syncthing/vendor/github.com/dustin/go-humanize/times.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

118 lines
3.2 KiB
Go

package humanize
import (
"fmt"
"math"
"sort"
"time"
)
// Seconds-based time units
const (
Day = 24 * time.Hour
Week = 7 * Day
Month = 30 * Day
Year = 12 * Month
LongTime = 37 * Year
)
// Time formats a time into a relative string.
//
// Time(someT) -> "3 weeks ago"
func Time(then time.Time) string {
return RelTime(then, time.Now(), "ago", "from now")
}
// A RelTimeMagnitude struct contains a relative time point at which
// the relative format of time will switch to a new format string. A
// slice of these in ascending order by their "D" field is passed to
// CustomRelTime to format durations.
//
// The Format field is a string that may contain a "%s" which will be
// replaced with the appropriate signed label (e.g. "ago" or "from
// now") and a "%d" that will be replaced by the quantity.
//
// The DivBy field is the amount of time the time difference must be
// divided by in order to display correctly.
//
// e.g. if D is 2*time.Minute and you want to display "%d minutes %s"
// DivBy should be time.Minute so whatever the duration is will be
// expressed in minutes.
type RelTimeMagnitude struct {
D time.Duration
Format string
DivBy time.Duration
}
var defaultMagnitudes = []RelTimeMagnitude{
{time.Second, "now", time.Second},
{2 * time.Second, "1 second %s", 1},
{time.Minute, "%d seconds %s", time.Second},
{2 * time.Minute, "1 minute %s", 1},
{time.Hour, "%d minutes %s", time.Minute},
{2 * time.Hour, "1 hour %s", 1},
{Day, "%d hours %s", time.Hour},
{2 * Day, "1 day %s", 1},
{Week, "%d days %s", Day},
{2 * Week, "1 week %s", 1},
{Month, "%d weeks %s", Week},
{2 * Month, "1 month %s", 1},
{Year, "%d months %s", Month},
{18 * Month, "1 year %s", 1},
{2 * Year, "2 years %s", 1},
{LongTime, "%d years %s", Year},
{math.MaxInt64, "a long while %s", 1},
}
// RelTime formats a time into a relative string.
//
// It takes two times and two labels. In addition to the generic time
// delta string (e.g. 5 minutes), the labels are used applied so that
// the label corresponding to the smaller time is applied.
//
// RelTime(timeInPast, timeInFuture, "earlier", "later") -> "3 weeks earlier"
func RelTime(a, b time.Time, albl, blbl string) string {
return CustomRelTime(a, b, albl, blbl, defaultMagnitudes)
}
// CustomRelTime formats a time into a relative string.
//
// It takes two times two labels and a table of relative time formats.
// In addition to the generic time delta string (e.g. 5 minutes), the
// labels are used applied so that the label corresponding to the
// smaller time is applied.
func CustomRelTime(a, b time.Time, albl, blbl string, magnitudes []RelTimeMagnitude) string {
lbl := albl
diff := b.Sub(a)
if a.After(b) {
lbl = blbl
diff = a.Sub(b)
}
n := sort.Search(len(magnitudes), func(i int) bool {
return magnitudes[i].D > diff
})
if n >= len(magnitudes) {
n = len(magnitudes) - 1
}
mag := magnitudes[n]
args := []interface{}{}
escaped := false
for _, ch := range mag.Format {
if escaped {
switch ch {
case 's':
args = append(args, lbl)
case 'd':
args = append(args, diff/mag.DivBy)
}
escaped = false
} else {
escaped = ch == '%'
}
}
return fmt.Sprintf(mag.Format, args...)
}