blob: 37799b3bb425391629ced27495754c82757da27d [file] [log] [blame]
// Copyright 2015 The LUCI Authors.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
// Package archive constructs a LogDog archive out of log stream components.
// Records are read from the stream and emitted as an archive.
package archive
import (
// safeLogEntrySource wraps a renderer.Source and guarantees that all emitted
// log entries' index parameters are >= those of the previous entry.
// Any LogEntry that violates this will be silently discarded.
type safeLogEntrySource struct {
lastPrefixIndex uint64
lastStreamIndex uint64
lastSequence uint64
lastTimeOffset time.Duration
func (s *safeLogEntrySource) NextLogEntry() (*logpb.LogEntry, error) {
// Loop until we find a LogEntry to return.
for {
le, err := s.Source.NextLogEntry()
if le != nil {
// Ingest the log entry.
if err := s.normalizeLogEntry(le); err != nil {
s.logger().Warningf("Discarding out-of-order log stream entry %d: %v", le.StreamIndex, err)
} else if err == nil {
err = errors.New("source returned nil LogEntry and no error")
return le, err
func (s *safeLogEntrySource) normalizeLogEntry(le *logpb.LogEntry) error {
// Calculate the time offset Duration once.
timeOffset := le.TimeOffset.AsDuration()
// Are any of our order constraints violated?
switch {
case le.PrefixIndex < s.lastPrefixIndex:
return fmt.Errorf("prefix index is out of order (%d < %d)", le.PrefixIndex, s.lastPrefixIndex)
case le.StreamIndex < s.lastStreamIndex:
return fmt.Errorf("stream index is out of order (%d < %d)", le.StreamIndex, s.lastStreamIndex)
case le.Sequence < s.lastSequence:
return fmt.Errorf("sequence is out of order (%d < %d)", le.Sequence, s.lastSequence)
s.lastPrefixIndex = le.PrefixIndex
s.lastStreamIndex = le.StreamIndex
s.lastSequence = le.Sequence
if timeOffset < s.lastTimeOffset {
s.logger().Warningf("Adjusting out-of-order timestamp (%s < %s) for log stream entry %d.",
timeOffset, s.lastTimeOffset, le.StreamIndex)
le.TimeOffset = durationpb.New(s.lastTimeOffset)
} else {
s.lastTimeOffset = timeOffset
return nil