105 lines
3.2 KiB
Go
105 lines
3.2 KiB
Go
/*
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Copyright 2021 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 request
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import (
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"fmt"
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"net/http"
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"time"
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apirequest "k8s.io/apiserver/pkg/endpoints/request"
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"k8s.io/klog/v2"
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)
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const (
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// the minimum number of seats a request must occupy
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minimumSeats = 1
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// the maximum number of seats a request can occupy
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maximumSeats = 10
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)
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type WorkEstimate struct {
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// InitialSeats is the number of seats occupied while the server is
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// executing this request.
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InitialSeats uint
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// FinalSeats is the number of seats occupied at the end,
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// during the AdditionalLatency.
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FinalSeats uint
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// AdditionalLatency specifies the additional duration the seats allocated
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// to this request must be reserved after the given request had finished.
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// AdditionalLatency should not have any impact on the user experience, the
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// caller must not experience this additional latency.
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AdditionalLatency time.Duration
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}
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// MaxSeats returns the number of seats this request requires, it is the maximum
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// of the two, WorkEstimate.InitialSeats and WorkEstimate.FinalSeats.
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func (we *WorkEstimate) MaxSeats() int {
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if we.InitialSeats >= we.FinalSeats {
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return int(we.InitialSeats)
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}
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return int(we.FinalSeats)
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}
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// objectCountGetterFunc represents a function that gets the total
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// number of objects for a given resource.
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type objectCountGetterFunc func(string) (int64, error)
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// NewWorkEstimator estimates the work that will be done by a given request,
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// if no WorkEstimatorFunc matches the given request then the default
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// work estimate of 1 seat is allocated to the request.
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func NewWorkEstimator(countFn objectCountGetterFunc) WorkEstimatorFunc {
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estimator := &workEstimator{
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listWorkEstimator: newListWorkEstimator(countFn),
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}
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return estimator.estimate
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}
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// WorkEstimatorFunc returns the estimated work of a given request.
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// This function will be used by the Priority & Fairness filter to
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// estimate the work of of incoming requests.
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type WorkEstimatorFunc func(*http.Request) WorkEstimate
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func (e WorkEstimatorFunc) EstimateWork(r *http.Request) WorkEstimate {
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return e(r)
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}
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type workEstimator struct {
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// listWorkEstimator estimates work for list request(s)
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listWorkEstimator WorkEstimatorFunc
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}
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func (e *workEstimator) estimate(r *http.Request) WorkEstimate {
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requestInfo, ok := apirequest.RequestInfoFrom(r.Context())
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if !ok {
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klog.ErrorS(fmt.Errorf("no RequestInfo found in context"), "Failed to estimate work for the request", "URI", r.RequestURI)
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// no RequestInfo should never happen, but to be on the safe side let's return maximumSeats
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return WorkEstimate{InitialSeats: maximumSeats}
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}
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switch requestInfo.Verb {
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case "list":
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return e.listWorkEstimator.EstimateWork(r)
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}
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return WorkEstimate{InitialSeats: minimumSeats}
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}
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