set nil cache entry based on old cache

fix tests

update old entry logic

staging/src/k8s.io/legacy-cloud-providers/azure/azure_cache.go

@@ -38,6 +38,9 @@ const (
 	// active/expired. If entry doesn't exist in cache, then data is fetched
 	// using getter, saved in cache and returned
 	cacheReadTypeUnsafe
+	// cacheReadTypeForceRefresh force refreshes the cache even if the cache entry
+	// is not expired
+	cacheReadTypeForceRefresh
 )
 
 // getFunc defines a getter function for timedCache.
@@ -120,20 +123,20 @@ func (t *timedCache) Get(key string, crt cacheReadType) (interface{}, error) {
 	entry.lock.Lock()
 	defer entry.lock.Unlock()
 
-	// entry exists
-	if entry.data != nil {
+	// entry exists and if cache is not force refreshed
+	if entry.data != nil && crt != cacheReadTypeForceRefresh {
 		// allow unsafe read, so return data even if expired
 		if crt == cacheReadTypeUnsafe {
 			return entry.data, nil
 		}
 		// if cached data is not expired, return cached data
-		if time.Since(entry.createdOn) < t.ttl {
+		if crt == cacheReadTypeDefault && time.Since(entry.createdOn) < t.ttl {
 			return entry.data, nil
 		}
 	}
-	// Data is not cached yet or cache data is expired, cache it by getter.
-	// entry is locked before getting to ensure concurrent gets don't result in
-	// multiple ARM calls.
+	// Data is not cached yet, cache data is expired or requested force refresh
+	// cache it by getter. entry is locked before getting to ensure concurrent
+	// gets don't result in multiple ARM calls.
 	data, err := t.getter(key)
 	if err != nil {
 		return nil, err

staging/src/k8s.io/legacy-cloud-providers/azure/azure_cache_test.go

@@ -204,3 +204,23 @@ func TestCacheNoConcurrentGet(t *testing.T) {
 	assert.Equal(t, 1, dataSource.called)
 	assert.Equal(t, val, v, "cache should get correct data")
 }
+
+func TestCacheForceRefresh(t *testing.T) {
+	key := "key1"
+	val := &fakeDataObj{}
+	data := map[string]*fakeDataObj{
+		key: val,
+	}
+	dataSource, cache := newFakeCache(t)
+	dataSource.set(data)
+
+	v, err := cache.Get(key, cacheReadTypeDefault)
+	assert.NoError(t, err)
+	assert.Equal(t, 1, dataSource.called)
+	assert.Equal(t, val, v, "cache should get correct data")
+
+	v, err = cache.Get(key, cacheReadTypeForceRefresh)
+	assert.NoError(t, err)
+	assert.Equal(t, 2, dataSource.called)
+	assert.Equal(t, val, v, "should refetch unexpired data as forced refresh")
+}

staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss.go

@@ -130,19 +130,21 @@ func (ss *scaleSet) getVMSS(vmssName string, crt cacheReadType) (*compute.Virtua
 // getVmssVM gets virtualMachineScaleSetVM by nodeName from cache.
 // It returns cloudprovider.InstanceNotFound if node does not belong to any scale sets.
 func (ss *scaleSet) getVmssVM(nodeName string, crt cacheReadType) (string, string, *compute.VirtualMachineScaleSetVM, error) {
-	getter := func(nodeName string) (string, string, *compute.VirtualMachineScaleSetVM, error) {
+	getter := func(nodeName string, crt cacheReadType) (string, string, *compute.VirtualMachineScaleSetVM, bool, error) {
+		var found bool
 		cached, err := ss.vmssVMCache.Get(vmssVirtualMachinesKey, crt)
 		if err != nil {
-			return "", "", nil, err
+			return "", "", nil, found, err
 		}
 
 		virtualMachines := cached.(*sync.Map)
 		if vm, ok := virtualMachines.Load(nodeName); ok {
 			result := vm.(*vmssVirtualMachinesEntry)
-			return result.vmssName, result.instanceID, result.virtualMachine, nil
+			found = true
+			return result.vmssName, result.instanceID, result.virtualMachine, found, nil
 		}
 
-		return "", "", nil, nil
+		return "", "", nil, found, nil
 	}
 
 	_, err := getScaleSetVMInstanceID(nodeName)
@@ -150,22 +152,24 @@ func (ss *scaleSet) getVmssVM(nodeName string, crt cacheReadType) (string, strin
 		return "", "", nil, err
 	}
 
-	vmssName, instanceID, vm, err := getter(nodeName)
+	vmssName, instanceID, vm, found, err := getter(nodeName, crt)
 	if err != nil {
 		return "", "", nil, err
 	}
-	if vm != nil {
+
+	if !found {
+		klog.V(3).Infof("Couldn't find VMSS VM with nodeName %s, refreshing the cache", nodeName)
+		vmssName, instanceID, vm, found, err = getter(nodeName, cacheReadTypeForceRefresh)
+		if err != nil {
+			return "", "", nil, err
+		}
+	}
+
+	if found && vm != nil {
 		return vmssName, instanceID, vm, nil
 	}
 
-	klog.V(3).Infof("Couldn't find VMSS VM with nodeName %s, refreshing the cache", nodeName)
-	ss.vmssVMCache.Delete(vmssVirtualMachinesKey)
-	vmssName, instanceID, vm, err = getter(nodeName)
-	if err != nil {
-		return "", "", nil, err
-	}
-
-	if vm == nil {
+	if !found || vm == nil {
 		return "", "", nil, cloudprovider.InstanceNotFound
 	}
 	return vmssName, instanceID, vm, nil
@@ -196,7 +200,7 @@ func (ss *scaleSet) GetPowerStatusByNodeName(name string) (powerState string, er
 // getCachedVirtualMachineByInstanceID gets scaleSetVMInfo from cache.
 // The node must belong to one of scale sets.
 func (ss *scaleSet) getVmssVMByInstanceID(resourceGroup, scaleSetName, instanceID string, crt cacheReadType) (*compute.VirtualMachineScaleSetVM, error) {
-	getter := func() (vm *compute.VirtualMachineScaleSetVM, found bool, err error) {
+	getter := func(crt cacheReadType) (vm *compute.VirtualMachineScaleSetVM, found bool, err error) {
 		cached, err := ss.vmssVMCache.Get(vmssVirtualMachinesKey, crt)
 		if err != nil {
 			return nil, false, err
@@ -219,21 +223,21 @@ func (ss *scaleSet) getVmssVMByInstanceID(resourceGroup, scaleSetName, instanceI
 		return vm, found, nil
 	}
 
-	vm, found, err := getter()
-	if err != nil {
-		return nil, err
-	}
-	if found {
-		return vm, nil
-	}
-
-	klog.V(3).Infof("Couldn't find VMSS VM with scaleSetName %q and instanceID %q, refreshing the cache", scaleSetName, instanceID)
-	ss.vmssVMCache.Delete(vmssVirtualMachinesKey)
-	vm, found, err = getter()
+	vm, found, err := getter(crt)
 	if err != nil {
 		return nil, err
 	}
 	if !found {
+		klog.V(3).Infof("Couldn't find VMSS VM with scaleSetName %q and instanceID %q, refreshing the cache", scaleSetName, instanceID)
+		vm, found, err = getter(cacheReadTypeForceRefresh)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if found && vm != nil {
+		return vm, nil
+	}
+	if !found || vm == nil {
 		return nil, cloudprovider.InstanceNotFound
 	}
 

staging/src/k8s.io/legacy-cloud-providers/azure/azure_vmss_cache.go

@@ -111,6 +111,26 @@ func (ss *scaleSet) newVMSSVirtualMachinesCache() (*timedCache, error) {
 	getter := func(key string) (interface{}, error) {
 		localCache := &sync.Map{} // [nodeName]*vmssVirtualMachinesEntry
 
+		oldCache := make(map[string]vmssVirtualMachinesEntry)
+
+		if ss.vmssVMCache != nil {
+			// get old cache before refreshing the cache
+			entry, exists, err := ss.vmssVMCache.store.GetByKey(vmssVirtualMachinesKey)
+			if err != nil {
+				return nil, err
+			}
+			if exists {
+				cached := entry.(*cacheEntry).data
+				if cached != nil {
+					virtualMachines := cached.(*sync.Map)
+					virtualMachines.Range(func(key, value interface{}) bool {
+						oldCache[key.(string)] = *value.(*vmssVirtualMachinesEntry)
+						return true
+					})
+				}
+			}
+		}
+
 		allResourceGroups, err := ss.GetResourceGroups()
 		if err != nil {
 			return nil, err
@@ -143,8 +163,38 @@ func (ss *scaleSet) newVMSSVirtualMachinesCache() (*timedCache, error) {
 						virtualMachine: &vm,
 						lastUpdate:     time.Now().UTC(),
 					})
+
+					if _, exists := oldCache[computerName]; exists {
+						delete(oldCache, computerName)
+					}
 				}
 			}
+
+			// add old missing cache data with nil entries to prevent aggressive
+			// ARM calls during cache invalidation
+			for name, vmEntry := range oldCache {
+				// if the nil cache entry has existed for 15 minutes in the cache
+				// then it should not be added back to the cache
+				if vmEntry.virtualMachine == nil || time.Since(vmEntry.lastUpdate) > 15*time.Minute {
+					klog.V(5).Infof("ignoring expired entries from old cache for %s", name)
+					continue
+				}
+				lastUpdate := time.Now().UTC()
+				if vmEntry.virtualMachine == nil {
+					// if this is already a nil entry then keep the time the nil
+					// entry was first created, so we can cleanup unwanted entries
+					lastUpdate = vmEntry.lastUpdate
+				}
+
+				klog.V(5).Infof("adding old entries to new cache for %s", name)
+				localCache.Store(name, &vmssVirtualMachinesEntry{
+					resourceGroup:  vmEntry.resourceGroup,
+					vmssName:       vmEntry.vmssName,
+					instanceID:     vmEntry.instanceID,
+					virtualMachine: nil,
+					lastUpdate:     lastUpdate,
+				})
+			}
 		}
 
 		return localCache, nil