| // Copyright 2017 The Netstack Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // +build !race |
| // +build !amd64 |
| |
| package sleep |
| |
| import "sync/atomic" |
| |
| // commitSleep signals to wakers that the given g is now sleeping. Wakers can |
| // then fetch it and wake it. |
| // |
| // The commit may fail if wakers have been asserted after our last check, in |
| // which case they will have set s.waitingG to zero. |
| // |
| // It is written in assembly because it is called from g0, so it doesn't have |
| // a race context. |
| func commitSleep(g uintptr, waitingG *uintptr) bool { |
| for { |
| // Check if the wait was aborted. |
| if atomic.LoadUintptr(waitingG) == 0 { |
| return false |
| } |
| |
| // Try to store the G so that wakers know who to wake. |
| if atomic.CompareAndSwapUintptr(waitingG, preparingG, g) { |
| return true |
| } |
| } |
| } |