// Copyright (c) 2016-2021 Tigera, Inc. All rights reserved.

// 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 ipam

import (
	"context"
	"fmt"
	"sync"

	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"
	"k8s.io/client-go/kubernetes"

	log "github.com/sirupsen/logrus"

	v3 "github.com/projectcalico/api/pkg/apis/projectcalico/v3"

	"github.com/projectcalico/calico/libcalico-go/lib/apiconfig"
	"github.com/projectcalico/calico/libcalico-go/lib/backend"
	"github.com/projectcalico/calico/libcalico-go/lib/backend/api"
	"github.com/projectcalico/calico/libcalico-go/lib/backend/k8s"
	"github.com/projectcalico/calico/libcalico-go/lib/backend/model"
	cerrors "github.com/projectcalico/calico/libcalico-go/lib/errors"
	cnet "github.com/projectcalico/calico/libcalico-go/lib/net"
	"github.com/projectcalico/calico/libcalico-go/lib/testutils"
)

func newFakeClient() *fakeClient {
	return &fakeClient{
		createFuncs:    map[string]func(ctx context.Context, object *model.KVPair) (*model.KVPair, error){},
		updateFuncs:    map[string]func(ctx context.Context, object *model.KVPair) (*model.KVPair, error){},
		getFuncs:       map[string]func(ctx context.Context, key model.Key, revision string) (*model.KVPair, error){},
		deleteKVPFuncs: map[string]func(ctx context.Context, object *model.KVPair) (*model.KVPair, error){},
		deleteFuncs:    map[string]func(ctx context.Context, key model.Key, revision string) (*model.KVPair, error){},
		listFuncs:      map[string]func(ctx context.Context, list model.ListInterface, revision string) (*model.KVPairList, error){},
	}
}

// fakeClient implements the backend api.Client interface.
type fakeClient struct {
	createFuncs    map[string]func(ctx context.Context, object *model.KVPair) (*model.KVPair, error)
	updateFuncs    map[string]func(ctx context.Context, object *model.KVPair) (*model.KVPair, error)
	getFuncs       map[string]func(ctx context.Context, key model.Key, revision string) (*model.KVPair, error)
	deleteFuncs    map[string]func(ctx context.Context, key model.Key, revision string) (*model.KVPair, error)
	deleteKVPFuncs map[string]func(ctx context.Context, kvp *model.KVPair) (*model.KVPair, error)
	listFuncs      map[string]func(ctx context.Context, list model.ListInterface, revision string) (*model.KVPairList, error)
}

// We don't implement any of the CRUD related methods, just the Watch method to return
// a fake watcher that the test code will drive.
func (c *fakeClient) Create(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
	if f, ok := c.createFuncs[object.Key.String()]; ok {
		return f(ctx, object)
	} else if f, ok := c.createFuncs["default"]; ok {
		return f(ctx, object)
	}

	panic(fmt.Sprintf("Create called on unexpected object: %+v", object))
	return nil, nil
}
func (c *fakeClient) Update(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
	if f, ok := c.updateFuncs[object.Key.String()]; ok {
		return f(ctx, object)
	} else if f, ok := c.updateFuncs["default"]; ok {
		return f(ctx, object)
	}
	panic(fmt.Sprintf("Update called on unexpected object: %+v", object))
	return nil, nil

}
func (c *fakeClient) Apply(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
	panic("should not be called")
	return nil, nil
}

func (c *fakeClient) DeleteKVP(ctx context.Context, kvp *model.KVPair) (*model.KVPair, error) {
	if f, ok := c.deleteKVPFuncs[kvp.Key.String()]; ok {
		return f(ctx, kvp)
	} else if f, ok := c.deleteKVPFuncs["default"]; ok {
		return f(ctx, kvp)
	}

	panic(fmt.Sprintf("DeleteKVP called on unexpected object: %+v", kvp.Key))
	return nil, nil
}

func (c *fakeClient) Delete(ctx context.Context, key model.Key, revision string) (*model.KVPair, error) {
	if f, ok := c.deleteFuncs[key.String()]; ok {
		return f(ctx, key, revision)
	} else if f, ok := c.deleteFuncs["default"]; ok {
		return f(ctx, key, revision)
	}

	panic(fmt.Sprintf("Delete called on unexpected object: %+v", key))
	return nil, nil
}

func (c *fakeClient) Get(ctx context.Context, key model.Key, revision string) (*model.KVPair, error) {
	if f, ok := c.getFuncs[key.String()]; ok {
		return f(ctx, key, revision)
	} else if f, ok := c.getFuncs["default"]; ok {
		return f(ctx, key, revision)
	}
	panic(fmt.Sprintf("Get called on unexpected object: %+v", key))
	return nil, nil
}

func (c *fakeClient) Syncer(callbacks api.SyncerCallbacks) api.Syncer {
	panic("should not be called")
	return nil
}

func (c *fakeClient) EnsureInitialized() error {
	panic("should not be called")
	return nil
}

func (c *fakeClient) Clean() error {
	panic("should not be called")
	return nil
}

func (c *fakeClient) List(ctx context.Context, list model.ListInterface, revision string) (*model.KVPairList, error) {
	if f, ok := c.listFuncs[fmt.Sprintf("%s", list)]; ok {
		return f(ctx, list, revision)
	} else if f, ok := c.listFuncs["default"]; ok {
		return f(ctx, list, revision)
	}
	panic(fmt.Sprintf("List called on unexpected object: %+v", list))
	return nil, nil
}

func (c *fakeClient) Watch(ctx context.Context, list model.ListInterface, revision string) (api.WatchInterface, error) {
	panic("should not be called")
	return nil, nil
}

// backendClientAccessor is an interface used to access the backend client from the main clientv3.
type backendClientAccessor interface {
	Backend() api.Client
}

var _ = testutils.E2eDatastoreDescribe("IPAM affine block allocation tests", testutils.DatastoreAll, func(config apiconfig.CalicoAPIConfig) {

	log.SetLevel(log.DebugLevel)

	Context("IPAM block allocation race conditions", func() {

		var (
			bc           api.Client
			net          *cnet.IPNet
			ctx          context.Context
			hostA, hostB string
			fc           *fakeClient
			resv         *fakeReservations
			pools        *ipPoolAccessor
			rw           blockReaderWriter
			ic           *ipamClient
			kc           *kubernetes.Clientset
		)

		BeforeEach(func() {
			var err error

			// Make the client and clean the data store.
			bc, err = backend.NewClient(config)
			Expect(err).NotTo(HaveOccurred())
			bc.Clean()

			// If running in KDD mode, extract the k8s clientset.
			if config.Spec.DatastoreType == "kubernetes" {
				kc = bc.(*k8s.KubeClient).ClientSet
			}

			resv = &fakeReservations{}

			hostA = "host-a"
			hostB = "host-b"
			applyNode(bc, kc, hostA, nil)
			applyNode(bc, kc, hostB, nil)

			pools = &ipPoolAccessor{pools: map[string]pool{"10.0.0.0/26": {enabled: true}}}

			ctx = context.Background()

			_, net, err = cnet.ParseCIDR("10.0.0.0/26")
			Expect(err).NotTo(HaveOccurred())
		})

		It("should handle multiple racing block affinity claims from different hosts", func() {
			By("setting up the client for the test", func() {
				// Pool has room for 16 blocks.
				pls := &ipPoolAccessor{pools: map[string]pool{"10.0.0.0/22": {enabled: true}}}
				rw = blockReaderWriter{client: bc, pools: pls}
				ic = &ipamClient{
					reservations:      resv,
					client:            bc,
					pools:             pls,
					blockReaderWriter: rw,
				}
			})

			By("assigning from host twice the number of available blocks all at once", func() {
				wg := sync.WaitGroup{}
				var testErr error

				for i := 0; i < 32; i++ {
					wg.Add(1)
					j := i
					go func() {
						defer GinkgoRecover()
						defer wg.Done()

						testhost := fmt.Sprintf("host-%d", j)
						applyNode(bc, kc, testhost, nil)
						defer deleteNode(bc, kc, testhost)

						ia, err := ic.autoAssign(ctx, 1, &testhost, nil, nil, 4, testhost, 0, nil, v3.IPPoolAllowedUseWorkload)
						if err != nil {
							log.WithError(err).Errorf("Auto assign failed for host %s", testhost)
							testErr = err
						}
						if len(ia.IPs) != 1 {
							// All hosts should get an IP, although some will be from non-affine blocks.
							log.WithError(err).Errorf("No IPs assigned for host %s", testhost)
							testErr = fmt.Errorf("No IPs assigned to %s", testhost)
						}
					}()
				}

				// Wait for allocations to finish, then assert success.
				wg.Wait()
				Expect(testErr).NotTo(HaveOccurred())
			})

			By("correctly allocating affinities", func() {
				affs, err := bc.List(ctx, model.BlockAffinityListOptions{}, "")
				Expect(err).NotTo(HaveOccurred())

				// Each block in the IP pool should have exactly one corresponding affinity.
				Expect(len(affs.KVPairs)).To(Equal(16))

				// Validate the affinities.
				for _, a := range affs.KVPairs {
					log.Infof("Validaing affinity: %+v", a)
					b, err := bc.Get(ctx, model.BlockKey{CIDR: a.Key.(model.BlockAffinityKey).CIDR}, "")
					Expect(err).NotTo(HaveOccurred())
					Expect(b).NotTo(BeNil())

					// Each affinity should match the block it points to.
					Expect(*b.Value.(*model.AllocationBlock).Affinity).To(Equal(fmt.Sprintf("host:%s", a.Key.(model.BlockAffinityKey).Host)))

					// Each affinity should be confirmed.
					Expect(a.Value.(*model.BlockAffinity).State).To(Equal(model.StateConfirmed))
				}
			})

			By("checking each allocated IP is within the correct block for that host", func() {
				// Iterate through all the hosts. If the host has an affine block,
				// make sure the IPs assigned to that host are within the block.
				for i := 0; i < 32; i++ {
					hostname := fmt.Sprintf("host-%d", i)
					affs, err := bc.List(ctx, model.BlockAffinityListOptions{Host: hostname}, "")
					Expect(err).NotTo(HaveOccurred())
					if len(affs.KVPairs) != 0 {
						// This host has an affine block. Check the IP allocation is from it.
						// Get the IPs assigned to this host.
						ips, err := ic.IPsByHandle(ctx, hostname)
						Expect(err).NotTo(HaveOccurred())
						Expect(len(ips)).To(Equal(1))

						// Expect that the IP address is within the affine block.
						cidr := affs.KVPairs[0].Key.(model.BlockAffinityKey).CIDR
						ip := ips[0]
						Expect(cidr.Contains(ip.IP)).To(BeTrue())
					}
				}
			})
		})

		It("should handle multiple racing block affinity claims from the same host", func() {
			By("setting up the client for the test", func() {
				// Pool has room for 16 blocks.
				pls := &ipPoolAccessor{pools: map[string]pool{"10.0.0.0/25": {enabled: true}}}
				rw = blockReaderWriter{client: bc, pools: pls}
				ic = &ipamClient{
					client:            bc,
					pools:             pls,
					blockReaderWriter: rw,
					reservations:      resv,
				}
			})

			By("assigning from the same host several times at once", func() {
				wg := sync.WaitGroup{}
				var testErr error

				testhost := "single-host"
				applyNode(bc, kc, testhost, nil)
				for i := 0; i < 4; i++ {
					wg.Add(1)
					go func() {
						defer GinkgoRecover()
						defer wg.Done()

						ia, err := ic.autoAssign(ctx, 1, nil, nil, nil, 4, testhost, 0, nil, v3.IPPoolAllowedUseWorkload)
						if err != nil {
							log.WithError(err).Errorf("Auto assign failed for host %s", testhost)
							testErr = err
						}
						if len(ia.IPs) != 1 {
							log.WithError(err).Errorf("No IPs assigned for host %s", testhost)
							testErr = fmt.Errorf("No IPs assigned to %s", testhost)
						}
					}()
				}

				// Wait for allocations to finish, then assert success.
				wg.Wait()
				Expect(testErr).NotTo(HaveOccurred())
			})

			By("correctly allocating affinities", func() {
				affs, err := bc.List(ctx, model.BlockAffinityListOptions{}, "")
				Expect(err).NotTo(HaveOccurred())

				// Should only have a single affinity, for the test host.
				// Note: There is a known race condition where this may not always be true, resulting
				// in test flakes on this line. The race occurs when multiple calls on the same host attempt to pick a new block
				// CIDR and one of them succeeds in claiming the block before the other finishes selecting a CIDR. As a
				// result, two affine blocks are successfully claimed for the host.
				Expect(len(affs.KVPairs)).To(Equal(1))

				// For each affinity, expect the corresponding block to have the same affinity.
				for _, a := range affs.KVPairs {
					log.Infof("Validaing affinity: %+v", a)
					b, err := bc.Get(ctx, model.BlockKey{CIDR: a.Key.(model.BlockAffinityKey).CIDR}, "")
					Expect(err).NotTo(HaveOccurred())
					Expect(*b.Value.(*model.AllocationBlock).Affinity).To(Equal(fmt.Sprintf("host:%s", a.Key.(model.BlockAffinityKey).Host)))

					// Each affinity should be confirmed.
					Expect(a.Value.(*model.BlockAffinity).State).To(Equal(model.StateConfirmed))
				}
			})
		})

		It("should handle multiple racing claims for the same affinity", func() {
			By("setting up the client for the test", func() {
				// Pool has room for 16 blocks.
				pls := &ipPoolAccessor{pools: map[string]pool{"10.0.0.0/22": {enabled: true}}}
				rw = blockReaderWriter{client: bc, pools: pls}
				ic = &ipamClient{
					client:            bc,
					pools:             pls,
					blockReaderWriter: rw,
					reservations:      resv,
				}

				var err error
				_, net, err = cnet.ParseCIDR("10.0.0.0/22")
				Expect(err).NotTo(HaveOccurred())
			})

			By("racing to claim the same cidr on the same host", func() {
				wg := sync.WaitGroup{}
				var testErr error

				for i := 0; i < 4; i++ {
					wg.Add(1)
					go func() {
						defer GinkgoRecover()
						defer wg.Done()

						testhost := "same-host"
						success, failed, err := ic.ClaimAffinity(ctx, *net, testhost)
						if err != nil {
							log.WithError(err).Errorf("ClaimAffinity failed for host %s", testhost)
							testErr = err
						}
						if len(failed) != 0 || len(success) != 16 {
							s := fmt.Sprintf("%s failed to claim affinity for %v, succeeded on %v", testhost, failed, success)
							log.WithError(err).Error(s)
							testErr = fmt.Errorf(s)
						}
					}()
				}

				// Wait for allocations to finish, then assert success.
				wg.Wait()
				Expect(testErr).NotTo(HaveOccurred())
			})

			By("correctly allocating affinities", func() {
				affs, err := bc.List(ctx, model.BlockAffinityListOptions{}, "")
				Expect(err).NotTo(HaveOccurred())

				// Each block in the IP pool should have exactly one corresponding affinity.
				Expect(len(affs.KVPairs)).To(Equal(16))

				// Validate the affinities.
				for _, a := range affs.KVPairs {
					log.Infof("Validaing affinity: %+v", a)
					b, err := bc.Get(ctx, model.BlockKey{CIDR: a.Key.(model.BlockAffinityKey).CIDR}, "")
					Expect(err).NotTo(HaveOccurred())

					// Each affinity should match the block it points to.
					Expect(*b.Value.(*model.AllocationBlock).Affinity).To(Equal(fmt.Sprintf("host:%s", a.Key.(model.BlockAffinityKey).Host)))

					// Each affinity should be confirmed.
					Expect(a.Value.(*model.BlockAffinity).State).To(Equal(model.StateConfirmed))
				}
			})

			By("racing to release the affinities", func() {
				wg := sync.WaitGroup{}
				var testErr error

				for i := 0; i < 4; i++ {
					wg.Add(1)
					go func() {
						defer GinkgoRecover()
						defer wg.Done()

						testhost := "same-host"
						err := ic.ReleaseAffinity(ctx, *net, testhost, false)
						if err != nil {
							log.WithError(err).Errorf("Failed to release affinity for host %s", testhost)
							testErr = err
						}

					}()
				}

				// Wait for releases to finish, then assert success.
				wg.Wait()
				Expect(testErr).NotTo(HaveOccurred())
			})
		})

		It("should handle releasing an affinity while another claim has created the block", func() {
			// Tests the scenario where:
			// - hostA proc1 marks the affinity pending
			// - hostA proc1 creates the block
			// - hostA proc2 marks the affinity pending delete.
			// - hostA proc2 deletes the block
			// - hostA proc1 tries to confirm the affinity.
			// - hostA proc2 deletes the affinity (not included in test).
			// Expect that hostA proc 1 fails to confirm the affinity, leaving it in pending state.

			blockKVP := model.KVPair{
				Key:   model.BlockKey{CIDR: *net},
				Value: &model.AllocationBlock{},
			}
			affinityKVP := model.KVPair{
				Key:   model.BlockAffinityKey{Host: hostA, CIDR: *net},
				Value: &model.BlockAffinity{},
			}

			By("setting up the client for the test", func() {
				fc = newFakeClient()

				// Sneak in a side-effect such that when hostA-proc1 tries to create the block,
				// it actually simulates the other process marking the affinity as pending delete
				// and deletes the block.
				fc.createFuncs[blockKVP.Key.String()] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
					// Mark the affinity pending deletion. Query the affinity and update it.
					a, err := bc.Get(ctx, affinityKVP.Key, "")
					if err != nil {
						panic(err)
					}
					a.Value.(*model.BlockAffinity).State = model.StatePendingDeletion
					_, err = bc.Update(ctx, a)
					if err != nil {
						panic(err)
					}

					// Don't actually create the block (simulates another process deleting it), but return it
					// so the calling code thinks it succeeded.
					return object, nil
				}

				// For any other objects, just create/update them as normal.
				fc.createFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) { return bc.Create(ctx, object) }
				fc.updateFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) { return bc.Update(ctx, object) }
				fc.getFuncs["default"] = func(ctx context.Context, k model.Key, r string) (*model.KVPair, error) { return bc.Get(ctx, k, r) }

				rw = blockReaderWriter{client: fc, pools: pools}
				ic = &ipamClient{
					client:            bc,
					pools:             pools,
					blockReaderWriter: rw,
					reservations:      resv,
				}
			})

			By("attempting to claim the block", func() {
				pa, err := rw.getPendingAffinity(ctx, hostA, *net)
				Expect(err).NotTo(HaveOccurred())

				config := IPAMConfig{}
				_, err = rw.claimAffineBlock(ctx, pa, config, nil)
				Expect(err).NotTo(BeNil())

				// Should hit a resource update conflict.
				_, ok := err.(cerrors.ErrorResourceUpdateConflict)
				Expect(ok).To(BeTrue())
			})

			By("verifying that hostA was not able to claim the affinity as confirmed", func() {
				// On a real system, the releasing process would delete the affinity, but since this
				// is a mock the best we can do is assert that the affinity hasn't been confirmed by the
				// affinity claim request.
				a, err := bc.Get(ctx, affinityKVP.Key, "")
				Expect(err).NotTo(HaveOccurred())
				Expect(a.Value.(*model.BlockAffinity).State).NotTo(Equal(model.StateConfirmed))
			})
		})

		It("should handle claiming an affinity while it is being deleted", func() {
			// Tests the scenario where:
			// - hostA proc1 marks the affinity pending deletion.
			// - hostA proc1 deletes the block.
			// - hostA proc2 marks the affinity pending.
			// - hostA proc2 creates the block.
			// - hostA proc1 tries to delete the affinity.

			var (
				blockKVP, affinityKVP model.KVPair
			)

			By("setting up the client for the test", func() {
				b := newBlock(*net, nil)
				blockKVP = model.KVPair{
					Key:   model.BlockKey{CIDR: *net},
					Value: b.AllocationBlock,
				}
				affinityKVP = model.KVPair{
					Key:   model.BlockAffinityKey{Host: hostA, CIDR: *net},
					Value: &model.BlockAffinity{},
				}

				fc = newFakeClient()

				// Sneak in a side-effect such that when hostA-proc1 tries to delete the block,
				// it actually simulates the other process marking the affinity as pending
				// and creating the block.
				fc.deleteKVPFuncs[blockKVP.Key.String()] = func(ctx context.Context, kvp *model.KVPair) (*model.KVPair, error) {
					// Delete the block, but then immediately create it again below to simulate another process claiming
					// the block.
					kvp, err := bc.DeleteKVP(ctx, kvp)

					// Mark the affinity pending. Query the affinity and update it.
					a, err := bc.Get(ctx, affinityKVP.Key, "")
					if err != nil {
						panic(err)
					}

					a.Value.(*model.BlockAffinity).State = model.StatePending
					_, err = bc.Update(ctx, a)
					if err != nil {
						panic(err)
					}

					// We don't want to return an error on create, just panic.
					// We'll return the delete from error if there as one.
					kvp.Revision = ""
					_, nerr := bc.Create(ctx, kvp)
					if nerr != nil {
						panic(nerr)
					}
					return kvp, err
				}

				// For any other objects, just create/update/delete them as normal.
				fc.createFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) { return bc.Create(ctx, object) }
				fc.updateFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) { return bc.Update(ctx, object) }
				fc.deleteKVPFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
					return bc.DeleteKVP(ctx, object)
				}
				fc.getFuncs["default"] = func(ctx context.Context, k model.Key, r string) (*model.KVPair, error) { return bc.Get(ctx, k, r) }

				rw = blockReaderWriter{client: fc, pools: pools}
				ic = &ipamClient{
					client:            bc,
					pools:             pools,
					blockReaderWriter: rw,
					reservations:      resv,
				}
			})

			By("creating the affinity and block", func() {
				_, err := bc.Create(ctx, &affinityKVP)
				Expect(err).To(BeNil())

				_, err = bc.Create(ctx, &blockKVP)
				Expect(err).To(BeNil())
			})

			By("attempting to release the block", func() {
				err := rw.releaseBlockAffinity(ctx, hostA, *net, false)
				Expect(err).NotTo(BeNil())

				// Should hit a resource update conflict.
				_, ok := err.(cerrors.ErrorResourceUpdateConflict)
				Expect(ok).To(BeTrue())
			})
		})

		It("should support multiple async block affinity claims on the same block", func() {
			affStrA := fmt.Sprintf("host:%s", hostA)
			affStrB := fmt.Sprintf("host:%s", hostB)

			// Configure a fake client such that we successfully create the
			// block affininty, but fail to create the actual block.
			fc := newFakeClient()

			// Creation function for a block affinity - actually create it.
			affKVP := &model.KVPair{
				Key:   model.BlockAffinityKey{Host: hostA, CIDR: *net},
				Value: &model.BlockAffinity{},
			}
			affKVP2 := &model.KVPair{
				Key:   model.BlockAffinityKey{Host: hostB, CIDR: *net},
				Value: &model.BlockAffinity{State: model.StateConfirmed},
			}

			fc.createFuncs[affKVP.Key.String()] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
				// Create the affinity for the other racing host.
				_, err := bc.Create(ctx, affKVP2)
				if err != nil {
					return nil, err
				}

				// And create it for the host requesting it.
				return bc.Create(ctx, object)
			}

			// Creation function for the actual block - should return an error indicating the block
			// was already taken by another host.
			b := newBlock(*net, nil)
			b.Affinity = &affStrA
			blockKVP := &model.KVPair{
				Key:   model.BlockKey{CIDR: *net},
				Value: b.AllocationBlock,
			}

			b2 := newBlock(*net, nil)
			b2.Affinity = &affStrB
			blockKVP2 := &model.KVPair{
				Key:   model.BlockKey{CIDR: *net},
				Value: b2.AllocationBlock,
			}
			fc.createFuncs[blockKVP.Key.String()] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
				// Create the "stolen" block from the other racing host.
				_, err := bc.Create(ctx, blockKVP2)
				if err != nil {
					return nil, err
				}

				// Return that the object already exists.
				return nil, cerrors.ErrorResourceAlreadyExists{}
			}

			// Get function for the block. The first time, it should return nil to indicate nobody has the block. On subsequent calls,
			// return the real data from etcd representing the block belonging to another host.
			calls := 0
			fc.getFuncs[blockKVP.Key.String()] = func(ctx context.Context, k model.Key, r string) (*model.KVPair, error) {
				return func(ctx context.Context, k model.Key, r string) (*model.KVPair, error) {
					calls++

					if calls == 1 {
						// First time the block doesn't exist yet.
						return nil, cerrors.ErrorResourceDoesNotExist{}
					}
					return bc.Get(ctx, k, r)
				}(ctx, k, r)
			}

			fc.getFuncs["default"] = func(ctx context.Context, k model.Key, r string) (*model.KVPair, error) {
				return bc.Get(ctx, k, r)
			}

			// Delete function for the affinity - this should fail, triggering the scenario under test where two hosts now think they
			// have affinity to the block.
			deleteCalls := 0
			fc.deleteKVPFuncs[affKVP.Key.String()] = func(ctx context.Context, kvp *model.KVPair) (*model.KVPair, error) {
				return func(ctx context.Context, kvp *model.KVPair) (*model.KVPair, error) {
					deleteCalls = deleteCalls + 1

					if deleteCalls == 1 {
						// First time around, the delete fails - this triggers the scenario.
						return nil, fmt.Errorf("block affinity deletion failure")
					}

					// Subsequent calls succeed.
					return bc.DeleteKVP(ctx, kvp)
				}(ctx, kvp)
			}

			// List function should behave normally.
			fc.listFuncs["default"] = func(ctx context.Context, list model.ListInterface, revision string) (*model.KVPairList, error) {
				return bc.List(ctx, list, revision)
			}

			// Update function should behave normally.
			fc.updateFuncs["default"] = func(ctx context.Context, kvp *model.KVPair) (*model.KVPair, error) {
				return bc.Update(ctx, kvp)
			}

			// Create the block reader / writer which will simulate the failure scenario.
			rw = blockReaderWriter{client: fc, pools: pools}
			ic = &ipamClient{
				client:            bc,
				pools:             pools,
				blockReaderWriter: rw,
				reservations:      resv,
			}

			By("attempting to claim the block on multiple hosts at the same time", func() {
				ia, err := ic.autoAssign(ctx, 1, nil, nil, nil, 4, hostA, 0, nil, v3.IPPoolAllowedUseWorkload)

				// Shouldn't return an error.
				Expect(err).NotTo(HaveOccurred())

				// Should return a single IP.
				Expect(len(ia.IPs)).To(Equal(1))
			})

			By("checking that the other host has the affinity", func() {
				// The block should have the affinity field set properly.
				opts := model.BlockAffinityListOptions{Host: hostB}
				objs, err := rw.client.List(ctx, opts, "")
				Expect(err).NotTo(HaveOccurred())

				// Should be a single block affinity, assigned to the other host.
				Expect(len(objs.KVPairs)).To(Equal(1))
				Expect(objs.KVPairs[0].Value.(*model.BlockAffinity).State).To(Equal(model.StateConfirmed))
			})

			By("checking that the requested host does not have a confirmed affinity", func() {
				// The block should have the affinity field set properly.
				opts := model.BlockAffinityListOptions{Host: hostA}
				objs, err := rw.client.List(ctx, opts, "")
				Expect(err).NotTo(HaveOccurred())
				Expect(len(objs.KVPairs)).To(Equal(1))
				Expect(objs.KVPairs[0].Value.(*model.BlockAffinity).State).To(Equal(model.StatePending))
			})

			By("attempting to claim another address", func() {
				ia, err := ic.autoAssign(ctx, 1, nil, nil, nil, 4, hostA, 0, nil, v3.IPPoolAllowedUseWorkload)

				// Shouldn't return an error.
				Expect(err).NotTo(HaveOccurred())

				// Should return a single IP.
				Expect(len(ia.IPs)).To(Equal(1))
			})

			By("checking that the pending affinity was cleaned up", func() {
				// The block should have the affinity field set properly.
				opts := model.BlockAffinityListOptions{Host: hostA}
				objs, err := rw.client.List(ctx, opts, "")
				Expect(err).NotTo(HaveOccurred())

				// Should be a single block affinity, assigned to the other host.
				Expect(len(objs.KVPairs)).To(Equal(0))
			})
		})

		It("should not delete an IPAM block when affinity released when empty but another process allocates an IP at the same time", func() {
			// Tests the scenario where:
			// - hostA proc1 queries for the block
			// - hostA proc2 queries for the block
			// - hostA proc2 releases affinity (marks PendingDeletion)
			// - hostA proc1 allocates IP from block
			// - hostA proc1 updates block
			// - hostA proc2 attempts to delete block (tries to mark but fails)
			b := newBlock(*net, nil)
			aff := "host:" + hostA
			b.AllocationBlock.Affinity = &aff
			blockKVP := model.KVPair{
				Key:   model.BlockKey{CIDR: *net},
				Value: b.AllocationBlock,
			}

			affinityKVP := model.KVPair{
				Key: model.BlockAffinityKey{Host: hostA, CIDR: *net},
				Value: &model.BlockAffinity{
					State: model.StateConfirmed,
				},
			}

			By("setting up the client for the test", func() {
				fc = newFakeClient()

				// Sneak in a side-effect such that when hostA-proc1 tries to release the affinity of an empty block,
				// another IP will get allocated from it.
				call := 0
				fc.updateFuncs[affinityKVP.Key.String()] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
					updated, err := bc.Update(ctx, object)
					if err != nil {
						return nil, err
					}

					call++
					if call == 1 {
						// proc1 allocates an IP from block
						kvpb, err := bc.Get(ctx, blockKVP.Key, "")
						if err != nil {
							return nil, err
						}
						b1 := allocationBlock{kvpb.Value.(*model.AllocationBlock)}
						b1.autoAssign(1, nil, hostA, nil, false, nilAddrFilter{})
						if _, err := bc.Update(ctx, kvpb); err != nil {
							return nil, err
						}
					}

					return updated, nil
				}

				// For any other objects, just create/update/delete them as normal.
				fc.createFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) { return bc.Create(ctx, object) }
				fc.updateFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) { return bc.Update(ctx, object) }
				fc.deleteKVPFuncs["default"] = func(ctx context.Context, object *model.KVPair) (*model.KVPair, error) {
					return bc.DeleteKVP(ctx, object)
				}
				fc.getFuncs["default"] = func(ctx context.Context, k model.Key, r string) (*model.KVPair, error) { return bc.Get(ctx, k, r) }

				rw = blockReaderWriter{client: fc, pools: pools}
				ic = &ipamClient{
					client:            bc,
					pools:             pools,
					blockReaderWriter: rw,
					reservations:      resv,
				}
			})

			By("allocating an IP and creating a block", func() {
				_, err := bc.Create(ctx, &blockKVP)
				Expect(err).To(BeNil())

				_, err = bc.Create(ctx, &affinityKVP)
				Expect(err).To(BeNil())
			})

			By("calling ReleaseAffinity", func() {
				err := ic.ReleaseAffinity(ctx, *net, hostA, false)
				Expect(err).NotTo(HaveOccurred())
			})

			By("verfiying that the block was not deleted", func() {
				b, err := bc.Get(ctx, blockKVP.Key, "")
				Expect(err).To(BeNil())
				Expect(b).NotTo(BeNil())
			})
		})
	})

	Context("test claiming / releasing affinities", func() {
		var (
			rw   blockReaderWriter
			p    *ipPoolAccessor
			bc   api.Client
			ctx  context.Context
			host string
			net  *cnet.IPNet
		)

		BeforeEach(func() {
			var err error

			// Make the client and clean the data store.
			bc, err = backend.NewClient(config)
			Expect(err).NotTo(HaveOccurred())
			bc.Clean()

			// Create a fake client which we can use to simulate data store
			// error situations.
			// fc := newFakeClient()

			// Configure a BRW with a real datastore client.
			rw = blockReaderWriter{
				client: bc,
				pools:  p,
			}
			p = &ipPoolAccessor{pools: map[string]pool{}}
			ctx = context.Background()

			_, net, err = cnet.ParseCIDR("10.1.0.0/26")
			Expect(err).NotTo(HaveOccurred())

			host = "test-hostname"
		})

		It("should claim and release a block affinity", func() {
			By("claiming an affinity for a host", func() {
				pa, err := rw.getPendingAffinity(ctx, host, *net)
				Expect(err).NotTo(HaveOccurred())

				config := IPAMConfig{}
				_, err = rw.claimAffineBlock(ctx, pa, config, nil)
				Expect(err).NotTo(HaveOccurred())
			})

			By("claiming the existing affinity again", func() {
				pa, err := rw.getPendingAffinity(ctx, host, *net)
				Expect(err).NotTo(HaveOccurred())

				config := IPAMConfig{}
				_, err = rw.claimAffineBlock(ctx, pa, config, nil)
				Expect(err).NotTo(HaveOccurred())
			})

			By("checking the affinity exists", func() {
				k := model.BlockAffinityKey{Host: host, CIDR: *net}
				aff, err := bc.Get(ctx, k, "")
				Expect(err).NotTo(HaveOccurred())
				Expect(aff.Value.(*model.BlockAffinity).State).To(Equal(model.StateConfirmed))
			})

			By("checking the block exists", func() {
				k := model.BlockKey{CIDR: *net}
				_, err := bc.Get(ctx, k, "")
				Expect(err).NotTo(HaveOccurred())
			})

			By("releasing the affinity", func() {
				err := rw.releaseBlockAffinity(ctx, host, *net, false)
				Expect(err).NotTo(HaveOccurred())
			})

			By("checking the affinity no longer exists", func() {
				k := model.BlockAffinityKey{Host: host, CIDR: *net}
				_, err := bc.Get(ctx, k, "")
				Expect(err).To(HaveOccurred())
			})

			By("checking the block no longer exists", func() {
				k := model.BlockKey{CIDR: *net}
				_, err := bc.Get(ctx, k, "")
				Expect(err).To(HaveOccurred())
			})

			By("releasing the affinity again", func() {
				err := rw.releaseBlockAffinity(ctx, host, *net, false)
				Expect(err).To(HaveOccurred())
				_, ok := err.(cerrors.ErrorResourceDoesNotExist)
				Expect(ok).To(BeTrue())
			})
		})
	})

	Context("test block allocation with host reserves", func() {
		var (
			rw       blockReaderWriter
			p        *ipPoolAccessor
			bc       api.Client
			ctx      context.Context
			host     string
			net      *cnet.IPNet
			kc       *kubernetes.Clientset
			rsvdAttr *HostReservedAttr
		)

		BeforeEach(func() {
			var err error

			// Make the client and clean the data store.
			bc, err = backend.NewClient(config)
			Expect(err).NotTo(HaveOccurred())
			bc.Clean()

			// If running in KDD mode, extract the k8s clientset.
			if config.Spec.DatastoreType == "kubernetes" {
				kc = bc.(*k8s.KubeClient).ClientSet
			}

			// Configure a BRW with a real datastore client.
			rw = blockReaderWriter{
				client: bc,
				pools:  p,
			}
			p = &ipPoolAccessor{pools: map[string]pool{"10.0.0.0/30": {enabled: true, blockSize: 30, cidr: "10.0.0.0/30"}}}
			ctx = context.Background()

			_, net, err = cnet.ParseCIDR("10.0.0.0/30")
			Expect(err).NotTo(HaveOccurred())

			host = "test-hostname"
			applyNode(bc, kc, host, nil)

			rsvdAttr = &HostReservedAttr{
				StartOfBlock: 2,
				EndOfBlock:   1,
				Handle:       "test-handle",
				Note:         "ipam ut",
			}
		})

		It("should allocate new block", func() {
			b := newBlock(*net, rsvdAttr)
			// Block should have one unallocated IP and one attribute.
			Expect(b.NumFreeAddresses(nilAddrFilter{})).To(Equal(1))
			Expect(len(b.Attributes)).To(Equal(1))
			// First two IPs should point at the reservation, as should the last.
			// The only IP available for allocation is the third one.
			Expect(*b.Allocations[0]).To(Equal(0))
			Expect(*b.Allocations[1]).To(Equal(0))
			Expect(b.Allocations[2]).To(BeNil())
			Expect(*b.Allocations[3]).To(Equal(0))
			// Attributes[0] should be the reservation attribute.
			Expect(*b.Attributes[0].AttrPrimary).To(Equal("test-handle"))
			Expect(b.Attributes[0].AttrSecondary["note"]).To(Equal("ipam ut"))

		})

		It("should allocate one ip", func() {
			ic := &ipamClient{
				client:            bc,
				pools:             p,
				blockReaderWriter: rw,
				reservations:      &fakeReservations{},
			}
			ia, err := ic.autoAssign(ctx, 1, nil, nil, nil, 4, host, 0, rsvdAttr, v3.IPPoolAllowedUseTunnel /* for variety */)
			Expect(err).ShouldNot(HaveOccurred())
			Expect(len(ia.IPs)).To(Equal(1))
			Expect(ia.IPs[0].String()).To(Equal("10.0.0.2/30"))
		})
	})
})

var _ = testutils.E2eDatastoreDescribe("IPAM affine block allocation tests (kdd only)", testutils.DatastoreK8s, func(config apiconfig.CalicoAPIConfig) {

	var (
		bc  api.Client
		net *cnet.IPNet
		ctx context.Context
	)

	BeforeEach(func() {
		var err error
		bc, err = backend.NewClient(config)
		Expect(err).NotTo(HaveOccurred())
		bc.Clean()
		ctx = context.Background()
		_, net, err = cnet.ParseCIDR("10.0.0.0/26")
		Expect(err).NotTo(HaveOccurred())
	})

	It("should respect Kubernetes UID for affinities", func() {
		// Create a block affinity
		initKVP := &model.KVPair{
			Key:   model.BlockAffinityKey{Host: "somehost", CIDR: *net},
			Value: &model.BlockAffinity{},
		}
		kvpa, err := bc.Create(ctx, initKVP)
		Expect(err).NotTo(HaveOccurred())

		// Delete the block affinity, and re-create it.
		_, err = bc.DeleteKVP(ctx, kvpa)
		Expect(err).NotTo(HaveOccurred())
		kvpb, err := bc.Create(ctx, initKVP)
		Expect(err).NotTo(HaveOccurred())

		// Try to delete it using the original UID - it should fail.
		_, err = bc.DeleteKVP(ctx, kvpa)
		Expect(err).To(HaveOccurred())

		// Try to delete it using the new UID - it should succeed.
		_, err = bc.DeleteKVP(ctx, kvpb)
		Expect(err).NotTo(HaveOccurred())
	})

	It("should respect Kubernetes UID for blocks", func() {
		// Create a block
		initKVP := &model.KVPair{
			Key: model.BlockKey{CIDR: *net},
			Value: &model.AllocationBlock{
				CIDR:        cnet.MustParseCIDR("10.0.1.0/29"),
				Allocations: []*int{nil, nil, nil},
				Unallocated: []int{0, 1, 2},
			},
		}
		kvpa, err := bc.Create(ctx, initKVP)
		Expect(err).NotTo(HaveOccurred())

		// Delete the block, and re-create it.
		_, err = bc.DeleteKVP(ctx, kvpa)
		Expect(err).NotTo(HaveOccurred())
		kvpb, err := bc.Create(ctx, initKVP)
		Expect(err).NotTo(HaveOccurred())

		// Try to delete it using the original UID - it should fail.
		_, err = bc.DeleteKVP(ctx, kvpa)
		Expect(err).To(HaveOccurred())

		// Try to delete it using the new UID - it should succeed.
		_, err = bc.DeleteKVP(ctx, kvpb)
		Expect(err).NotTo(HaveOccurred())
	})

	It("should respect Kubernetes UID for handles", func() {
		// Create a handle
		initKVP := &model.KVPair{
			Key: model.IPAMHandleKey{HandleID: "someid"},
			Value: &model.IPAMHandle{
				HandleID: "someid",
				Block:    map[string]int{"block1": 1},
			},
		}
		kvpa, err := bc.Create(ctx, initKVP)
		Expect(err).NotTo(HaveOccurred())

		// Delete the handle, and re-create it.
		_, err = bc.DeleteKVP(ctx, kvpa)
		Expect(err).NotTo(HaveOccurred())
		kvpb, err := bc.Create(ctx, initKVP)
		Expect(err).NotTo(HaveOccurred())

		// Try to delete it using the original UID - it should fail.
		_, err = bc.DeleteKVP(ctx, kvpa)
		Expect(err).To(HaveOccurred())

		// Try to delete it using the new UID - it should succeed.
		_, err = bc.DeleteKVP(ctx, kvpb)
		Expect(err).NotTo(HaveOccurred())
	})

})
