpdateConsistentIndex(tx backend.BatchTx, index uint64) {
+	bs := make([]byte, 8) // this is kept on stack (not heap) so its quick.
+	binary.BigEndian.PutUint64(bs, index)
+	// put the index into the underlying backend
+	// tx has been locked in TxnBegin, so there is no need to lock it again
+	tx.UnsafePut(MetaBucketName, ConsistentIndexKeyName, bs)
+}
+
+func UpdateConsistentIndex(tx backend.BatchTx, index uint64) {
+	tx.Lock()
+	defer tx.Unlock()
+
+	oldi := unsafeReadConsistentIndex(tx)
+	if index <= oldi {
+		return
+	}
+	unsafeUpdateConsistentIndex(tx, index)
+}
diff --git a/server/mvcc/kvstore.go b/server/mvcc/kvstore.go
index 2256902fe..ac79b07b1 100644
--- a/server/mvcc/kvstore.go
+++ b/server/mvcc/kvstore.go
@@ -35,9 +35,8 @@ import (
 
 var (
 	keyBucketName  = []byte("key")
-	metaBucketName = []byte("meta")
+	metaBucketName = cindex.MetaBucketName
 
-	consistentIndexKeyName  = []byte("consistent_index")
 	scheduledCompactKeyName = []byte("scheduledCompactRev")
 	finishedCompactKeyName  = []byte("finishedCompactRev")
 
@@ -128,7 +127,7 @@ func NewStore(lg *zap.Logger, b backend.Backend, le lease.Lessor, ci cindex.Cons
 	tx := s.b.BatchTx()
 	tx.Lock()
 	tx.UnsafeCreateBucket(keyBucketName)
-	tx.UnsafeCreateBucket(metaBucketName)
+	cindex.UnsafeCreateMetaBucket(tx)
 	tx.Unlock()
 	s.b.ForceCommit()
 
@@ -308,7 +307,7 @@ func init() {
 	DefaultIgnores = map[backend.IgnoreKey]struct{}{
 		// consistent index might be changed due to v2 internal sync, which
 		// is not controllable by the user.
-		{Bucket: string(metaBucketName), Key: string(consistentIndexKeyName)}: {},
+		{Bucket: string(metaBucketName), Key: string(cindex.ConsistentIndexKeyName)}: {},
 	}
 }
 
diff --git a/server/mvcc/util.go b/server/mvcc/util.go
index fad79c572..254676090 100644
--- a/server/mvcc/util.go
+++ b/server/mvcc/util.go
@@ -15,33 +15,12 @@
 package mvcc
 
 import (
-	"encoding/binary"
 	"fmt"
 
 	"go.etcd.io/etcd/api/v3/mvccpb"
 	"go.etcd.io/etcd/server/v3/mvcc/backend"
 )
 
-func UpdateConsistentIndex(be backend.Backend, index uint64) {
-	tx := be.BatchTx()
-	tx.Lock()
-	defer tx.Unlock()
-
-	var oldi uint64
-	_, vs := tx.UnsafeRange(metaBucketName, consistentIndexKeyName, nil, 0)
-	if len(vs) != 0 {
-		oldi = binary.BigEndian.Uint64(vs[0])
-	}
-
-	if index <= oldi {
-		return
-	}
-
-	bs := make([]byte, 8)
-	binary.BigEndian.PutUint64(bs, index)
-	tx.UnsafePut(metaBucketName, consistentIndexKeyName, bs)
-}
-
 func WriteKV(be backend.Backend, kv mvccpb.KeyValue) {
 	ibytes := newRevBytes()
 	revToBytes(revision{main: kv.ModRevision}, ibytes)