00001 /* SVN FILE INFO 00002 * $Revision: 174 $ : Last Committed Revision 00003 * $Date: 2008年06月24日 10:50:29 -0700 (2008年6月24日) $ : Last Committed Date */ 00004 /*[ 00005 * Copyright (c) 2007 Integration Engineering Laboratory 00006 University of California, Davis 00007 * 00008 * Permission to use, copy, and distribute this software and its 00009 * documentation for any purpose with or without fee is hereby granted, 00010 * provided that the above copyright notice appear in all copies and 00011 * that both that copyright notice and this permission notice appear 00012 * in supporting documentation. 00013 * 00014 * Permission to modify the software is granted, but not the right to 00015 * distribute the complete modified source code. Modifications are to 00016 * be distributed as patches to the released version. Permission to 00017 * distribute binaries produced by compiling modified sources is granted, 00018 * provided you 00019 * 1. distribute the corresponding source modifications from the 00020 * released version in the form of a patch file along with the binaries, 00021 * 2. add special version identification to distinguish your version 00022 * in addition to the base release version number, 00023 * 3. provide your name and address as the primary contact for the 00024 * support of your modified version, and 00025 * 4. retain our contact information in regard to use of the base 00026 * software. 00027 * Permission to distribute the released version of the source code along 00028 * with corresponding source modifications in the form of a patch file is 00029 * granted with same provisions 2 through 4 for binary distributions. 00030 * 00031 * This software is provided "as is" without express or implied warranty 00032 * to the extent permitted by applicable law. 00033 ]*/ 00034 00035 #include <stdio.h> 00036 #include <stdlib.h> 00037 #include "include/macros.h" 00038 #include "include/mc_error.h" 00039 #include "include/mc_rwlock.h" 00040 00041 int mc_rwlock_init(mc_rwlock_p rwlock) 00042 { 00043 /* Init values */ 00044 rwlock->num_readers = 0; 00045 rwlock->write_flag = 0; 00046 rwlock->write_request = 0; 00047 00048 /* Alloc sync */ 00049 rwlock->lock = (MUTEX_T*)malloc(sizeof(MUTEX_T)); 00050 CHECK_NULL(rwlock->lock, return MC_ERR_MEMORY;); 00051 rwlock->cond = (COND_T*)malloc(sizeof(COND_T)); 00052 CHECK_NULL(rwlock->cond, return MC_ERR_MEMORY;); 00053 00054 /* Init sync */ 00055 MUTEX_INIT(rwlock->lock); 00056 COND_INIT(rwlock->cond); 00057 00058 return 0; 00059 } 00060 00061 int mc_rwlock_destroy(mc_rwlock_p rwlock) 00062 { 00063 /* Destroy mutex/conds */ 00064 MUTEX_DESTROY(rwlock->lock); 00065 COND_DESTROY(rwlock->cond); 00066 00067 /* De-alloc */ 00068 free(rwlock->lock); 00069 free(rwlock->cond); 00070 00071 return 0; 00072 } 00073 00074 int mc_rwlock_rdlock(mc_rwlock_p rwlock) 00075 { 00076 MUTEX_LOCK(rwlock->lock); 00077 while ( 00078 (rwlock->write_flag != 0) || 00079 (rwlock->write_request != 0) 00080 ) 00081 { 00082 COND_WAIT(rwlock->cond, rwlock->lock); 00083 } 00084 rwlock->num_readers++; 00085 MUTEX_UNLOCK(rwlock->lock); 00086 return 0; 00087 } 00088 00089 int mc_rwlock_rdunlock(mc_rwlock_p rwlock) 00090 { 00091 MUTEX_LOCK(rwlock->lock); 00092 if (rwlock->num_readers > 0) { 00093 rwlock->num_readers--; 00094 } 00095 if (rwlock->num_readers == 0) { 00096 COND_SIGNAL( rwlock->cond ); 00097 } 00098 MUTEX_UNLOCK(rwlock->lock); 00099 return 0; 00100 } 00101 00102 int mc_rwlock_wrlock(mc_rwlock_p rwlock) 00103 { 00104 MUTEX_LOCK(rwlock->lock); 00105 rwlock->write_request++; 00106 00107 while ( 00108 (rwlock->num_readers != 0) || 00109 (rwlock->write_flag != 0) 00110 ) 00111 { 00112 COND_WAIT(rwlock->cond, rwlock->lock); 00113 } 00114 00115 rwlock->write_request--; 00116 rwlock->write_flag++; 00117 MUTEX_UNLOCK(rwlock->lock); 00118 return 0; 00119 } 00120 00121 int mc_rwlock_wrunlock(mc_rwlock_p rwlock) 00122 { 00123 MUTEX_LOCK(rwlock->lock); 00124 rwlock->write_flag = 0; 00125 COND_SIGNAL(rwlock->cond); 00126 MUTEX_UNLOCK(rwlock->lock); 00127 return 0; 00128 }