73 lines
2.6 KiB
Go
73 lines
2.6 KiB
Go
/*
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Copyright 2020 PayPal.
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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 katbox
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import (
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"errors"
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"math"
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"os"
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"path/filepath"
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"github.com/golang/glog"
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)
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// fullpath returns the location where the katbox volume will be created inside the container
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// running the katbox plugin
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func fullpath(workdir, podUUID, p string) string {
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return filepath.Join(workdir, podUUID, p)
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}
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// pressureFactor returns a value to be used with afterlife calculations.
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// The more space we're using in the head room, the more aggressive the early eviction should be.
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// Therefore, as the the ratio of headroom space available diminishes, our ratio gets lower and lower.
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// Since we will be multiplying by a type time.Duration which is added to the deletion time, we multiply by
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// the complement of the percentage of used headroom.
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// e.g:
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// 40% of our headroom is being used. Therefore we need to reduce the afterlife by 40% (use 60% of afterlife).
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// e.g: 600 seconds * .60 = 360 seconds.
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// Thus when we check if we should evict, the calculation will be done using 360 seconds after the delete
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// happened instead of 600 after the delete happened.
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// This concept is inspired by the Apache Mesos disk pressure feature.
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func pressureFactor(total, free uint64, headroom float64) (float64, error) {
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if headroom < 0.0 || headroom > 1.0 {
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return 0, errors.New("headroom must be a value between 0 and 1.0 (inclusive)")
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}
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headroomSpace := uint64(math.Ceil(float64(total) * headroom))
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glog.V(5).Infof("Total Size: %v\nTotal Free: %v\nTotal Headroom Space: %v", total, free, headroomSpace)
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if free >= headroomSpace {
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return 1.0, nil
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}
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// Determines how far into the headroom space we currently are and returns the inverse as that's how
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// much of the afterlife we should be using.
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return 1.0 - float64(headroomSpace-free)/float64(headroomSpace), nil
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}
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// makeFile ensures that the file exists, creating it if necessary.
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// The parent directory must exist.
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func makeFile(pathname string) error {
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f, err := os.OpenFile(pathname, os.O_CREATE, os.FileMode(0644))
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defer f.Close()
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if err != nil {
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if !os.IsExist(err) {
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return err
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}
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}
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return nil
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}
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