labeler.go

Documentation: go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp

     1  // Copyright The OpenTelemetry Authors
     2  // SPDX-License-Identifier: Apache-2.0
     3  
     4  package otelhttp // import "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
     5  
     6  import (
     7  	"context"
     8  	"sync"
     9  
    10  	"go.opentelemetry.io/otel/attribute"
    11  )
    12  
    13  // Labeler is used to allow instrumented HTTP handlers to add custom attributes to
    14  // the metrics recorded by the net/http instrumentation.
    15  type Labeler struct {
    16  	mu         sync.Mutex
    17  	attributes []attribute.KeyValue
    18  }
    19  
    20  // Add attributes to a Labeler.
    21  func (l *Labeler) Add(ls ...attribute.KeyValue) {
    22  	l.mu.Lock()
    23  	defer l.mu.Unlock()
    24  	l.attributes = append(l.attributes, ls...)
    25  }
    26  
    27  // Get returns a copy of the attributes added to the Labeler.
    28  func (l *Labeler) Get() []attribute.KeyValue {
    29  	l.mu.Lock()
    30  	defer l.mu.Unlock()
    31  	ret := make([]attribute.KeyValue, len(l.attributes))
    32  	copy(ret, l.attributes)
    33  	return ret
    34  }
    35  
    36  type labelerContextKeyType int
    37  
    38  const lablelerContextKey labelerContextKeyType = 0
    39  
    40  func injectLabeler(ctx context.Context, l *Labeler) context.Context {
    41  	return context.WithValue(ctx, lablelerContextKey, l)
    42  }
    43  
    44  // LabelerFromContext retrieves a Labeler instance from the provided context if
    45  // one is available.  If no Labeler was found in the provided context a new, empty
    46  // Labeler is returned and the second return value is false.  In this case it is
    47  // safe to use the Labeler but any attributes added to it will not be used.
    48  func LabelerFromContext(ctx context.Context) (*Labeler, bool) {
    49  	l, ok := ctx.Value(lablelerContextKey).(*Labeler)
    50  	if !ok {
    51  		l = &Labeler{}
    52  	}
    53  	return l, ok
    54  }
    55
View as plain text