go.uber.org/yarpc@v1.72.1/peer/tworandomchoices/config.go (about)

     1  // Copyright (c) 2022 Uber Technologies, Inc.
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     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
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     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package tworandomchoices
    22  
    23  import (
    24  	"fmt"
    25  
    26  	"go.uber.org/yarpc/api/peer"
    27  	"go.uber.org/yarpc/yarpcconfig"
    28  	"go.uber.org/yarpc/yarpcerrors"
    29  )
    30  
    31  // Configuration describes how to construct a two-random-choices peer list.
    32  type Configuration struct {
    33  	Capacity *int `config:"capacity"`
    34  	FailFast bool `config:"failFast"`
    35  }
    36  
    37  // Spec returns a configuration specification for the "fewest pending requests
    38  // of two random peers" implementation, making it possible to select the better
    39  // of two random peer with transports that use outbound peer list configuration
    40  // (like HTTP).
    41  //
    42  //  cfg := yarpcconfig.New()
    43  //  cfg.MustRegisterPeerList(tworandomchoices.Spec())
    44  //
    45  // This enables the random peer list:
    46  //
    47  //  outbounds:
    48  //    otherservice:
    49  //      unary:
    50  //        http:
    51  //          url: https://host:port/rpc
    52  //          two-random-choices:
    53  //            peers:
    54  //              - 127.0.0.1:8080
    55  //              - 127.0.0.1:8081
    56  func Spec() yarpcconfig.PeerListSpec {
    57  	return SpecWithOptions()
    58  }
    59  
    60  // SpecWithOptions accepts additional list constructor options.
    61  func SpecWithOptions(options ...ListOption) yarpcconfig.PeerListSpec {
    62  	return yarpcconfig.PeerListSpec{
    63  		Name: "two-random-choices",
    64  		BuildPeerList: func(cfg Configuration, t peer.Transport, k *yarpcconfig.Kit) (peer.ChooserList, error) {
    65  			opts := make([]ListOption, 0, len(options)+2)
    66  
    67  			opts = append(opts, options...)
    68  
    69  			if cfg.Capacity != nil {
    70  				if *cfg.Capacity <= 0 {
    71  					return nil, yarpcerrors.Newf(yarpcerrors.CodeInvalidArgument,
    72  						fmt.Sprintf("Capacity must be greater than 0. Got: %d.", *cfg.Capacity))
    73  				}
    74  				opts = append(opts, Capacity(*cfg.Capacity))
    75  			}
    76  
    77  			if cfg.FailFast {
    78  				opts = append(opts, FailFast())
    79  			}
    80  
    81  			return New(t, opts...), nil
    82  		},
    83  	}
    84  }