prometheus/vendor/github.com/petermattis/goid/goid_go1.4.go

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// Copyright 2015 Peter Mattis.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License. See the AUTHORS file
// for names of contributors.
// +build go1.4,!go1.5
package goid
import "unsafe"
var pointerSize = unsafe.Sizeof(uintptr(0))
// Backdoor access to runtime·getg().
func getg() uintptr // in goid_go1.4.s
// Get returns the id of the current goroutine.
func Get() int64 {
// The goid is the 16th field in the G struct where each field is a
// pointer, uintptr or padded to that size. See runtime.h from the
// Go sources. I'm not aware of a cleaner way to determine the
// offset.
return *(*int64)(unsafe.Pointer(getg() + 16*pointerSize))
}