68 lines
1.4 KiB
Go
68 lines
1.4 KiB
Go
package resilience
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import (
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"errors"
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"io"
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"net/http"
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)
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// Transport isolates one logical upstream. Create separate Breakers for
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// different dependencies. Slots remain occupied until body Close/EOF.
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type Transport struct {
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Base http.RoundTripper
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Breaker *Breaker
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}
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func (t Transport) RoundTrip(r *http.Request) (*http.Response, error) {
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if t.Breaker == nil {
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return nil, errors.New("resilience: breaker required")
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}
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done, err := t.Breaker.Acquire(r.Context())
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if err != nil {
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return nil, err
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}
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defer func() {
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if v := recover(); v != nil {
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done(false)
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panic(v)
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}
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}()
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base := t.Base
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if base == nil {
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base = http.DefaultTransport
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}
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response, err := base.RoundTrip(r)
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if err != nil {
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done(!t.Breaker.config.IsFailure(err))
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if response != nil && response.Body != nil {
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response.Body.Close()
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}
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return nil, err
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}
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if response == nil || response.Body == nil {
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done(false)
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return nil, errors.New("resilience: invalid transport response")
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}
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response.Body = &breakerBody{ReadCloser: response.Body, done: done, success: response.StatusCode < 500}
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return response, nil
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}
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type breakerBody struct {
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io.ReadCloser
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done func(bool)
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success bool
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}
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func (b *breakerBody) Read(p []byte) (int, error) {
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n, err := b.ReadCloser.Read(p)
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if err != nil {
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b.done(b.success && err == io.EOF)
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}
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return n, err
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}
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func (b *breakerBody) Close() error {
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err := b.ReadCloser.Close()
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b.done(b.success && err == nil)
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return err
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}
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