vendor/github.com/googleapis/gax-go/v2/call_option.go

   1 // Copyright 2016, Google Inc.
   2 // All rights reserved.
   3 //
   4 // Redistribution and use in source and binary forms, with or without
   5 // modification, are permitted provided that the following conditions are
   6 // met:
   7 //
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   9 // notice, this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above
  11 // copyright notice, this list of conditions and the following disclaimer
  12 // in the documentation and/or other materials provided with the
  13 // distribution.
  14 //     * Neither the name of Google Inc. nor the names of its
  15 // contributors may be used to endorse or promote products derived from
  16 // this software without specific prior written permission.
  17 //
  18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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  21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29
  30 package gax
  31
  32 import (
  33         "math/rand"
  34         "time"
  35
  36         "google.golang.org/grpc"
  37         "google.golang.org/grpc/codes"
  38         "google.golang.org/grpc/status"
  39 )
  40
  41 // CallOption is an option used by Invoke to control behaviors of RPC calls.
  42 // CallOption works by modifying relevant fields of CallSettings.
  43 type CallOption interface {
  44         // Resolve applies the option by modifying cs.
  45         Resolve(cs *CallSettings)
  46 }
  47
  48 // Retryer is used by Invoke to determine retry behavior.
  49 type Retryer interface {
  50         // Retry reports whether a request should be retriedand how long to pause before retrying
  51         // if the previous attempt returned with err. Invoke never calls Retry with nil error.
  52         Retry(err error) (pause time.Duration, shouldRetry bool)
  53 }
  54
  55 type retryerOption func() Retryer
  56
  57 func (o retryerOption) Resolve(s *CallSettings) {
  58         s.Retry = o
  59 }
  60
  61 // WithRetry sets CallSettings.Retry to fn.
  62 func WithRetry(fn func() Retryer) CallOption {
  63         return retryerOption(fn)
  64 }
  65
  66 // OnCodes returns a Retryer that retries if and only if
  67 // the previous attempt returns a GRPC error whose error code is stored in cc.
  68 // Pause times between retries are specified by bo.
  69 //
  70 // bo is only used for its parameters; each Retryer has its own copy.
  71 func OnCodes(cc []codes.Code, bo Backoff) Retryer {
  72         return &boRetryer{
  73                 backoff: bo,
  74                 codes:   append([]codes.Code(nil), cc...),
  75         }
  76 }
  77
  78 type boRetryer struct {
  79         backoff Backoff
  80         codes   []codes.Code
  81 }
  82
  83 func (r *boRetryer) Retry(err error) (time.Duration, bool) {
  84         st, ok := status.FromError(err)
  85         if !ok {
  86                 return 0, false
  87         }
  88         c := st.Code()
  89         for _, rc := range r.codes {
  90                 if c == rc {
  91                         return r.backoff.Pause(), true
  92                 }
  93         }
  94         return 0, false
  95 }
  96
  97 // Backoff implements exponential backoff.
  98 // The wait time between retries is a random value between 0 and the "retry envelope".
  99 // The envelope starts at Initial and increases by the factor of Multiplier every retry,
 100 // but is capped at Max.
 101 type Backoff struct {
 102         // Initial is the initial value of the retry envelope, defaults to 1 second.
 103         Initial time.Duration
 104
 105         // Max is the maximum value of the retry envelope, defaults to 30 seconds.
 106         Max time.Duration
 107
 108         // Multiplier is the factor by which the retry envelope increases.
 109         // It should be greater than 1 and defaults to 2.
 110         Multiplier float64
 111
 112         // cur is the current retry envelope
 113         cur time.Duration
 114 }
 115
 116 // Pause returns the next time.Duration that the caller should use to backoff.
 117 func (bo *Backoff) Pause() time.Duration {
 118         if bo.Initial == 0 {
 119                 bo.Initial = time.Second
 120         }
 121         if bo.cur == 0 {
 122                 bo.cur = bo.Initial
 123         }
 124         if bo.Max == 0 {
 125                 bo.Max = 30 * time.Second
 126         }
 127         if bo.Multiplier < 1 {
 128                 bo.Multiplier = 2
 129         }
 130         // Select a duration between 1ns and the current max. It might seem
 131         // counterintuitive to have so much jitter, but
 132         // https://www.awsarchitectureblog.com/2015/03/backoff.html argues that
 133         // that is the best strategy.
 134         d := time.Duration(1 + rand.Int63n(int64(bo.cur)))
 135         bo.cur = time.Duration(float64(bo.cur) * bo.Multiplier)
 136         if bo.cur > bo.Max {
 137                 bo.cur = bo.Max
 138         }
 139         return d
 140 }
 141
 142 type grpcOpt []grpc.CallOption
 143
 144 func (o grpcOpt) Resolve(s *CallSettings) {
 145         s.GRPC = o
 146 }
 147
 148 // WithGRPCOptions allows passing gRPC call options during client creation.
 149 func WithGRPCOptions(opt ...grpc.CallOption) CallOption {
 150         return grpcOpt(append([]grpc.CallOption(nil), opt...))
 151 }
 152
 153 // CallSettings allow fine-grained control over how calls are made.
 154 type CallSettings struct {
 155         // Retry returns a Retryer to be used to control retry logic of a method call.
 156         // If Retry is nil or the returned Retryer is nil, the call will not be retried.
 157         Retry func() Retryer
 158
 159         // CallOptions to be forwarded to GRPC.
 160         GRPC []grpc.CallOption
 161 }