fix data race

iterator.go

@@ -28,7 +28,7 @@ import (
 	"github.com/dgryski/go-farm"
 )
 
-type prefetchStatus uint8
+type prefetchStatus = uint32
 
 const (
 	prefetched prefetchStatus = 1
@@ -89,7 +89,7 @@ func (item *Item) Version() uint64 {
 // instead, or copy it yourself. Value might change once discard or commit is called.
 // Use ValueCopy if you want to do a Set after Get.
 func (item *Item) Value() ([]byte, error) {
-	if item.status == noPrefetch {
+	if item.getStatus() == noPrefetch {
 		if (item.meta & bitValuePointer) == 0 {
 			return item.vptr, nil
 		}
@@ -98,12 +98,16 @@ func (item *Item) Value() ([]byte, error) {
 		return item.db.vlog.Read(vp, item.slice)
 	}
 	item.wg.Wait()
-	if item.status == prefetched {
+	if item.getStatus() == prefetched {
 		return item.val, item.err
 	}
 	return item.yieldItemValue(nil)
 }
 
+func (item *Item) getStatus() uint32 {
+	return atomic.LoadUint32(&item.status)
+}
+
 // ValueCopy returns a copy of the value of the item from the value log, writing it to dst slice.
 // If nil is passed, or capacity of dst isn't sufficient, a new slice would be allocated and
 // returned. Tip: It might make sense to reuse the returned slice as dst argument for the next call.
@@ -112,7 +116,7 @@ func (item *Item) Value() ([]byte, error) {
 // See Github issue: https://github.com/coocood/badger/issues/315
 func (item *Item) ValueCopy(dst []byte) ([]byte, error) {
 	item.wg.Wait()
-	if item.status == prefetched {
+	if item.getStatus() == prefetched {
 		return y.SafeCopy(dst, item.val), item.err
 	}
 	buf, err := item.yieldItemValue(dst)
@@ -172,7 +176,7 @@ func (item *Item) yieldItemValue(dst []byte) ([]byte, error) {
 func (item *Item) prefetchValue() {
 	val, err := item.yieldItemValue(nil)
 	item.err = err
-	item.status = prefetched
+	atomic.StoreUint32(&item.status, prefetched)
 	if val == nil {
 		return
 	}

level_handler.go

@@ -134,7 +134,6 @@ func (s *levelHandler) replaceTables(newTables []*table.Table) error {
 	}
 
 	assertTablesOrder(newTables)
-	assertTablesOrder(s.tables)
 
 	s.Lock() // We s.Unlock() below.
 
@@ -167,8 +166,8 @@ func (s *levelHandler) replaceTables(newTables []*table.Table) error {
 	y.Assert(numAdded == copy(t, newTables))
 	t = t[numAdded:]
 	y.Assert(len(s.tables[right:]) == copy(t, s.tables[right:]))
-	s.tables = tables
 	assertTablesOrder(tables)
+	s.tables = tables
 	s.Unlock() // s.Unlock before we DecrRef tables -- that can be slow.
 	return decrRefs(toDecr)
 }

table/mem_table.go

@@ -42,7 +42,7 @@ func (mt *MemTable) Get(key []byte) y.ValueStruct {
 		if v, ok := curr.get(key); ok {
 			return v
 		}
-		curr = (*listNode)(curr.next)
+		curr = (*listNode)(atomic.LoadPointer(&curr.next))
 	}
 	return mt.skl.Get(key)
 }
@@ -55,7 +55,7 @@ func (mt *MemTable) NewIterator(reverse bool) y.Iterator {
 	curr := (*listNode)(atomic.LoadPointer(&mt.pendingList))
 	for curr != nil {
 		its = append(its, curr.newIterator(reverse))
-		curr = (*listNode)(curr.next)
+		curr = (*listNode)(atomic.LoadPointer(&curr.next))
 	}
 
 	if len(its) == 0 {
@@ -70,7 +70,7 @@ func (mt *MemTable) MemSize() int64 {
 	curr := (*listNode)(atomic.LoadPointer(&mt.pendingList))
 	for curr != nil {
 		sz += curr.memSize
-		curr = (*listNode)(curr.next)
+		curr = (*listNode)(atomic.LoadPointer(&curr.next))
 	}
 	return mt.skl.MemSize() + sz
 }