vendor/cloud.google.com/go/internal/retry.go

   1 // Copyright 2016 Google LLC
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //      http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 package internal
  16
  17 import (
  18         "context"
  19         "time"
  20
  21         gax "github.com/googleapis/gax-go/v2"
  22 )
  23
  24 // Retry calls the supplied function f repeatedly according to the provided
  25 // backoff parameters. It returns when one of the following occurs:
  26 // When f's first return value is true, Retry immediately returns with f's second
  27 // return value.
  28 // When the provided context is done, Retry returns with an error that
  29 // includes both ctx.Error() and the last error returned by f.
  30 func Retry(ctx context.Context, bo gax.Backoff, f func() (stop bool, err error)) error {
  31         return retry(ctx, bo, f, gax.Sleep)
  32 }
  33
  34 func retry(ctx context.Context, bo gax.Backoff, f func() (stop bool, err error),
  35         sleep func(context.Context, time.Duration) error) error {
  36         var lastErr error
  37         for {
  38                 stop, err := f()
  39                 if stop {
  40                         return err
  41                 }
  42                 // Remember the last "real" error from f.
  43                 if err != nil && err != context.Canceled && err != context.DeadlineExceeded {
  44                         lastErr = err
  45                 }
  46                 p := bo.Pause()
  47                 if cerr := sleep(ctx, p); cerr != nil {
  48                         if lastErr != nil {
  49                                 return Annotatef(lastErr, "retry failed with %v; last error", cerr)
  50                         }
  51                         return cerr
  52                 }
  53         }
  54 }