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feat: More optimal IterateHierarchyV2 and iterateChildrenV2 [argoproj…
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…#600] (argoproj#601)

* chore: More optimal IterateHierarchyV2 and iterateChildrenV2 [argoproj#600]

Closes argoproj#600

The existing (effectively v1) implementations are suboptimal since they don't construct a graph before the iteration. They search for children by looking at all namespace resources and checking `isParentOf`, which can give `O(tree_size * namespace_resources_count)` time complexity. The v2 algorithms construct the graph and have `O(namespace_resources_count)` time complexity. See more details in the linked issues.

Signed-off-by: Andrii Korotkov <andrii.korotkov@verkada.com>

* improvements to graph building

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* use old name

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* chore: More optimal IterateHierarchyV2 and iterateChildrenV2 [argoproj#600]

Closes argoproj#600

The existing (effectively v1) implementations are suboptimal since they don't construct a graph before the iteration. They search for children by looking at all namespace resources and checking `isParentOf`, which can give `O(tree_size * namespace_resources_count)` time complexity. The v2 algorithms construct the graph and have `O(namespace_resources_count)` time complexity. See more details in the linked issues.

Signed-off-by: Andrii Korotkov <andrii.korotkov@verkada.com>

* finish merge

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* chore: More optimal IterateHierarchyV2 and iterateChildrenV2 [argoproj#600]

Closes argoproj#600

The existing (effectively v1) implementations are suboptimal since they don't construct a graph before the iteration. They search for children by looking at all namespace resources and checking `isParentOf`, which can give `O(tree_size * namespace_resources_count)` time complexity. The v2 algorithms construct the graph and have `O(namespace_resources_count)` time complexity. See more details in the linked issues.

Signed-off-by: Andrii Korotkov <andrii.korotkov@verkada.com>

* discard unneeded copies of child resources as we go

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* remove unnecessary comment

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* make childrenByUID sparse

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* eliminate duplicate map

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* fix comment

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* add useful comment back

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* use nsNodes instead of dupe map

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* remove unused struct

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* skip invalid APIVersion

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

---------

Signed-off-by: Andrii Korotkov <andrii.korotkov@verkada.com>
Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>
Co-authored-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>
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@andrii-korotkov-verkada @crenshaw-dev @mpelekh
2 people authored and mpelekh committed Aug 27, 2024
1 parent 67b6776 commit 03c6077
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Showing 5 changed files with 405 additions and 34 deletions.
104 changes: 104 additions & 0 deletions pkg/cache/cluster.go
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,9 @@ type ClusterCache interface {
// IterateHierarchy iterates resource tree starting from the specified top level resource and executes callback for each resource in the tree.
// The action callback returns true if iteration should continue and false otherwise.
IterateHierarchy(key kube.ResourceKey, action func(resource *Resource, namespaceResources map[kube.ResourceKey]*Resource) bool)
// IterateHierarchyV2 iterates resource tree starting from the specified top level resources and executes callback for each resource in the tree.
// The action callback returns true if iteration should continue and false otherwise.
IterateHierarchyV2(keys []kube.ResourceKey, action func(resource *Resource, namespaceResources map[kube.ResourceKey]*Resource) bool)
// IsNamespaced answers if specified group/kind is a namespaced resource API or not
IsNamespaced(gk schema.GroupKind) (bool, error)
// GetManagedLiveObjs helps finding matching live K8S resources for a given resources list.
Expand Down Expand Up @@ -1023,6 +1026,107 @@ func (c *clusterCache) IterateHierarchy(key kube.ResourceKey, action func(resour
}
}

// IterateHierarchy iterates resource tree starting from the specified top level resources and executes callback for each resource in the tree
func (c *clusterCache) IterateHierarchyV2(keys []kube.ResourceKey, action func(resource *Resource, namespaceResources map[kube.ResourceKey]*Resource) bool) {
c.lock.RLock()
defer c.lock.RUnlock()
keysPerNamespace := make(map[string][]kube.ResourceKey)
for _, key := range keys {
_, ok := c.resources[key]
if !ok {
continue
}
keysPerNamespace[key.Namespace] = append(keysPerNamespace[key.Namespace], key)
}
for namespace, namespaceKeys := range keysPerNamespace {
nsNodes := c.nsIndex[namespace]
graph := buildGraph(nsNodes)
visited := make(map[kube.ResourceKey]int)
for _, key := range namespaceKeys {
visited[key] = 0
}
for _, key := range namespaceKeys {
// The check for existence of key is done above.
res := c.resources[key]
if visited[key] == 2 || !action(res, nsNodes) {
continue
}
visited[key] = 1
if _, ok := graph[key]; ok {
for _, child := range graph[key] {
if visited[child.ResourceKey()] == 0 && action(child, nsNodes) {
child.iterateChildrenV2(graph, nsNodes, visited, func(err error, child *Resource, namespaceResources map[kube.ResourceKey]*Resource) bool {
if err != nil {
c.log.V(2).Info(err.Error())
return false
}
return action(child, namespaceResources)
})
}
}
}
visited[key] = 2
}
}
}

func buildGraph(nsNodes map[kube.ResourceKey]*Resource) map[kube.ResourceKey]map[types.UID]*Resource {
// Prepare to construct a graph
nodesByUID := make(map[types.UID][]*Resource, len(nsNodes))
for _, node := range nsNodes {
nodesByUID[node.Ref.UID] = append(nodesByUID[node.Ref.UID], node)
}

// In graph, they key is the parent and the value is a list of children.
graph := make(map[kube.ResourceKey]map[types.UID]*Resource)

// Loop through all nodes, calling each one "childNode," because we're only bothering with it if it has a parent.
for _, childNode := range nsNodes {
for i, ownerRef := range childNode.OwnerRefs {
// First, backfill UID of inferred owner child references.
if ownerRef.UID == "" {
group, err := schema.ParseGroupVersion(ownerRef.APIVersion)
if err != nil {
// APIVersion is invalid, so we couldn't find the parent.
continue
}
graphKeyNode, ok := nsNodes[kube.ResourceKey{Group: group.Group, Kind: ownerRef.Kind, Namespace: childNode.Ref.Namespace, Name: ownerRef.Name}]
if ok {
ownerRef.UID = graphKeyNode.Ref.UID
childNode.OwnerRefs[i] = ownerRef
} else {
// No resource found with the given graph key, so move on.
continue
}
}

// Now that we have the UID of the parent, update the graph.
uidNodes, ok := nodesByUID[ownerRef.UID]
if ok {
for _, uidNode := range uidNodes {
// Update the graph for this owner to include the child.
if _, ok := graph[uidNode.ResourceKey()]; !ok {
graph[uidNode.ResourceKey()] = make(map[types.UID]*Resource)
}
r, ok := graph[uidNode.ResourceKey()][childNode.Ref.UID]
if !ok {
graph[uidNode.ResourceKey()][childNode.Ref.UID] = childNode
} else if r != nil {
// The object might have multiple children with the same UID (e.g. replicaset from apps and extensions group).
// It is ok to pick any object, but we need to make sure we pick the same child after every refresh.
key1 := r.ResourceKey()
key2 := childNode.ResourceKey()
if strings.Compare(key1.String(), key2.String()) > 0 {
graph[uidNode.ResourceKey()][childNode.Ref.UID] = childNode
}
}
}
}
}
}
return graph
}

// IsNamespaced answers if specified group/kind is a namespaced resource API or not
func (c *clusterCache) IsNamespaced(gk schema.GroupKind) (bool, error) {
if isNamespaced, ok := c.namespacedResources[gk]; ok {
Expand Down
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