func (self *LevelDbDatastore) fetchSinglePoint(database, series string, fields []*Field,
query *parser.SelectQuery) (*protocol.Series, error) {
fieldCount := len(fields)
fieldNames := make([]string, 0, fieldCount)
point := &protocol.Point{Values: make([]*protocol.FieldValue, 0, fieldCount)}
timestampBuffer := bytes.NewBuffer(make([]byte, 0, 8))
sequenceNumberBuffer := bytes.NewBuffer(make([]byte, 0, 8))
timestamp := common.TimeToMicroseconds(query.GetStartTime())
sequenceNumber, err := query.GetSinglePointQuerySequenceNumber()
if err != nil {
return nil, err
}
binary.Write(timestampBuffer, binary.BigEndian, self.convertTimestampToUint(×tamp))
binary.Write(sequenceNumberBuffer, binary.BigEndian, sequenceNumber)
sequenceNumber_uint64 := uint64(sequenceNumber)
point.SequenceNumber = &sequenceNumber_uint64
point.SetTimestampInMicroseconds(timestamp)
for _, field := range fields {
pointKey := append(append(field.Id, timestampBuffer.Bytes()...), sequenceNumberBuffer.Bytes()...)
if data, err := self.db.Get(self.readOptions, pointKey); err != nil {
return nil, err
} else {
fieldValue := &protocol.FieldValue{}
err := proto.Unmarshal(data, fieldValue)
if err != nil {
return nil, err
}
if data != nil {
fieldNames = append(fieldNames, field.Name)
point.Values = append(point.Values, fieldValue)
}
}
}
result := &protocol.Series{Name: &series, Fields: fieldNames, Points: []*protocol.Point{point}}
return result, nil
}
func (self *LevelDbDatastore) executeQueryForSeries(database, series string, columns []string,
query *parser.SelectQuery, yield func(*protocol.Series) error,
ringFilter func(database, series *string, time *int64) bool) error {
startTimeBytes, endTimeBytes := self.byteArraysForStartAndEndTimes(common.TimeToMicroseconds(query.GetStartTime()), common.TimeToMicroseconds(query.GetEndTime()))
emptyResult := &protocol.Series{Name: &series, Points: nil}
fields, err := self.getFieldsForSeries(database, series, columns)
if err != nil {
// because a db is distributed across the cluster, it's possible we don't have the series indexed here. ignore
switch err := err.(type) {
case FieldLookupError:
return yield(emptyResult)
default:
return err
}
}
fieldCount := len(fields)
rawColumnValues := make([]*rawColumnValue, fieldCount, fieldCount)
if query.IsSinglePointQuery() {
result, err := self.fetchSinglePoint(database, series, fields, query)
if err != nil {
return err
}
if err := yield(result); err != nil {
return err
}
return nil
}
fieldNames, iterators := self.getIterators(fields, startTimeBytes, endTimeBytes, query.Ascending)
result := &protocol.Series{Name: &series, Fields: fieldNames, Points: make([]*protocol.Point, 0)}
limit := query.Limit
shouldLimit := true
if limit == 0 {
limit = -1
shouldLimit = false
}
resultByteCount := 0
// TODO: clean up, this is super gnarly
// optimize for the case where we're pulling back only a single column or aggregate
for {
isValid := false
point := &protocol.Point{Values: make([]*protocol.FieldValue, fieldCount, fieldCount)}
for i, it := range iterators {
if rawColumnValues[i] != nil || !it.Valid() {
continue
}
key := it.Key()
if len(key) < 16 {
continue
}
if !isPointInRange(fields[i].Id, startTimeBytes, endTimeBytes, key) {
continue
}
value := it.Value()
sequenceNumber := key[16:]
rawTime := key[8:16]
rawValue := &rawColumnValue{time: rawTime, sequence: sequenceNumber, value: value}
rawColumnValues[i] = rawValue
}
var pointTimeRaw []byte
var pointSequenceRaw []byte
// choose the highest (or lowest in case of ascending queries) timestamp
// and sequence number. that will become the timestamp and sequence of
// the next point.
for _, value := range rawColumnValues {
if value == nil {
continue
}
pointTimeRaw, pointSequenceRaw = value.updatePointTimeAndSequence(pointTimeRaw,
pointSequenceRaw, query.Ascending)
}
for i, iterator := range iterators {
// if the value is nil or doesn't match the point's timestamp and sequence number
// then skip it
if rawColumnValues[i] == nil ||
!bytes.Equal(rawColumnValues[i].time, pointTimeRaw) ||
!bytes.Equal(rawColumnValues[i].sequence, pointSequenceRaw) {
point.Values[i] = &protocol.FieldValue{IsNull: &TRUE}
continue
}
// if we emitted at lease one column, then we should keep
// trying to get more points
isValid = true
// advance the iterator to read a new value in the next iteration
if query.Ascending {
iterator.Next()
} else {
iterator.Prev()
}
fv := &protocol.FieldValue{}
resultByteCount += len(rawColumnValues[i].value)
err := proto.Unmarshal(rawColumnValues[i].value, fv)
if err != nil {
return err
}
point.Values[i] = fv
rawColumnValues[i] = nil
}
var sequence uint64
// set the point sequence number and timestamp
binary.Read(bytes.NewBuffer(pointSequenceRaw), binary.BigEndian, &sequence)
var t uint64
binary.Read(bytes.NewBuffer(pointTimeRaw), binary.BigEndian, &t)
time := self.convertUintTimestampToInt64(&t)
point.SetTimestampInMicroseconds(time)
point.SequenceNumber = &sequence
// stop the loop if we ran out of points
if !isValid {
break
}
limit -= 1
if ringFilter != nil && ringFilter(&database, &series, point.Timestamp) {
continue
}
result.Points = append(result.Points, point)
// add byte count for the timestamp and the sequence
resultByteCount += 16
// check if we should send the batch along
if resultByteCount > MAX_SERIES_SIZE || (shouldLimit && limit == 0) {
dropped, err := self.sendBatch(query, result, yield)
if err != nil {
return err
}
limit += dropped
resultByteCount = 0
result = &protocol.Series{Name: &series, Fields: fieldNames, Points: make([]*protocol.Point, 0)}
}
if shouldLimit && limit < 1 {
break
}
}
if _, err := self.sendBatch(query, result, yield); err != nil {
return err
}
_, err = self.sendBatch(query, emptyResult, yield)
return err
}