remove unnecessary rwlock (#54)

cursor.go

@@ -41,21 +41,16 @@ func (c *Collection) NewCursor() (*Cursor, error) {
  }
 
  var rec *record
- cur.current.lock.RLock()
- for (cur.current.Deleted != 0 && cur.current.Deleted <= cur.snapshot) ||
+ for (atomic.LoadInt64(&cur.current.Deleted) != 0 && atomic.LoadInt64(&cur.current.Deleted) <= cur.snapshot) ||
  (cur.current.Offset >= cur.snapshot) {
  rec, err = cur.collection.readRecord(atomic.LoadInt64(&cur.current.Next[0]), false)
  if err != nil {
- cur.current.lock.RUnlock()
  cur.current = nil
  cur.err = err
  return cur, nil
  }
- cur.current.lock.RUnlock()
  cur.current = rec
- cur.current.lock.RLock()
  }
- cur.current.lock.RUnlock()
 
  return cur, nil
 }
@@ -84,36 +79,28 @@ func (c *Cursor) Next() bool {
  return true
  }
 
- c.current.lock.RLock()
  rec, err := c.collection.readRecord(atomic.LoadInt64(&c.current.Next[0]), false)
  if err != nil {
- c.current.lock.RUnlock()
  if atomic.LoadInt64(&c.current.Next[0]) != 0 {
  c.err = err
  }
  c.current = nil
  return false
  }
- c.current.lock.RUnlock()
  c.current = rec
 
- c.current.lock.RLock()
  for (atomic.LoadInt64(&c.current.Deleted) != 0 && atomic.LoadInt64(&c.current.Deleted) <= c.snapshot) ||
  (c.current.Offset >= c.snapshot) {
  rec, err = c.collection.readRecord(atomic.LoadInt64(&c.current.Next[0]), false)
  if err != nil {
- c.current.lock.RUnlock()
  if atomic.LoadInt64(&c.current.Next[0]) != 0 {
  c.err = err
  }
  c.current = nil
  return false
  }
- c.current.lock.RUnlock()
  c.current = rec
- c.current.lock.RLock()
  }
- c.current.lock.RUnlock()
 
  return true
 }
@@ -171,10 +158,8 @@ func (c *Cursor) Seek(key string) {
  c.current = rec
  c.first = true
  for rec != nil {
- rec.lock.RLock()
  if rec.Key >= key {
  if (rec.Deleted > 0 && rec.Deleted <= c.snapshot) || (rec.Offset >= c.snapshot) {
- oldRec := rec
  rec, err = c.collection.nextRecord(rec, 0, false)
  if err != nil {
  if atomic.LoadInt64(&c.current.Next[0]) != 0 {
@@ -183,15 +168,12 @@ func (c *Cursor) Seek(key string) {
  c.current = nil
  return
  }
- oldRec.lock.RUnlock()
  c.current = rec
  continue
  }
- rec.lock.RUnlock()
  break
  }
  if (rec.Deleted > 0 && rec.Deleted <= c.snapshot) || (rec.Offset >= c.snapshot) {
- oldRec := rec
  rec, err = c.collection.nextRecord(rec, 0, false)
  if err != nil {
  if atomic.LoadInt64(&c.current.Next[0]) != 0 {
@@ -200,13 +182,11 @@ func (c *Cursor) Seek(key string) {
  c.current = nil
  return
  }
- oldRec.lock.RUnlock()
  continue
  }
  if rec.Key < key {
  c.current = rec
  }
- oldRec := rec
  rec, err = c.collection.nextRecord(rec, 0, false)
  if err != nil {
  if atomic.LoadInt64(&c.current.Next[0]) != 0 {
@@ -215,7 +195,6 @@ func (c *Cursor) Seek(key string) {
  c.current = nil
  return
  }
- oldRec.lock.RUnlock()
  }
 }
 

lm2.go

@@ -113,8 +113,6 @@ type record struct {
  Offset int64
  Key string
  Value string
-
- lock sync.RWMutex
 }
 
 func generateLevel() int {

update.go

@@ -87,9 +87,7 @@ func (c *Collection) findLastLessThanOrEqual(key string, startingOffset int64, l
  }
 
  for rec != nil {
- rec.lock.RLock()
  if (!equal && rec.Key == key) || rec.Key > key {
- rec.lock.RUnlock()
  break
  }
  offset = rec.Offset
@@ -98,7 +96,6 @@ func (c *Collection) findLastLessThanOrEqual(key string, startingOffset int64, l
  if err != nil {
  return 0, err
  }
- oldRec.lock.RUnlock()
  }
 
  return offset, nil
@@ -209,9 +206,7 @@ KEYS_LOOP:
  rollbackErr = err
  break KEYS_LOOP
  }
- readRec.lock.RLock()
  *prevRec = *readRec
- readRec.lock.RUnlock()
  }
  atomic.StoreInt64(&rec.Next[level], prevRec.Next[level])
  atomic.StoreInt64(&prevRec.Next[level], newRecordOffset)
@@ -292,9 +287,7 @@ KEYS_LOOP:
  rollbackErr = err
  goto ROLLBACK
  }
- readRec.lock.RLock()
  *rec = *readRec
- readRec.lock.RUnlock()
  }
  if rec.Key != key {
  continue
@@ -318,9 +311,7 @@ KEYS_LOOP:
  rollbackErr = err
  goto ROLLBACK
  }
- readRec.lock.RLock()
  *rec = *readRec
- readRec.lock.RUnlock()
  }
  atomic.StoreInt64(&rec.Deleted, currentOffset)
  c.setDirty(rec.Offset, rec)