github.com/m3db/m3@v1.5.0/src/metrics/matcher/namespace/resolver.go (about)

     1  // Copyright (c) 2021 Uber Technologies, Inc.
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    19  // THE SOFTWARE.
    20  
    21  // Package namespace provides namespace functionality for the matcher.
    22  package namespace
    23  
    24  import (
    25  	"github.com/m3db/m3/src/metrics/metric/id"
    26  )
    27  
    28  var (
    29  	defaultNamespaceTag   = []byte("namespace")
    30  	defaultNamespaceValue = []byte("default")
    31  	// Default is the default Resolver.
    32  	Default = NewResolver(defaultNamespaceTag, defaultNamespaceValue)
    33  )
    34  
    35  // Resolver resolves a namespace value from an encoded metric id.
    36  type Resolver interface {
    37  	// Resolve the namespace value.
    38  	Resolve(id id.ID) []byte
    39  }
    40  
    41  // NewResolver creates a new Resolver.
    42  func NewResolver(namespaceTag, defaultNamespace []byte) Resolver {
    43  	if namespaceTag == nil {
    44  		namespaceTag = defaultNamespaceTag
    45  	}
    46  	if defaultNamespace == nil {
    47  		defaultNamespace = defaultNamespaceValue
    48  	}
    49  	return &resolver{
    50  		namespaceTag:     namespaceTag,
    51  		defaultNamespace: defaultNamespace,
    52  	}
    53  }
    54  
    55  type resolver struct {
    56  	namespaceTag     []byte
    57  	defaultNamespace []byte
    58  }
    59  
    60  func (r resolver) Resolve(id id.ID) []byte {
    61  	ns, found := id.TagValue(r.namespaceTag)
    62  	if !found {
    63  		ns = r.defaultNamespace
    64  	}
    65  	return ns
    66  }