| 1 | /* Read-write locks (native Windows implementation).
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| 2 | Copyright (C) 2005-2022 Free Software Foundation, Inc.
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| 3 |
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| 4 | This file is free software: you can redistribute it and/or modify
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| 5 | it under the terms of the GNU Lesser General Public License as
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| 6 | published by the Free Software Foundation; either version 2.1 of the
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| 7 | License, or (at your option) any later version.
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| 8 |
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| 9 | This file is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU Lesser General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU Lesser General Public License
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| 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | /* Written by Bruno Haible <bruno@clisp.org>, 2005.
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| 18 | Based on GCC's gthr-win32.h. */
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| 19 |
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| 20 | #ifndef _WINDOWS_RWLOCK_H
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| 21 | #define _WINDOWS_RWLOCK_H
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| 22 |
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| 23 | #define WIN32_LEAN_AND_MEAN /* avoid including junk */
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| 24 | #include <windows.h>
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| 25 |
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| 26 | #include "windows-initguard.h"
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| 27 |
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| 28 | /* It is impossible to implement read-write locks using plain locks, without
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| 29 | introducing an extra thread dedicated to managing read-write locks.
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| 30 | Therefore here we need to use the low-level Event type. */
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| 31 |
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| 32 | typedef struct
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| 33 | {
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| 34 | HANDLE *array; /* array of waiting threads, each represented by an event */
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| 35 | unsigned int count; /* number of waiting threads */
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| 36 | unsigned int alloc; /* length of allocated array */
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| 37 | unsigned int offset; /* index of first waiting thread in array */
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| 38 | }
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| 39 | glwthread_carray_waitqueue_t;
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| 40 | typedef struct
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| 41 | {
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| 42 | glwthread_initguard_t guard; /* protects the initialization */
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| 43 | CRITICAL_SECTION lock; /* protects the remaining fields */
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| 44 | glwthread_carray_waitqueue_t waiting_readers; /* waiting readers */
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| 45 | glwthread_carray_waitqueue_t waiting_writers; /* waiting writers */
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| 46 | int runcount; /* number of readers running, or -1 when a writer runs */
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| 47 | }
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| 48 | glwthread_rwlock_t;
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| 49 |
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| 50 | #define GLWTHREAD_RWLOCK_INIT { GLWTHREAD_INITGUARD_INIT }
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| 51 |
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| 52 | #ifdef __cplusplus
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| 53 | extern "C" {
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| 54 | #endif
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| 55 |
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| 56 | extern void glwthread_rwlock_init (glwthread_rwlock_t *lock);
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| 57 | extern int glwthread_rwlock_rdlock (glwthread_rwlock_t *lock);
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| 58 | extern int glwthread_rwlock_wrlock (glwthread_rwlock_t *lock);
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| 59 | extern int glwthread_rwlock_tryrdlock (glwthread_rwlock_t *lock);
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| 60 | extern int glwthread_rwlock_trywrlock (glwthread_rwlock_t *lock);
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| 61 | extern int glwthread_rwlock_unlock (glwthread_rwlock_t *lock);
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| 62 | extern int glwthread_rwlock_destroy (glwthread_rwlock_t *lock);
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| 63 |
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| 64 | #ifdef __cplusplus
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| 65 | }
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| 66 | #endif
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| 67 |
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| 68 | #endif /* _WINDOWS_RWLOCK_H */
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