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allocation_cache.go
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allocation_cache.go
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// Copyright 2021 Google LLC 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 gameserverallocations
import (
"context"
"sort"
"agones.dev/agones/pkg/apis/agones"
agonesv1 "agones.dev/agones/pkg/apis/agones/v1"
allocationv1 "agones.dev/agones/pkg/apis/allocation/v1"
informerv1 "agones.dev/agones/pkg/client/informers/externalversions/agones/v1"
listerv1 "agones.dev/agones/pkg/client/listers/agones/v1"
"agones.dev/agones/pkg/gameservers"
"agones.dev/agones/pkg/util/logfields"
"agones.dev/agones/pkg/util/runtime"
"agones.dev/agones/pkg/util/workerqueue"
"github.com/heptiolabs/healthcheck"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/client-go/tools/cache"
)
type matcher func(*agonesv1.GameServer) bool
// readyOrAllocatedGameServerMatcher returns true when a GameServer is in a Ready or Allocated state.
func readyOrAllocatedGameServerMatcher(gs *agonesv1.GameServer) bool {
return gs.Status.State == agonesv1.GameServerStateReady || gs.Status.State == agonesv1.GameServerStateAllocated
}
// AllocationCache maintains a cache of GameServers that could potentially be allocated.
type AllocationCache struct {
baseLogger *logrus.Entry
cache gameServerCache
gameServerLister listerv1.GameServerLister
gameServerSynced cache.InformerSynced
workerqueue *workerqueue.WorkerQueue
counter *gameservers.PerNodeCounter
matcher matcher
}
// NewAllocationCache creates a new instance of AllocationCache
func NewAllocationCache(informer informerv1.GameServerInformer, counter *gameservers.PerNodeCounter, health healthcheck.Handler) *AllocationCache {
c := &AllocationCache{
gameServerSynced: informer.Informer().HasSynced,
gameServerLister: informer.Lister(),
counter: counter,
matcher: readyOrAllocatedGameServerMatcher,
}
_, _ = informer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
UpdateFunc: func(oldObj, newObj interface{}) {
// only interested in if the old / new state was/is Ready
oldGs := oldObj.(*agonesv1.GameServer)
newGs := newObj.(*agonesv1.GameServer)
key, ok := c.getKey(newGs)
if !ok {
return
}
if oldGs.ObjectMeta.ResourceVersion == newGs.ObjectMeta.ResourceVersion {
return
}
switch {
case newGs.IsBeingDeleted():
c.cache.Delete(key)
case c.matcher(newGs):
c.cache.Store(key, newGs)
case c.matcher(oldGs):
c.cache.Delete(key)
}
},
DeleteFunc: func(obj interface{}) {
gs, ok := obj.(*agonesv1.GameServer)
if !ok {
return
}
var key string
if key, ok = c.getKey(gs); ok {
c.cache.Delete(key)
}
},
})
c.baseLogger = runtime.NewLoggerWithType(c)
c.workerqueue = workerqueue.NewWorkerQueue(c.SyncGameServers, c.baseLogger, logfields.GameServerKey, agones.GroupName+".AllocationCache")
health.AddLivenessCheck("allocationcache-workerqueue", healthcheck.Check(c.workerqueue.Healthy))
return c
}
func (c *AllocationCache) loggerForGameServerKey(key string) *logrus.Entry {
return logfields.AugmentLogEntry(c.baseLogger, logfields.GameServerKey, key)
}
// RemoveGameServer removes a gameserver from the cache of game servers
func (c *AllocationCache) RemoveGameServer(gs *agonesv1.GameServer) error {
key, _ := cache.MetaNamespaceKeyFunc(gs)
if ok := c.cache.Delete(key); !ok {
return ErrConflictInGameServerSelection
}
return nil
}
// Sync builds the initial cache from the current set GameServers in the cluster
func (c *AllocationCache) Sync(ctx context.Context) error {
c.baseLogger.Debug("Wait for AllocationCache cache sync")
if !cache.WaitForCacheSync(ctx.Done(), c.gameServerSynced) {
return errors.New("failed to wait for caches to sync")
}
// build the cache
return c.syncCache()
}
// Resync enqueues an empty game server to be synced. Using queue helps avoiding multiple threads syncing at the same time.
func (c *AllocationCache) Resync() {
// this will trigger syncing of the cache (assuming cache might not be up to date)
c.workerqueue.EnqueueImmediately(&agonesv1.GameServer{})
}
// Run prepares cache to start
func (c *AllocationCache) Run(ctx context.Context) error {
if err := c.Sync(ctx); err != nil {
return err
}
// we don't want mutiple workers refresh cache at the same time so one worker will be better.
// Also we don't expect to have too many failures when allocating
go c.workerqueue.Run(ctx, 1)
return nil
}
// AddGameServer adds a gameserver to the cache of allocatable GameServers
func (c *AllocationCache) AddGameServer(gs *agonesv1.GameServer) {
key, _ := cache.MetaNamespaceKeyFunc(gs)
c.cache.Store(key, gs)
}
// getGameServers returns a list of game servers in the cache.
func (c *AllocationCache) getGameServers() []*agonesv1.GameServer {
length := c.cache.Len()
if length == 0 {
return nil
}
list := make([]*agonesv1.GameServer, 0, length)
c.cache.Range(func(_ string, gs *agonesv1.GameServer) bool {
list = append(list, gs)
return true
})
return list
}
// ListSortedGameServers returns a list of the cached gameservers
// sorted by most allocated to least.
func (c *AllocationCache) ListSortedGameServers(gsa *allocationv1.GameServerAllocation) []*agonesv1.GameServer {
list := c.getGameServers()
if list == nil {
return []*agonesv1.GameServer{}
}
counts := c.counter.Counts()
sort.Slice(list, func(i, j int) bool {
gs1 := list[i]
gs2 := list[j]
// Search Allocated GameServers first.
if gs1.Status.State != gs2.Status.State {
return gs1.Status.State == agonesv1.GameServerStateAllocated
}
c1, ok := counts[gs1.Status.NodeName]
if !ok {
return false
}
c2, ok := counts[gs2.Status.NodeName]
if !ok {
return true
}
if c1.Allocated > c2.Allocated {
return true
}
if c1.Allocated < c2.Allocated {
return false
}
// prefer nodes that have the most Ready gameservers on them - they are most likely to be
// completely filled and least likely target for scale down.
if c1.Ready < c2.Ready {
return false
}
if c1.Ready > c2.Ready {
return true
}
// if player tracking is enabled, prefer game servers with the least amount of room left
if runtime.FeatureEnabled(runtime.FeaturePlayerAllocationFilter) {
if gs1.Status.Players != nil && gs2.Status.Players != nil {
cap1 := gs1.Status.Players.Capacity - gs1.Status.Players.Count
cap2 := gs2.Status.Players.Capacity - gs2.Status.Players.Count
// if they are equal, pass the comparison through.
if cap1 < cap2 {
return true
} else if cap2 < cap1 {
return false
}
}
}
// if we end up here, then break the tie with Counter or List Priority.
if runtime.FeatureEnabled(runtime.FeatureCountsAndLists) && (gsa != nil) {
for _, priority := range gsa.Spec.Priorities {
res := compareGameServers(&priority, gs1, gs2)
switch priority.Order {
case agonesv1.GameServerPriorityAscending:
if res == -1 {
return true
}
if res == 1 {
return false
}
case agonesv1.GameServerPriorityDescending:
if res == -1 {
return false
}
if res == 1 {
return true
}
}
}
}
// finally sort lexicographically, so we have a stable order
return gs1.GetObjectMeta().GetName() < gs2.GetObjectMeta().GetName()
})
return list
}
// ListSortedGameServersPriorities sorts and returns a list of game servers based on the
// list of Priorities.
func (c *AllocationCache) ListSortedGameServersPriorities(gsa *allocationv1.GameServerAllocation) []*agonesv1.GameServer {
list := c.getGameServers()
if list == nil {
return []*agonesv1.GameServer{}
}
sort.Slice(list, func(i, j int) bool {
gs1 := list[i]
gs2 := list[j]
if runtime.FeatureEnabled(runtime.FeatureCountsAndLists) && (gsa != nil) {
for _, priority := range gsa.Spec.Priorities {
res := compareGameServers(&priority, gs1, gs2)
switch priority.Order {
case agonesv1.GameServerPriorityAscending:
if res == -1 {
return true
}
if res == 1 {
return false
}
case agonesv1.GameServerPriorityDescending:
if res == -1 {
return false
}
if res == 1 {
return true
}
}
}
}
// finally sort lexicographically, so we have a stable order
return gs1.GetObjectMeta().GetName() < gs2.GetObjectMeta().GetName()
})
return list
}
// compareGameServers compares two game servers based on a CountsAndLists Priority using available
// capacity (Capacity - Count for Counters, and Capacity - len(Values) for Lists) as the comparison.
// Returns -1 if gs1 < gs2; 1 if gs1 > gs2; 0 if gs1 == gs2; 0 if neither gamer server has the Priority.
// If only one game server has the Priority, prefer that server. I.e. nil < gsX when Priority
// Order is Descending (3, 2, 1, 0, nil), and nil > gsX when Order is Ascending (0, 1, 2, 3, nil).
func compareGameServers(p *agonesv1.Priority, gs1, gs2 *agonesv1.GameServer) int {
var gs1ok, gs2ok bool
switch p.Type {
case agonesv1.GameServerPriorityCounter:
// Check if both game servers contain the Counter.
counter1, ok1 := gs1.Status.Counters[p.Key]
counter2, ok2 := gs2.Status.Counters[p.Key]
// If both game servers have the Counter
if ok1 && ok2 {
availCapacity1 := counter1.Capacity - counter1.Count
availCapacity2 := counter2.Capacity - counter2.Count
if availCapacity1 < availCapacity2 {
return -1
}
if availCapacity1 > availCapacity2 {
return 1
}
if availCapacity1 == availCapacity2 {
return 0
}
}
gs1ok = ok1
gs2ok = ok2
case agonesv1.GameServerPriorityList:
// Check if both game servers contain the List.
list1, ok1 := gs1.Status.Lists[p.Key]
list2, ok2 := gs2.Status.Lists[p.Key]
// If both game servers have the List
if ok1 && ok2 {
availCapacity1 := list1.Capacity - int64(len(list1.Values))
availCapacity2 := list2.Capacity - int64(len(list2.Values))
if availCapacity1 < availCapacity2 {
return -1
}
if availCapacity1 > availCapacity2 {
return 1
}
if availCapacity1 == availCapacity2 {
return 0
}
}
gs1ok = ok1
gs2ok = ok2
}
// If only one game server has the Priority, prefer that server. I.e. nil < gsX when Order is
// Descending (3, 2, 1, 0, nil), and nil > gsX when Order is Ascending (0, 1, 2, 3, nil).
if (gs1ok && p.Order == agonesv1.GameServerPriorityDescending) ||
(gs2ok && p.Order == agonesv1.GameServerPriorityAscending) {
return 1
}
if (gs1ok && p.Order == agonesv1.GameServerPriorityAscending) ||
(gs2ok && p.Order == agonesv1.GameServerPriorityDescending) {
return -1
}
// If neither game server has the Priority
return 0
}
// SyncGameServers synchronises the GameServers to Gameserver cache. This is called when a failure
// happened during the allocation. This method will sync and make sure the cache is up to date.
func (c *AllocationCache) SyncGameServers(ctx context.Context, key string) error {
c.loggerForGameServerKey(key).Debug("Refreshing Allocation Gameserver cache")
return c.syncCache()
}
// syncCache syncs the gameserver cache and updates the local cache for any changes.
func (c *AllocationCache) syncCache() error {
// build the cache
gsList, err := c.gameServerLister.List(labels.Everything())
if err != nil {
return errors.Wrap(err, "could not list GameServers")
}
// convert list of current gameservers to map for faster access
currGameservers := make(map[string]*agonesv1.GameServer)
for _, gs := range gsList {
if key, ok := c.getKey(gs); ok {
currGameservers[key] = gs
}
}
// first remove the gameservers are not in the list anymore
tobeDeletedGSInCache := make([]string, 0)
c.cache.Range(func(key string, gs *agonesv1.GameServer) bool {
if _, ok := currGameservers[key]; !ok {
tobeDeletedGSInCache = append(tobeDeletedGSInCache, key)
}
return true
})
for _, staleGSKey := range tobeDeletedGSInCache {
c.cache.Delete(staleGSKey)
}
// refresh the cache of possible allocatable GameServers
for key, gs := range currGameservers {
if gsCache, ok := c.cache.Load(key); ok {
if !(gs.DeletionTimestamp.IsZero() && c.matcher(gs)) {
c.cache.Delete(key)
} else if gs.ObjectMeta.ResourceVersion != gsCache.ObjectMeta.ResourceVersion {
c.cache.Store(key, gs)
}
} else if gs.DeletionTimestamp.IsZero() && c.matcher(gs) {
c.cache.Store(key, gs)
}
}
return nil
}
// getKey extract the key of gameserver object
func (c *AllocationCache) getKey(gs *agonesv1.GameServer) (string, bool) {
var key string
ok := true
var err error
if key, err = cache.MetaNamespaceKeyFunc(gs); err != nil {
ok = false
err = errors.Wrap(err, "Error creating key for object")
runtime.HandleError(c.baseLogger.WithField("obj", gs), err)
}
return key, ok
}