Example #1
0
func newDiskFrontier(i leveldb.Iterator) (d *diskFrontier, err error) {

	if !i.SeekToLast() || i.Key() == nil {
		return
	}

	lastKey, err := extractSampleKey(i)
	if err != nil {
		panic(err)
	}

	if !i.SeekToFirst() || i.Key() == nil {
		return
	}
	firstKey, err := extractSampleKey(i)
	if i.Key() == nil {
		return
	}
	if err != nil {
		panic(err)
	}

	d = &diskFrontier{}

	d.firstFingerprint = model.NewFingerprintFromRowKey(*firstKey.Fingerprint.Signature)
	d.firstSupertime = indexable.DecodeTime(firstKey.Timestamp)
	d.lastFingerprint = model.NewFingerprintFromRowKey(*lastKey.Fingerprint.Signature)
	d.lastSupertime = indexable.DecodeTime(lastKey.Timestamp)

	return
}
Example #2
0
// Load deserializes this SampleKey from a DTO.
func (s *SampleKey) Load(d *dto.SampleKey) {
	f := &clientmodel.Fingerprint{}
	loadFingerprint(f, d.GetFingerprint())
	s.Fingerprint = f
	s.FirstTimestamp = indexable.DecodeTime(d.Timestamp)
	s.LastTimestamp = clientmodel.TimestampFromUnix(d.GetLastTimestamp())
	s.SampleCount = d.GetSampleCount()
}
Example #3
0
func (l *LevelDBMetricPersistence) GetValueAtTime(fp model.Fingerprint, t time.Time, s StalenessPolicy) (sample *model.Sample, err error) {
	begin := time.Now()

	defer func() {
		duration := time.Since(begin)

		recordOutcome(duration, err, map[string]string{operation: getValueAtTime, result: success}, map[string]string{operation: getValueAtTime, result: failure})
	}()

	// TODO: memoize/cache this or change the return type to metric.SamplePair.
	m, err := l.GetMetricForFingerprint(fp)
	if err != nil {
		return
	}

	// Candidate for Refactoring
	k := &dto.SampleKey{
		Fingerprint: fp.ToDTO(),
		Timestamp:   indexable.EncodeTime(t),
	}

	e, err := coding.NewProtocolBuffer(k).Encode()
	if err != nil {
		return
	}

	iterator := l.metricSamples.NewIterator(true)
	defer iterator.Close()

	if !iterator.Seek(e) {
		/*
		 * Two cases for this:
		 * 1.) Corruption in LevelDB.
		 * 2.) Key seek after AND outside known range.
		 *
		 * Once a LevelDB iterator goes invalid, it cannot be recovered; thusly,
		 * we need to create a new in order to check if the last value in the
		 * database is sufficient for our purposes.  This is, in all reality, a
		 * corner case but one that could bring down the system.
		 */
		iterator = l.metricSamples.NewIterator(true)
		defer iterator.Close()

		if !iterator.SeekToLast() {
			/*
			 * For whatever reason, the LevelDB cannot be recovered.
			 */
			return
		}
	}

	var (
		firstKey   *dto.SampleKey
		firstValue *dto.SampleValueSeries
	)

	firstKey, err = extractSampleKey(iterator)
	if err != nil {
		return
	}

	peekAhead := false

	if !fingerprintsEqual(firstKey.Fingerprint, k.Fingerprint) {
		/*
		 * This allows us to grab values for metrics if our request time is after
		 * the last recorded time subject to the staleness policy due to the nuances
		 * of LevelDB storage:
		 *
		 * # Assumptions:
		 * - K0 < K1 in terms of sorting.
		 * - T0 < T1 in terms of sorting.
		 *
		 * # Data
		 *
		 * K0-T0
		 * K0-T1
		 * K0-T2
		 * K1-T0
		 * K1-T1
		 *
		 * # Scenario
		 * K0-T3, which does not exist, is requested.  LevelDB will thusly seek to
		 * K1-T1, when K0-T2 exists as a perfectly good candidate to check subject
		 * to the provided staleness policy and such.
		 */
		peekAhead = true
	}

	firstTime := indexable.DecodeTime(firstKey.Timestamp)
	if t.Before(firstTime) || peekAhead {
		if !iterator.Previous() {
			/*
			 * Two cases for this:
			 * 1.) Corruption in LevelDB.
			 * 2.) Key seek before AND outside known range.
			 *
			 * This is an explicit validation to ensure that if no previous values for
			 * the series are found, the query aborts.
			 */
			return
		}

		var (
			alternativeKey   *dto.SampleKey
			alternativeValue *dto.SampleValueSeries
		)

		alternativeKey, err = extractSampleKey(iterator)
		if err != nil {
			return
		}

		if !fingerprintsEqual(alternativeKey.Fingerprint, k.Fingerprint) {
			return
		}

		/*
		 * At this point, we found a previous value in the same series in the
		 * database.  LevelDB originally seeked to the subsequent element given
		 * the key, but we need to consider this adjacency instead.
		 */
		alternativeTime := indexable.DecodeTime(alternativeKey.Timestamp)

		firstKey = alternativeKey
		firstValue = alternativeValue
		firstTime = alternativeTime
	}

	firstDelta := firstTime.Sub(t)
	if firstDelta < 0 {
		firstDelta *= -1
	}
	if firstDelta > s.DeltaAllowance {
		return
	}

	firstValue, err = extractSampleValues(iterator)
	if err != nil {
		return
	}

	sample = model.SampleFromDTO(m, &t, firstValue)

	if firstDelta == time.Duration(0) {
		return
	}

	if !iterator.Next() {
		/*
		 * Two cases for this:
		 * 1.) Corruption in LevelDB.
		 * 2.) Key seek after AND outside known range.
		 *
		 * This means that there are no more values left in the storage; and if this
		 * point is reached, we know that the one that has been found is within the
		 * allowed staleness limits.
		 */
		return
	}

	var secondKey *dto.SampleKey

	secondKey, err = extractSampleKey(iterator)
	if err != nil {
		return
	}

	if !fingerprintsEqual(secondKey.Fingerprint, k.Fingerprint) {
		return
	} else {
		/*
		 * At this point, current entry in the database has the same key as the
		 * previous.  For this reason, the validation logic will expect that the
		 * distance between the two points shall not exceed the staleness policy
		 * allowed limit to reduce interpolation errors.
		 *
		 * For this reason, the sample is reset in case of other subsequent
		 * validation behaviors.
		 */
		sample = nil
	}

	secondTime := indexable.DecodeTime(secondKey.Timestamp)

	totalDelta := secondTime.Sub(firstTime)
	if totalDelta > s.DeltaAllowance {
		return
	}

	var secondValue *dto.SampleValueSeries

	secondValue, err = extractSampleValues(iterator)
	if err != nil {
		return
	}

	fValue := *firstValue.Value[0].Value
	sValue := *secondValue.Value[0].Value

	interpolated := interpolate(firstTime, secondTime, fValue, sValue, t)

	sampleValue := &dto.SampleValueSeries{}
	sampleValue.Value = append(sampleValue.Value, &dto.SampleValueSeries_Value{Value: &interpolated})

	sample = model.SampleFromDTO(m, &t, sampleValue)

	return
}
Example #4
0
func keyIsAtMostOld(t time.Time) sampleKeyPredicate {
	return func(k *dto.SampleKey) bool {
		return !indexable.DecodeTime(k.Timestamp).After(t)
	}
}
Example #5
0
func keyIsOlderThan(t time.Time) sampleKeyPredicate {
	return func(k *dto.SampleKey) bool {
		return indexable.DecodeTime(k.Timestamp).After(t)
	}
}
Example #6
0
func (l *LevelDBMetricPersistence) GetRangeValues(fp model.Fingerprint, i model.Interval) (v *model.SampleSet, err error) {
	begin := time.Now()

	defer func() {
		duration := time.Since(begin)

		recordOutcome(duration, err, map[string]string{operation: getRangeValues, result: success}, map[string]string{operation: getRangeValues, result: failure})
	}()

	k := &dto.SampleKey{
		Fingerprint: fp.ToDTO(),
		Timestamp:   indexable.EncodeTime(i.OldestInclusive),
	}

	e, err := coding.NewProtocolBuffer(k).Encode()
	if err != nil {
		return
	}

	iterator := l.metricSamples.NewIterator(true)
	defer iterator.Close()

	predicate := keyIsOlderThan(i.NewestInclusive)

	for valid := iterator.Seek(e); valid; valid = iterator.Next() {
		retrievedKey := &dto.SampleKey{}

		retrievedKey, err = extractSampleKey(iterator)
		if err != nil {
			return
		}

		if predicate(retrievedKey) {
			break
		}

		if !fingerprintsEqual(retrievedKey.Fingerprint, k.Fingerprint) {
			break
		}

		retrievedValue, err := extractSampleValues(iterator)
		if err != nil {
			return nil, err
		}

		if v == nil {
			// TODO: memoize/cache this or change the return type to metric.SamplePair.
			m, err := l.GetMetricForFingerprint(fp)
			if err != nil {
				return v, err
			}
			v = &model.SampleSet{
				Metric: *m,
			}
		}

		v.Values = append(v.Values, model.SamplePair{
			Value:     model.SampleValue(*retrievedValue.Value[0].Value),
			Timestamp: indexable.DecodeTime(retrievedKey.Timestamp),
		})
	}

	// XXX: We should not explicitly sort here but rather rely on the datastore.
	//      This adds appreciable overhead.
	if v != nil {
		sort.Sort(v.Values)
	}

	return
}
Example #7
0
// newSeriesFrontier furnishes a populated diskFrontier for a given
// fingerprint.  A nil diskFrontier will be returned if the series cannot
// be found in the store.
func newSeriesFrontier(f model.Fingerprint, d diskFrontier, i leveldb.Iterator) (s *seriesFrontier, err error) {
	var (
		lowerSeek = firstSupertime
		upperSeek = lastSupertime
	)

	// If the diskFrontier for this iterator says that the candidate fingerprint
	// is outside of its seeking domain, there is no way that a seriesFrontier
	// could be materialized.  Simply bail.
	if !d.ContainsFingerprint(f) {
		return
	}

	// If we are either the first or the last key in the database, we need to use
	// pessimistic boundary frontiers.
	if f.Equal(d.firstFingerprint) {
		lowerSeek = indexable.EncodeTime(d.firstSupertime)
	}
	if f.Equal(d.lastFingerprint) {
		upperSeek = indexable.EncodeTime(d.lastSupertime)
	}

	key := &dto.SampleKey{
		Fingerprint: f.ToDTO(),
		Timestamp:   upperSeek,
	}

	raw, err := coding.NewProtocolBuffer(key).Encode()
	if err != nil {
		panic(err)
	}
	i.Seek(raw)

	if i.Key() == nil {
		return
	}

	retrievedKey, err := extractSampleKey(i)
	if err != nil {
		panic(err)
	}

	retrievedFingerprint := model.NewFingerprintFromRowKey(*retrievedKey.Fingerprint.Signature)

	// The returned fingerprint may not match if the original seek key lives
	// outside of a metric's frontier.  This is probable, for we are seeking to
	// to the maximum allowed time, which could advance us to the next
	// fingerprint.
	//
	//
	if !retrievedFingerprint.Equal(f) {
		i.Previous()

		retrievedKey, err = extractSampleKey(i)
		if err != nil {
			panic(err)
		}
		retrievedFingerprint := model.NewFingerprintFromRowKey(*retrievedKey.Fingerprint.Signature)
		// If the previous key does not match, we know that the requested
		// fingerprint does not live in the database.
		if !retrievedFingerprint.Equal(f) {
			return
		}
	}

	s = &seriesFrontier{
		lastSupertime: indexable.DecodeTime(retrievedKey.Timestamp),
		lastTime:      time.Unix(*retrievedKey.LastTimestamp, 0),
	}

	key.Timestamp = lowerSeek

	raw, err = coding.NewProtocolBuffer(key).Encode()
	if err != nil {
		panic(err)
	}

	i.Seek(raw)

	retrievedKey, err = extractSampleKey(i)
	if err != nil {
		panic(err)
	}

	retrievedFingerprint = model.NewFingerprintFromRowKey(*retrievedKey.Fingerprint.Signature)

	s.firstSupertime = indexable.DecodeTime(retrievedKey.Timestamp)

	return
}
Example #8
0
func (t *tieredStorage) loadChunkAroundTime(iterator leveldb.Iterator, frontier *seriesFrontier, fingerprint model.Fingerprint, ts time.Time) (chunk []model.SamplePair) {
	var (
		targetKey = &dto.SampleKey{
			Fingerprint: fingerprint.ToDTO(),
		}
		foundKey   = &dto.SampleKey{}
		foundValue *dto.SampleValueSeries
	)

	// Limit the target key to be within the series' keyspace.
	if ts.After(frontier.lastSupertime) {
		targetKey.Timestamp = indexable.EncodeTime(frontier.lastSupertime)
	} else {
		targetKey.Timestamp = indexable.EncodeTime(ts)
	}

	// Try seeking to target key.
	rawKey, _ := coding.NewProtocolBuffer(targetKey).Encode()
	iterator.Seek(rawKey)

	foundKey, err := extractSampleKey(iterator)
	if err != nil {
		panic(err)
	}

	// Figure out if we need to rewind by one block.
	// Imagine the following supertime blocks with time ranges:
	//
	// Block 1: ft 1000 - lt 1009 <data>
	// Block 1: ft 1010 - lt 1019 <data>
	//
	// If we are aiming to find time 1005, we would first seek to the block with
	// supertime 1010, then need to rewind by one block by virtue of LevelDB
	// iterator seek behavior.
	//
	// Only do the rewind if there is another chunk before this one.
	rewound := false
	firstTime := indexable.DecodeTime(foundKey.Timestamp)
	if ts.Before(firstTime) && !frontier.firstSupertime.After(ts) {
		iterator.Previous()
		rewound = true
	}

	foundValue, err = extractSampleValues(iterator)
	if err != nil {
		panic(err)
	}

	// If we rewound, but the target time is still past the current block, return
	// the last value of the current (rewound) block and the entire next block.
	if rewound {
		foundKey, err = extractSampleKey(iterator)
		if err != nil {
			panic(err)
		}
		currentChunkLastTime := time.Unix(*foundKey.LastTimestamp, 0)

		if ts.After(currentChunkLastTime) {
			sampleCount := len(foundValue.Value)
			chunk = append(chunk, model.SamplePair{
				Timestamp: time.Unix(*foundValue.Value[sampleCount-1].Timestamp, 0),
				Value:     model.SampleValue(*foundValue.Value[sampleCount-1].Value),
			})
			// We know there's a next block since we have rewound from it.
			iterator.Next()

			foundValue, err = extractSampleValues(iterator)
			if err != nil {
				panic(err)
			}
		}
	}

	// Now append all the samples of the currently seeked block to the output.
	for _, sample := range foundValue.Value {
		chunk = append(chunk, model.SamplePair{
			Timestamp: time.Unix(*sample.Timestamp, 0),
			Value:     model.SampleValue(*sample.Value),
		})
	}

	return
}