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UPSTREAM <carry>: Fix event loss after compaction #255

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UPSTREAM <carry>: Fix event loss after compaction #255

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1 change: 1 addition & 0 deletions server/etcdserver/api/v3rpc/watch.go
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Original file line number Diff line number Diff line change
Expand Up @@ -460,6 +460,7 @@ func (sws *serverWatchStream) sendLoop() {
sws.mu.RUnlock()

var serr error
// gofail: var beforeSendWatchResponse struct{}
if !fragmented && !ok {
serr = sws.gRPCStream.Send(wr)
} else {
Expand Down
7 changes: 7 additions & 0 deletions server/mvcc/watchable_store.go
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@ var (
maxWatchersPerSync = 512
)

func ChanBufLen() int { return chanBufLen }

type watchable interface {
watch(key, end []byte, startRev int64, id WatchID, ch chan<- WatchResponse, fcs ...FilterFunc) (*watcher, cancelFunc)
progress(w *watcher)
Expand Down Expand Up @@ -366,6 +368,11 @@ func (s *watchableStore) syncWatchers() int {
var victims watcherBatch
wb := newWatcherBatch(wg, evs)
for w := range wg.watchers {
if w.minRev < compactionRev {
// Skip the watcher that failed to send compacted watch response due to w.ch is full.
// Next retry of syncWatchers would try to resend the compacted watch response to w.ch
continue
}
w.minRev = curRev + 1

eb, ok := wb[w]
Expand Down
177 changes: 111 additions & 66 deletions server/mvcc/watchable_store_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,56 +17,52 @@ package mvcc
import (
"bytes"
"fmt"
"os"
"reflect"
"sync"
"testing"
"time"

"github.com/stretchr/testify/require"
"go.uber.org/zap/zaptest"

"go.etcd.io/etcd/api/v3/mvccpb"
"go.etcd.io/etcd/pkg/v3/traceutil"
"go.etcd.io/etcd/server/v3/lease"
betesting "go.etcd.io/etcd/server/v3/mvcc/backend/testing"
"go.uber.org/zap"
betesting "go.etcd.io/etcd/server/v3/storage/backend/testing"
)

func TestWatch(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})

defer func() {
s.store.Close()
os.Remove(tmpPath)
}()
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s, b)

testKey := []byte("foo")
testValue := []byte("bar")
s.Put(testKey, testValue, lease.NoLease)

w := s.NewWatchStream()
w.Watch(0, testKey, nil, 0)
defer w.Close()

w.Watch(0, testKey, nil, 0)
if !s.synced.contains(string(testKey)) {
// the key must have had an entry in synced
t.Errorf("existence = false, want true")
}
}

func TestNewWatcherCancel(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s, b)

defer func() {
s.store.Close()
os.Remove(tmpPath)
}()
testKey := []byte("foo")
testValue := []byte("bar")
s.Put(testKey, testValue, lease.NoLease)

w := s.NewWatchStream()
wt, _ := w.Watch(0, testKey, nil, 0)
defer w.Close()

wt, _ := w.Watch(0, testKey, nil, 0)
if err := w.Cancel(wt); err != nil {
t.Error(err)
}
Expand All @@ -79,25 +75,23 @@ func TestNewWatcherCancel(t *testing.T) {

// TestCancelUnsynced tests if running CancelFunc removes watchers from unsynced.
func TestCancelUnsynced(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
b, _ := betesting.NewDefaultTmpBackend(t)

// manually create watchableStore instead of newWatchableStore
// because newWatchableStore automatically calls syncWatchers
// method to sync watchers in unsynced map. We want to keep watchers
// in unsynced to test if syncWatchers works as expected.
s := &watchableStore{
store: NewStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{}),
store: NewStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{}),
unsynced: newWatcherGroup(),

// to make the test not crash from assigning to nil map.
// 'synced' doesn't get populated in this test.
synced: newWatcherGroup(),
stopc: make(chan struct{}),
}

defer func() {
s.store.Close()
os.Remove(tmpPath)
}()
defer cleanup(s, b)

// Put a key so that we can spawn watchers on that key.
// (testKey in this test). This increases the rev to 1,
Expand All @@ -108,6 +102,7 @@ func TestCancelUnsynced(t *testing.T) {
s.Put(testKey, testValue, lease.NoLease)

w := s.NewWatchStream()
defer w.Close()

// arbitrary number for watchers
watcherN := 100
Expand Down Expand Up @@ -138,24 +133,23 @@ func TestCancelUnsynced(t *testing.T) {
// method to see if it correctly sends events to channel of unsynced watchers
// and moves these watchers to synced.
func TestSyncWatchers(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
b, _ := betesting.NewDefaultTmpBackend(t)

s := &watchableStore{
store: NewStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{}),
store: NewStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{}),
unsynced: newWatcherGroup(),
synced: newWatcherGroup(),
stopc: make(chan struct{}),
}

defer func() {
s.store.Close()
os.Remove(tmpPath)
}()
defer cleanup(s, b)

testKey := []byte("foo")
testValue := []byte("bar")
s.Put(testKey, testValue, lease.NoLease)

w := s.NewWatchStream()
defer w.Close()

// arbitrary number for watchers
watcherN := 100
Expand Down Expand Up @@ -223,13 +217,10 @@ func TestSyncWatchers(t *testing.T) {

// TestWatchCompacted tests a watcher that watches on a compacted revision.
func TestWatchCompacted(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s, b)

defer func() {
s.store.Close()
os.Remove(tmpPath)
}()
testKey := []byte("foo")
testValue := []byte("bar")

Expand All @@ -244,8 +235,9 @@ func TestWatchCompacted(t *testing.T) {
}

w := s.NewWatchStream()
wt, _ := w.Watch(0, testKey, nil, compactRev-1)
defer w.Close()

wt, _ := w.Watch(0, testKey, nil, compactRev-1)
select {
case resp := <-w.Chan():
if resp.WatchID != wt {
Expand All @@ -259,19 +251,74 @@ func TestWatchCompacted(t *testing.T) {
}
}

func TestWatchFutureRev(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})
func TestWatchNoEventLossOnCompact(t *testing.T) {
oldChanBufLen, oldMaxWatchersPerSync := chanBufLen, maxWatchersPerSync

b, _ := betesting.NewDefaultTmpBackend(t)
lg := zaptest.NewLogger(t)
s := newWatchableStore(lg, b, &lease.FakeLessor{}, StoreConfig{})

defer func() {
s.store.Close()
os.Remove(tmpPath)
cleanup(s, b)
chanBufLen, maxWatchersPerSync = oldChanBufLen, oldMaxWatchersPerSync
}()

chanBufLen, maxWatchersPerSync = 1, 4
testKey, testValue := []byte("foo"), []byte("bar")

maxRev := 10
compactRev := int64(5)
for i := 0; i < maxRev; i++ {
s.Put(testKey, testValue, lease.NoLease)
}
_, err := s.Compact(traceutil.TODO(), compactRev)
require.NoErrorf(t, err, "failed to compact kv (%v)", err)

w := s.NewWatchStream()
defer w.Close()

watchers := map[WatchID]int64{
0: 1,
1: 1, // create unsyncd watchers with startRev < compactRev
2: 6, // create unsyncd watchers with compactRev < startRev < currentRev
}
for id, startRev := range watchers {
_, err := w.Watch(id, testKey, nil, startRev)
require.NoError(t, err)
}
// fill up w.Chan() with 1 buf via 2 compacted watch response
s.syncWatchers()

for len(watchers) > 0 {
resp := <-w.Chan()
if resp.CompactRevision != 0 {
require.Equal(t, resp.CompactRevision, compactRev)
require.Contains(t, watchers, resp.WatchID)
delete(watchers, resp.WatchID)
continue
}
nextRev := watchers[resp.WatchID]
for _, ev := range resp.Events {
require.Equalf(t, nextRev, ev.Kv.ModRevision, "got event revision %d but want %d for watcher with watch ID %d", ev.Kv.ModRevision, nextRev, resp.WatchID)
nextRev++
}
if nextRev == s.rev()+1 {
delete(watchers, resp.WatchID)
}
}
}

func TestWatchFutureRev(t *testing.T) {
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s, b)

testKey := []byte("foo")
testValue := []byte("bar")

w := s.NewWatchStream()
defer w.Close()

wrev := int64(10)
w.Watch(0, testKey, nil, wrev)

Expand Down Expand Up @@ -301,9 +348,9 @@ func TestWatchFutureRev(t *testing.T) {
func TestWatchRestore(t *testing.T) {
test := func(delay time.Duration) func(t *testing.T) {
return func(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s, b, tmpPath)
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s, b)

testKey := []byte("foo")
testValue := []byte("bar")
Expand Down Expand Up @@ -348,13 +395,13 @@ func readEventsForSecond(ws <-chan WatchResponse) (events []mvccpb.Event) {
// 4. restore operation moves "synced" to "unsynced" watcher group
// 5. choose the watcher from step 1, without panic
func TestWatchRestoreSyncedWatcher(t *testing.T) {
b1, b1Path := betesting.NewDefaultTmpBackend(t)
s1 := newWatchableStore(zap.NewExample(), b1, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s1, b1, b1Path)
b1, _ := betesting.NewDefaultTmpBackend(t)
s1 := newWatchableStore(zaptest.NewLogger(t), b1, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s1, b1)

b2, b2Path := betesting.NewDefaultTmpBackend(t)
s2 := newWatchableStore(zap.NewExample(), b2, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s2, b2, b2Path)
b2, _ := betesting.NewDefaultTmpBackend(t)
s2 := newWatchableStore(zaptest.NewLogger(t), b2, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s2, b2)

testKey, testValue := []byte("foo"), []byte("bar")
rev := s1.Put(testKey, testValue, lease.NoLease)
Expand All @@ -363,6 +410,8 @@ func TestWatchRestoreSyncedWatcher(t *testing.T) {
// create a watcher with a future revision
// add to "synced" watcher group (startRev > s.store.currentRev)
w1 := s1.NewWatchStream()
defer w1.Close()

w1.Watch(0, testKey, nil, startRev)

// make "s2" ends up with a higher last revision
Expand Down Expand Up @@ -399,14 +448,13 @@ func TestWatchRestoreSyncedWatcher(t *testing.T) {

// TestWatchBatchUnsynced tests batching on unsynced watchers
func TestWatchBatchUnsynced(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})

oldMaxRevs := watchBatchMaxRevs
defer func() {
watchBatchMaxRevs = oldMaxRevs
s.store.Close()
os.Remove(tmpPath)
cleanup(s, b)
}()
batches := 3
watchBatchMaxRevs = 4
Expand All @@ -417,6 +465,8 @@ func TestWatchBatchUnsynced(t *testing.T) {
}

w := s.NewWatchStream()
defer w.Close()

w.Watch(0, v, nil, 1)
for i := 0; i < batches; i++ {
if resp := <-w.Chan(); len(resp.Events) != watchBatchMaxRevs {
Expand Down Expand Up @@ -533,12 +583,11 @@ func TestNewMapwatcherToEventMap(t *testing.T) {
func TestWatchVictims(t *testing.T) {
oldChanBufLen, oldMaxWatchersPerSync := chanBufLen, maxWatchersPerSync

b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})

defer func() {
s.store.Close()
os.Remove(tmpPath)
cleanup(s, b)
chanBufLen, maxWatchersPerSync = oldChanBufLen, oldMaxWatchersPerSync
}()

Expand Down Expand Up @@ -611,13 +660,9 @@ func TestWatchVictims(t *testing.T) {
// TestStressWatchCancelClose tests closing a watch stream while
// canceling its watches.
func TestStressWatchCancelClose(t *testing.T) {
b, tmpPath := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zap.NewExample(), b, &lease.FakeLessor{}, StoreConfig{})

defer func() {
s.store.Close()
os.Remove(tmpPath)
}()
b, _ := betesting.NewDefaultTmpBackend(t)
s := newWatchableStore(zaptest.NewLogger(t), b, &lease.FakeLessor{}, StoreConfig{})
defer cleanup(s, b)

testKey, testValue := []byte("foo"), []byte("bar")
var wg sync.WaitGroup
Expand Down
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