1 /* Read-write locks (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 #ifndef _WINDOWS_RWLOCK_H 21 #define _WINDOWS_RWLOCK_H 22 23 #define WIN32_LEAN_AND_MEAN /* avoid including junk */ 24 #include <windows.h> 25 26 #include "windows-initguard.h" 27 28 /* It is impossible to implement read-write locks using plain locks, without 29 introducing an extra thread dedicated to managing read-write locks. 30 Therefore here we need to use the low-level Event type. */ 31 32 typedef struct 33 { 34 HANDLE *array; /* array of waiting threads, each represented by an event */ 35 unsigned int count; /* number of waiting threads */ 36 unsigned int alloc; /* length of allocated array */ 37 unsigned int offset; /* index of first waiting thread in array */ 38 } 39 glwthread_carray_waitqueue_t; 40 typedef struct 41 { 42 glwthread_initguard_t guard; /* protects the initialization */ 43 CRITICAL_SECTION lock; /* protects the remaining fields */ 44 glwthread_carray_waitqueue_t waiting_readers; /* waiting readers */ 45 glwthread_carray_waitqueue_t waiting_writers; /* waiting writers */ 46 int runcount; /* number of readers running, or -1 when a writer runs */ 47 } 48 glwthread_rwlock_t; 49 50 #define GLWTHREAD_RWLOCK_INIT { GLWTHREAD_INITGUARD_INIT } 51 52 #ifdef __cplusplus 53 extern "C" { 54 #endif 55 56 extern void glwthread_rwlock_init (glwthread_rwlock_t *lock); 57 extern int glwthread_rwlock_rdlock (glwthread_rwlock_t *lock); 58 extern int glwthread_rwlock_wrlock (glwthread_rwlock_t *lock); 59 extern int glwthread_rwlock_tryrdlock (glwthread_rwlock_t *lock); 60 extern int glwthread_rwlock_trywrlock (glwthread_rwlock_t *lock); 61 extern int glwthread_rwlock_unlock (glwthread_rwlock_t *lock); 62 extern int glwthread_rwlock_destroy (glwthread_rwlock_t *lock); 63 64 #ifdef __cplusplus 65 } 66 #endif 67 68 #endif /* _WINDOWS_RWLOCK_H */ 69