git.sur5r.net Git - openldap/blob - libraries/libldap_r/tpool.c

   1 /* $OpenLDAP$ */
   2 /*
   3  * Copyright 1998-2003 The OpenLDAP Foundation, Redwood City, California, USA
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms are permitted only
   7  * as authorized by the OpenLDAP Public License.  A copy of this
   8  * license is available at http://www.OpenLDAP.org/license.html or
   9  * in file LICENSE in the top-level directory of the distribution.
  10  */
  11
  12 #include "portable.h"
  13
  14 #include <stdio.h>
  15
  16 #include <ac/stdarg.h>
  17 #include <ac/stdlib.h>
  18 #include <ac/string.h>
  19 #include <ac/time.h>
  20 #include <ac/errno.h>
  21
  22 #include "ldap-int.h"
  23 #include "ldap_pvt_thread.h"
  24 #include "ldap_queue.h"
  25
  26 #ifndef LDAP_THREAD_HAVE_TPOOL
  27
  28 enum ldap_int_thread_pool_state {
  29         LDAP_INT_THREAD_POOL_RUNNING,
  30         LDAP_INT_THREAD_POOL_FINISHING,
  31         LDAP_INT_THREAD_POOL_STOPPING
  32 };
  33
  34 typedef struct ldap_int_thread_key_s {
  35         void *ltk_key;
  36         void *ltk_data;
  37         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  38 } ldap_int_thread_key_t;
  39
  40 /* Max number of thread-specific keys we store per thread.
  41  * We don't expect to use many...
  42  */
  43 #define MAXKEYS 32
  44 #define MAXTHREADS      1024    /* must be a power of 2 */
  45
  46 static struct {
  47         ldap_pvt_thread_t id;
  48         ldap_int_thread_key_t *ctx;
  49 } thread_keys[MAXTHREADS];
  50
  51
  52 typedef struct ldap_int_thread_ctx_s {
  53         union {
  54         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  55         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  56         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  57         } ltc_next;
  58         ldap_pvt_thread_start_t *ltc_start_routine;
  59         void *ltc_arg;
  60 } ldap_int_thread_ctx_t;
  61
  62 struct ldap_int_thread_pool_s {
  63         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  64         ldap_pvt_thread_mutex_t ltp_mutex;
  65         ldap_pvt_thread_cond_t ltp_cond;
  66         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  67         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  68         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  69         long ltp_state;
  70         long ltp_max_count;
  71         long ltp_max_pending;
  72         long ltp_pending_count;
  73         long ltp_active_count;
  74         long ltp_open_count;
  75         long ltp_starting;
  76 };
  77
  78 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  79         ldap_int_thread_pool_list =
  80         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  81
  82 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  83
  84 static void *ldap_int_thread_pool_wrapper( void *pool );
  85
  86 int
  87 ldap_int_thread_pool_startup ( void )
  88 {
  89         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
  90 }
  91
  92 int
  93 ldap_int_thread_pool_shutdown ( void )
  94 {
  95         struct ldap_int_thread_pool_s *pool;
  96
  97         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
  98                 LDAP_STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
  99                 ldap_pvt_thread_pool_destroy( &pool, 0);
 100         }
 101         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 102         return(0);
 103 }
 104
 105 int
 106 ldap_pvt_thread_pool_init (
 107         ldap_pvt_thread_pool_t *tpool,
 108         int max_threads,
 109         int max_pending )
 110 {
 111         ldap_pvt_thread_pool_t pool;
 112         int rc;
 113
 114         *tpool = NULL;
 115         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 116                 sizeof(struct ldap_int_thread_pool_s));
 117
 118         if (pool == NULL) return(-1);
 119
 120         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 121         if (rc != 0)
 122                 return(rc);
 123         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 124         if (rc != 0)
 125                 return(rc);
 126         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 127         pool->ltp_max_count = max_threads;
 128         pool->ltp_max_pending = max_pending;
 129         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 130         LDAP_SLIST_INIT(&pool->ltp_free_list);
 131         LDAP_SLIST_INIT(&pool->ltp_active_list);
 132         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 133         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 134         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 135
 136 #if 0
 137         /* THIS WILL NOT WORK on some systems.  If the process
 138          * forks after starting a thread, there is no guarantee
 139          * that the thread will survive the fork.  For example,
 140          * slapd forks in order to daemonize, and does so after
 141          * calling ldap_pvt_thread_pool_init.  On some systems,
 142          * this initial thread does not run in the child process,
 143          * but ltp_open_count == 1, so two things happen:
 144          * 1) the first client connection fails, and 2) when
 145          * slapd is kill'ed, it never terminates since it waits
 146          * for all worker threads to exit. */
 147
 148         /* start up one thread, just so there is one. no need to
 149          * lock the mutex right now, since no threads are running.
 150          */
 151         pool->ltp_open_count++;
 152
 153         ldap_pvt_thread_t thr;
 154         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 155
 156         if( rc != 0) {
 157                 /* couldn't start one?  then don't start any */
 158                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 159                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 160                         ldap_int_thread_pool_s, ltp_next);
 161                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 162                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 163                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 164                 LDAP_FREE(pool);
 165                 return(-1);
 166         }
 167 #endif
 168
 169         *tpool = pool;
 170         return(0);
 171 }
 172
 173 int
 174 ldap_pvt_thread_pool_submit (
 175         ldap_pvt_thread_pool_t *tpool,
 176         ldap_pvt_thread_start_t *start_routine, void *arg )
 177 {
 178         struct ldap_int_thread_pool_s *pool;
 179         ldap_int_thread_ctx_t *ctx;
 180         int need_thread = 0;
 181         ldap_pvt_thread_t thr;
 182
 183         if (tpool == NULL)
 184                 return(-1);
 185
 186         pool = *tpool;
 187
 188         if (pool == NULL)
 189                 return(-1);
 190
 191         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 192         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 193                 || (pool->ltp_max_pending > 0
 194                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 195         {
 196                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 197                 return(-1);
 198         }
 199         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 200         if (ctx) {
 201                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 202         } else {
 203                 int i;
 204                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 205                         sizeof(ldap_int_thread_ctx_t));
 206                 if (ctx == NULL) {
 207                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 208                         return(-1);
 209                 }
 210         }
 211
 212         ctx->ltc_start_routine = start_routine;
 213         ctx->ltc_arg = arg;
 214
 215         pool->ltp_pending_count++;
 216         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 217         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 218         if ((pool->ltp_open_count <= 0
 219 #if 0
 220                         || pool->ltp_pending_count > 1
 221 #endif
 222                         || pool->ltp_open_count == pool->ltp_active_count)
 223                 && (pool->ltp_max_count <= 0
 224                         || pool->ltp_open_count < pool->ltp_max_count))
 225         {
 226                 pool->ltp_open_count++;
 227                 pool->ltp_starting++;
 228                 need_thread = 1;
 229         }
 230         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 231
 232         if (need_thread) {
 233                 int rc;
 234
 235                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 236
 237                 rc = ldap_pvt_thread_create( &thr, 1,
 238                         ldap_int_thread_pool_wrapper, pool );
 239                 if (rc == 0) {
 240                         pool->ltp_starting--;
 241
 242                         /* assign this thread ID to a key slot; start
 243                          * at the thread ID itself (mod MAXTHREADS) and
 244                          * look for an empty slot.
 245                          */
 246                         for (rc = thr & (MAXTHREADS-1); thread_keys[rc].id;
 247                                 rc = (rc+1) & (MAXTHREADS-1));
 248                         thread_keys[rc].id = thr;
 249                 } else {
 250                         /* couldn't create thread.  back out of
 251                          * ltp_open_count and check for even worse things.
 252                          */
 253                         pool->ltp_open_count--;
 254                         pool->ltp_starting--;
 255                         if (pool->ltp_open_count == 0) {
 256                                 /* no open threads at all?!?
 257                                  */
 258                                 ldap_int_thread_ctx_t *ptr;
 259                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 260                                         if (ptr == ctx) break;
 261                                 if (ptr == ctx) {
 262                                         /* no open threads, context not handled, so
 263                                          * back out of ltp_pending_count, free the context,
 264                                          * report the error.
 265                                          */
 266                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 267                                                 ldap_int_thread_ctx_s, ltc_next.q);
 268                                         pool->ltp_pending_count++;
 269                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 270                                         LDAP_FREE(ctx);
 271                                         return(-1);
 272                                 }
 273                         }
 274                         /* there is another open thread, so this
 275                          * context will be handled eventually.
 276                          * continue on and signal that the context
 277                          * is waiting.
 278                          */
 279                 }
 280                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 281         }
 282
 283         return(0);
 284 }
 285
 286 int
 287 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 288 {
 289         struct ldap_int_thread_pool_s *pool;
 290
 291         if (tpool == NULL)
 292                 return(-1);
 293
 294         pool = *tpool;
 295
 296         if (pool == NULL)
 297                 return(-1);
 298
 299         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 300         pool->ltp_max_count = max_threads;
 301         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 302         return(0);
 303 }
 304
 305 int
 306 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 307 {
 308         struct ldap_int_thread_pool_s *pool;
 309         int count;
 310
 311         if (tpool == NULL)
 312                 return(-1);
 313
 314         pool = *tpool;
 315
 316         if (pool == NULL)
 317                 return(0);
 318
 319         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 320         count = pool->ltp_pending_count + pool->ltp_active_count;
 321         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 322         return(count);
 323 }
 324
 325 int
 326 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 327 {
 328         struct ldap_int_thread_pool_s *pool, *pptr;
 329         long waiting;
 330         ldap_int_thread_ctx_t *ctx;
 331
 332         if (tpool == NULL)
 333                 return(-1);
 334
 335         pool = *tpool;
 336
 337         if (pool == NULL) return(-1);
 338
 339         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 340         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 341                 if (pptr == pool) break;
 342         if (pptr == pool)
 343                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 344                         ldap_int_thread_pool_s, ltp_next);
 345         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 346
 347         if (pool != pptr) return(-1);
 348
 349         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 350         pool->ltp_state = run_pending
 351                 ? LDAP_INT_THREAD_POOL_FINISHING
 352                 : LDAP_INT_THREAD_POOL_STOPPING;
 353
 354         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 355         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 356
 357         do {
 358                 ldap_pvt_thread_yield();
 359                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 360                 waiting = pool->ltp_open_count;
 361                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 362         } while (waiting > 0);
 363
 364         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 365         {
 366                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 367                 LDAP_FREE(ctx);
 368         }
 369
 370         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 371         {
 372                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 373                 LDAP_FREE(ctx);
 374         }
 375
 376         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 377         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 378         LDAP_FREE(pool);
 379         return(0);
 380 }
 381
 382 static void *
 383 ldap_int_thread_pool_wrapper (
 384         void *xpool )
 385 {
 386         struct ldap_int_thread_pool_s *pool = xpool;
 387         ldap_int_thread_ctx_t *ctx;
 388         ldap_int_thread_key_t ltc_key[MAXKEYS];
 389         ldap_pvt_thread_t tid;
 390         int i, keyslot;
 391
 392         if (pool == NULL)
 393                 return NULL;
 394
 395         for ( i=0; i<MAXKEYS; i++ ) {
 396                 ltc_key[i].ltk_key = NULL;
 397         }
 398
 399         tid = ldap_pvt_thread_self();
 400
 401         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 402
 403         /* store pointer to our keys */
 404         for (i = tid & (MAXTHREADS-1); thread_keys[i].id != tid;
 405                                 i = (i+1) & (MAXTHREADS-1));
 406         thread_keys[i].ctx = ltc_key;
 407         keyslot = i;
 408
 409         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 410                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 411                 if (ctx) {
 412                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 413                 } else {
 414                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 415                                 break;
 416                         if (pool->ltp_max_count > 0
 417                                 && pool->ltp_open_count > pool->ltp_max_count)
 418                         {
 419                                 /* too many threads running (can happen if the
 420                                  * maximum threads value is set during ongoing
 421                                  * operation using ldap_pvt_thread_pool_maxthreads)
 422                                  * so let this thread die.
 423                                  */
 424                                 break;
 425                         }
 426
 427                         /* we could check an idle timer here, and let the
 428                          * thread die if it has been inactive for a while.
 429                          * only die if there are other open threads (i.e.,
 430                          * always have at least one thread open).  the check
 431                          * should be like this:
 432                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 433                          *       check timer, leave thread (break;)
 434                          */
 435
 436                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 437                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 438
 439                         continue;
 440                 }
 441
 442                 pool->ltp_pending_count--;
 443
 444                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 445                 pool->ltp_active_count++;
 446                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 447
 448                 ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
 449
 450                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 451                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 452                         ldap_int_thread_ctx_s, ltc_next.al);
 453                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 454                 pool->ltp_active_count--;
 455                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 456
 457                 ldap_pvt_thread_yield();
 458
 459                 /* if we use an idle timer, here's
 460                  * a good place to update it
 461                  */
 462
 463                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 464         }
 465
 466         for ( i=0; i<MAXKEYS && ltc_key[i].ltk_key; i++ ) {
 467                 if (ltc_key[i].ltk_free)
 468                         ltc_key[i].ltk_free(
 469                                 ltc_key[i].ltk_key,
 470                                 ltc_key[i].ltk_data );
 471         }
 472
 473         thread_keys[keyslot].ctx = NULL;
 474         thread_keys[keyslot].id = 0;
 475
 476         pool->ltp_open_count--;
 477         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 478
 479         ldap_pvt_thread_exit(NULL);
 480         return(NULL);
 481 }
 482
 483 int ldap_pvt_thread_pool_getkey(
 484         void *xctx,
 485         void *key,
 486         void **data,
 487         ldap_pvt_thread_pool_keyfree_t **kfree )
 488 {
 489         ldap_int_thread_key_t *ctx = xctx;
 490         int i;
 491
 492         if ( !ctx || !data ) return EINVAL;
 493
 494         for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++ ) {
 495                 if ( ctx[i].ltk_key == key ) {
 496                         *data = ctx[i].ltk_data;
 497                         if ( kfree ) *kfree = ctx[i].ltk_free;
 498                         return 0;
 499                 }
 500         }
 501         return ENOENT;
 502 }
 503
 504 int ldap_pvt_thread_pool_setkey(
 505         void *xctx,
 506         void *key,
 507         void *data,
 508         ldap_pvt_thread_pool_keyfree_t *kfree )
 509 {
 510         ldap_int_thread_key_t *ctx = xctx;
 511         int i;
 512
 513         if ( !ctx || !key ) return EINVAL;
 514
 515         for ( i=0; i<MAXKEYS; i++ ) {
 516                 if ( !ctx[i].ltk_key || ctx[i].ltk_key == key ) {
 517                         ctx[i].ltk_key = key;
 518                         ctx[i].ltk_data = data;
 519                         ctx[i].ltk_free = kfree;
 520                         return 0;
 521                 }
 522         }
 523         return ENOMEM;
 524 }
 525
 526 /*
 527  * This is necessary if the caller does not have access to the
 528  * thread context handle (for example, a slapd plugin calling
 529  * slapi_search_internal()). No doubt it is more efficient to
 530  * for the application to keep track of the thread context
 531  * handles itself.
 532  */
 533 void *ldap_pvt_thread_pool_context( )
 534 {
 535         ldap_pvt_thread_t tid;
 536         int i;
 537
 538         tid = ldap_pvt_thread_self();
 539
 540         for (i = tid & (MAXTHREADS-1); thread_keys[i].id &&
 541                 thread_keys[i].id != tid; i = (i+1) & (MAXTHREADS-1));
 542
 543         return thread_keys[i].ctx;
 544 }
 545
 546 #endif /* LDAP_HAVE_THREAD_POOL */