// Creates an iterator.
func (c *compaction) newIterator() iterator.Iterator {
// Creates iterator slice.
icap := len(c.tables)
if c.level == 0 {
// Special case for level-0
icap = len(c.tables[0]) + 1
}
its := make([]iterator.Iterator, 0, icap)
// Options.
ro := &opt.ReadOptions{
DontFillCache: true,
}
strict := c.s.o.GetStrict(opt.StrictIterator)
for i, tables := range c.tables {
if len(tables) == 0 {
continue
}
// Level-0 is not sorted and may overlaps each other.
if c.level+i == 0 {
for _, t := range tables {
its = append(its, c.s.tops.newIterator(t, nil, ro))
}
} else {
it := iterator.NewIndexedIterator(tables.newIndexIterator(c.s.tops, c.s.icmp, nil, ro), strict, true)
its = append(its, it)
}
}
return iterator.NewMergedIterator(its, c.s.icmp, true)
}
// NewIterator creates an iterator from the table.
//
// Slice allows slicing the iterator to only contains keys in the given
// range. A nil Range.Start is treated as a key before all keys in the
// table. And a nil Range.Limit is treated as a key after all keys in
// the table.
//
// The returned iterator is not goroutine-safe and should be released
// when not used.
//
// Also read Iterator documentation of the leveldb/iterator package.
func (r *Reader) NewIterator(slice *util.Range, ro *opt.ReadOptions) iterator.Iterator {
if r.err != nil {
return iterator.NewEmptyIterator(r.err)
}
fillCache := !ro.GetDontFillCache()
b, rel, err := r.readBlockCached(r.indexBH, true, fillCache)
if err != nil {
return iterator.NewEmptyIterator(err)
}
index := &indexIter{
blockIter: b.newIterator(slice, true, rel),
slice: slice,
checksum: ro.GetStrict(opt.StrictBlockChecksum),
fillCache: !ro.GetDontFillCache(),
}
return iterator.NewIndexedIterator(index, r.strictIter || ro.GetStrict(opt.StrictIterator), false)
}
func (v *version) getIterators(slice *util.Range, ro *opt.ReadOptions) (its []iterator.Iterator) {
// Merge all level zero files together since they may overlap
for _, t := range v.tables[0] {
it := v.s.tops.newIterator(t, slice, ro)
its = append(its, it)
}
strict := v.s.o.GetStrict(opt.StrictIterator) || ro.GetStrict(opt.StrictIterator)
for _, tables := range v.tables[1:] {
if len(tables) == 0 {
continue
}
it := iterator.NewIndexedIterator(tables.newIndexIterator(v.s.tops, v.s.icmp, slice, ro), strict, true)
its = append(its, it)
}
return
}