Daniel Veillard | b847864 | 2001-10-12 17:29:10 +0000 | [diff] [blame] | 1 | /** |
| 2 | * threads.c: set of generic threading related routines |
| 3 | * |
| 4 | * See Copyright for the status of this software. |
| 5 | * |
| 6 | * Gary Pennington <Gary.Pennington@uk.sun.com> |
| 7 | * daniel@veillard.com |
| 8 | */ |
| 9 | |
| 10 | #include "libxml.h" |
| 11 | |
| 12 | #include <string.h> |
| 13 | |
| 14 | #include <libxml/threads.h> |
| 15 | #include <libxml/globals.h> |
| 16 | |
| 17 | #ifdef HAVE_SYS_TYPES_H |
| 18 | #include <sys/types.h> |
| 19 | #endif |
| 20 | #ifdef HAVE_UNISTD_H |
| 21 | #include <unistd.h> |
| 22 | #endif |
| 23 | #ifdef HAVE_STDLIB_H |
| 24 | #include <stdlib.h> |
| 25 | #endif |
| 26 | #ifdef HAVE_PTHREAD_H |
| 27 | #include <pthread.h> |
| 28 | #endif |
| 29 | |
| 30 | #if defined(SOLARIS) |
| 31 | #include <note.h> |
| 32 | #endif |
| 33 | |
| 34 | |
| 35 | /* |
| 36 | * TODO: this module still uses malloc/free and not xmlMalloc/xmlFree |
| 37 | * to avoid some crazyness since xmlMalloc/xmlFree may actually |
| 38 | * be hosted on allocated blocks needing them for the allocation ... |
| 39 | */ |
| 40 | |
| 41 | /* |
| 42 | * xmlMutex are a simple mutual exception locks |
| 43 | */ |
| 44 | struct _xmlMutex { |
| 45 | #ifdef HAVE_PTHREAD_H |
| 46 | pthread_mutex_t lock; |
| 47 | #else |
| 48 | int empty; |
| 49 | #endif |
| 50 | }; |
| 51 | |
| 52 | /* |
| 53 | * xmlRMutex are reentrant mutual exception locks |
| 54 | */ |
| 55 | struct _xmlRMutex { |
| 56 | #ifdef HAVE_PTHREAD_H |
| 57 | pthread_mutex_t lock; |
| 58 | unsigned int held; |
| 59 | unsigned int waiters; |
| 60 | pthread_t tid; |
| 61 | pthread_cond_t cv; |
| 62 | #else |
| 63 | int empty; |
| 64 | #endif |
| 65 | }; |
| 66 | /* |
| 67 | * This module still has some internal static data. |
| 68 | * - xmlLibraryLock a global lock |
| 69 | * - globalkey used for per-thread data |
| 70 | * - keylock protecting globalkey |
| 71 | * - keyonce to mark initialization of globalkey |
| 72 | */ |
| 73 | #ifdef HAVE_PTHREAD_H |
| 74 | static pthread_mutex_t keylock; |
| 75 | static pthread_key_t globalkey; |
| 76 | static int keyonce = 0; |
| 77 | #endif |
| 78 | static xmlRMutexPtr xmlLibraryLock = NULL; |
| 79 | |
| 80 | #if defined(SOLARIS) |
| 81 | NOTE(DATA_READABLE_WITHOUT_LOCK(keyonce)) |
| 82 | #endif |
| 83 | |
| 84 | /** |
| 85 | * xmlMutexPtr: |
| 86 | * |
| 87 | * xmlNewMutex() is used to allocate a libxml2 token struct for use in |
| 88 | * synchronizing access to data. |
| 89 | * |
| 90 | * Returns a new simple mutex pointer or NULL in case of error |
| 91 | */ |
| 92 | xmlMutexPtr |
| 93 | xmlNewMutex(void) |
| 94 | { |
| 95 | xmlMutexPtr tok; |
| 96 | |
| 97 | if ((tok = malloc(sizeof(xmlMutex))) == NULL) |
| 98 | return (NULL); |
| 99 | #ifdef HAVE_PTHREAD_H |
| 100 | pthread_mutex_init(&tok->lock, NULL); |
| 101 | #endif |
| 102 | return (tok); |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * xmlFreeMutex: |
| 107 | * @tok: the simple mutex |
| 108 | * |
| 109 | * xmlFreeMutex() is used to reclaim resources associated with a libxml2 token |
| 110 | * struct. |
| 111 | */ |
| 112 | void |
| 113 | xmlFreeMutex(xmlMutexPtr tok) |
| 114 | { |
| 115 | #ifdef HAVE_PTHREAD_H |
| 116 | pthread_mutex_destroy(&tok->lock); |
| 117 | #endif |
| 118 | free(tok); |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * xmlMutexLock: |
| 123 | * @tok: the simple mutex |
| 124 | * |
| 125 | * xmlMutexLock() is used to lock a libxml2 token. |
| 126 | */ |
| 127 | void |
| 128 | xmlMutexLock(xmlMutexPtr tok) |
| 129 | { |
| 130 | #ifdef HAVE_PTHREAD_H |
| 131 | pthread_mutex_lock(&tok->lock); |
| 132 | #endif |
| 133 | |
| 134 | } |
| 135 | |
| 136 | /** |
| 137 | * xmlMutexUnlock: |
| 138 | * @tok: the simple mutex |
| 139 | * |
| 140 | * xmlMutexUnlock() is used to unlock a libxml2 token. |
| 141 | */ |
| 142 | void |
| 143 | xmlMutexUnlock(xmlMutexPtr tok) |
| 144 | { |
| 145 | #ifdef HAVE_PTHREAD_H |
| 146 | pthread_mutex_unlock(&tok->lock); |
| 147 | #endif |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * xmlRNewMutex: |
| 152 | * |
| 153 | * xmlRNewMutex() is used to allocate a reentrant mutex for use in |
| 154 | * synchronizing access to data. token_r is a re-entrant lock and thus useful |
| 155 | * for synchronizing access to data structures that may be manipulated in a |
| 156 | * recursive fashion. |
| 157 | * |
| 158 | * Returns the new reentrant mutex pointer or NULL in case of error |
| 159 | */ |
| 160 | xmlRMutexPtr |
| 161 | xmlNewRMutex(void) |
| 162 | { |
| 163 | xmlRMutexPtr tok; |
| 164 | |
| 165 | if ((tok = malloc(sizeof(xmlRMutex))) == NULL) |
| 166 | return (NULL); |
| 167 | #ifdef HAVE_PTHREAD_H |
| 168 | pthread_mutex_init(&tok->lock, NULL); |
| 169 | tok->held = 0; |
| 170 | tok->waiters = 0; |
| 171 | #endif |
| 172 | return (tok); |
| 173 | } |
| 174 | |
| 175 | /** |
| 176 | * xmlRFreeMutex: |
| 177 | * @tok: the reentrant mutex |
| 178 | * |
| 179 | * xmlRFreeMutex() is used to reclaim resources associated with a |
| 180 | * reentrant mutex. |
| 181 | */ |
| 182 | void |
| 183 | xmlFreeRMutex(xmlRMutexPtr tok) |
| 184 | { |
| 185 | #ifdef HAVE_PTHREAD_H |
| 186 | pthread_mutex_destroy(&tok->lock); |
| 187 | #endif |
| 188 | free(tok); |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * xmlRMutexLock: |
| 193 | * @tok: the reentrant mutex |
| 194 | * |
| 195 | * xmlRMutexLock() is used to lock a libxml2 token_r. |
| 196 | */ |
| 197 | void |
| 198 | xmlRMutexLock(xmlRMutexPtr tok) |
| 199 | { |
| 200 | #ifdef HAVE_PTHREAD_H |
| 201 | pthread_mutex_lock(&tok->lock); |
| 202 | if (tok->held) { |
| 203 | if (pthread_equal(tok->tid, pthread_self())) { |
| 204 | tok->held++; |
| 205 | pthread_mutex_unlock(&tok->lock); |
| 206 | return; |
| 207 | } else { |
| 208 | tok->waiters++; |
| 209 | while (tok->held) |
| 210 | pthread_cond_wait(&tok->cv, &tok->lock); |
| 211 | tok->waiters--; |
| 212 | } |
| 213 | } |
| 214 | tok->tid = pthread_self(); |
| 215 | tok->held = 1; |
| 216 | pthread_mutex_unlock(&tok->lock); |
| 217 | #endif |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * xmlRMutexUnlock: |
| 222 | * @tok: the reentrant mutex |
| 223 | * |
| 224 | * xmlRMutexUnlock() is used to unlock a libxml2 token_r. |
| 225 | */ |
| 226 | void |
| 227 | xmlRMutexUnlock(xmlRMutexPtr tok) |
| 228 | { |
| 229 | #ifdef HAVE_PTHREAD_H |
| 230 | pthread_mutex_lock(&tok->lock); |
| 231 | tok->held--; |
| 232 | if (tok->held == 0) { |
| 233 | if (tok->waiters) |
| 234 | pthread_cond_signal(&tok->cv); |
| 235 | tok->tid = 0; |
| 236 | } |
| 237 | pthread_mutex_unlock(&tok->lock); |
| 238 | #endif |
| 239 | } |
| 240 | |
| 241 | /************************************************************************ |
| 242 | * * |
| 243 | * Per thread global state handling * |
| 244 | * * |
| 245 | ************************************************************************/ |
| 246 | |
| 247 | /** |
| 248 | * xmlFreeGlobalState: |
| 249 | * @state: a thread global state |
| 250 | * |
| 251 | * xmlFreeGlobalState() is called when a thread terminates with a non-NULL |
| 252 | * global state. It is is used here to reclaim memory resources. |
| 253 | */ |
| 254 | static void |
| 255 | xmlFreeGlobalState(void *state) |
| 256 | { |
| 257 | free(state); |
| 258 | } |
| 259 | |
| 260 | /** |
| 261 | * xmlNewGlobalState: |
| 262 | * |
| 263 | * xmlNewGlobalState() allocates a global state. This structure is used to |
| 264 | * hold all data for use by a thread when supporting backwards compatibility |
| 265 | * of libmxml2 to pre-thread-safe behaviour. |
| 266 | * |
| 267 | * Returns the newly allocated xmlGlobalStatePtr or NULL in case of error |
| 268 | */ |
| 269 | static xmlGlobalStatePtr |
| 270 | xmlNewGlobalState(void) |
| 271 | { |
| 272 | xmlGlobalState *gs; |
| 273 | |
| 274 | gs = malloc(sizeof(xmlGlobalState)); |
| 275 | if (gs == NULL) |
| 276 | return(NULL); |
| 277 | |
| 278 | memset(gs, 0, sizeof(gs)); |
| 279 | xmlInitializeGlobalState(gs); |
| 280 | return (gs); |
| 281 | } |
| 282 | |
| 283 | |
| 284 | /** |
| 285 | * xmlGetGlobalState: |
| 286 | * |
| 287 | * xmlGetGlobalState() is called to retrieve the global state for a thread. |
| 288 | * keyonce will only be set once during a library invocation and is used |
| 289 | * to create globalkey, the key used to store each thread's TSD. |
| 290 | * |
| 291 | * Note: it should not be called for the "main" thread as this thread uses |
| 292 | * the existing global variables defined in the library. |
| 293 | * |
| 294 | * Returns the thread global state or NULL in case of error |
| 295 | */ |
| 296 | xmlGlobalStatePtr |
| 297 | xmlGetGlobalState(void) |
| 298 | { |
| 299 | #ifdef HAVE_PTHREAD_H |
| 300 | xmlGlobalState *globalval; |
| 301 | |
| 302 | if (keyonce == 0) { |
| 303 | (void) pthread_mutex_lock(&keylock); |
| 304 | if (keyonce == 0) { |
| 305 | keyonce++; |
| 306 | (void) pthread_key_create(&globalkey, xmlFreeGlobalState); |
| 307 | } |
| 308 | (void) pthread_mutex_unlock(&keylock); |
| 309 | } |
| 310 | if ((globalval = (xmlGlobalState *) |
| 311 | pthread_getspecific(globalkey)) == NULL) { |
| 312 | xmlGlobalState *tsd = xmlNewGlobalState(); |
| 313 | |
| 314 | pthread_setspecific(globalkey, tsd); |
| 315 | return (tsd); |
| 316 | } else |
| 317 | return (globalval); |
| 318 | #endif |
| 319 | } |
| 320 | |
| 321 | |
| 322 | /************************************************************************ |
| 323 | * * |
| 324 | * Library wide thread interfaces * |
| 325 | * * |
| 326 | ************************************************************************/ |
| 327 | |
| 328 | /** |
| 329 | * xmlLockLibrary: |
| 330 | * |
| 331 | * xmlLockLibrary() is used to take out a re-entrant lock on the libxml2 |
| 332 | * library. |
| 333 | */ |
| 334 | void |
| 335 | xmlLockLibrary(void) |
| 336 | { |
| 337 | xmlRMutexLock(xmlLibraryLock); |
| 338 | } |
| 339 | |
| 340 | /** |
| 341 | * xmlUnlockLibrary: |
| 342 | * |
| 343 | * xmlUnlockLibrary() is used to release a re-entrant lock on the libxml2 |
| 344 | * library. |
| 345 | */ |
| 346 | void |
| 347 | xmlUnlockLibrary(void) |
| 348 | { |
| 349 | xmlRMutexUnlock(xmlLibraryLock); |
| 350 | } |
| 351 | |
| 352 | /** |
| 353 | * xmlInitThreads: |
| 354 | * |
| 355 | * xmlInitThreads() is used to to initialize all the thread related |
| 356 | * data of the libxml2 library. |
| 357 | */ |
| 358 | void |
| 359 | xmlInitThreads(void) |
| 360 | { |
| 361 | } |
| 362 | |
| 363 | /** |
| 364 | * xmlCleanupThreads: |
| 365 | * |
| 366 | * xmlCleanupThreads() is used to to cleanup all the thread related |
| 367 | * data of the libxml2 library once processing has ended. |
| 368 | */ |
| 369 | void |
| 370 | xmlCleanupThreads(void) |
| 371 | { |
| 372 | } |