src/runtime/lfstack.go

   1 // Copyright 2012 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 // Lock-free stack.
   6 // The following code runs only on g0 stack.
   7
   8 package runtime
   9
  10 import "unsafe"
  11
  12 func lfstackpush(head *uint64, node *lfnode) {
  13         node.pushcnt++
  14         new := lfstackPack(node, node.pushcnt)
  15         for {
  16                 old := atomicload64(head)
  17                 node.next = old
  18                 if cas64(head, old, new) {
  19                         break
  20                 }
  21         }
  22 }
  23
  24 func lfstackpop(head *uint64) unsafe.Pointer {
  25         for {
  26                 old := atomicload64(head)
  27                 if old == 0 {
  28                         return nil
  29                 }
  30                 node, _ := lfstackUnpack(old)
  31                 next := atomicload64(&node.next)
  32                 if cas64(head, old, next) {
  33                         return unsafe.Pointer(node)
  34                 }
  35         }
  36 }