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2.2 KiB
2.2 KiB
Backoff
A simple exponential backoff counter in Go (Golang)
Install
$ go get -v github.com/jpillora/backoff
Usage
Backoff is a time.Duration
counter. It starts at Min
. After every call to Duration()
it is multiplied by Factor
. It is capped at Max
. It returns to Min
on every call to Reset()
. Jitter
adds randomness (see below). Used in conjunction with the time
package.
Simple example
b := &backoff.Backoff{
//These are the defaults
Min: 100 * time.Millisecond,
Max: 10 * time.Second,
Factor: 2,
Jitter: false,
}
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("Reset!\n")
b.Reset()
fmt.Printf("%s\n", b.Duration())
100ms
200ms
400ms
Reset!
100ms
Example using net
package
b := &backoff.Backoff{
Max: 5 * time.Minute,
}
for {
conn, err := net.Dial("tcp", "example.com:5309")
if err != nil {
d := b.Duration()
fmt.Printf("%s, reconnecting in %s", err, d)
time.Sleep(d)
continue
}
//connected
b.Reset()
conn.Write([]byte("hello world!"))
// ... Read ... Write ... etc
conn.Close()
//disconnected
}
Example using Jitter
Enabling Jitter
adds some randomization to the backoff durations. See Amazon's writeup of performance gains using jitter. Seeding is not necessary but doing so gives repeatable results.
import "math/rand"
b := &backoff.Backoff{
Jitter: true,
}
rand.Seed(42)
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("Reset!\n")
b.Reset()
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
fmt.Printf("%s\n", b.Duration())
100ms
106.600049ms
281.228155ms
Reset!
100ms
104.381845ms
214.957989ms
Documentation
https://godoc.org/github.com/jpillora/backoff
Credits
Forked from some JavaScript written by @tj