syncthing/vendor/github.com/dustin/go-humanize/bytes.go
Jakob Borg 916ec63af6 cmd/stdiscosrv: New discovery server (fixes #4618)
This is a new revision of the discovery server. Relevant changes and
non-changes:

- Protocol towards clients is unchanged.

- Recommended large scale design is still to be deployed nehind nginx (I
  tested, and it's still a lot faster at terminating TLS).

- Database backend is leveldb again, only. It scales enough, is easy to
  setup, and we don't need any backend to take care of.

- Server supports replication. This is a simple TCP channel - protect it
  with a firewall when deploying over the internet. (We deploy this within
  the same datacenter, and with firewall.) Any incoming client announces
  are sent over the replication channel(s) to other peer discosrvs.
  Incoming replication changes are applied to the database as if they came
  from clients, but without the TLS/certificate overhead.

- Metrics are exposed using the prometheus library, when enabled.

- The database values and replication protocol is protobuf, because JSON
  was quite CPU intensive when I tried that and benchmarked it.

- The "Retry-After" value for failed lookups gets slowly increased from
  a default of 120 seconds, by 5 seconds for each failed lookup,
  independently by each discosrv. This lowers the query load over time for
  clients that are never seen. The Retry-After maxes out at 3600 after a
  couple of weeks of this increase. The number of failed lookups is
  stored in the database, now and then (avoiding making each lookup a
  database put).

All in all this means clients can be pointed towards a cluster using
just multiple A / AAAA records to gain both load sharing and redundancy
(if one is down, clients will talk to the remaining ones).

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4648
2018-01-14 08:52:31 +00:00

144 lines
2.5 KiB
Go

package humanize
import (
"fmt"
"math"
"strconv"
"strings"
"unicode"
)
// IEC Sizes.
// kibis of bits
const (
Byte = 1 << (iota * 10)
KiByte
MiByte
GiByte
TiByte
PiByte
EiByte
)
// SI Sizes.
const (
IByte = 1
KByte = IByte * 1000
MByte = KByte * 1000
GByte = MByte * 1000
TByte = GByte * 1000
PByte = TByte * 1000
EByte = PByte * 1000
)
var bytesSizeTable = map[string]uint64{
"b": Byte,
"kib": KiByte,
"kb": KByte,
"mib": MiByte,
"mb": MByte,
"gib": GiByte,
"gb": GByte,
"tib": TiByte,
"tb": TByte,
"pib": PiByte,
"pb": PByte,
"eib": EiByte,
"eb": EByte,
// Without suffix
"": Byte,
"ki": KiByte,
"k": KByte,
"mi": MiByte,
"m": MByte,
"gi": GiByte,
"g": GByte,
"ti": TiByte,
"t": TByte,
"pi": PiByte,
"p": PByte,
"ei": EiByte,
"e": EByte,
}
func logn(n, b float64) float64 {
return math.Log(n) / math.Log(b)
}
func humanateBytes(s uint64, base float64, sizes []string) string {
if s < 10 {
return fmt.Sprintf("%d B", s)
}
e := math.Floor(logn(float64(s), base))
suffix := sizes[int(e)]
val := math.Floor(float64(s)/math.Pow(base, e)*10+0.5) / 10
f := "%.0f %s"
if val < 10 {
f = "%.1f %s"
}
return fmt.Sprintf(f, val, suffix)
}
// Bytes produces a human readable representation of an SI size.
//
// See also: ParseBytes.
//
// Bytes(82854982) -> 83 MB
func Bytes(s uint64) string {
sizes := []string{"B", "kB", "MB", "GB", "TB", "PB", "EB"}
return humanateBytes(s, 1000, sizes)
}
// IBytes produces a human readable representation of an IEC size.
//
// See also: ParseBytes.
//
// IBytes(82854982) -> 79 MiB
func IBytes(s uint64) string {
sizes := []string{"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"}
return humanateBytes(s, 1024, sizes)
}
// ParseBytes parses a string representation of bytes into the number
// of bytes it represents.
//
// See Also: Bytes, IBytes.
//
// ParseBytes("42 MB") -> 42000000, nil
// ParseBytes("42 mib") -> 44040192, nil
func ParseBytes(s string) (uint64, error) {
lastDigit := 0
hasComma := false
for _, r := range s {
if !(unicode.IsDigit(r) || r == '.' || r == ',') {
break
}
if r == ',' {
hasComma = true
}
lastDigit++
}
num := s[:lastDigit]
if hasComma {
num = strings.Replace(num, ",", "", -1)
}
f, err := strconv.ParseFloat(num, 64)
if err != nil {
return 0, err
}
extra := strings.ToLower(strings.TrimSpace(s[lastDigit:]))
if m, ok := bytesSizeTable[extra]; ok {
f *= float64(m)
if f >= math.MaxUint64 {
return 0, fmt.Errorf("too large: %v", s)
}
return uint64(f), nil
}
return 0, fmt.Errorf("unhandled size name: %v", extra)
}