68 lines
2.6 KiB
C
68 lines
2.6 KiB
C
/* Read-write locks (native Windows implementation).
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Copyright (C) 2005-2023 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible <bruno@clisp.org>, 2005.
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Based on GCC's gthr-win32.h. */
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#ifndef _WINDOWS_RWLOCK_H
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#define _WINDOWS_RWLOCK_H
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#define WIN32_LEAN_AND_MEAN /* avoid including junk */
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#include <windows.h>
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#include "windows-initguard.h"
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/* It is impossible to implement read-write locks using plain locks, without
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introducing an extra thread dedicated to managing read-write locks.
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Therefore here we need to use the low-level Event type. */
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typedef struct
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{
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HANDLE *array; /* array of waiting threads, each represented by an event */
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unsigned int count; /* number of waiting threads */
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unsigned int alloc; /* length of allocated array */
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unsigned int offset; /* index of first waiting thread in array */
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}
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glwthread_carray_waitqueue_t;
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typedef struct
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{
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glwthread_initguard_t guard; /* protects the initialization */
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CRITICAL_SECTION lock; /* protects the remaining fields */
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glwthread_carray_waitqueue_t waiting_readers; /* waiting readers */
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glwthread_carray_waitqueue_t waiting_writers; /* waiting writers */
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int runcount; /* number of readers running, or -1 when a writer runs */
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}
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glwthread_rwlock_t;
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#define GLWTHREAD_RWLOCK_INIT { GLWTHREAD_INITGUARD_INIT }
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#ifdef __cplusplus
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extern "C" {
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#endif
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extern void glwthread_rwlock_init (glwthread_rwlock_t *lock);
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extern int glwthread_rwlock_rdlock (glwthread_rwlock_t *lock);
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extern int glwthread_rwlock_wrlock (glwthread_rwlock_t *lock);
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extern int glwthread_rwlock_tryrdlock (glwthread_rwlock_t *lock);
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extern int glwthread_rwlock_trywrlock (glwthread_rwlock_t *lock);
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extern int glwthread_rwlock_unlock (glwthread_rwlock_t *lock);
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extern int glwthread_rwlock_destroy (glwthread_rwlock_t *lock);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _WINDOWS_RWLOCK_H */
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