mirror of https://github.com/k3s-io/k3s
121 lines
4.8 KiB
Go
121 lines
4.8 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package cache
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import (
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"k8s.io/api/core/v1"
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"k8s.io/apimachinery/pkg/labels"
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"k8s.io/kubernetes/pkg/scheduler/algorithm"
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schedulercache "k8s.io/kubernetes/pkg/scheduler/cache"
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)
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// Cache collects pods' information and provides node-level aggregated information.
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// It's intended for generic scheduler to do efficient lookup.
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// Cache's operations are pod centric. It does incremental updates based on pod events.
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// Pod events are sent via network. We don't have guaranteed delivery of all events:
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// We use Reflector to list and watch from remote.
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// Reflector might be slow and do a relist, which would lead to missing events.
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//
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// State Machine of a pod's events in scheduler's cache:
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//
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//
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// +-------------------------------------------+ +----+
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// | Add | | |
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// | | | | Update
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// + Assume Add v v |
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//Initial +--------> Assumed +------------+---> Added <--+
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// ^ + + | +
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// | | | | |
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// | | | Add | | Remove
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// | | | | |
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// | | | + |
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// +----------------+ +-----------> Expired +----> Deleted
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// Forget Expire
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//
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//
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// Note that an assumed pod can expire, because if we haven't received Add event notifying us
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// for a while, there might be some problems and we shouldn't keep the pod in cache anymore.
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//
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// Note that "Initial", "Expired", and "Deleted" pods do not actually exist in cache.
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// Based on existing use cases, we are making the following assumptions:
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// - No pod would be assumed twice
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// - A pod could be added without going through scheduler. In this case, we will see Add but not Assume event.
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// - If a pod wasn't added, it wouldn't be removed or updated.
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// - Both "Expired" and "Deleted" are valid end states. In case of some problems, e.g. network issue,
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// a pod might have changed its state (e.g. added and deleted) without delivering notification to the cache.
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type Cache interface {
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// AssumePod assumes a pod scheduled and aggregates the pod's information into its node.
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// The implementation also decides the policy to expire pod before being confirmed (receiving Add event).
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// After expiration, its information would be subtracted.
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AssumePod(pod *v1.Pod) error
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// FinishBinding signals that cache for assumed pod can be expired
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FinishBinding(pod *v1.Pod) error
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// ForgetPod removes an assumed pod from cache.
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ForgetPod(pod *v1.Pod) error
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// AddPod either confirms a pod if it's assumed, or adds it back if it's expired.
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// If added back, the pod's information would be added again.
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AddPod(pod *v1.Pod) error
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// UpdatePod removes oldPod's information and adds newPod's information.
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UpdatePod(oldPod, newPod *v1.Pod) error
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// RemovePod removes a pod. The pod's information would be subtracted from assigned node.
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RemovePod(pod *v1.Pod) error
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// GetPod returns the pod from the cache with the same namespace and the
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// same name of the specified pod.
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GetPod(pod *v1.Pod) (*v1.Pod, error)
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// IsAssumedPod returns true if the pod is assumed and not expired.
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IsAssumedPod(pod *v1.Pod) (bool, error)
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// AddNode adds overall information about node.
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AddNode(node *v1.Node) error
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// UpdateNode updates overall information about node.
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UpdateNode(oldNode, newNode *v1.Node) error
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// RemoveNode removes overall information about node.
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RemoveNode(node *v1.Node) error
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// UpdateNodeNameToInfoMap updates the passed infoMap to the current contents of Cache.
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// The node info contains aggregated information of pods scheduled (including assumed to be)
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// on this node.
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UpdateNodeNameToInfoMap(infoMap map[string]*schedulercache.NodeInfo) error
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// List lists all cached pods (including assumed ones).
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List(labels.Selector) ([]*v1.Pod, error)
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// FilteredList returns all cached pods that pass the filter.
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FilteredList(filter algorithm.PodFilter, selector labels.Selector) ([]*v1.Pod, error)
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// Snapshot takes a snapshot on current cache
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Snapshot() *Snapshot
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// NodeTree returns a node tree structure
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NodeTree() *NodeTree
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}
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// Snapshot is a snapshot of cache state
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type Snapshot struct {
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AssumedPods map[string]bool
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Nodes map[string]*schedulercache.NodeInfo
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}
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