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addresspool.go
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addresspool.go
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/*
* This file is part of the KubeVirt project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2021 Red Hat, Inc.
*
*/
package hostdevice
import (
"fmt"
"os"
"strings"
"kubevirt.io/client-go/log"
"kubevirt.io/kubevirt/pkg/util"
)
type AddressPool struct {
addressesByResource map[string][]string
}
// NewAddressPool creates an address pool based on the provided list of resources and
// the environment variables that correspond to it.
func NewAddressPool(resourcePrefix string, resources []string) *AddressPool {
pool := &AddressPool{
addressesByResource: make(map[string][]string),
}
pool.load(resourcePrefix, resources)
return pool
}
func (p *AddressPool) load(resourcePrefix string, resources []string) {
for _, resource := range resources {
addressEnvVarName := util.ResourceNameToEnvVar(resourcePrefix, resource)
addressString, isSet := os.LookupEnv(addressEnvVarName)
if !isSet {
log.Log.Warningf("%s not set for resource %s", addressEnvVarName, resource)
continue
}
addressString = strings.TrimSuffix(addressString, ",")
if addressString != "" {
p.addressesByResource[resource] = strings.Split(addressString, ",")
} else {
p.addressesByResource[resource] = nil
}
}
}
// Pop gets the next address available to a particular resource. The
// function makes sure that the allocated address is not allocated to next
// callers, whether they request an address for the same resource or another
// resource (covering cases of addresses that are share by multiple resources).
func (p *AddressPool) Pop(resource string) (string, error) {
addresses, exists := p.addressesByResource[resource]
if !exists {
return "", fmt.Errorf("resource %s does not exist", resource)
}
if len(addresses) > 0 {
selectedAddress := addresses[0]
for resourceName, resourceAddresses := range p.addressesByResource {
p.addressesByResource[resourceName] = filterOutAddress(resourceAddresses, selectedAddress)
}
return selectedAddress, nil
}
return "", fmt.Errorf("no more addresses to allocate for resource %s", resource)
}
func filterOutAddress(addrs []string, addr string) []string {
var res []string
for _, a := range addrs {
if a != addr {
res = append(res, a)
}
}
return res
}
type BestEffortAddressPool struct {
pool AddressPooler
}
// NewBestEffortAddressPool creates a pool that wraps a provided pool
// and allows `Pop` calls to always succeed (even when a resource is missing).
func NewBestEffortAddressPool(pool AddressPooler) *BestEffortAddressPool {
return &BestEffortAddressPool{pool}
}
func (p *BestEffortAddressPool) Pop(resource string) (string, error) {
address, _ := p.pool.Pop(resource)
return address, nil
}