916ec63af6
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
118 lines
3.2 KiB
Go
118 lines
3.2 KiB
Go
package humanize
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import (
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"fmt"
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"math"
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"sort"
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"time"
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)
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// Seconds-based time units
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const (
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Day = 24 * time.Hour
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Week = 7 * Day
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Month = 30 * Day
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Year = 12 * Month
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LongTime = 37 * Year
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)
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// Time formats a time into a relative string.
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//
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// Time(someT) -> "3 weeks ago"
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func Time(then time.Time) string {
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return RelTime(then, time.Now(), "ago", "from now")
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}
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// A RelTimeMagnitude struct contains a relative time point at which
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// the relative format of time will switch to a new format string. A
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// slice of these in ascending order by their "D" field is passed to
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// CustomRelTime to format durations.
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//
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// The Format field is a string that may contain a "%s" which will be
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// replaced with the appropriate signed label (e.g. "ago" or "from
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// now") and a "%d" that will be replaced by the quantity.
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//
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// The DivBy field is the amount of time the time difference must be
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// divided by in order to display correctly.
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//
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// e.g. if D is 2*time.Minute and you want to display "%d minutes %s"
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// DivBy should be time.Minute so whatever the duration is will be
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// expressed in minutes.
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type RelTimeMagnitude struct {
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D time.Duration
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Format string
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DivBy time.Duration
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}
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var defaultMagnitudes = []RelTimeMagnitude{
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{time.Second, "now", time.Second},
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{2 * time.Second, "1 second %s", 1},
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{time.Minute, "%d seconds %s", time.Second},
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{2 * time.Minute, "1 minute %s", 1},
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{time.Hour, "%d minutes %s", time.Minute},
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{2 * time.Hour, "1 hour %s", 1},
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{Day, "%d hours %s", time.Hour},
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{2 * Day, "1 day %s", 1},
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{Week, "%d days %s", Day},
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{2 * Week, "1 week %s", 1},
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{Month, "%d weeks %s", Week},
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{2 * Month, "1 month %s", 1},
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{Year, "%d months %s", Month},
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{18 * Month, "1 year %s", 1},
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{2 * Year, "2 years %s", 1},
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{LongTime, "%d years %s", Year},
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{math.MaxInt64, "a long while %s", 1},
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}
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// RelTime formats a time into a relative string.
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//
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// It takes two times and two labels. In addition to the generic time
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// delta string (e.g. 5 minutes), the labels are used applied so that
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// the label corresponding to the smaller time is applied.
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//
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// RelTime(timeInPast, timeInFuture, "earlier", "later") -> "3 weeks earlier"
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func RelTime(a, b time.Time, albl, blbl string) string {
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return CustomRelTime(a, b, albl, blbl, defaultMagnitudes)
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}
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// CustomRelTime formats a time into a relative string.
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//
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// It takes two times two labels and a table of relative time formats.
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// In addition to the generic time delta string (e.g. 5 minutes), the
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// labels are used applied so that the label corresponding to the
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// smaller time is applied.
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func CustomRelTime(a, b time.Time, albl, blbl string, magnitudes []RelTimeMagnitude) string {
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lbl := albl
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diff := b.Sub(a)
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if a.After(b) {
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lbl = blbl
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diff = a.Sub(b)
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}
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n := sort.Search(len(magnitudes), func(i int) bool {
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return magnitudes[i].D > diff
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})
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if n >= len(magnitudes) {
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n = len(magnitudes) - 1
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}
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mag := magnitudes[n]
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args := []interface{}{}
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escaped := false
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for _, ch := range mag.Format {
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if escaped {
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switch ch {
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case 's':
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args = append(args, lbl)
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case 'd':
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args = append(args, diff/mag.DivBy)
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}
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escaped = false
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} else {
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escaped = ch == '%'
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}
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}
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return fmt.Sprintf(mag.Format, args...)
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}
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