/* Read-write locks (native Windows implementation). Copyright (C) 2005-2020 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see <https://www.gnu.org/licenses/>. */ /* Written by Bruno Haible <bruno@clisp.org>, 2005. Based on GCC's gthr-win32.h. */ #ifndef _WINDOWS_RWLOCK_H #define _WINDOWS_RWLOCK_H #define WIN32_LEAN_AND_MEAN /* avoid including junk */ #include <windows.h> #include "windows-initguard.h" /* It is impossible to implement read-write locks using plain locks, without introducing an extra thread dedicated to managing read-write locks. Therefore here we need to use the low-level Event type. */ typedef struct { HANDLE *array; /* array of waiting threads, each represented by an event */ unsigned int count; /* number of waiting threads */ unsigned int alloc; /* length of allocated array */ unsigned int offset; /* index of first waiting thread in array */ } glwthread_carray_waitqueue_t; typedef struct { glwthread_initguard_t guard; /* protects the initialization */ CRITICAL_SECTION lock; /* protects the remaining fields */ glwthread_carray_waitqueue_t waiting_readers; /* waiting readers */ glwthread_carray_waitqueue_t waiting_writers; /* waiting writers */ int runcount; /* number of readers running, or -1 when a writer runs */ } glwthread_rwlock_t; #define GLWTHREAD_RWLOCK_INIT { GLWTHREAD_INITGUARD_INIT } #ifdef __cplusplus extern "C" { #endif extern void glwthread_rwlock_init (glwthread_rwlock_t *lock); extern int glwthread_rwlock_rdlock (glwthread_rwlock_t *lock); extern int glwthread_rwlock_wrlock (glwthread_rwlock_t *lock); extern int glwthread_rwlock_tryrdlock (glwthread_rwlock_t *lock); extern int glwthread_rwlock_trywrlock (glwthread_rwlock_t *lock); extern int glwthread_rwlock_unlock (glwthread_rwlock_t *lock); extern int glwthread_rwlock_destroy (glwthread_rwlock_t *lock); #ifdef __cplusplus } #endif #endif /* _WINDOWS_RWLOCK_H */ |