// Entries implements the raft.Storage interface. Note that maxBytes is advisory
// and this method will always return at least one entry even if it exceeds
// maxBytes. Passing maxBytes equal to zero disables size checking.
// TODO(bdarnell): consider caching for recent entries, if rocksdb's builtin caching
// is insufficient.
func (r *Range) Entries(lo, hi, maxBytes uint64) ([]raftpb.Entry, error) {
// Scan over the log to find the requested entries in the range [lo, hi),
// stopping once we have enough.
var ents []raftpb.Entry
size := uint64(0)
var ent raftpb.Entry
scanFunc := func(kv proto.KeyValue) (bool, error) {
err := gogoproto.Unmarshal(kv.Value.GetBytes(), &ent)
if err != nil {
return false, err
}
size += uint64(ent.Size())
ents = append(ents, ent)
return maxBytes > 0 && size > maxBytes, nil
}
_, err := engine.MVCCIterate(r.rm.Engine(),
keys.RaftLogKey(r.Desc().RaftID, lo),
keys.RaftLogKey(r.Desc().RaftID, hi),
proto.ZeroTimestamp, true /* consistent */, nil /* txn */, scanFunc)
if err != nil {
return nil, err
}
// If neither the number of entries nor the size limitations had an
// effect, we weren't able to supply everything the client wanted.
if len(ents) != int(hi-lo) && (maxBytes == 0 || size < maxBytes) {
return nil, raft.ErrUnavailable
}
return ents, nil
}
// getEntries returns entries between [lo, hi) for specified range.
// If any entries are returned for the specified indexes, they will
// start with index lo and proceed sequentially without gaps until
// 1) all entries exclusive of hi are fetched, 2) > maxBytes of
// entries data is fetched, or 3) a cache miss occurs.
func (rec *raftEntryCache) getEntries(rangeID roachpb.RangeID, lo, hi, maxBytes uint64) (
[]raftpb.Entry, uint64 /* size in bytes */, uint64 /* next log index */) {
rec.Lock()
defer rec.Unlock()
var ents []raftpb.Entry
var ent raftpb.Entry
var bytes uint64
nextIndex := lo
fromKey := entryCacheKey{RangeID: rangeID, Index: lo}
toKey := entryCacheKey{RangeID: rangeID, Index: hi}
rec.cache.DoRange(func(k, v interface{}) bool {
ecKey := k.(entryCacheKey)
if ecKey.Index != nextIndex {
return true
}
ent = v.(raftpb.Entry)
ents = append(ents, ent)
bytes += uint64(ent.Size())
nextIndex++
if maxBytes > 0 && bytes > maxBytes {
return true
}
return false
}, fromKey, toKey)
return ents, bytes, nextIndex
}
func writeEntryTo(w io.Writer, ent *raftpb.Entry) error {
size := ent.Size()
if err := binary.Write(w, binary.BigEndian, uint64(size)); err != nil {
return err
}
b, err := ent.Marshal()
if err != nil {
return err
}
_, err = w.Write(b)
return err
}
func (ew *entryWriter) writeEntry(ent *raftpb.Entry) error {
size := ent.Size()
if err := binary.Write(ew.w, binary.BigEndian, uint64(size)); err != nil {
return err
}
b, err := ent.Marshal()
if err != nil {
return err
}
_, err = ew.w.Write(b)
return err
}
func TestSlice(t *testing.T) {
var i uint64
offset := uint64(100)
num := uint64(100)
last := offset + num
half := offset + num/2
halfe := pb.Entry{Index: half, Term: half}
storage := NewMemoryStorage()
storage.ApplySnapshot(pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: offset}})
for i = 1; i < num/2; i++ {
storage.Append([]pb.Entry{{Index: offset + i, Term: offset + i}})
}
l := newLog(storage)
for i = num / 2; i < num; i++ {
l.append(pb.Entry{Index: offset + i, Term: offset + i})
}
tests := []struct {
from uint64
to uint64
limit uint64
w []pb.Entry
wpanic bool
}{
// test no limit
{offset - 1, offset + 1, noLimit, nil, true},
{offset, offset + 1, noLimit, nil, true},
{half - 1, half + 1, noLimit, []pb.Entry{{Index: half - 1, Term: half - 1}, {Index: half, Term: half}}, false},
{half, half + 1, noLimit, []pb.Entry{{Index: half, Term: half}}, false},
{last - 1, last, noLimit, []pb.Entry{{Index: last - 1, Term: last - 1}}, false},
{last, last + 1, noLimit, nil, true},
// test limit
{half - 1, half + 1, 0, []pb.Entry{{Index: half - 1, Term: half - 1}}, false},
{half - 1, half + 1, uint64(halfe.Size() + 1), []pb.Entry{{Index: half - 1, Term: half - 1}}, false},
{half - 1, half + 1, uint64(halfe.Size() * 2), []pb.Entry{{Index: half - 1, Term: half - 1}, {Index: half, Term: half}}, false},
{half - 1, half + 2, uint64(halfe.Size() * 3), []pb.Entry{{Index: half - 1, Term: half - 1}, {Index: half, Term: half}, {Index: half + 1, Term: half + 1}}, false},
{half, half + 2, uint64(halfe.Size()), []pb.Entry{{Index: half, Term: half}}, false},
{half, half + 2, uint64(halfe.Size() * 2), []pb.Entry{{Index: half, Term: half}, {Index: half + 1, Term: half + 1}}, false},
}
for j, tt := range tests {
func() {
defer func() {
if r := recover(); r != nil {
if !tt.wpanic {
t.Errorf("%d: panic = %v, want %v: %v", j, true, false, r)
}
}
}()
g := l.slice(tt.from, tt.to, tt.limit)
if !reflect.DeepEqual(g, tt.w) {
t.Errorf("#%d: from %d to %d = %v, want %v", j, tt.from, tt.to, g, tt.w)
}
}()
}
}
// Entries implements the raft.Storage interface
func (s *raftStorage) Entries(lo, hi, maxSize uint64) (entries []raftpb.Entry, err error) {
it := s.db.NewIterator(&kv.Range{Start: s.getEntryKey(lo), Limit: s.getEntryKey(hi)})
defer it.Release()
entries = make([]raftpb.Entry, 0)
sizeSoFar := uint64(0)
for ok := it.First(); ok; ok = it.Next() {
var entry raftpb.Entry
err = entry.Unmarshal(it.Value())
if err != nil {
return
}
sizeSoFar += uint64(entry.Size())
// Only stop if we already have at least one entry
if sizeSoFar > maxSize && len(entries) > 0 {
break
}
entries = append(entries, entry)
if sizeSoFar >= maxSize {
break
}
}
err = it.Error()
return
}
func (r *Replica) entries(e engine.Engine, lo, hi, maxBytes uint64) ([]raftpb.Entry, error) {
if lo > hi {
return nil, util.Errorf("lo:%d is greater than hi:%d", lo, hi)
}
// Scan over the log to find the requested entries in the range [lo, hi),
// stopping once we have enough.
var ents []raftpb.Entry
size := uint64(0)
var ent raftpb.Entry
expectedIndex := lo
exceededMaxBytes := false
scanFunc := func(kv roachpb.KeyValue) (bool, error) {
if err := kv.Value.GetProto(&ent); err != nil {
return false, err
}
// Exit early if we have any gaps or it has been compacted.
if ent.Index != expectedIndex {
return true, nil
}
expectedIndex++
size += uint64(ent.Size())
ents = append(ents, ent)
exceededMaxBytes = maxBytes > 0 && size > maxBytes
return exceededMaxBytes, nil
}
rangeID := r.RangeID
_, err := engine.MVCCIterate(e,
keys.RaftLogKey(rangeID, lo),
keys.RaftLogKey(rangeID, hi),
roachpb.ZeroTimestamp,
true /* consistent */, nil /* txn */, false /* !reverse */, scanFunc)
if err != nil {
return nil, err
}
// Did the correct number of results come back? If so, we're all good.
if len(ents) == int(hi)-int(lo) {
return ents, nil
}
// Did we hit the size limit? If so, return what we have.
if exceededMaxBytes {
return ents, nil
}
// Did we get any results at all? Because something went wrong.
if len(ents) > 0 {
// Was the lo already truncated?
if ents[0].Index > lo {
return nil, raft.ErrCompacted
}
// Was the missing index after the last index?
lastIndex, err := r.LastIndex()
if err != nil {
return nil, err
}
if lastIndex <= expectedIndex {
return nil, raft.ErrUnavailable
}
// We have a gap in the record, if so, return a nasty error.
return nil, util.Errorf("there is a gap in the index record between lo:%d and hi:%d at index:%d", lo, hi, expectedIndex)
}
// No results, was it due to unavailability or truncation?
ts, err := r.raftTruncatedStateLocked()
if err != nil {
return nil, err
}
if ts.Index >= lo {
// The requested lo index has already been truncated.
return nil, raft.ErrCompacted
}
// The requested lo index does not yet exist.
return nil, raft.ErrUnavailable
}
func entries(
ctx context.Context,
e engine.Reader,
rangeID roachpb.RangeID,
eCache *raftEntryCache,
lo, hi, maxBytes uint64,
) ([]raftpb.Entry, error) {
if lo > hi {
return nil, errors.Errorf("lo:%d is greater than hi:%d", lo, hi)
}
// Scan over the log to find the requested entries in the range [lo, hi),
// stopping once we have enough.
ents := make([]raftpb.Entry, 0, hi-lo)
size := uint64(0)
hitEnts, hitSize, hitIndex := eCache.getEntries(rangeID, lo, hi, maxBytes)
// Return results if the correct number of results came back or if
// we ran into the max bytes limit.
if uint64(len(hitEnts)) == hi-lo || (maxBytes > 0 && hitSize > maxBytes) {
return hitEnts, nil
}
ents = append(ents, hitEnts...)
size += hitSize
expectedIndex := hitIndex
var ent raftpb.Entry
exceededMaxBytes := false
scanFunc := func(kv roachpb.KeyValue) (bool, error) {
if err := kv.Value.GetProto(&ent); err != nil {
return false, err
}
// Exit early if we have any gaps or it has been compacted.
if ent.Index != expectedIndex {
return true, nil
}
expectedIndex++
size += uint64(ent.Size())
ents = append(ents, ent)
exceededMaxBytes = maxBytes > 0 && size > maxBytes
return exceededMaxBytes, nil
}
if err := iterateEntries(ctx, e, rangeID, expectedIndex, hi, scanFunc); err != nil {
return nil, err
}
// Cache the fetched entries.
eCache.addEntries(rangeID, ents)
// Did the correct number of results come back? If so, we're all good.
if uint64(len(ents)) == hi-lo {
return ents, nil
}
// Did we hit the size limit? If so, return what we have.
if exceededMaxBytes {
return ents, nil
}
// Did we get any results at all? Because something went wrong.
if len(ents) > 0 {
// Was the lo already truncated?
if ents[0].Index > lo {
return nil, raft.ErrCompacted
}
// Was the missing index after the last index?
lastIndex, err := loadLastIndex(ctx, e, rangeID)
if err != nil {
return nil, err
}
if lastIndex <= expectedIndex {
return nil, raft.ErrUnavailable
}
// We have a gap in the record, if so, return a nasty error.
return nil, errors.Errorf("there is a gap in the index record between lo:%d and hi:%d at index:%d", lo, hi, expectedIndex)
}
// No results, was it due to unavailability or truncation?
ts, err := loadTruncatedState(ctx, e, rangeID)
if err != nil {
return nil, err
}
if ts.Index >= lo {
// The requested lo index has already been truncated.
return nil, raft.ErrCompacted
}
// The requested lo index does not yet exist.
return nil, raft.ErrUnavailable
}
