mirror of
https://github.com/crazybber/go-pattern-examples.git
synced 2024-11-27 06:06:02 +03:00
197 lines
4.2 KiB
Go
197 lines
4.2 KiB
Go
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package breaker
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import (
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"errors"
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"testing"
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"time"
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)
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var errSomeError = errors.New("errSomeError")
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func alwaysPanics() error {
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panic("foo")
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}
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func returnsError() error {
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return errSomeError
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}
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func returnsSuccess() error {
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return nil
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}
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func TestBreakerErrorExpiry(t *testing.T) {
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breaker := New(2, 1, 1*time.Second)
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for i := 0; i < 3; i++ {
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if err := breaker.Run(returnsError); err != errSomeError {
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t.Error(err)
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}
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time.Sleep(1 * time.Second)
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}
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for i := 0; i < 3; i++ {
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if err := breaker.Go(returnsError); err != nil {
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t.Error(err)
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}
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time.Sleep(1 * time.Second)
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}
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}
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func TestBreakerPanicsCountAsErrors(t *testing.T) {
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breaker := New(3, 2, 1*time.Second)
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// three errors opens the breaker
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for i := 0; i < 3; i++ {
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func() {
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defer func() {
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val := recover()
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if val.(string) != "foo" {
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t.Error("incorrect panic")
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}
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}()
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if err := breaker.Run(alwaysPanics); err != nil {
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t.Error(err)
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}
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t.Error("shouldn't get here")
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}()
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}
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// breaker is open
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for i := 0; i < 5; i++ {
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if err := breaker.Run(returnsError); err != ErrBreakerOpen {
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t.Error(err)
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}
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}
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}
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func TestBreakerStateTransitions(t *testing.T) {
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breaker := New(3, 2, 1*time.Second)
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// three errors opens the breaker
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for i := 0; i < 3; i++ {
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if err := breaker.Run(returnsError); err != errSomeError {
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t.Error(err)
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}
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}
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// breaker is open
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for i := 0; i < 5; i++ {
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if err := breaker.Run(returnsError); err != ErrBreakerOpen {
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t.Error(err)
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}
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}
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// wait for it to half-close
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time.Sleep(2 * time.Second)
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// one success works, but is not enough to fully close
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if err := breaker.Run(returnsSuccess); err != nil {
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t.Error(err)
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}
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// error works, but re-opens immediately
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if err := breaker.Run(returnsError); err != errSomeError {
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t.Error(err)
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}
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// breaker is open
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if err := breaker.Run(returnsError); err != ErrBreakerOpen {
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t.Error(err)
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}
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// wait for it to half-close
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time.Sleep(2 * time.Second)
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// two successes is enough to close it for good
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for i := 0; i < 2; i++ {
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if err := breaker.Run(returnsSuccess); err != nil {
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t.Error(err)
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}
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}
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// error works
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if err := breaker.Run(returnsError); err != errSomeError {
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t.Error(err)
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}
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// breaker is still closed
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if err := breaker.Run(returnsSuccess); err != nil {
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t.Error(err)
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}
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}
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func TestBreakerAsyncStateTransitions(t *testing.T) {
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breaker := New(3, 2, 1*time.Second)
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// three errors opens the breaker
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for i := 0; i < 3; i++ {
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if err := breaker.Go(returnsError); err != nil {
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t.Error(err)
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}
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}
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// just enough to yield the scheduler and let the goroutines work off
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time.Sleep(1 * time.Millisecond)
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// breaker is open
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for i := 0; i < 5; i++ {
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if err := breaker.Go(returnsError); err != ErrBreakerOpen {
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t.Error(err)
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}
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}
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// wait for it to half-close
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time.Sleep(2 * time.Second)
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// one success works, but is not enough to fully close
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if err := breaker.Go(returnsSuccess); err != nil {
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t.Error(err)
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}
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// error works, but re-opens immediately
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if err := breaker.Go(returnsError); err != nil {
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t.Error(err)
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}
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// just enough to yield the scheduler and let the goroutines work off
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time.Sleep(1 * time.Millisecond)
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// breaker is open
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if err := breaker.Go(returnsError); err != ErrBreakerOpen {
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t.Error(err)
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}
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// wait for it to half-close
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time.Sleep(2 * time.Second)
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// two successes is enough to close it for good
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for i := 0; i < 2; i++ {
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if err := breaker.Go(returnsSuccess); err != nil {
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t.Error(err)
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}
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}
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// just enough to yield the scheduler and let the goroutines work off
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time.Sleep(1 * time.Millisecond)
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// error works
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if err := breaker.Go(returnsError); err != nil {
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t.Error(err)
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}
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// just enough to yield the scheduler and let the goroutines work off
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time.Sleep(1 * time.Millisecond)
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// breaker is still closed
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if err := breaker.Go(returnsSuccess); err != nil {
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t.Error(err)
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}
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}
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func ExampleBreaker() {
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breaker := New(3, 1, 5*time.Second)
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for {
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result := breaker.Run(func() error {
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// communicate with some external service and
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// return an error if the communication failed
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return nil
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})
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switch result {
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case nil:
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// success!
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case ErrBreakerOpen:
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// our function wasn't run because the breaker was open
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default:
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// some other error
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}
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}
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}
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