forked from canonical/dqlite
/
range.go
59 lines (49 loc) · 1.37 KB
/
range.go
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package store
import (
"github.com/hashicorp/raft"
"github.com/pkg/errors"
)
// DefaultRange returns a Range spanning all available indexes.
func DefaultRange(logs raft.LogStore) (*Range, error) {
first, err := logs.FirstIndex()
if err != nil {
return nil, errors.Wrap(err, "failed to get first index")
}
last, err := logs.LastIndex()
if err != nil {
return nil, errors.Wrap(err, "failed to get last index")
}
return &Range{First: first, Last: last}, nil
}
// HeadRange returns a range that includes only the first n entries.
func HeadRange(logs raft.LogStore, n int) (*Range, error) {
first, err := logs.FirstIndex()
if err != nil {
return nil, errors.Wrap(err, "failed to get first index")
}
last, err := logs.LastIndex()
if err != nil {
return nil, errors.Wrap(err, "failed to get last index")
}
if first+uint64(n) < last {
last = first + uint64(n)
}
return &Range{First: first, Last: last}, nil
}
// TailRange returns a range that includes only the last n entries.
func TailRange(logs raft.LogStore, n int) (*Range, error) {
last, err := logs.LastIndex()
if err != nil {
return nil, errors.Wrap(err, "failed to get last index")
}
first := uint64(0)
if last > uint64(n) {
first = last - uint64(n)
}
return &Range{First: first, Last: last}, nil
}
// Range contains the first and last index of a dump.
type Range struct {
First uint64
Last uint64
}