| // Copyright 2016 Google LLC |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package internal |
| |
| import ( |
| "context" |
| "fmt" |
| "time" |
| |
| gax "github.com/googleapis/gax-go/v2" |
| "google.golang.org/grpc/status" |
| ) |
| |
| // Retry calls the supplied function f repeatedly according to the provided |
| // backoff parameters. It returns when one of the following occurs: |
| // When f's first return value is true, Retry immediately returns with f's second |
| // return value. |
| // When the provided context is done, Retry returns with an error that |
| // includes both ctx.Error() and the last error returned by f. |
| func Retry(ctx context.Context, bo gax.Backoff, f func() (stop bool, err error)) error { |
| return retry(ctx, bo, f, gax.Sleep) |
| } |
| |
| func retry(ctx context.Context, bo gax.Backoff, f func() (stop bool, err error), |
| sleep func(context.Context, time.Duration) error) error { |
| var lastErr error |
| for { |
| stop, err := f() |
| if stop { |
| return err |
| } |
| // Remember the last "real" error from f. |
| if err != nil && err != context.Canceled && err != context.DeadlineExceeded { |
| lastErr = err |
| } |
| p := bo.Pause() |
| if ctxErr := sleep(ctx, p); ctxErr != nil { |
| if lastErr != nil { |
| return wrappedCallErr{ctxErr: ctxErr, wrappedErr: lastErr} |
| } |
| return ctxErr |
| } |
| } |
| } |
| |
| // Use this error type to return an error which allows introspection of both |
| // the context error and the error from the service. |
| type wrappedCallErr struct { |
| ctxErr error |
| wrappedErr error |
| } |
| |
| func (e wrappedCallErr) Error() string { |
| return fmt.Sprintf("retry failed with %v; last error: %v", e.ctxErr, e.wrappedErr) |
| } |
| |
| func (e wrappedCallErr) Unwrap() error { |
| return e.wrappedErr |
| } |
| |
| // Is allows errors.Is to match the error from the call as well as context |
| // sentinel errors. |
| func (e wrappedCallErr) Is(err error) bool { |
| return e.ctxErr == err || e.wrappedErr == err |
| } |
| |
| // GRPCStatus allows the wrapped error to be used with status.FromError. |
| func (e wrappedCallErr) GRPCStatus() *status.Status { |
| if s, ok := status.FromError(e.wrappedErr); ok { |
| return s |
| } |
| return nil |
| } |