README
¶
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
Documentation
¶
Overview ¶
Package backoff provides an exponential-backoff implementation.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Backoff ¶
type Backoff struct {
// Factor is the multiplying factor for each increment step
Factor float64
// Jitter eases contention by randomizing backoff steps
Jitter bool
// Min and Max are the minimum and maximum values of the counter
Min, Max time.Duration
// contains filtered or unexported fields
}
Backoff is a time.Duration counter, starting at Min. After every call to the Duration method the current timing is multiplied by Factor, but it never exceeds Max.
Backoff is not generally concurrent-safe, but the ForAttempt method can be used concurrently.
func (*Backoff) Duration ¶
Duration returns the duration for the current attempt before incrementing the attempt counter. See ForAttempt.
func (*Backoff) ForAttempt ¶
ForAttempt returns the duration for a specific attempt. This is useful if you have a large number of independent Backoffs, but don't want use unnecessary memory storing the Backoff parameters per Backoff. The first attempt should be 0.
ForAttempt is concurrent-safe.
Source Files