1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
// Copyright 2020 PingCAP, Inc.
//
// 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package utils
import (
"net"
"sync"
"time"
)
// To avoid the same port be generated twice in a short time
var portCache sync.Map
func getFreePort(host string, defaultPort int) (int, error) {
//revive:disable
if port, err := getPort(host, defaultPort); err == nil {
return port, nil
} else if port, err := getPort(host, 0); err == nil {
return port, nil
} else {
return 0, err
}
//revive:enable
}
// MustGetFreePort asks the kernel for a free open port that is ready to use, if fail, panic
func MustGetFreePort(host string, defaultPort int, portOffset int) int {
bestPort := defaultPort + portOffset
if port, err := getFreePort(host, bestPort); err == nil {
return port
}
panic("can't get a free port")
}
func getPort(host string, port int) (int, error) {
addr, err := net.ResolveTCPAddr("tcp", JoinHostPort(host, port))
if err != nil {
return 0, err
}
l, err := net.ListenTCP("tcp", addr)
if err != nil {
return 0, err
}
port = l.Addr().(*net.TCPAddr).Port
l.Close()
key := JoinHostPort(host, port)
if t, ok := portCache.Load(key); ok && t.(time.Time).Add(time.Minute).After(time.Now()) {
return getPort(host, (port+1)%65536)
}
portCache.Store(key, time.Now())
return port, nil
}
|
