github.com/kaleido-io/firefly@v0.0.0-20210622132723-8b4b6aacb971/internal/retry/retry.go (about)

     1  // Copyright © 2021 Kaleido, Inc.
     2  //
     3  // SPDX-License-Identifier: Apache-2.0
     4  //
     5  // Licensed under the Apache License, Version 2.0 (the "License");
     6  // you may not use this file except in compliance with the License.
     7  // You may obtain a copy of the License at
     8  //
     9  //     http://www.apache.org/licenses/LICENSE-2.0
    10  //
    11  // Unless required by applicable law or agreed to in writing, software
    12  // distributed under the License is distributed on an "AS IS" BASIS,
    13  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14  // See the License for the specific language governing permissions and
    15  // limitations under the License.
    16  
    17  package retry
    18  
    19  import (
    20  	"context"
    21  	"time"
    22  
    23  	"github.com/kaleido-io/firefly/internal/i18n"
    24  	"github.com/kaleido-io/firefly/internal/log"
    25  )
    26  
    27  const (
    28  	defaultFactor = 2.0
    29  )
    30  
    31  // Retry is a concurrency safe retry structure that configures a simple backoff retry mechanism
    32  type Retry struct {
    33  	InitialDelay time.Duration
    34  	MaximumDelay time.Duration
    35  	Factor       float64
    36  }
    37  
    38  // DoCustomLog disables the automatic attempt logging, so the caller should do logging for each attempt
    39  func (r *Retry) DoCustomLog(ctx context.Context, f func(attempt int) (retry bool, err error)) error {
    40  	return r.Do(ctx, "", f)
    41  }
    42  
    43  // Do invokes the function until the function returns false, or the retry pops.
    44  // This simple interface doesn't pass through errors or return values, on the basis
    45  // you'll be using a closure for that.
    46  func (r *Retry) Do(ctx context.Context, logDescription string, f func(attempt int) (retry bool, err error)) error {
    47  	attempt := 0
    48  	delay := r.InitialDelay
    49  	factor := r.Factor
    50  	if factor < 1 { // Can't reduce
    51  		factor = defaultFactor
    52  	}
    53  	for {
    54  		attempt++
    55  		retry, err := f(attempt)
    56  		if err != nil && logDescription != "" {
    57  			log.L(ctx).Errorf("%s attempt %d: %s", logDescription, attempt, err)
    58  		}
    59  		if !retry || err == nil {
    60  			return err
    61  		}
    62  
    63  		// Check the context isn't cancelled
    64  		select {
    65  		case <-ctx.Done():
    66  			return i18n.NewError(ctx, i18n.MsgContextCanceled)
    67  		default:
    68  		}
    69  
    70  		// Limit the delay based on the context deadline and maximum delay
    71  		deadline, dok := ctx.Deadline()
    72  		now := time.Now()
    73  		if delay > r.MaximumDelay {
    74  			delay = r.MaximumDelay
    75  		}
    76  		if dok {
    77  			timeleft := deadline.Sub(now)
    78  			if timeleft < delay {
    79  				delay = timeleft
    80  			}
    81  		}
    82  
    83  		// Sleep and set the delay for next time
    84  		time.Sleep(delay)
    85  		delay = time.Duration(float64(delay) * factor)
    86  	}
    87  }