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port.go
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port.go
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// Copyright 2021 The Kubernetes Authors.
//
// 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.
//
// This file was copied from the kubernetes-sigs/controller-runtime project
// https://github.com/kubernetes-sigs/controller-runtime/blob/v0.8.0/pkg/internal/testing/integration/addr/manager.go
//
// Modifications Copyright (c) 2021 SAP SE or an SAP affiliate company. All rights reserved.
package envtest
import (
"fmt"
"net"
"sync"
"time"
)
const (
portReserveTime = 1 * time.Minute
portConflictRetry = 100
)
type portCache struct {
lock sync.Mutex
ports map[int]time.Time
}
func (c *portCache) add(port int) bool {
c.lock.Lock()
defer c.lock.Unlock()
// remove outdated port
for p, t := range c.ports {
if time.Since(t) > portReserveTime {
delete(c.ports, p)
}
}
// try allocating new port
if _, ok := c.ports[port]; ok {
return false
}
c.ports[port] = time.Now()
return true
}
var cache = &portCache{
ports: make(map[int]time.Time),
}
func suggest(listenHost string) (port int, resolvedHost string, err error) {
if listenHost == "" {
listenHost = "localhost"
}
addr, err := net.ResolveTCPAddr("tcp", net.JoinHostPort(listenHost, "0"))
if err != nil {
return
}
l, err := net.ListenTCP("tcp", addr)
if err != nil {
return
}
port = l.Addr().(*net.TCPAddr).Port
defer func() {
err = l.Close()
}()
resolvedHost = addr.IP.String()
return
}
// suggestPort suggests an address a process can listen on. It returns
// a tuple consisting of a free port and the hostname resolved to its IP.
// It makes sure that new port allocated does not conflict with old ports
// allocated within 1 minute.
func suggestPort(listenHost string) (port int, resolvedHost string, err error) {
for i := 0; i < portConflictRetry; i++ {
port, resolvedHost, err = suggest(listenHost)
if err != nil {
return
}
if cache.add(port) {
return
}
}
err = fmt.Errorf("no free ports found after %d retries", portConflictRetry)
return
}