func (v *version) getIterators(slice *util.Range, ro *opt.ReadOptions) (its []iterator.Iterator) {
strict := opt.GetStrict(v.s.o.Options, ro, opt.StrictReader)
for level, tables := range v.levels {
if level == 0 {
// Merge all level zero files together since they may overlap.
for _, t := range tables {
its = append(its, v.s.tops.newIterator(t, slice, ro))
}
} else if len(tables) != 0 {
its = append(its, iterator.NewIndexedIterator(tables.newIndexIterator(v.s.tops, v.s.icmp, slice, ro), strict))
}
}
return
}
// 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 {
r.mu.RLock()
defer r.mu.RUnlock()
if r.err != nil {
return iterator.NewEmptyIterator(r.err)
}
fillCache := !ro.GetDontFillCache()
indexBlock, rel, err := r.getIndexBlock(fillCache)
if err != nil {
return iterator.NewEmptyIterator(err)
}
index := &indexIter{
blockIter: r.newBlockIter(indexBlock, rel, slice, true),
tr: r,
slice: slice,
fillCache: !ro.GetDontFillCache(),
}
return iterator.NewIndexedIterator(index, opt.GetStrict(r.o, ro, opt.StrictReader))
}
// Creates an iterator.
func (c *compaction) newIterator() iterator.Iterator {
// Creates iterator slice.
icap := len(c.levels)
if c.sourceLevel == 0 {
// Special case for level-0.
icap = len(c.levels[0]) + 1
}
its := make([]iterator.Iterator, 0, icap)
// Options.
ro := &opt.ReadOptions{
DontFillCache: true,
Strict: opt.StrictOverride,
}
strict := c.s.o.GetStrict(opt.StrictCompaction)
if strict {
ro.Strict |= opt.StrictReader
}
for i, tables := range c.levels {
if len(tables) == 0 {
continue
}
// Level-0 is not sorted and may overlaps each other.
if c.sourceLevel+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)
its = append(its, it)
}
}
return iterator.NewMergedIterator(its, c.s.icmp, strict)
}