github.com/m3db/m3@v1.5.0/src/dbnode/namespace/watch.go (about)

     1  // Copyright (c) 2017 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
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     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 namespace
    22  
    23  import (
    24  	xwatch "github.com/m3db/m3/src/x/watch"
    25  )
    26  
    27  type mapWatch struct {
    28  	xwatch.Watch
    29  }
    30  
    31  // NewWatch creates a new watch on a topology map
    32  // from a generic watch that watches a Map
    33  func NewWatch(w xwatch.Watch) Watch {
    34  	return &mapWatch{w}
    35  }
    36  
    37  func (w *mapWatch) C() <-chan struct{} {
    38  	return w.Watch.C()
    39  }
    40  
    41  func (w *mapWatch) Get() Map {
    42  	value := w.Watch.Get()
    43  	if value == nil {
    44  		return nil
    45  	}
    46  	return value.(Map)
    47  }
    48  
    49  func (w *mapWatch) Close() error {
    50  	w.Watch.Close()
    51  	return nil
    52  }