From d7c5692ba225803ff776cff811363802157ed743 Mon Sep 17 00:00:00 2001
From: David Cheung <cheungdavid@google.com>
Date: Thu, 13 Oct 2022 22:24:48 +0000
Subject: [PATCH] Create Error State Interface

Added error checking functions in transactionSyncer.go for syncer's
error state get/set/reset.
---
 pkg/neg/manager_test.go        | 1 +
 pkg/neg/syncers/syncer.go      | 7 +++++++
 pkg/neg/syncers/syncer_test.go | 6 ++++++
 pkg/neg/syncers/transaction.go | 5 +++++
 pkg/neg/types/interfaces.go    | 2 ++
 5 files changed, 21 insertions(+)

diff --git a/pkg/neg/manager_test.go b/pkg/neg/manager_test.go
index ba097f349e..6d06d9f1e8 100644
--- a/pkg/neg/manager_test.go
+++ b/pkg/neg/manager_test.go
@@ -1535,6 +1535,7 @@ func (s *fakeSyncer) Stop()                {}
 func (s *fakeSyncer) Sync() bool           { return s.syncFunc() }
 func (s *fakeSyncer) IsStopped() bool      { return s.isStopped }
 func (s *fakeSyncer) IsShuttingDown() bool { return false }
+func (s *fakeSyncer) InErrorState() bool   { return false }
 
 // getNegObjectRefs generates the NegObjectReference list of all negs with the specified negName in the specified zones
 func getNegObjectRefs(t *testing.T, cloud negtypes.NetworkEndpointGroupCloud, zones []string, negName string, version meta.Version) []negv1beta1.NegObjectReference {
diff --git a/pkg/neg/syncers/syncer.go b/pkg/neg/syncers/syncer.go
index b74291cd31..47f6c63bf5 100644
--- a/pkg/neg/syncers/syncer.go
+++ b/pkg/neg/syncers/syncer.go
@@ -31,6 +31,9 @@ import (
 
 type syncerCore interface {
 	sync() error
+	inErrorState() bool
+	setErrorState()
+	resetErrorState()
 }
 
 // syncer is a NEG syncer skeleton.
@@ -164,3 +167,7 @@ func (s *syncer) IsShuttingDown() bool {
 	defer s.stateLock.Unlock()
 	return s.shuttingDown
 }
+
+func (s *syncer) InErrorState() bool {
+	return s.core.inErrorState()
+}
diff --git a/pkg/neg/syncers/syncer_test.go b/pkg/neg/syncers/syncer_test.go
index dd43e52819..4441c24f83 100644
--- a/pkg/neg/syncers/syncer_test.go
+++ b/pkg/neg/syncers/syncer_test.go
@@ -77,6 +77,12 @@ func (t *syncerTester) sync() error {
 	return nil
 }
 
+func (t *syncerTester) inErrorState() bool { return false }
+
+func (t *syncerTester) setErrorState() {}
+
+func (t *syncerTester) resetErrorState() {}
+
 func newSyncerTester() *syncerTester {
 	testNegName := "test-neg-name"
 	testContext := negtypes.NewTestContext()
diff --git a/pkg/neg/syncers/transaction.go b/pkg/neg/syncers/transaction.go
index e27da180f0..95751cd899 100644
--- a/pkg/neg/syncers/transaction.go
+++ b/pkg/neg/syncers/transaction.go
@@ -176,6 +176,11 @@ func (s *transactionSyncer) sync() error {
 }
 
 func (s *transactionSyncer) syncInternal() error {
+	// TODO: enter degraded mode before reset and sync
+	if s.inErrorState() {
+		s.resetErrorState()
+	}
+
 	s.syncLock.Lock()
 	defer s.syncLock.Unlock()
 
diff --git a/pkg/neg/types/interfaces.go b/pkg/neg/types/interfaces.go
index e34837730f..bd1f82e3c3 100644
--- a/pkg/neg/types/interfaces.go
+++ b/pkg/neg/types/interfaces.go
@@ -61,6 +61,8 @@ type NegSyncer interface {
 	IsStopped() bool
 	// IsShuttingDown returns true if syncer is shutting down
 	IsShuttingDown() bool
+	// InErrorState returns true if syncer is in error state
+	InErrorState() bool
 }
 
 // NegSyncerManager is an interface for controllers to manage syncer