Adding EndpointSliceMirroring controller

This will mirror custom Endpoints to EndpointSlices to ensure that
applications will not need to maintain both separately.

pkg/controller/endpointslicemirroring/reconciler_helpers.go

@@ -0,0 +1,137 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package endpointslicemirroring
+
+import (
+	"k8s.io/api/core/v1"
+	discovery "k8s.io/api/discovery/v1beta1"
+)
+
+// slicesByAction includes lists of slices to create, update, or delete.
+type slicesByAction struct {
+	toCreate, toUpdate, toDelete []*discovery.EndpointSlice
+}
+
+// append appends slices from another slicesByAction struct.
+func (s *slicesByAction) append(slices slicesByAction) {
+	s.toCreate = append(s.toCreate, slices.toCreate...)
+	s.toUpdate = append(s.toUpdate, slices.toUpdate...)
+	s.toDelete = append(s.toDelete, slices.toDelete...)
+}
+
+// totalsByAction includes total numbers for added and removed.
+type totalsByAction struct {
+	added, updated, removed int
+}
+
+// add adds totals from another totalsByAction struct.
+func (t *totalsByAction) add(totals totalsByAction) {
+	t.added += totals.added
+	t.updated += totals.updated
+	t.removed += totals.removed
+}
+
+// newDesiredCalc initializes and returns a new desiredCalc.
+func newDesiredCalc() *desiredCalc {
+	return &desiredCalc{
+		portsByKey:          map[addrTypePortMapKey][]discovery.EndpointPort{},
+		endpointsByKey:      map[addrTypePortMapKey]endpointSet{},
+		numDesiredEndpoints: 0,
+	}
+}
+
+// desiredCalc helps calculate desired endpoints and ports.
+type desiredCalc struct {
+	portsByKey          map[addrTypePortMapKey][]discovery.EndpointPort
+	endpointsByKey      map[addrTypePortMapKey]endpointSet
+	numDesiredEndpoints int
+}
+
+// multiAddrTypePortMapKey stores addrTypePortMapKey for different address
+// types.
+type multiAddrTypePortMapKey map[discovery.AddressType]addrTypePortMapKey
+
+// initPorts initializes ports for a subset and address type and returns the
+// corresponding addrTypePortMapKey.
+func (d *desiredCalc) initPorts(subsetPorts []v1.EndpointPort) multiAddrTypePortMapKey {
+	endpointPorts := epPortsToEpsPorts(subsetPorts)
+	addrTypes := []discovery.AddressType{discovery.AddressTypeIPv4, discovery.AddressTypeIPv6}
+	multiKey := multiAddrTypePortMapKey{}
+
+	for _, addrType := range addrTypes {
+		multiKey[addrType] = newAddrTypePortMapKey(endpointPorts, addrType)
+		if _, ok := d.endpointsByKey[multiKey[addrType]]; !ok {
+			d.endpointsByKey[multiKey[addrType]] = endpointSet{}
+		}
+		d.portsByKey[multiKey[addrType]] = endpointPorts
+	}
+
+	return multiKey
+}
+
+// addAddress adds an EndpointAddress to the desired state if it is valid. It
+// returns false if the address was invalid.
+func (d *desiredCalc) addAddress(address v1.EndpointAddress, multiKey multiAddrTypePortMapKey, ready bool) bool {
+	endpoint := addressToEndpoint(address, ready)
+	addrType := getAddressType(address.IP)
+	if addrType == nil {
+		return false
+	}
+
+	d.endpointsByKey[multiKey[*addrType]].Insert(endpoint)
+	d.numDesiredEndpoints++
+	return true
+}
+
+type slicesByAddrType map[discovery.AddressType][]*discovery.EndpointSlice
+
+// recycleSlices will recycle the slices marked for deletion by replacing
+// creates with updates of slices that would otherwise be deleted.
+func recycleSlices(slices *slicesByAction) {
+	toCreateByAddrType := toSlicesByAddrType(slices.toCreate)
+	toDeleteByAddrType := toSlicesByAddrType(slices.toDelete)
+
+	for addrType, slicesToCreate := range toCreateByAddrType {
+		slicesToDelete := toDeleteByAddrType[addrType]
+		for i := 0; len(slicesToCreate) > i && len(slicesToDelete) > i; i++ {
+			slices.toCreate = removeSlice(slices.toCreate, slicesToCreate[i])
+			slices.toDelete = removeSlice(slices.toDelete, slicesToDelete[i])
+			slice := slicesToCreate[i]
+			slice.Name = slicesToDelete[i].Name
+			slices.toUpdate = append(slices.toUpdate, slice)
+		}
+	}
+}
+
+// removeSlice removes an EndpointSlice from a list of EndpointSlices.
+func removeSlice(slices []*discovery.EndpointSlice, sliceToRemove *discovery.EndpointSlice) []*discovery.EndpointSlice {
+	for i, slice := range slices {
+		if slice.Name == sliceToRemove.Name {
+			return append(slices[:i], slices[i+1:]...)
+		}
+	}
+	return slices
+}
+
+// toSliceByAddrType returns lists of EndpointSlices grouped by address.
+func toSlicesByAddrType(slices []*discovery.EndpointSlice) slicesByAddrType {
+	byAddrType := slicesByAddrType{}
+	for _, slice := range slices {
+		byAddrType[slice.AddressType] = append(byAddrType[slice.AddressType], slice)
+	}
+	return byAddrType
+}