func (k *kvChangeIndexReader) GetStableClock() (clock base.SequenceClock, err error) {
// Validation partition map is available.
_, err = k.indexPartitionsCallback()
if err != nil {
// Unable to load partitions. Check whether the index has data (stable counter is non-zero)
count, err := base.LoadClockCounter(base.KStableSequenceKey, k.indexReadBucket)
// Index has data, but we can't get partition map. Return error
if err == nil && count > 0 {
return nil, errors.New("Error: Unable to retrieve index partition map, but index counter exists")
} else {
// Index doesn't have data. Return zero clock as stable clock
return base.NewSequenceClockImpl(), nil
}
}
clock = base.NewSequenceClockImpl()
stableShardedClock, err := k.loadStableSequence()
if err != nil {
base.Warn("Stable sequence and clock not found in index - returning err")
return nil, err
} else {
clock = stableShardedClock.AsClock()
}
return clock, nil
}
func parseClockSequenceID(str string, sequenceHasher *sequenceHasher) (s SequenceID, err error) {
if str == "" {
return SequenceID{
SeqType: ClockSequenceType,
Clock: base.NewSequenceClockImpl(),
}, nil
}
s.SeqType = ClockSequenceType
components := strings.Split(str, ":")
if len(components) == 1 {
// Convert simple zero to empty clock, to handle clients sending zero to mean 'no previous since'
if components[0] == "0" {
s.Clock = base.NewSequenceClockImpl()
} else {
// Standard clock hash
if s.Clock, err = sequenceHasher.GetClock(components[0]); err != nil {
return SequenceID{}, err
}
}
} else if len(components) == 2 {
// TriggeredBy Clock Hash, and vb.seq sequence
if s.TriggeredByClock, err = sequenceHasher.GetClock(components[0]); err != nil {
return SequenceID{}, err
}
sequenceComponents := strings.Split(components[1], ".")
if len(sequenceComponents) != 2 {
base.Warn("Unexpected sequence format - ignoring and relying on triggered by")
return
} else {
if vb64, err := strconv.ParseUint(sequenceComponents[0], 10, 16); err != nil {
base.Warn("Unable to convert sequence %v to int.", sequenceComponents[0])
} else {
s.vbNo = uint16(vb64)
s.Seq, err = strconv.ParseUint(sequenceComponents[1], 10, 64)
}
}
} else if len(components) == 3 {
// Low hash, and vb.seq sequence. Use low hash as clock, ignore vb.seq
if s.Clock, err = sequenceHasher.GetClock(components[0]); err != nil {
return SequenceID{}, err
}
} else {
err = base.HTTPErrorf(400, "Invalid sequence")
}
if err != nil {
err = base.HTTPErrorf(400, "Invalid sequence")
}
return s, err
}
// Tests hash expiry. Requires a real couchbase server bucket - walrus doesn't support expiry yet
func CouchbaseOnlyTestHashExpiry(t *testing.T) {
// Create a hasher with a small range (0-256) and short expiry for testing
seqHasher, err := testSequenceHasher(8, 5)
defer seqHasher.bucket.Close()
assertNoError(t, err, "Error creating new sequence hasher")
// Add first hash entry
clock := base.NewSequenceClockImpl()
clock.SetSequence(50, 100)
clock.SetSequence(80, 20)
clock.SetSequence(150, 150)
hashValue, err := seqHasher.GetHash(clock)
assertNoError(t, err, "Error creating hash")
// Validate that expiry is reset every time sequence for hash is requested.
for i := 0; i < 20; i++ {
clockBack, err := seqHasher.GetClock(hashValue)
assertNoError(t, err, "Error getting clock")
assert.Equals(t, clockBack.GetSequence(50), uint64(100))
time.Sleep(2 * time.Second)
}
// Validate it disappears after expiry time when no active requests
time.Sleep(10 * time.Second)
clockBack, err := seqHasher.GetClock(hashValue)
assertNoError(t, err, "Error getting clock")
log.Println("Got clockback:", clockBack)
assert.Equals(t, clockBack.GetSequence(50), uint64(0))
}
func TestConcurrentHashStorage(t *testing.T) {
// Create a hasher with a small range (0-256) for testing
seqHasher, err := testSequenceHasher(8, 0)
defer seqHasher.bucket.Close()
assertNoError(t, err, "Error creating new sequence hasher")
// Simulate multiple processes writing hashes for different clocks concurrently - ensure cache is still valid
var wg sync.WaitGroup
for i := 0; i < 20; i++ {
wg.Add(1)
go func(i int) {
defer wg.Done()
clock := base.NewSequenceClockImpl()
clock.SetSequence(uint16(i), uint64(i))
value, err := seqHasher.GetHash(clock)
assertNoError(t, err, "Error getting hash")
assert.Equals(t, value, fmt.Sprintf("%d-0", i))
}(i)
}
wg.Wait()
// Retrieve values
for i := 0; i < 20; i++ {
loadedClock, err := seqHasher.GetClock(fmt.Sprintf("%d-0", i))
assertTrue(t, err == nil, "Shouldn't return error")
assert.Equals(t, loadedClock.GetSequence(uint16(i)), uint64(i))
}
}
// Adds a set
func (b *BitFlagStorage) AddEntrySet(entries []*LogEntry) (clockUpdates base.SequenceClock, err error) {
// Update the sequences in the appropriate cache block
if len(entries) == 0 {
return clockUpdates, nil
}
// The set of updates may be distributed over multiple partitions and blocks.
// To support this, iterate over the set, and define groups of sequences by block
// TODO: this approach feels like it's generating a lot of GC work. Considered an iterative
// approach where a set update returned a list of entries that weren't targeted at the
// same block as the first entry in the list, but this would force sequential
// processing of the blocks. Might be worth revisiting if we see high GC overhead.
blockSets := make(BlockSet)
clockUpdates = base.NewSequenceClockImpl()
for _, entry := range entries {
// Update the sequence in the appropriate cache block
base.LogTo("DIndex+", "Add to channel index [%s], vbNo=%d, isRemoval:%v", b.channelName, entry.VbNo, entry.isRemoved())
blockKey := GenerateBlockKey(b.channelName, entry.Sequence, b.partitions.VbMap[entry.VbNo])
if _, ok := blockSets[blockKey]; !ok {
blockSets[blockKey] = make([]*LogEntry, 0)
}
blockSets[blockKey] = append(blockSets[blockKey], entry)
clockUpdates.SetMaxSequence(entry.VbNo, entry.Sequence)
}
err = b.writeBlockSetsWithCas(blockSets)
if err != nil {
base.Warn("Error writing blockSets with cas for block %s: %+v", blockSets, err)
}
return clockUpdates, err
}
func getClockForMap(values map[uint16]uint64) base.SequenceClock {
clock := base.NewSequenceClockImpl()
for vb, seq := range values {
clock.SetSequence(vb, seq)
}
return clock
}
func (h *handler) readChangesOptionsFromJSON(jsonData []byte) (feed string, options db.ChangesOptions, filter string, channelsArray []string, docIdsArray []string, compress bool, err error) {
var input struct {
Feed string `json:"feed"`
Since db.SequenceID `json:"since"`
Limit int `json:"limit"`
Style string `json:"style"`
IncludeDocs bool `json:"include_docs"`
Filter string `json:"filter"`
Channels string `json:"channels"` // a filter query param, so it has to be a string
DocIds []string `json:"doc_ids"`
HeartbeatMs *uint64 `json:"heartbeat"`
TimeoutMs *uint64 `json:"timeout"`
AcceptEncoding string `json:"accept_encoding"`
ActiveOnly bool `json:"active_only"` // Return active revisions only
}
// Initialize since clock and hasher ahead of unmarshalling sequence
if h.db != nil && h.db.SequenceType == db.ClockSequenceType {
input.Since.Clock = base.NewSequenceClockImpl()
input.Since.SeqType = h.db.SequenceType
input.Since.SequenceHasher = h.db.SequenceHasher
}
if err = json.Unmarshal(jsonData, &input); err != nil {
return
}
feed = input.Feed
options.Since = input.Since
options.Limit = input.Limit
options.Conflicts = input.Style == "all_docs"
options.ActiveOnly = input.ActiveOnly
options.IncludeDocs = input.IncludeDocs
filter = input.Filter
if input.Channels != "" {
channelsArray = strings.Split(input.Channels, ",")
}
docIdsArray = input.DocIds
options.HeartbeatMs = getRestrictedInt(
input.HeartbeatMs,
kDefaultHeartbeatMS,
kMinHeartbeatMS,
h.server.config.MaxHeartbeat*1000,
true,
)
options.TimeoutMs = getRestrictedInt(
input.TimeoutMs,
kDefaultTimeoutMS,
0,
kMaxTimeoutMS,
true,
)
compress = (input.AcceptEncoding == "gzip")
return
}
func getZeroSequence(db *Database) ChangesOptions {
if db.SequenceType == IntSequenceType {
return ChangesOptions{Since: SequenceID{Seq: 0}}
} else {
return ChangesOptions{Since: SequenceID{Clock: base.NewSequenceClockImpl()}}
}
}
func (k *kvChangeIndexReader) GetChanges(channelName string, options ChangesOptions) ([]*LogEntry, error) {
var sinceClock base.SequenceClock
if options.Since.Clock == nil {
// If there's no since clock, we may be in backfill for another channel - revert to the triggered by clock.
if options.Since.TriggeredByClock != nil {
sinceClock = options.Since.TriggeredByClock
} else {
sinceClock = base.NewSequenceClockImpl()
}
} else {
sinceClock = options.Since.Clock
}
reader, err := k.getOrCreateReader(channelName, options)
if err != nil {
base.Warn("Error obtaining channel reader (need partition index?) for channel %s", channelName)
return nil, err
}
changes, err := reader.getChanges(sinceClock)
if err != nil {
base.LogTo("DIndex+", "No clock found for channel %s, assuming no entries in index", channelName)
return nil, nil
}
// Limit handling
if options.Limit > 0 && len(changes) > options.Limit {
limitResult := make([]*LogEntry, options.Limit)
copy(limitResult[0:], changes[0:])
return limitResult, nil
}
return changes, nil
}
// Returns a clock-base SequenceID with all vb values set to seq
func simpleClockSequence(seq uint64) SequenceID {
result := SequenceID{
SeqType: ClockSequenceType,
Clock: base.NewSequenceClockImpl(),
}
for i := 0; i < 1024; i++ {
result.Clock.SetSequence(uint16(i), seq)
}
return result
}
func (k *kvChannelIndex) loadClock() {
if k.clock == nil {
k.clock = base.NewSequenceClockImpl()
}
data, cas, err := k.indexBucket.GetRaw(getChannelClockKey(k.channelName))
if err != nil {
base.LogTo("DIndex+", "Unable to find existing channel clock for channel %s - treating as new", k.channelName)
}
k.clock.Unmarshal(data)
k.clock.SetCas(cas)
}
func (s *sequenceHasher) GetClock(sequence string) (base.SequenceClock, error) {
clock := base.NewSequenceClockImpl()
var err error
var seqHash sequenceHash
components := strings.Split(sequence, "-")
if len(components) == 1 {
seqHash.hashValue, err = strconv.ParseUint(sequence, 10, 64)
if err != nil {
return clock, errors.New(fmt.Sprintf("Error converting hash sequence %s to string: %v", sequence, err))
}
} else if len(components) == 2 {
seqHash.hashValue, err = strconv.ParseUint(components[0], 10, 64)
if err != nil {
return clock, errors.New(fmt.Sprintf("Error converting hash sequence %s to string: %v", sequence, err))
}
index, err := strconv.ParseUint(components[1], 10, 16)
seqHash.collisionIndex = uint16(index)
if err != nil {
return clock, errors.New(fmt.Sprintf("Error converting collision index %s to int: %v", components[1], err))
}
}
cachedValue := s.getCacheValue(seqHash.hashValue)
storedClocks, loadErr := cachedValue.load(s.loadClocks)
if loadErr != nil {
return clock, loadErr
}
if uint16(len(storedClocks.Sequences)) <= seqHash.collisionIndex {
return clock, errors.New(fmt.Sprintf("Stored hash not found for sequence [%s], returning zero clock", sequence))
}
clock = base.NewSequenceClockImpl()
clock.Init(storedClocks.Sequences[seqHash.collisionIndex], seqHash.String())
return clock, nil
}
func TestHashCalculation(t *testing.T) {
// Create a hasher with a small range (0-256) for testing
seqHasher, err := testSequenceHasher(8, 0)
defer seqHasher.bucket.Close()
assertNoError(t, err, "Error creating new sequence hasher")
clock := base.NewSequenceClockImpl()
clock.SetSequence(50, 100)
clock.SetSequence(80, 20)
clock.SetSequence(150, 150)
hashValue := seqHasher.calculateHash(clock)
assert.Equals(t, hashValue, uint64(14)) // (100 + 20 + 150) mod 256
clock.SetSequence(55, 300)
clock.SetSequence(200, 513)
hashValue = seqHasher.calculateHash(clock)
assert.Equals(t, hashValue, uint64(59)) // (100 + 20 + 150 + (300 mod 256) + (513 mod 256)) mod 256
}
func (k *kvChannelIndex) getChannelClock() (base.SequenceClock, error) {
var channelClock base.SequenceClock
var err error
// If we're polling, return a copy
k.lastPolledLock.RLock()
defer k.lastPolledLock.RUnlock()
if k.lastPolledChannelClock != nil {
channelClock = base.NewSequenceClockImpl()
channelClock.SetTo(k.lastPolledChannelClock)
} else {
channelClock, err = k.loadChannelClock()
if err != nil {
return nil, err
}
}
return channelClock, nil
}
// Returns the set of index entries for the channel more recent than the
// specified since SequenceClock. Index entries with sequence values greater than
// the index stable sequence are not returned.
func (k *kvChannelIndex) getChanges(since base.SequenceClock) ([]*LogEntry, error) {
var results []*LogEntry
// Someone is still interested in this channel - reset poll counts
atomic.StoreUint32(&k.pollCount, 0)
atomic.StoreUint32(&k.unreadPollCount, 0)
chanClock, err := k.getChannelClock()
if err != nil {
// Note: gocb returns "Key not found.", go-couchbase returns "MCResponse status=KEY_ENOENT, opcode=GET, opaque=0, msg: Not found"
// Using string matching to identify key not found for now - really need a better API in go-couchbase/gocb for gets that allows us to distinguish
// between errors and key not found with something more robust than string matching.
if IsNotFoundError(err) {
// initialize chanClock as empty clock
chanClock = base.NewSequenceClockImpl()
} else {
return results, err
}
}
// If requested clock is later than the channel clock, return empty
if since.AllAfter(chanClock) {
base.LogTo("DIndex+", "requested clock is later than channel clock - no new changes to report")
return results, nil
}
// If the since value is more recent than the last polled clock, return the results from the
// last polling. Has the potential to return values earlier than since and later than
// lastPolledClock, but these duplicates will be ignored by replication. Could validate
// greater than since inside this if clause, but leaving out as a performance optimization for
// now
if lastPolledResults := k.checkLastPolled(since); len(lastPolledResults) > 0 {
indexExpvars.Add("getChanges_lastPolled_hit", 1)
return lastPolledResults, nil
}
indexExpvars.Add("getChanges_lastPolled_miss", 1)
return k.channelStorage.GetChanges(since, chanClock)
}
// Creates a go-channel of ChangeEntry for each channel in channelsSince. Each go-channel sends the ordered entries for that channel.
func (db *Database) initializeChannelFeeds(channelsSince channels.TimedSet, options ChangesOptions, addedChannels base.Set, userVbNo uint16) ([]<-chan *ChangeEntry, error) {
// Populate the array of feed channels:
feeds := make([]<-chan *ChangeEntry, 0, len(channelsSince))
base.LogTo("Changes+", "GotChannelSince... %v", channelsSince)
for name, vbSeqAddedAt := range channelsSince {
seqAddedAt := vbSeqAddedAt.Sequence
// If there's no vbNo on the channelsSince, it indicates a user doc channel grant - use the userVbNo.
var vbAddedAt uint16
if vbSeqAddedAt.VbNo == nil {
vbAddedAt = userVbNo
} else {
vbAddedAt = *vbSeqAddedAt.VbNo
}
base.LogTo("Changes+", "Starting for channel... %s, %d", name, seqAddedAt)
chanOpts := options
// Check whether requires backfill based on addedChannels in this _changes feed
isNewChannel := false
if addedChannels != nil {
_, isNewChannel = addedChannels[name]
}
// Three possible scenarios for backfill handling, based on whether the incoming since value indicates a backfill in progress
// for this channel, and whether the channel requires a new backfill to be started
// Case 1. No backfill in progress, no backfill required - use the incoming since to get changes
// Case 2. No backfill in progress, backfill required for this channel. Get changes since zero, backfilling to the incoming since
// Case 3. Backfill in progress. Get changes since zero, backfilling to incoming triggered by, filtered to later than incoming since.
backfillInProgress := false
if options.Since.TriggeredByClock != nil {
// There's a backfill in progress for SOME channel - check if it's this one
if options.Since.TriggeredByClock.GetSequence(vbAddedAt) == seqAddedAt {
backfillInProgress = true
}
}
sinceSeq := getChangesClock(options.Since).GetSequence(vbAddedAt)
backfillRequired := vbSeqAddedAt.Sequence > 0 && sinceSeq < seqAddedAt
if isNewChannel || (backfillRequired && !backfillInProgress) {
// Case 2. No backfill in progress, backfill required
base.LogTo("Changes+", "Starting backfill for channel... %s, %d", name, seqAddedAt)
chanOpts.Since = SequenceID{
Seq: 0,
vbNo: 0,
Clock: base.NewSequenceClockImpl(),
TriggeredBy: seqAddedAt,
TriggeredByVbNo: vbAddedAt,
TriggeredByClock: getChangesClock(options.Since).Copy(),
}
} else if backfillInProgress {
// Case 3. Backfill in progress.
chanOpts.Since = SequenceID{
Seq: options.Since.Seq,
vbNo: options.Since.vbNo,
Clock: base.NewSequenceClockImpl(),
TriggeredBy: seqAddedAt,
TriggeredByVbNo: vbAddedAt,
TriggeredByClock: options.Since.TriggeredByClock,
}
} else {
// Case 1. Leave chanOpts.Since set to options.Since.
}
feed, err := db.vectorChangesFeed(name, chanOpts)
if err != nil {
base.Warn("MultiChangesFeed got error reading changes feed %q: %v", name, err)
return feeds, err
}
feeds = append(feeds, feed)
}
// If the user object has changed, create a special pseudo-feed for it:
if db.user != nil {
feeds, _ = db.appendVectorUserFeed(feeds, []string{}, options, userVbNo)
}
return feeds, nil
}
func (k *kvChangeIndexReader) pollReaders() bool {
k.channelIndexReaderLock.Lock()
defer k.channelIndexReaderLock.Unlock()
if len(k.channelIndexReaders) == 0 {
return true
}
// Build the set of clock keys to retrieve. Stable sequence, plus one per channel reader
keySet := make([]string, len(k.channelIndexReaders))
index := 0
for _, reader := range k.channelIndexReaders {
keySet[index] = GetChannelClockKey(reader.channelName)
index++
}
bulkGetResults, err := k.indexReadBucket.GetBulkRaw(keySet)
if err != nil {
base.Warn("Error retrieving channel clocks: %v", err)
}
IndexExpvars.Add("bulkGet_channelClocks", 1)
IndexExpvars.Add("bulkGet_channelClocks_keyCount", int64(len(keySet)))
changedChannels := make(chan string, len(k.channelIndexReaders))
cancelledChannels := make(chan string, len(k.channelIndexReaders))
var wg sync.WaitGroup
for _, reader := range k.channelIndexReaders {
// For each channel, unmarshal new channel clock, then check with reader whether this represents changes
wg.Add(1)
go func(reader *KvChannelIndex, wg *sync.WaitGroup) {
defer func() {
wg.Done()
}()
// Unmarshal channel clock. If not present in the bulk get results, use empty clock to support
// channels that don't have any indexed data yet. If clock was previously found successfully (i.e. empty clock is
// due to temporary error from server), empty clock treated safely as a non-update by pollForChanges.
clockKey := GetChannelClockKey(reader.channelName)
var newChannelClock *base.SequenceClockImpl
clockBytes, found := bulkGetResults[clockKey]
if !found {
newChannelClock = base.NewSequenceClockImpl()
} else {
var err error
newChannelClock, err = base.NewSequenceClockForBytes(clockBytes)
if err != nil {
base.Warn("Error unmarshalling channel clock - skipping polling for channel %s: %v", reader.channelName, err)
return
}
}
// Poll for changes
hasChanges, cancelPolling := reader.pollForChanges(k.readerStableSequence.AsClock(), newChannelClock)
if hasChanges {
changedChannels <- reader.channelName
}
if cancelPolling {
cancelledChannels <- reader.channelName
}
}(reader, &wg)
}
wg.Wait()
close(changedChannels)
close(cancelledChannels)
// Build channel set from the changed channels
var channels []string
for channelName := range changedChannels {
channels = append(channels, channelName)
}
if len(channels) > 0 && k.onChange != nil {
k.onChange(base.SetFromArray(channels))
}
// Remove cancelled channels from channel readers
for channelName := range cancelledChannels {
IndexExpvars.Add("pollingChannels_active", -1)
delete(k.channelIndexReaders, channelName)
}
return true
}
// Index a group of entries. Iterates over the entry set to build updates per channel, then
// updates using channel index.
func (k *kvChangeIndexWriter) indexEntries(entries []*LogEntry, indexPartitions base.IndexPartitionMap, channelStorage ChannelStorage) error {
channelSets := make(map[string][]*LogEntry)
updatedSequences := base.NewSequenceClockImpl()
// Wait group tracks when the current buffer has been completely processed
var entryWg sync.WaitGroup
entryErrorCount := uint32(0)
// Iterate over entries to write index entry docs, and group entries for subsequent channel index updates
for _, logEntry := range entries {
// If principal, update the stable sequence and continue
if logEntry.IsPrincipal {
updatedSequences.SetSequence(logEntry.VbNo, logEntry.Sequence)
continue
}
// Remove channels from entry to save space in memory, index entries
ch := logEntry.Channels
// Add index log entry if needed
if channelStorage.StoresLogEntries() {
entryWg.Add(1)
go func(logEntry *LogEntry, errorCount uint32) {
defer entryWg.Done()
err := channelStorage.WriteLogEntry(logEntry)
if err != nil {
atomic.AddUint32(&errorCount, 1)
}
}(logEntry, entryErrorCount)
}
// Collect entries by channel
for channelName, removal := range ch {
if removal == nil || removal.RevID == logEntry.RevID {
// Store by channel and partition, to avoid having to iterate over results again in the channel index to group by partition
_, found := channelSets[channelName]
if !found {
// TODO: maxCacheUpdate may be unnecessarily large memory allocation here
channelSets[channelName] = make([]*LogEntry, 0, maxCacheUpdate)
}
if removal != nil {
removalEntry := *logEntry
removalEntry.Flags |= channels.Removed
channelSets[channelName] = append(channelSets[channelName], &removalEntry)
} else {
channelSets[channelName] = append(channelSets[channelName], logEntry)
}
}
}
if EnableStarChannelLog {
_, found := channelSets[channels.UserStarChannel]
if !found {
// TODO: maxCacheUpdate may be unnecessarily large memory allocation here
channelSets[channels.UserStarChannel] = make([]*LogEntry, 0, maxCacheUpdate)
}
channelSets[channels.UserStarChannel] = append(channelSets[channels.UserStarChannel], logEntry)
}
// Track vbucket sequences for clock update
updatedSequences.SetSequence(logEntry.VbNo, logEntry.Sequence)
}
// Wait group tracks when the current buffer has been completely processed
var channelWg sync.WaitGroup
channelErrorCount := uint32(0)
// Iterate over channel sets to update channel index
for channelName, entrySet := range channelSets {
channelWg.Add(1)
go func(channelName string, entrySet []*LogEntry, errorCount uint32) {
defer channelWg.Done()
err := k.addSetToChannelIndex(channelName, entrySet)
if err != nil {
atomic.AddUint32(&errorCount, 1)
}
}(channelName, entrySet, channelErrorCount)
}
// Wait for entry and channel processing to complete
entryWg.Wait()
channelWg.Wait()
if atomic.LoadUint32(&entryErrorCount) > 0 || atomic.LoadUint32(&channelErrorCount) > 0 {
return errors.New("Unrecoverable error indexing entry or channel")
}
// Update stable sequence
err := k.getWriterStableSequence().UpdateAndWrite(updatedSequences)
return err
}
func TestHashStorage(t *testing.T) {
// Create a hasher with a small range (0-256) for testing
seqHasher, err := testSequenceHasher(8, 0)
defer seqHasher.bucket.Close()
assertNoError(t, err, "Error creating new sequence hasher")
// Add first hash entry
clock := base.NewSequenceClockImpl()
clock.SetSequence(50, 100)
clock.SetSequence(80, 20)
clock.SetSequence(150, 150)
hashValue, err := seqHasher.GetHash(clock)
assertNoError(t, err, "Error getting hash")
assert.Equals(t, hashValue, "14-0")
// Add different hash entry
clock2 := base.NewSequenceClockImpl()
clock2.SetSequence(50, 1)
clock2.SetSequence(80, 2)
clock2.SetSequence(150, 5)
hashValue2, err := seqHasher.GetHash(clock2)
assertNoError(t, err, "Error getting hash")
assert.Equals(t, hashValue2, "8-0")
// Retrieve first hash entry
clockBack, err := seqHasher.GetClock(hashValue)
assertNoError(t, err, "Error getting clock")
assert.Equals(t, clockBack.GetSequence(50), uint64(100))
assert.Equals(t, clockBack.GetSequence(80), uint64(20))
assert.Equals(t, clockBack.GetSequence(150), uint64(150))
// Create hash for the first clock again - ensure retrieves existing, and doesn't create new
hashValue, err = seqHasher.GetHash(clock)
assertNoError(t, err, "Error getting hash")
assert.Equals(t, hashValue, "14-0")
// Add a second clock that hashes to the same value
secondClock := base.NewSequenceClockImpl()
secondClock.SetSequence(50, 100)
secondClock.SetSequence(80, 20)
secondClock.SetSequence(150, 150)
secondClock.SetSequence(300, 256)
hashValue, err = seqHasher.GetHash(secondClock)
assertNoError(t, err, "Error getting hash")
assert.Equals(t, hashValue, "14-1")
// Simulate multiple processes requesting a hash for the same clock concurrently - ensures cas write checks
// whether clock has already been added before writing
var wg sync.WaitGroup
for i := 0; i < 20; i++ {
wg.Add(1)
go func() {
defer wg.Done()
thirdClock := base.NewSequenceClockImpl()
thirdClock.SetSequence(50, 100)
thirdClock.SetSequence(80, 20)
thirdClock.SetSequence(150, 150)
thirdClock.SetSequence(300, 256)
thirdClock.SetSequence(500, 256)
value, err := seqHasher.GetHash(thirdClock)
assertNoError(t, err, "Error getting hash")
assert.Equals(t, value, "14-2")
}()
}
wg.Wait()
// Retrieve non-existent hash
missingClock, err := seqHasher.GetClock("1234")
assertTrue(t, err != nil, "Should return error for non-existent hash")
assert.Equals(t, missingClock.GetSequence(50), uint64(0))
assert.Equals(t, missingClock.GetSequence(80), uint64(0))
assert.Equals(t, missingClock.GetSequence(150), uint64(0))
}
