libgo/go/runtime/pprof/runtime.go

   1 // Copyright 2017 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package pprof
   6
   7 import (
   8         "context"
   9         "unsafe"
  10 )
  11
  12 // runtime_setProfLabel is defined in runtime/proflabel.go.
  13 func runtime_setProfLabel(labels unsafe.Pointer)
  14
  15 // runtime_getProfLabel is defined in runtime/proflabel.go.
  16 func runtime_getProfLabel() unsafe.Pointer
  17
  18 // SetGoroutineLabels sets the current goroutine's labels to match ctx.
  19 // This is a lower-level API than Do, which should be used instead when possible.
  20 func SetGoroutineLabels(ctx context.Context) {
  21         ctxLabels, _ := ctx.Value(labelContextKey{}).(*labelMap)
  22         runtime_setProfLabel(unsafe.Pointer(ctxLabels))
  23 }
  24
  25 // Do calls f with a copy of the parent context with the
  26 // given labels added to the parent's label map.
  27 // Each key/value pair in labels is inserted into the label map in the
  28 // order provided, overriding any previous value for the same key.
  29 // The augmented label map will be set for the duration of the call to f
  30 // and restored once f returns.
  31 func Do(ctx context.Context, labels LabelSet, f func(context.Context)) {
  32         defer SetGoroutineLabels(ctx)
  33         ctx = WithLabels(ctx, labels)
  34         SetGoroutineLabels(ctx)
  35         f(ctx)
  36 }