| 1 | /* Once-only control (native Windows implementation). |
| 2 | Copyright (C) 2005-2020 Free Software Foundation, Inc. |
| 3 | |
| 4 | This program is free software; you can redistribute it and/or modify |
| 5 | it under the terms of the GNU General Public License as published by |
| 6 | the Free Software Foundation; either version 3, or (at your option) |
| 7 | any later version. |
| 8 | |
| 9 | This program is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | GNU General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU General Public License |
| 15 | along with this program; if not, see <https://www.gnu.org/licenses/>. */ |
| 16 | |
| 17 | /* Written by Bruno Haible <bruno@clisp.org>, 2005. |
| 18 | Based on GCC's gthr-win32.h. */ |
| 19 | |
| 20 | #include <config.h> |
| 21 | |
| 22 | /* Specification. */ |
| 23 | #include "windows-once.h" |
| 24 | |
| 25 | #include <stdlib.h> |
| 26 | |
| 27 | void |
| 28 | glwthread_once (glwthread_once_t *once_control, void (*initfunction) (void)) |
| 29 | { |
| 30 | if (once_control->inited <= 0) |
| 31 | { |
| 32 | if (InterlockedIncrement (&once_control->started) == 0) |
| 33 | { |
| 34 | /* This thread is the first one to come to this once_control. */ |
| 35 | InitializeCriticalSection (&once_control->lock); |
| 36 | EnterCriticalSection (&once_control->lock); |
| 37 | once_control->inited = 0; |
| 38 | initfunction (); |
| 39 | once_control->inited = 1; |
| 40 | LeaveCriticalSection (&once_control->lock); |
| 41 | } |
| 42 | else |
| 43 | { |
| 44 | /* Don't let once_control->started grow and wrap around. */ |
| 45 | InterlockedDecrement (&once_control->started); |
| 46 | /* Some other thread has already started the initialization. |
| 47 | Yield the CPU while waiting for the other thread to finish |
| 48 | initializing and taking the lock. */ |
| 49 | while (once_control->inited < 0) |
| 50 | Sleep (0); |
| 51 | if (once_control->inited <= 0) |
| 52 | { |
| 53 | /* Take the lock. This blocks until the other thread has |
| 54 | finished calling the initfunction. */ |
| 55 | EnterCriticalSection (&once_control->lock); |
| 56 | LeaveCriticalSection (&once_control->lock); |
| 57 | if (!(once_control->inited > 0)) |
| 58 | abort (); |
| 59 | } |
| 60 | } |
| 61 | } |
| 62 | } |