github.com/choleraehyq/piD@v0.0.11/goid_go1.4.go (about)

     1  // Copyright 2015 Peter Mattis.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
    12  // implied. See the License for the specific language governing
    13  // permissions and limitations under the License. See the AUTHORS file
    14  // for names of contributors.
    15  
    16  // +build go1.4,!go1.5
    17  
    18  package goid
    19  
    20  import "unsafe"
    21  
    22  var pointerSize = unsafe.Sizeof(uintptr(0))
    23  
    24  // Backdoor access to runtime·getg().
    25  func getg() uintptr // in goid_go1.4.s
    26  
    27  // Get returns the id of the current goroutine.
    28  func Get() int64 {
    29  	// The goid is the 16th field in the G struct where each field is a
    30  	// pointer, uintptr or padded to that size. See runtime.h from the
    31  	// Go sources. I'm not aware of a cleaner way to determine the
    32  	// offset.
    33  	return *(*int64)(unsafe.Pointer(getg() + 16*pointerSize))
    34  }