146 lines
3.7 KiB
Go
146 lines
3.7 KiB
Go
package backoff
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import (
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"errors"
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"time"
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)
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// An OperationWithData is executing by RetryWithData() or RetryNotifyWithData().
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// The operation will be retried using a backoff policy if it returns an error.
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type OperationWithData[T any] func() (T, error)
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// An Operation is executing by Retry() or RetryNotify().
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// The operation will be retried using a backoff policy if it returns an error.
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type Operation func() error
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func (o Operation) withEmptyData() OperationWithData[struct{}] {
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return func() (struct{}, error) {
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return struct{}{}, o()
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}
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}
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// Notify is a notify-on-error function. It receives an operation error and
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// backoff delay if the operation failed (with an error).
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//
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// NOTE that if the backoff policy stated to stop retrying,
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// the notify function isn't called.
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type Notify func(error, time.Duration)
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// Retry the operation o until it does not return error or BackOff stops.
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// o is guaranteed to be run at least once.
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//
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// If o returns a *PermanentError, the operation is not retried, and the
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// wrapped error is returned.
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//
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// Retry sleeps the goroutine for the duration returned by BackOff after a
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// failed operation returns.
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func Retry(o Operation, b BackOff) error {
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return RetryNotify(o, b, nil)
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}
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// RetryWithData is like Retry but returns data in the response too.
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func RetryWithData[T any](o OperationWithData[T], b BackOff) (T, error) {
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return RetryNotifyWithData(o, b, nil)
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}
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// RetryNotify calls notify function with the error and wait duration
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// for each failed attempt before sleep.
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func RetryNotify(operation Operation, b BackOff, notify Notify) error {
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return RetryNotifyWithTimer(operation, b, notify, nil)
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}
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// RetryNotifyWithData is like RetryNotify but returns data in the response too.
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func RetryNotifyWithData[T any](operation OperationWithData[T], b BackOff, notify Notify) (T, error) {
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return doRetryNotify(operation, b, notify, nil)
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}
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// RetryNotifyWithTimer calls notify function with the error and wait duration using the given Timer
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// for each failed attempt before sleep.
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// A default timer that uses system timer is used when nil is passed.
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func RetryNotifyWithTimer(operation Operation, b BackOff, notify Notify, t Timer) error {
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_, err := doRetryNotify(operation.withEmptyData(), b, notify, t)
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return err
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}
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// RetryNotifyWithTimerAndData is like RetryNotifyWithTimer but returns data in the response too.
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func RetryNotifyWithTimerAndData[T any](operation OperationWithData[T], b BackOff, notify Notify, t Timer) (T, error) {
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return doRetryNotify(operation, b, notify, t)
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}
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func doRetryNotify[T any](operation OperationWithData[T], b BackOff, notify Notify, t Timer) (T, error) {
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var (
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err error
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next time.Duration
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res T
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)
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if t == nil {
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t = &defaultTimer{}
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}
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defer func() {
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t.Stop()
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}()
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ctx := getContext(b)
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b.Reset()
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for {
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res, err = operation()
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if err == nil {
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return res, nil
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}
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var permanent *PermanentError
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if errors.As(err, &permanent) {
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return res, permanent.Err
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}
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if next = b.NextBackOff(); next == Stop {
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if cerr := ctx.Err(); cerr != nil {
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return res, cerr
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}
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return res, err
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}
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if notify != nil {
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notify(err, next)
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}
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t.Start(next)
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select {
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case <-ctx.Done():
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return res, ctx.Err()
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case <-t.C():
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}
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}
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}
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// PermanentError signals that the operation should not be retried.
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type PermanentError struct {
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Err error
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}
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func (e *PermanentError) Error() string {
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return e.Err.Error()
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}
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func (e *PermanentError) Unwrap() error {
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return e.Err
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}
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func (e *PermanentError) Is(target error) bool {
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_, ok := target.(*PermanentError)
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return ok
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}
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// Permanent wraps the given err in a *PermanentError.
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func Permanent(err error) error {
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if err == nil {
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return nil
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}
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return &PermanentError{
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Err: err,
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}
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}
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