utils.go

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strings"

	"github.com/Sirupsen/logrus"
)

// fatal prints the error's details if it is a libcontainer specific error type
// then exits the program with an exit status of 1.
func fatal(err error) {
	// make sure the error is written to the logger
	logrus.Error(err)
	fmt.Fprintln(os.Stderr, err)
	os.Exit(1)
}

func Uniq(list []string) []string {
	uniqset := make(map[string]bool, len(list))
	for _, x := range list {
		uniqset[x] = true
	}
	result := make([]string, 0, len(uniqset))
	for x := range uniqset {
		result = append(result, x)
	}
	return result
}

func MergeNumArray2NumRange(array []int) string {
	var i = 0
	var result = ""

	for j, value := range array {
		if j == len(array)-1 {
			if i == j {
				result += fmt.Sprintf("%d", array[j])
			} else {
				result += fmt.Sprintf("%d-%d", array[i], array[j])
			}
			break
		}

		if value != array[j+1]-1 {
			if j == i {
				result += fmt.Sprintf("%d,", array[i])
			} else {
				result += fmt.Sprintf("%d-%d,", array[i], array[j])
			}
			i = j + 1
		}
	}

	return result
}

func ToInterfaceArray(in []string) []interface{} {
	result := make([]interface{}, len(in))

	for i, val := range in {
		result[i] = interface{}(val)
	}

	return result
}

func ToStringArray(in []interface{}) []string {
	result := make([]string, len(in))

	for i, val := range in {
		result[i] = fmt.Sprintf("%s", val)
	}

	return result
}

func YesOrDie(msg string) {
	fmt.Printf("%s (type 'yes' to accept): ", msg)

	reader := bufio.NewReader(os.Stdin)
	text, _ := reader.ReadString('\n')

	if !strings.EqualFold(strings.TrimSpace(text), "yes") {
		logrus.Fatalf("*** Aborting...")
	}
}

func Round(num float64) int {
	return int(num + math.Copysign(0.5, num))
}

func ClusterNodeArray2String(nodes [](*ClusterNode)) (result string) {
	for _, node := range nodes {
		if node != nil {
			result += node.String() + ","
		}
	}

	if len(result) > 0 {
		strings.TrimRight(result, ",")
	}

	return result
}

func NumArray2String(nums []int) (result string) {
	if len(nums) > 0 {
		result = fmt.Sprintf("%d", nums[0])
		for _, id := range nums[1:] {
			result += fmt.Sprintf("%s,%d", result, id)
		}
		if len(result) > 0 {
			strings.TrimRight(result, ",")
		}
	}
	return result
}

/* CRC16 implementation according to CCITT standards.
 *
 * Note by @antirez: this is actually the XMODEM CRC 16 algorithm, using the
 * following parameters:
 *
 * Name                       : "XMODEM", also known as "ZMODEM", "CRC-16/ACORN"
 * Width                      : 16 bit
 * Poly                       : 1021 (That is actually x^16 + x^12 + x^5 + 1)
 * Initialization             : 0000
 * Reflect Input byte         : False
 * Reflect Output CRC         : False
 * Xor constant to output CRC : 0000
 * Output for "123456789"     : 31C3
 */

var crc16tab = [...]uint16{
	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
	0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
	0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
	0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
	0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
	0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
	0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
	0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
	0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
	0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
	0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
	0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
	0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
	0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
	0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
	0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
	0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
	0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
	0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
	0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
	0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
	0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
	0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
	0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
	0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
	0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
	0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
	0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
	0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
	0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
	0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
}

func crc16(s string) uint16 {
	var crc uint16
	for i := 0; i < len(s); i++ {
		b := s[i]
		crc = (crc << 8) ^ crc16tab[byte(crc>>8)^b]
	}
	return crc
}

const (
	HASHTAG_START    = "{"
	HASHTAG_END      = "}"
	DEFAULT_SLOT_NUM = 16384
)

// Turn a key name into the corrisponding Redis Cluster slot.
func Key2Slot(key string) uint16 {
	// Only hash what is inside {...} if there is such a pattern in the key.
	// Note that the specification requires the content that is between
	// the first { and the first } after the first {. If we found {} without
	// nothing in the middle, the whole key is hashed as usually.
	hashKey := key

	start := strings.Index(key, HASHTAG_START)
	if start >= 0 {
		end := strings.LastIndex(key, HASHTAG_END)
		if end >= 0 && start < end {
			hashKey = key[start:end]
		}
	}

	return crc16(hashKey) % DEFAULT_SLOT_NUM
}