passthrough.go

Documentation: google.golang.org/grpc/internal/resolver/passthrough

     1  /*
     2   *
     3   * Copyright 2017 gRPC authors.
     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   */
    18  
    19  // Package passthrough implements a pass-through resolver. It sends the target
    20  // name without scheme back to gRPC as resolved address.
    21  package passthrough
    22  
    23  import (
    24  	"errors"
    25  
    26  	"google.golang.org/grpc/resolver"
    27  )
    28  
    29  const scheme = "passthrough"
    30  
    31  type passthroughBuilder struct{}
    32  
    33  func (*passthroughBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
    34  	if target.Endpoint() == "" && opts.Dialer == nil {
    35  		return nil, errors.New("passthrough: received empty target in Build()")
    36  	}
    37  	r := &passthroughResolver{
    38  		target: target,
    39  		cc:     cc,
    40  	}
    41  	r.start()
    42  	return r, nil
    43  }
    44  
    45  func (*passthroughBuilder) Scheme() string {
    46  	return scheme
    47  }
    48  
    49  type passthroughResolver struct {
    50  	target resolver.Target
    51  	cc     resolver.ClientConn
    52  }
    53  
    54  func (r *passthroughResolver) start() {
    55  	r.cc.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: r.target.Endpoint()}}})
    56  }
    57  
    58  func (*passthroughResolver) ResolveNow(o resolver.ResolveNowOptions) {}
    59  
    60  func (*passthroughResolver) Close() {}
    61  
    62  func init() {
    63  	resolver.Register(&passthroughBuilder{})
    64  }
    65
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