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

     1  // Copyright (c) 2022 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
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     7  // copies of the Software, and to permit persons to whom the Software is
     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 pendingheap
    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 descripes how to build a fewest pending heap 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 pending heap peer list
    38  // implementation, making it possible to select the least recently chosen peer
    39  // with transports that use outbound peer list configuration (like HTTP).
    40  //
    41  //  cfg := yarpcconfig.New()
    42  //  cfg.MustRegisterPeerList(pendingheap.Spec())
    43  //
    44  // This enables the pending heap peer list:
    45  //
    46  //  outbounds:
    47  //    otherservice:
    48  //      unary:
    49  //        http:
    50  //          url: https://host:port/rpc
    51  //          fewest-pending-requests:
    52  //            peers:
    53  //              - 127.0.0.1:8080
    54  //              - 127.0.0.1:8081
    55  //
    56  // Other than a specific peer or peers list, use any peer list updater
    57  // registered with a yarpc Configurator.
    58  // The configuration allows for alternative initial allocation capacity and a
    59  // fail-fast option.
    60  // With fail-fast enabled, the peer list will return an error immediately if no
    61  // peers are available (connected) at the time the request is sent.
    62  //
    63  //  fewest-pending-requests:
    64  //    peers:
    65  //      - 127.0.0.1:8080
    66  //    capacity: 1
    67  //    failFast: true
    68  func Spec() yarpcconfig.PeerListSpec {
    69  	return SpecWithOptions()
    70  }
    71  
    72  // SpecWithOptions accepts additional list constructor options.
    73  func SpecWithOptions(options ...ListOption) yarpcconfig.PeerListSpec {
    74  	return yarpcconfig.PeerListSpec{
    75  		Name: "fewest-pending-requests",
    76  		BuildPeerList: func(cfg Configuration, t peer.Transport, k *yarpcconfig.Kit) (peer.ChooserList, error) {
    77  			opts := make([]ListOption, 0, len(options)+2)
    78  
    79  			opts = append(opts, options...)
    80  
    81  			if cfg.Capacity != nil {
    82  				if *cfg.Capacity <= 0 {
    83  					return nil, yarpcerrors.Newf(yarpcerrors.CodeInvalidArgument,
    84  						fmt.Sprintf("Capacity must be greater than 0. Got: %d.", *cfg.Capacity))
    85  				}
    86  				opts = append(opts, Capacity(*cfg.Capacity))
    87  			}
    88  
    89  			if cfg.FailFast {
    90  				opts = append(opts, FailFast())
    91  			}
    92  
    93  			return New(t, opts...), nil
    94  		},
    95  	}
    96  }