helpers.go

package shimgo

import (
	"fmt"
	"net"
	"time"
)

// Brought from here: https://blog.abourget.net/en/2016/01/04/my-favorite-golang-retry-function/
func retry(attempts int, sleep time.Duration, callback func() error) (err error) {
	for i := 0; ; i++ {
		err = callback()
		if err == nil {
			return
		}

		if i >= (attempts - 1) {
			break
		}

		time.Sleep(sleep)
	}
	return fmt.Errorf("after %d attempts, last error: %s", attempts, err)
}

// Copyright 2015 The Hugo Authors. All rights reserved.
//
// 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.
//
// FindAvailablePort returns an available and valid TCP port.
func findAvailablePort() (*net.TCPAddr, error) {
	l, err := net.Listen("tcp", ":0")
	if err == nil {
		defer l.Close()
		addr := l.Addr()
		if a, ok := addr.(*net.TCPAddr); ok {
			return a, nil
		}
		return nil, fmt.Errorf("Unable to obtain a valid tcp port. %v", addr)
	}
	return nil, err
}