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lockstore: compatible with Go 1.14's checkptr #402

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Jun 23, 2020
Merged

lockstore: compatible with Go 1.14's checkptr #402

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43 changes: 34 additions & 9 deletions lockstore/lockstore.go
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,10 @@ type node struct {
nodeHeader
// Height of the nexts.

nexts [maxHeight]uint64
// node is a variable length struct.
// The nextsBase is the first element of nexts slice,
// it act as the base pointer we do pointer arithmetic in `next` and `setNext`.
nextsBase uint64
}

type entry struct {
Expand All @@ -66,12 +69,25 @@ func (e *entry) getValue(arena *arena) []byte {
return nil
}

func (n *node) nexts(level int) uint64 {
return *n.nextsAddr(level)
}

func (n *node) setNexts(level int, val uint64) {
*n.nextsAddr(level) = val
}

func (n *node) nextsAddr(idx int) *uint64 {
offset := uintptr(idx) * unsafe.Sizeof(n.nextsBase)
return (*uint64)(unsafe.Pointer(uintptr(unsafe.Pointer(&n.nextsBase)) + offset))
}

func (n *node) getNextAddr(level int) arenaAddr {
return arenaAddr(atomic.LoadUint64(&n.nexts[level]))
return arenaAddr(atomic.LoadUint64(n.nextsAddr(level)))
}

func (n *node) setNextAddr(level int, addr arenaAddr) {
atomic.StoreUint64(&n.nexts[level], uint64(addr))
atomic.StoreUint64(n.nextsAddr(level), uint64(addr))
}

func (n *node) entryLen() int {
Expand All @@ -95,12 +111,21 @@ func (n *node) getValue(a *arena) []byte {
}

func NewMemStore(arenaBlockSize int) *MemStore {
return &MemStore{
ls := &MemStore{
height: 1,
head: new(node),
arenaPtr: unsafe.Pointer(newArenaLocator(arenaBlockSize)),
rand: rand.NewSource(time.Now().Unix()).(rand.Source64),
}
ls.setHeadNode()
return ls
}

func (ls *MemStore) setHeadNode() {
n := ls.newNode(ls.getArena(), nil, nil, maxHeight)
for i := 0; i < maxHeight; i++ {
n.setNexts(i, 0)
}
ls.head = n
}

func (ls *MemStore) getHeight() int {
Expand Down Expand Up @@ -301,9 +326,9 @@ func (ls *MemStore) PutWithHint(key []byte, v []byte, hint *Hint) bool {
// create a node in the level above because it would have discovered the node in the base level.
for i := 0; i < height; i++ {
if hint.next[i] != nil {
x.nexts[i] = uint64(hint.next[i].addr)
x.setNexts(i, uint64(hint.next[i].addr))
} else {
x.nexts[i] = uint64(nullArenaAddr)
x.setNexts(i, uint64(nullArenaAddr))
}
if hint.prev[i] == nil {
hint.prev[i] = ls.head
Expand All @@ -319,8 +344,8 @@ func (ls *MemStore) replace(key, v []byte, hint *Hint, old *node) {
x := ls.newNode(ls.getArena(), key, v, int(old.height))
arena := ls.getArena()
for i := 0; i < int(old.height); i++ {
nextAddr := atomic.LoadUint64(&old.nexts[i])
x.nexts[i] = nextAddr
nextAddr := atomic.LoadUint64(old.nextsAddr(i))
x.setNexts(i, nextAddr)
if nextAddr != uint64(nullArenaAddr) {
hint.next[i] = ls.getNode(arena, arenaAddr(nextAddr))
} else {
Expand Down