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main - bugfix

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- Nodes not being removed when deleted because when node gossips again
  it is readded.
- Keep track of highest vector clock we have removed and used this as a
  mark for determining if something is stale.
This commit is contained in:
Tim Beatham 2023-12-11 11:09:02 +00:00
parent 3222d7e388
commit 13bea10638
3 changed files with 20 additions and 6 deletions
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6
pkg/crdt/two_phase_map.go
View File

@ -151,7 +151,7 @@ func (m *TwoPhaseMap[K, D]) GenerateMessage() *TwoPhaseMapState[K] {
} }
} }
func (m *TwoPhaseMapState[K]) Difference(state *TwoPhaseMapState[K]) *TwoPhaseMapState[K] { func (m *TwoPhaseMapState[K]) Difference(highestStale uint64, state *TwoPhaseMapState[K]) *TwoPhaseMapState[K] {
mapState := &TwoPhaseMapState[K]{ mapState := &TwoPhaseMapState[K]{
AddContents: make(map[uint64]uint64), AddContents: make(map[uint64]uint64),
RemoveContents: make(map[uint64]uint64), RemoveContents: make(map[uint64]uint64),
@ -160,7 +160,7 @@ func (m *TwoPhaseMapState[K]) Difference(state *TwoPhaseMapState[K]) *TwoPhaseMa
for key, value := range state.AddContents { for key, value := range state.AddContents {
otherValue, ok := m.AddContents[key] otherValue, ok := m.AddContents[key]
if !ok || otherValue < value { if value > highestStale && (!ok || otherValue < value) {
mapState.AddContents[key] = value mapState.AddContents[key] = value
} }
} }
@ -168,7 +168,7 @@ func (m *TwoPhaseMapState[K]) Difference(state *TwoPhaseMapState[K]) *TwoPhaseMa
for key, value := range state.RemoveContents { for key, value := range state.RemoveContents {
otherValue, ok := m.RemoveContents[key] otherValue, ok := m.RemoveContents[key]
if !ok || otherValue < value { if value > highestStale && (!ok || otherValue < value) {
mapState.RemoveContents[key] = value mapState.RemoveContents[key] = value
} }
} }

4
pkg/crdt/two_phase_map_syncer.go
View File

@ -94,9 +94,9 @@ func present(syncer *TwoPhaseSyncer) ([]byte, bool) {
if err != nil { if err != nil {
logging.Log.WriteErrorf(err.Error()) logging.Log.WriteErrorf(err.Error())
} }
difference := syncer.mapState.Difference(&mapState) difference := syncer.mapState.Difference(syncer.manager.store.Clock.GetStaleCount(), &mapState)
syncer.manager.store.Clock.Merge(mapState.Vectors) syncer.manager.store.Clock.Merge(mapState.Vectors)
var sendBuffer bytes.Buffer var sendBuffer bytes.Buffer

16
pkg/crdt/vector_clock.go
View File

@ -23,6 +23,8 @@ type VectorClock[K cmp.Ordered] struct {
processID K processID K
staleTime uint64 staleTime uint64
hashFunc func(K) uint64 hashFunc func(K) uint64
// highest update that's been garbage collected
highestStale uint64
} }
// IncrementClock: increments the node's value in the vector clock // IncrementClock: increments the node's value in the vector clock
@ -78,6 +80,7 @@ func (m *VectorClock[K]) getStale() []uint64 {
for key, bucket := range m.vectors { for key, bucket := range m.vectors {
if maxTimeStamp-bucket.lastUpdate > m.staleTime { if maxTimeStamp-bucket.lastUpdate > m.staleTime {
toRemove = append(toRemove, key) toRemove = append(toRemove, key)
m.highestStale = max(bucket.clock, m.highestStale)
} }
} }
@ -85,6 +88,15 @@ func (m *VectorClock[K]) getStale() []uint64 {
return toRemove return toRemove
} }
// GetStaleCount: returns a vector clock which is considered to be stale.
// all updates must be greater than this
func (m *VectorClock[K]) GetStaleCount() uint64 {
m.lock.RLock()
staleCount := m.highestStale
m.lock.RUnlock()
return staleCount
}
func (m *VectorClock[K]) Prune() { func (m *VectorClock[K]) Prune() {
stale := m.getStale() stale := m.getStale()
@ -120,7 +132,9 @@ func (m *VectorClock[K]) put(key uint64, value uint64) {
clockValue = bucket.clock clockValue = bucket.clock
} }
if value > clockValue { // Make sure that entries that were garbage collected don't get
// addded back
if value > clockValue && value > m.highestStale {
newBucket := VectorBucket{ newBucket := VectorBucket{
clock: value, clock: value,
lastUpdate: uint64(time.Now().Unix()), lastUpdate: uint64(time.Now().Unix()),