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Types ¶
type Cache ¶
type Cache interface { // AssumePod assumes a pod scheduled and aggregates the pod's information into its node. // The implementation also decides the policy to expire pod before being confirmed (receiving Add event). // After expiration, its information would be subtracted. AssumePod(pod *v1.Pod) error // FinishBinding signals that cache for assumed pod can be expired FinishBinding(pod *v1.Pod) error // ForgetPod removes an assumed pod from cache. ForgetPod(pod *v1.Pod) error // AddPod either confirms a pod if it's assumed, or adds it back if it's expired. // If added back, the pod's information would be added again. AddPod(pod *v1.Pod) error // UpdatePod removes oldPod's information and adds newPod's information. UpdatePod(oldPod, newPod *v1.Pod) error // RemovePod removes a pod. The pod's information would be subtracted from assigned node. RemovePod(pod *v1.Pod) error // GetPod returns the pod from the cache with the same namespace and the // same name of the specified pod. GetPod(pod *v1.Pod) (*v1.Pod, error) // IsAssumedPod returns true if the pod is assumed and not expired. IsAssumedPod(pod *v1.Pod) (bool, error) // AddNode adds overall information about node. AddNode(node *v1.Node) error // UpdateNode updates overall information about node. UpdateNode(oldNode, newNode *v1.Node) error // RemoveNode removes overall information about node. RemoveNode(node *v1.Node) error // UpdateNodeInfoSnapshot updates the passed infoSnapshot to the current contents of Cache. // The node info contains aggregated information of pods scheduled (including assumed to be) // on this node. UpdateNodeInfoSnapshot(nodeSnapshot *NodeInfoSnapshot) error // List lists all cached pods (including assumed ones). List(labels.Selector) ([]*v1.Pod, error) // FilteredList returns all cached pods that pass the filter. FilteredList(filter algorithm.PodFilter, selector labels.Selector) ([]*v1.Pod, error) // Snapshot takes a snapshot on current cache Snapshot() *Snapshot // NodeTree returns a node tree structure NodeTree() *NodeTree }
Cache collects pods' information and provides node-level aggregated information. It's intended for generic scheduler to do efficient lookup. Cache's operations are pod centric. It does incremental updates based on pod events. Pod events are sent via network. We don't have guaranteed delivery of all events: We use Reflector to list and watch from remote. Reflector might be slow and do a relist, which would lead to missing events.
State Machine of a pod's events in scheduler's cache:
+-------------------------------------------+ +----+ | Add | | | | | | | Update + Assume Add v v |
Initial +--------> Assumed +------------+---> Added <--+
^ + + | + | | | | | | | | Add | | Remove | | | | | | | | + | +----------------+ +-----------> Expired +----> Deleted Forget Expire
Note that an assumed pod can expire, because if we haven't received Add event notifying us for a while, there might be some problems and we shouldn't keep the pod in cache anymore.
Note that "Initial", "Expired", and "Deleted" pods do not actually exist in cache. Based on existing use cases, we are making the following assumptions:
- No pod would be assumed twice
- A pod could be added without going through scheduler. In this case, we will see Add but not Assume event.
- If a pod wasn't added, it wouldn't be removed or updated.
- Both "Expired" and "Deleted" are valid end states. In case of some problems, e.g. network issue, a pod might have changed its state (e.g. added and deleted) without delivering notification to the cache.
type NodeInfoSnapshot ¶ added in v1.14.1
type NodeInfoSnapshot struct { NodeInfoMap map[string]*schedulernodeinfo.NodeInfo Generation int64 }
NodeInfoSnapshot is a snapshot of cache NodeInfo. The scheduler takes a snapshot at the beginning of each scheduling cycle and uses it for its operations in that cycle.
func NewNodeInfoSnapshot ¶ added in v1.14.1
func NewNodeInfoSnapshot() NodeInfoSnapshot
NewNodeInfoSnapshot initializes a NodeInfoSnapshot struct and returns it.
type NodeTree ¶
type NodeTree struct {
// contains filtered or unexported fields
}
NodeTree is a tree-like data structure that holds node names in each zone. Zone names are keys to "NodeTree.tree" and values of "NodeTree.tree" are arrays of node names.
func (*NodeTree) AddNode ¶
AddNode adds a node and its corresponding zone to the tree. If the zone already exists, the node is added to the array of nodes in that zone.
func (*NodeTree) Next ¶
Next returns the name of the next node. NodeTree iterates over zones and in each zone iterates over nodes in a round robin fashion.
func (*NodeTree) RemoveNode ¶
RemoveNode removes a node from the NodeTree.
func (*NodeTree) UpdateNode ¶
UpdateNode updates a node in the NodeTree.