github.com/vmware/govmomi@v0.43.0/vim25/retry.go (about)

     1  /*
     2  Copyright (c) 2015 VMware, Inc. All Rights Reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package vim25
    18  
    19  import (
    20  	"context"
    21  	"time"
    22  
    23  	"github.com/vmware/govmomi/vim25/soap"
    24  )
    25  
    26  type RetryFunc func(err error) (retry bool, delay time.Duration)
    27  
    28  // TemporaryNetworkError is deprecated. Use Retry() with RetryTemporaryNetworkError and retryAttempts instead.
    29  func TemporaryNetworkError(n int) RetryFunc {
    30  	return func(err error) (bool, time.Duration) {
    31  		if IsTemporaryNetworkError(err) {
    32  			// Don't retry if we're out of tries.
    33  			if n--; n <= 0 {
    34  				return false, 0
    35  			}
    36  			return true, 0
    37  		}
    38  		return false, 0
    39  	}
    40  }
    41  
    42  // RetryTemporaryNetworkError returns a RetryFunc that returns IsTemporaryNetworkError(err)
    43  func RetryTemporaryNetworkError(err error) (bool, time.Duration) {
    44  	return IsTemporaryNetworkError(err), 0
    45  }
    46  
    47  // IsTemporaryNetworkError returns false unless the error implements
    48  // a Temporary() bool method such as url.Error and net.Error.
    49  // Otherwise, returns the value of the Temporary() method.
    50  func IsTemporaryNetworkError(err error) bool {
    51  	t, ok := err.(interface {
    52  		// Temporary is implemented by url.Error and net.Error
    53  		Temporary() bool
    54  	})
    55  
    56  	if !ok {
    57  		// Not a Temporary error.
    58  		return false
    59  	}
    60  
    61  	return t.Temporary()
    62  }
    63  
    64  type retry struct {
    65  	roundTripper soap.RoundTripper
    66  
    67  	// fn is a custom function that is called when an error occurs.
    68  	// It returns whether or not to retry, and if so, how long to
    69  	// delay before retrying.
    70  	fn               RetryFunc
    71  	maxRetryAttempts int
    72  }
    73  
    74  // Retry wraps the specified soap.RoundTripper and invokes the
    75  // specified RetryFunc. The RetryFunc returns whether or not to
    76  // retry the call, and if so, how long to wait before retrying. If
    77  // the result of this function is to not retry, the original error
    78  // is returned from the RoundTrip function.
    79  // The soap.RoundTripper will return the original error if retryAttempts is specified and reached.
    80  func Retry(roundTripper soap.RoundTripper, fn RetryFunc, retryAttempts ...int) soap.RoundTripper {
    81  	r := &retry{
    82  		roundTripper:     roundTripper,
    83  		fn:               fn,
    84  		maxRetryAttempts: 1,
    85  	}
    86  
    87  	if len(retryAttempts) == 1 {
    88  		r.maxRetryAttempts = retryAttempts[0]
    89  	}
    90  
    91  	return r
    92  }
    93  
    94  func (r *retry) RoundTrip(ctx context.Context, req, res soap.HasFault) error {
    95  	var err error
    96  
    97  	for attempt := 0; attempt < r.maxRetryAttempts; attempt++ {
    98  		err = r.roundTripper.RoundTrip(ctx, req, res)
    99  		if err == nil {
   100  			break
   101  		}
   102  
   103  		// Invoke retry function to see if another attempt should be made.
   104  		if retry, delay := r.fn(err); retry {
   105  			time.Sleep(delay)
   106  			continue
   107  		}
   108  
   109  		break
   110  	}
   111  
   112  	return err
   113  }