github.com/kaydxh/golang@v0.0.131/go/net/resolver/register.reslover.go (about)

     1  /*
     2   *Copyright (c) 2022, kaydxh
     3   *
     4   *Permission is hereby granted, free of charge, to any person obtaining a copy
     5   *of this software and associated documentation files (the "Software"), to deal
     6   *in the Software without restriction, including without limitation the rights
     7   *to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     8   *copies of the Software, and to permit persons to whom the Software is
     9   *furnished to do so, subject to the following conditions:
    10   *
    11   *The above copyright notice and this permission notice shall be included in all
    12   *copies or substantial portions of the Software.
    13   *
    14   *THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    15   *IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    16   *FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    17   *AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    18   *LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    19   *OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    20   *SOFTWARE.
    21   */
    22  package resolver
    23  
    24  import "sync"
    25  
    26  var (
    27  	builderMu   sync.RWMutex
    28  	resolversMu sync.RWMutex
    29  	// m is a map from scheme to resolver builder.
    30  	m            = make(map[string]Builder)
    31  	resolverPool = make(map[string]Resolver)
    32  	// defaultScheme is the default scheme to use.
    33  	defaultScheme = "passthrough"
    34  )
    35  
    36  // TODO(bar) install dns resolver in init(){}.
    37  
    38  // Register registers the resolver builder to the resolver map. b.Scheme will be
    39  // used as the scheme registered with this builder.
    40  //
    41  func Register(b Builder) {
    42  	builderMu.Lock()
    43  	defer builderMu.Unlock()
    44  
    45  	if b == nil {
    46  		panic("register builder is nil")
    47  	}
    48  	if _, ok := m[b.Scheme()]; ok {
    49  		panic("double register scheme " + b.Scheme())
    50  	}
    51  	m[b.Scheme()] = b
    52  }
    53  
    54  // Get returns the resolver builder registered with the given scheme.
    55  //
    56  // If no builder is register with the scheme, nil will be returned.
    57  func Get(scheme string) Builder {
    58  	builderMu.Lock()
    59  	defer builderMu.Unlock()
    60  
    61  	if b, ok := m[scheme]; ok {
    62  		return b
    63  	}
    64  	return nil
    65  }
    66  
    67  func GetDefault() Builder {
    68  	builderMu.Lock()
    69  	defer builderMu.Unlock()
    70  
    71  	if b, ok := m[defaultScheme]; ok {
    72  		return b
    73  	}
    74  	return nil
    75  }
    76  
    77  func getResolver(target string) Resolver {
    78  	resolversMu.Lock()
    79  	defer resolversMu.Unlock()
    80  
    81  	if b, ok := resolverPool[target]; ok {
    82  		return b
    83  	}
    84  	return nil
    85  }
    86  
    87  func setResolver(target string, r Resolver) {
    88  	resolversMu.Lock()
    89  	defer resolversMu.Unlock()
    90  
    91  	if r == nil {
    92  		panic("register resolver is nil")
    93  	}
    94  	if _, ok := resolverPool[target]; ok {
    95  		panic("double register target " + target)
    96  	}
    97  	resolverPool[target] = r
    98  }
    99  
   100  // SetDefaultScheme sets the default scheme that will be used. The default
   101  // default scheme is "passthrough".
   102  //
   103  // NOTE: this function must only be called during initialization time (i.e. in
   104  // an init() function), and is not thread-safe. The scheme set last overrides
   105  // previously set values.
   106  func SetDefaultScheme(scheme string) {
   107  	defaultScheme = scheme
   108  }
   109  
   110  // GetDefaultScheme gets the default scheme that will be used.
   111  func GetDefaultScheme() string {
   112  	return defaultScheme
   113  }