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feat(ha_tracker): Replicadesc implement mergeable interface #10020

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merged 6 commits into from
Dec 2, 2024
Merged

feat(ha_tracker): Replicadesc implement mergeable interface #10020

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c44e5dd
feat(ha_tracker): make replicadesc mergeable
NickAnge Nov 25, 2024
2789864
test: add test with Memberlist as a KVStore
NickAnge Nov 25, 2024
116b7aa
refactor: merge logic is taking into account ElectedAt for different …
NickAnge Nov 27, 2024
6cfcd63
tests: utilize t.Run for tests and add failover constant
NickAnge Nov 27, 2024
2ceeadc
tests: improve testcases for TestReplicaDescMerge
NickAnge Nov 28, 2024
321f824
improve docs and tests of the Replicadesc Mergeable Implementation
NickAnge Dec 2, 2024
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tests: improve testcases for TestReplicaDescMerge
  • Loading branch information
@NickAnge
NickAnge committed Nov 28, 2024
commit 2ceeadc8c9dcb16ebd9540b074022255be21c72f
51 changes: 22 additions & 29 deletions pkg/distributor/ha_tracker.go
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,9 @@ func NewReplicaDesc() *ReplicaDesc {
return &ReplicaDesc{}
}

// Merge merges other ReplicaDesc into this one.
// The decision is made based on the ReceivedAt timestamp, if the Replica name is the same and at the ElectedAt if the
// Replica name is different
func (r *ReplicaDesc) Merge(other memberlist.Mergeable, _ bool) (change memberlist.Mergeable, error error) {
return r.mergeWithTime(other)
}
Expand All @@ -79,61 +82,51 @@ func (r *ReplicaDesc) mergeWithTime(mergeable memberlist.Mergeable) (memberlist.
return nil, nil
}

thisRDesc := r
otherRDesc := other

if otherRDesc.Replica == thisRDesc.Replica {
if other.Replica == r.Replica {
// Keeping the one with the most recent receivedAt timestamp
if otherRDesc.ReceivedAt > thisRDesc.ReceivedAt {
*thisRDesc = *other
} else if thisRDesc.ReceivedAt == otherRDesc.ReceivedAt && thisRDesc.DeletedAt == 0 && otherRDesc.DeletedAt != 0 {
*thisRDesc = *other
if other.ReceivedAt > r.ReceivedAt {
*r = *other
} else if r.ReceivedAt == other.ReceivedAt && r.DeletedAt == 0 && other.DeletedAt != 0 {
*r = *other
}
} else {
// keep the most recent Elected to reach consistency
if otherRDesc.ElectedAt > thisRDesc.ElectedAt {
*thisRDesc = *other
} else if otherRDesc.ElectedAt == thisRDesc.ElectedAt {
if other.ElectedAt > r.ElectedAt {
*r = *other
} else if other.ElectedAt == r.ElectedAt {
// if the timestamps are equal we compare receivedAt
if otherRDesc.ReceivedAt > thisRDesc.ReceivedAt {
*thisRDesc = *other
if other.ReceivedAt > r.ReceivedAt {
*r = *other
}
}
}

// No changes - return
if *thisRDesc != *otherRDesc {
// No changes
if *r != *other {
return nil, nil
}

out := NewReplicaDesc()
*out = *thisRDesc
*out = *r
return out, nil
}

// MergeContent noOp currently
// MergeContent describes content of this Mergeable.
// Given that ReplicaDesc can have only one instance at a time, it returns the ReplicaDesc it contains.
func (r *ReplicaDesc) MergeContent() []string {
result := []string(nil)
if len(r.Replica) != 0 {
result = append(result, r.Replica)
result = append(result, r.String())
}
return result
}

// RemoveTombstones noOp for now
func (r *ReplicaDesc) RemoveTombstones(limit time.Time) (total, removed int) {
if r.DeletedAt > 0 {
if limit.IsZero() || time.Unix(r.DeletedAt, 0).Before(limit) {
// need to implement the remove logic
removed = 1
} else {
total = 1
}
}
// RemoveTombstones noOp.
func (r *ReplicaDesc) RemoveTombstones(_ time.Time) (total, removed int) {
return
}

// Clone returns a deep copy of the ring state.
// Clone returns a deep copy of the ReplicaDesc.
func (r *ReplicaDesc) Clone() memberlist.Mergeable {
return proto.Clone(r).(*ReplicaDesc)
}
Expand Down
58 changes: 39 additions & 19 deletions pkg/distributor/ha_tracker_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -173,36 +173,56 @@ func TestReplicaDescMerge(t *testing.T) {
}
}

tests := []struct {
expectedFirstAndSecondMerge := func() *ReplicaDesc {
return &ReplicaDesc{
Replica: replica2,
ReceivedAt: now,
DeletedAt: 0,
ElectedAt: now + 5,
ElectedChanges: 2,
}
}

testsMerge := []struct {
name string
rDesc1 *ReplicaDesc
rDesc2 *ReplicaDesc
expectedOurs *ReplicaDesc
expectedRDesc *ReplicaDesc
expectedChange *ReplicaDesc
}{
{
name: "simple merge: firstReplica and firstReplicaWithHigherReceivedAt",
name: "Merge ReplicaDesc: Same replica name, different receivedAt should return ReplicaDesc with most recent receivedAt timestamp",
rDesc1: firstReplica(),
rDesc2: firstReplicaWithHigherReceivedAt(),
expectedOurs: expectedFirstAndFirstHigherReceivedAtMerge(),
expectedRDesc: expectedFirstAndFirstHigherReceivedAtMerge(),
expectedChange: expectedFirstAndFirstHigherReceivedAtMerge(),
},
{
name: "idempotency: no change after applying same Replica again",
rDesc1: expectedFirstAndFirstHigherReceivedAtMerge(),
name: "Merge ReplicaDesc: Different replica name, different electedAt should return ReplicaDesc with most recent electedAt timestamp",
rDesc1: firstReplica(),
rDesc2: secondReplica(),
expectedRDesc: expectedFirstAndSecondMerge(),
expectedChange: expectedFirstAndSecondMerge(),
},
{
name: "idempotency: no change after applying same ReplicaDesc again.",
rDesc1: func() *ReplicaDesc {
out, _ := merge(firstReplica(), secondReplica())
return out
}(),
rDesc2: firstReplica(),
expectedOurs: expectedFirstAndFirstHigherReceivedAtMerge(),
expectedRDesc: expectedFirstAndSecondMerge(),
expectedChange: nil,
},
{
name: "commutativity: Merge(firstReplicaWithHigherReceivedAt, first) == Merge(first, firstReplicaWithHigherReceivedAt)",
rDesc1: firstReplicaWithHigherReceivedAt(),
rDesc2: firstReplica(),
expectedOurs: func() *ReplicaDesc {
expected, _ := merge(firstReplica(), firstReplicaWithHigherReceivedAt())
name: "commutativity: Merge(first, second) == Merge(second, first)",
rDesc1: firstReplica(),
rDesc2: secondReplica(),
expectedRDesc: func() *ReplicaDesc {
expected, _ := merge(secondReplica(), firstReplica())
return expected
}(),
expectedChange: nil,
expectedChange: expectedFirstAndSecondMerge(),
},
{
name: "associativity: Merge(Merge(first, second), third) == Merge(first, Merge(second, third))",
Expand All @@ -212,19 +232,19 @@ func TestReplicaDescMerge(t *testing.T) {
return ours1
}(),
rDesc2: nil,
expectedOurs: func() *ReplicaDesc {
expectedRDesc: func() *ReplicaDesc {
ours2, _ := merge(secondReplica(), thirdReplica())
ours2, _ = merge(ours2, firstReplica())
ours2, _ = merge(firstReplica(), ours2)
return ours2
}(),
expectedChange: nil,
},
}

for _, tt := range tests {
for _, tt := range testsMerge {
t.Run(tt.name, func(t *testing.T) {
ours, ch := merge(tt.rDesc1, tt.rDesc2)
assert.Equal(t, tt.expectedOurs, ours)
rDesc, ch := merge(tt.rDesc1, tt.rDesc2)
assert.Equal(t, tt.expectedRDesc, rDesc)
assert.Equal(t, tt.expectedChange, ch)
})
}
Expand Down Expand Up @@ -291,7 +311,7 @@ func TestHaTrackerWithMemberList(t *testing.T) {
assert.Error(t, err)

// Wait more than the overwrite timeout.
now = now.Add(time.Millisecond * failoverTimeoutPlus100ms)
now = now.Add(failoverTimeoutPlus100ms)

// Another sample from replica2 to update its timestamp.
err = c.checkReplica(context.Background(), "user", cluster, replica2, now)
Expand Down