Revert "Improve push squashing" (istio#6677)

* Revert "Remove v2 transition commands since everything is now v2 (istio#6665)"

This reverts commit 6339eb6.

* Revert "Pilot param clusterRegistriesNamespace should default to pilot namespace (istio#6446)"

This reverts commit b9294f7.

* Revert "iptable just "return" by uid as the parameter u indicates (istio#6561)"

This reverts commit 22a0b88.

* Revert "Remove node agent service, residue from flexvolume driver. (istio#6651)"

This reverts commit db3da82.

* Revert "Continuously reapply galley CA bundle to prevent overwrite (istio#6599)"

This reverts commit f9e8fd8.

* Revert "Do not count typeConfigs if it is error. (istio#6527)"

This reverts commit eb1de31.

* Revert "Make racetest green - Fixed data races and flakiness (istio#6625)"

This reverts commit 30b8ecb.

* Revert "Improve push squashing (istio#6641)"

This reverts commit 399cd2d.

install/kubernetes/helm/istio/values.yaml

@@ -216,7 +216,7 @@ sidecarInjectorWebhook:
 # galley configuration
 #
 galley:
-  enabled: false
+  enabled: true
   replicaCount: 1
   image: galley
   resources: {}

pilot/pkg/proxy/envoy/discovery.go

@@ -112,21 +112,10 @@ var (
 
 var (
 	// Variables associated with clear cache squashing.
-
-	// lastClearCache is the time we last pushed
-	lastClearCache time.Time
-
-	// lastClearCacheEvent is the time of the last config event
-	lastClearCacheEvent time.Time
-
-	// clearCacheTimerSet is true if we are in squash mode, and a timer is already set
+	lastClearCache     time.Time
 	clearCacheTimerSet bool
-
-	clearCacheMutex sync.Mutex
-
-	// clearCacheTime is the max time to squash a series of events.
-	// The push will happen 1 sec after the last config change, or after 'clearCacheTime'
-	clearCacheTime = 1
+	clearCacheMutex    sync.Mutex
+	clearCacheTime     = 1
 
 	// V2ClearCache is a function to be called when the v1 cache is cleared. This is used to
 	// avoid adding a circular dependency from v1 to v2.
@@ -370,6 +359,7 @@ func NewDiscoveryService(ctl model.Controller, configCache model.ConfigStoreCach
 	}
 
 	if configCache != nil {
+		// FIXME: shouldn't listen to v1alpha3
 		// TODO: changes should not trigger a full recompute of LDS/RDS/CDS/EDS
 		// (especially mixerclient HTTP and quota)
 		configHandler := func(model.Config, model.Event) { out.clearCache() }
@@ -442,40 +432,23 @@ func (ds *DiscoveryService) clearCache() {
 	clearCacheMutex.Lock()
 	defer clearCacheMutex.Unlock()
 
-	// If last config change was > 1 second ago, push.
-	if time.Since(lastClearCacheEvent) > 1*time.Second {
-		lastClearCacheEvent = time.Now()
-		lastClearCache = time.Now()
-		log.Infof("Cleared discovery service cache after 1 sec of quiet")
-		V2ClearCache()
-		return
-	}
-
-	lastClearCacheEvent = time.Now()
-
-	// If last config change was < 1 second ago, but last push is > clearCacheTime ago -
-	// also push
-
-	if time.Since(lastClearCache) > time.Duration(clearCacheTime)*time.Second {
-		log.Infof("Cleared discovery service cache after %v", time.Since(lastClearCache))
-		lastClearCache = time.Now()
-		V2ClearCache()
+	if time.Since(lastClearCache) < time.Duration(clearCacheTime)*time.Second {
+		if !clearCacheTimerSet {
+			clearCacheTimerSet = true
+			time.AfterFunc(time.Duration(clearCacheTime)*time.Second, func() {
+				clearCacheMutex.Lock()
+				clearCacheTimerSet = false
+				clearCacheMutex.Unlock()
+				ds.clearCache() // it's after time - so will clear the cache
+			})
+		}
 		return
 	}
-
-	// Last config change was < 1 second ago, and we're continuing to get changes.
-	// Set a timer 1 second in the future, to evaluate again.
-	// if a timer was already set, don't bother.
-	if !clearCacheTimerSet {
-		clearCacheTimerSet = true
-		time.AfterFunc(1*time.Second, func() {
-			clearCacheMutex.Lock()
-			clearCacheTimerSet = false
-			clearCacheMutex.Unlock()
-			ds.clearCache() // re-evaluate after 1 second. If no activity - push will happen
-		})
-	}
-
+	// TODO: clear the RDS few seconds after CDS !!
+	lastClearCache = time.Now()
+	log.Infof("Cleared discovery service cache")
+	ds.sdsCache.clear()
+	V2ClearCache()
 }
 
 // ListAllEndpoints responds with all Services and is not restricted to a single service-key