runtime: add available godoc link

[gostls13.git] / src / runtime / pprof / label.go

diff --git a/src/runtime/pprof/label.go b/src/runtime/pprof/label.go
index 44da3f873724d72d32c22cce2e4ce29f1a2e3008..3684ae34e51cfcd8dac0306dff15bb2a5cadd061 100644 (file)
--- a/src/runtime/pprof/label.go
+++ b/src/runtime/pprof/label.go
@@ -6,6 +6,9 @@ package pprof
 
 import (
        "context"
+       "fmt"
+       "sort"
+       "strings"
 )
 
 type label struct {
@@ -34,11 +37,28 @@ func labelValue(ctx context.Context) labelMap {
 // that admits incremental immutable modification more efficiently.
 type labelMap map[string]string
 
-// WithLabels returns a new context.Context with the given labels added.
+// String satisfies Stringer and returns key, value pairs in a consistent
+// order.
+func (l *labelMap) String() string {
+       if l == nil {
+               return ""
+       }
+       keyVals := make([]string, 0, len(*l))
+
+       for k, v := range *l {
+               keyVals = append(keyVals, fmt.Sprintf("%q:%q", k, v))
+       }
+
+       sort.Strings(keyVals)
+
+       return "{" + strings.Join(keyVals, ", ") + "}"
+}
+
+// WithLabels returns a new [context.Context] with the given labels added.
 // A label overwrites a prior label with the same key.
 func WithLabels(ctx context.Context, labels LabelSet) context.Context {
-       childLabels := make(labelMap)
        parentLabels := labelValue(ctx)
+       childLabels := make(labelMap, len(parentLabels))
        // TODO(matloob): replace the map implementation with something
        // more efficient so creating a child context WithLabels doesn't need
        // to clone the map.
@@ -52,17 +72,20 @@ func WithLabels(ctx context.Context, labels LabelSet) context.Context {
 }
 
 // Labels takes an even number of strings representing key-value pairs
-// and makes a LabelList containing them.
+// and makes a [LabelSet] containing them.
 // A label overwrites a prior label with the same key.
+// Currently only the CPU and goroutine profiles utilize any labels
+// information.
+// See https://golang.org/issue/23458 for details.
 func Labels(args ...string) LabelSet {
        if len(args)%2 != 0 {
                panic("uneven number of arguments to pprof.Labels")
        }
-       labels := LabelSet{}
+       list := make([]label, 0, len(args)/2)
        for i := 0; i+1 < len(args); i += 2 {
-               labels.list = append(labels.list, label{key: args[i], value: args[i+1]})
+               list = append(list, label{key: args[i], value: args[i+1]})
        }
-       return labels
+       return LabelSet{list: list}
 }
 
 // Label returns the value of the label with the given key on ctx, and a boolean indicating