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optimize table iterator. #7

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merged 1 commit into from
May 30, 2018
Merged

optimize table iterator. #7

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54 changes: 28 additions & 26 deletions table/iterator.go
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Original file line number Diff line number Diff line change
Expand Up @@ -60,13 +60,19 @@ type blockIterator struct {
func (itr *blockIterator) Reset() {
itr.pos = 0
itr.err = nil
itr.baseKey = []byte{}
itr.key = []byte{}
itr.val = []byte{}
itr.baseKey = itr.baseKey[:0]
itr.key = itr.key[:0]
itr.val = itr.val[:0]
itr.init = false
itr.last = header{}
}

func (itr *blockIterator) SetBlock(b block) {
itr.Reset()
itr.data = b.data
itr.loadEntryIndex()
}

func (itr *blockIterator) Init() {
if !itr.init {
itr.Next()
Expand Down Expand Up @@ -183,15 +189,9 @@ func (itr *blockIterator) SeekToLast() {

// parseKV would allocate a new byte slice for key and for value.
func (itr *blockIterator) parseKV(h header) {
if cap(itr.key) < int(h.plen+h.klen) {
sz := int(h.plen) + int(h.klen) // Convert to int before adding to avoid uint16 overflow.
itr.key = make([]byte, 2*sz)
}
itr.key = itr.key[:h.plen+h.klen]
copy(itr.key, itr.baseKey[:h.plen])
copy(itr.key[h.plen:], itr.data[itr.pos:itr.pos+uint32(h.klen)])
itr.key = append(itr.key[:0], itr.baseKey[:h.plen]...)
itr.key = append(itr.key, itr.data[itr.pos:itr.pos+uint32(h.klen)]...)
itr.pos += uint32(h.klen)

if itr.pos+uint32(h.vlen) > uint32(len(itr.data)) {
itr.err = errors.Errorf("Value exceeded size of block: %d %d %d %d %v",
itr.pos, h.klen, h.vlen, len(itr.data), h)
Expand Down Expand Up @@ -268,7 +268,7 @@ func (itr *blockIterator) Value() []byte {
type Iterator struct {
t *Table
bpos int
bi *blockIterator
bi blockIterator
err error

// Internally, Iterator is bidirectional. However, we only expose the
Expand Down Expand Up @@ -311,7 +311,7 @@ func (itr *Iterator) seekToFirst() {
itr.err = err
return
}
itr.bi = block.NewIterator()
itr.bi.SetBlock(block)
itr.bi.SeekToFirst()
itr.err = itr.bi.Error()
}
Expand All @@ -328,7 +328,7 @@ func (itr *Iterator) seekToLast() {
itr.err = err
return
}
itr.bi = block.NewIterator()
itr.bi.SetBlock(block)
itr.bi.SeekToLast()
itr.err = itr.bi.Error()
}
Expand All @@ -340,7 +340,7 @@ func (itr *Iterator) seekHelper(blockIdx int, key []byte) {
itr.err = err
return
}
itr.bi = block.NewIterator()
itr.bi.SetBlock(block)
itr.bi.Seek(key, origin)
itr.err = itr.bi.Error()
}
Expand Down Expand Up @@ -407,13 +407,13 @@ func (itr *Iterator) next() {
return
}

if itr.bi == nil {
if itr.bi.data == nil {
block, err := itr.t.block(itr.bpos)
if err != nil {
itr.err = err
return
}
itr.bi = block.NewIterator()
itr.bi.SetBlock(block)
itr.bi.SeekToFirst()
itr.err = itr.bi.Error()
return
Expand All @@ -422,7 +422,7 @@ func (itr *Iterator) next() {
itr.bi.Next()
if !itr.bi.Valid() {
itr.bpos++
itr.bi = nil
itr.bi.data = nil
itr.next()
return
}
Expand All @@ -435,13 +435,13 @@ func (itr *Iterator) prev() {
return
}

if itr.bi == nil {
if itr.bi.data == nil {
block, err := itr.t.block(itr.bpos)
if err != nil {
itr.err = err
return
}
itr.bi = block.NewIterator()
itr.bi.SetBlock(block)
itr.bi.SeekToLast()
itr.err = itr.bi.Error()
return
Expand All @@ -450,7 +450,7 @@ func (itr *Iterator) prev() {
itr.bi.Prev()
if !itr.bi.Valid() {
itr.bpos--
itr.bi = nil
itr.bi.data = nil
itr.prev()
return
}
Expand Down Expand Up @@ -506,13 +506,9 @@ type ConcatIterator struct {

// NewConcatIterator creates a new concatenated iterator
func NewConcatIterator(tbls []*Table, reversed bool) *ConcatIterator {
iters := make([]*Iterator, len(tbls))
for i := 0; i < len(tbls); i++ {
iters[i] = tbls[i].NewIterator(reversed)
}
return &ConcatIterator{
reversed: reversed,
iters: iters,
iters: make([]*Iterator, len(tbls)),
tables: tbls,
idx: -1, // Not really necessary because s.it.Valid()=false, but good to have.
}
Expand All @@ -523,6 +519,9 @@ func (s *ConcatIterator) setIdx(idx int) {
if idx < 0 || idx >= len(s.iters) {
s.cur = nil
} else {
if s.iters[s.idx] == nil {
s.iters[s.idx] = s.tables[idx].NewIterator(s.reversed)
}
s.cur = s.iters[s.idx]
}
}
Expand Down Expand Up @@ -605,6 +604,9 @@ func (s *ConcatIterator) Next() {
// Close implements y.Interface.
func (s *ConcatIterator) Close() error {
for _, it := range s.iters {
if it == nil {
continue
}
if err := it.Close(); err != nil {
return errors.Wrap(err, "ConcatIterator")
}
Expand Down
6 changes: 0 additions & 6 deletions table/table.go
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Original file line number Diff line number Diff line change
Expand Up @@ -97,12 +97,6 @@ type block struct {
data []byte
}

func (b block) NewIterator() *blockIterator {
bi := &blockIterator{data: b.data}
bi.loadEntryIndex()
return bi
}

// OpenTable assumes file has only one table and opens it. Takes ownership of fd upon function
// entry. Returns a table with one reference count on it (decrementing which may delete the file!
// -- consider t.Close() instead). The fd has to writeable because we call Truncate on it before
Expand Down