// SortEntries sorts entries from c in memory and write to w in
// slightly over the maxSize bytes. Returns number of entries written
// and error.
func SortEntries(c sstable.Cursor, maxSize uint64, w *sstable.Writer) (n int, err error) {
es := Entries{}
size := uint64(0)
for !c.Done() && size < maxSize {
e := c.Entry()
c.Next()
size += e.Size()
es = append(es, HeapEntry{*e, nil})
}
heap.Init(&es)
for es.Len() > 0 {
e := heap.Pop(&es)
err = w.Write(e.(HeapEntry).Entry)
if err != nil {
return
}
n += 1
}
err = w.Close()
return
}
// Merge merges from multiple cursors and write SSTable to w.
func Merge(cursors []sstable.Cursor, w *sstable.Writer) error {
es := Entries{}
for i, c := range cursors {
if c.Done() {
continue
}
e := c.Entry()
c.Next()
es = append(es, HeapEntry{*e, i})
}
heap.Init(&es)
for es.Len() > 0 {
e := heap.Pop(&es).(HeapEntry)
i := e.data.(int)
if !cursors[i].Done() {
heap.Push(&es, HeapEntry{*cursors[i].Entry(), i})
cursors[i].Next()
}
if err := w.Write(e.Entry); err != nil {
return err
}
}
return nil
}
