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 #define TID_HASH(tid, hash) do { int i; \
 174         unsigned char *ptr = (unsigned char *)&(tid); \
 175         for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
 176
 177 int
 178 ldap_pvt_thread_pool_submit (
 179         ldap_pvt_thread_pool_t *tpool,
 180         ldap_pvt_thread_start_t *start_routine, void *arg )
 181 {
 182         struct ldap_int_thread_pool_s *pool;
 183         ldap_int_thread_ctx_t *ctx;
 184         int need_thread = 0;
 185         ldap_pvt_thread_t thr;
 186
 187         if (tpool == NULL)
 188                 return(-1);
 189
 190         pool = *tpool;
 191
 192         if (pool == NULL)
 193                 return(-1);
 194
 195         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 196         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 197                 || (pool->ltp_max_pending > 0
 198                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 199         {
 200                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 201                 return(-1);
 202         }
 203         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 204         if (ctx) {
 205                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 206         } else {
 207                 int i;
 208                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 209                         sizeof(ldap_int_thread_ctx_t));
 210                 if (ctx == NULL) {
 211                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 212                         return(-1);
 213                 }
 214         }
 215
 216         ctx->ltc_start_routine = start_routine;
 217         ctx->ltc_arg = arg;
 218
 219         pool->ltp_pending_count++;
 220         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 221         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 222         if ((pool->ltp_open_count <= 0
 223 #if 0
 224                         || pool->ltp_pending_count > 1
 225 #endif
 226                         || pool->ltp_open_count == pool->ltp_active_count)
 227                 && (pool->ltp_max_count <= 0
 228                         || pool->ltp_open_count < pool->ltp_max_count))
 229         {
 230                 pool->ltp_open_count++;
 231                 pool->ltp_starting++;
 232                 need_thread = 1;
 233         }
 234         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 235
 236         if (need_thread) {
 237                 int rc;
 238
 239                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 240
 241                 rc = ldap_pvt_thread_create( &thr, 1,
 242                         ldap_int_thread_pool_wrapper, pool );
 243                 if (rc == 0) {
 244                         int hash;
 245                         pool->ltp_starting--;
 246
 247                         /* assign this thread ID to a key slot; start
 248                          * at the thread ID itself (mod MAXTHREADS) and
 249                          * look for an empty slot.
 250                          */
 251                         TID_HASH(thr, hash);
 252                         for (rc = hash & (MAXTHREADS-1); thread_keys[rc].id;
 253                                 rc = (rc+1) & (MAXTHREADS-1));
 254                         thread_keys[rc].id = thr;
 255                 } else {
 256                         /* couldn't create thread.  back out of
 257                          * ltp_open_count and check for even worse things.
 258                          */
 259                         pool->ltp_open_count--;
 260                         pool->ltp_starting--;
 261                         if (pool->ltp_open_count == 0) {
 262                                 /* no open threads at all?!?
 263                                  */
 264                                 ldap_int_thread_ctx_t *ptr;
 265                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 266                                         if (ptr == ctx) break;
 267                                 if (ptr == ctx) {
 268                                         /* no open threads, context not handled, so
 269                                          * back out of ltp_pending_count, free the context,
 270                                          * report the error.
 271                                          */
 272                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 273                                                 ldap_int_thread_ctx_s, ltc_next.q);
 274                                         pool->ltp_pending_count++;
 275                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 276                                         LDAP_FREE(ctx);
 277                                         return(-1);
 278                                 }
 279                         }
 280                         /* there is another open thread, so this
 281                          * context will be handled eventually.
 282                          * continue on and signal that the context
 283                          * is waiting.
 284                          */
 285                 }
 286                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 287         }
 288
 289         return(0);
 290 }
 291
 292 int
 293 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 294 {
 295         struct ldap_int_thread_pool_s *pool;
 296
 297         if (tpool == NULL)
 298                 return(-1);
 299
 300         pool = *tpool;
 301
 302         if (pool == NULL)
 303                 return(-1);
 304
 305         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 306         pool->ltp_max_count = max_threads;
 307         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 308         return(0);
 309 }
 310
 311 int
 312 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 313 {
 314         struct ldap_int_thread_pool_s *pool;
 315         int count;
 316
 317         if (tpool == NULL)
 318                 return(-1);
 319
 320         pool = *tpool;
 321
 322         if (pool == NULL)
 323                 return(0);
 324
 325         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 326         count = pool->ltp_pending_count + pool->ltp_active_count;
 327         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 328         return(count);
 329 }
 330
 331 int
 332 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 333 {
 334         struct ldap_int_thread_pool_s *pool, *pptr;
 335         long waiting;
 336         ldap_int_thread_ctx_t *ctx;
 337
 338         if (tpool == NULL)
 339                 return(-1);
 340
 341         pool = *tpool;
 342
 343         if (pool == NULL) return(-1);
 344
 345         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 346         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 347                 if (pptr == pool) break;
 348         if (pptr == pool)
 349                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 350                         ldap_int_thread_pool_s, ltp_next);
 351         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 352
 353         if (pool != pptr) return(-1);
 354
 355         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 356         pool->ltp_state = run_pending
 357                 ? LDAP_INT_THREAD_POOL_FINISHING
 358                 : LDAP_INT_THREAD_POOL_STOPPING;
 359
 360         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 361         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 362
 363         do {
 364                 ldap_pvt_thread_yield();
 365                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 366                 waiting = pool->ltp_open_count;
 367                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 368         } while (waiting > 0);
 369
 370         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 371         {
 372                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 373                 LDAP_FREE(ctx);
 374         }
 375
 376         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 377         {
 378                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 379                 LDAP_FREE(ctx);
 380         }
 381
 382         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 383         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 384         LDAP_FREE(pool);
 385         return(0);
 386 }
 387
 388 static void *
 389 ldap_int_thread_pool_wrapper (
 390         void *xpool )
 391 {
 392         struct ldap_int_thread_pool_s *pool = xpool;
 393         ldap_int_thread_ctx_t *ctx;
 394         ldap_int_thread_key_t ltc_key[MAXKEYS];
 395         ldap_pvt_thread_t tid;
 396         int i, keyslot, hash;
 397
 398         if (pool == NULL)
 399                 return NULL;
 400
 401         for ( i=0; i<MAXKEYS; i++ ) {
 402                 ltc_key[i].ltk_key = NULL;
 403         }
 404
 405         tid = ldap_pvt_thread_self();
 406
 407         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 408
 409         /* store pointer to our keys */
 410         TID_HASH(tid, hash);
 411         for (i = hash & (MAXTHREADS-1); thread_keys[i].id != tid;
 412                                 i = (i+1) & (MAXTHREADS-1));
 413         thread_keys[i].ctx = ltc_key;
 414         keyslot = i;
 415
 416         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 417                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 418                 if (ctx) {
 419                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 420                 } else {
 421                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 422                                 break;
 423                         if (pool->ltp_max_count > 0
 424                                 && pool->ltp_open_count > pool->ltp_max_count)
 425                         {
 426                                 /* too many threads running (can happen if the
 427                                  * maximum threads value is set during ongoing
 428                                  * operation using ldap_pvt_thread_pool_maxthreads)
 429                                  * so let this thread die.
 430                                  */
 431                                 break;
 432                         }
 433
 434                         /* we could check an idle timer here, and let the
 435                          * thread die if it has been inactive for a while.
 436                          * only die if there are other open threads (i.e.,
 437                          * always have at least one thread open).  the check
 438                          * should be like this:
 439                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 440                          *       check timer, leave thread (break;)
 441                          */
 442
 443                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 444                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 445
 446                         continue;
 447                 }
 448
 449                 pool->ltp_pending_count--;
 450
 451                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 452                 pool->ltp_active_count++;
 453                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 454
 455                 ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
 456
 457                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 458                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 459                         ldap_int_thread_ctx_s, ltc_next.al);
 460                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 461                 pool->ltp_active_count--;
 462                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 463
 464                 ldap_pvt_thread_yield();
 465
 466                 /* if we use an idle timer, here's
 467                  * a good place to update it
 468                  */
 469
 470                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 471         }
 472
 473         for ( i=0; i<MAXKEYS && ltc_key[i].ltk_key; i++ ) {
 474                 if (ltc_key[i].ltk_free)
 475                         ltc_key[i].ltk_free(
 476                                 ltc_key[i].ltk_key,
 477                                 ltc_key[i].ltk_data );
 478         }
 479
 480         thread_keys[keyslot].ctx = NULL;
 481         thread_keys[keyslot].id = 0;
 482
 483         pool->ltp_open_count--;
 484         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 485
 486         ldap_pvt_thread_exit(NULL);
 487         return(NULL);
 488 }
 489
 490 int ldap_pvt_thread_pool_getkey(
 491         void *xctx,
 492         void *key,
 493         void **data,
 494         ldap_pvt_thread_pool_keyfree_t **kfree )
 495 {
 496         ldap_int_thread_key_t *ctx = xctx;
 497         int i;
 498
 499         if ( !ctx || !data ) return EINVAL;
 500
 501         for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++ ) {
 502                 if ( ctx[i].ltk_key == key ) {
 503                         *data = ctx[i].ltk_data;
 504                         if ( kfree ) *kfree = ctx[i].ltk_free;
 505                         return 0;
 506                 }
 507         }
 508         return ENOENT;
 509 }
 510
 511 int ldap_pvt_thread_pool_setkey(
 512         void *xctx,
 513         void *key,
 514         void *data,
 515         ldap_pvt_thread_pool_keyfree_t *kfree )
 516 {
 517         ldap_int_thread_key_t *ctx = xctx;
 518         int i;
 519
 520         if ( !ctx || !key ) return EINVAL;
 521
 522         for ( i=0; i<MAXKEYS; i++ ) {
 523                 if ( !ctx[i].ltk_key || ctx[i].ltk_key == key ) {
 524                         ctx[i].ltk_key = key;
 525                         ctx[i].ltk_data = data;
 526                         ctx[i].ltk_free = kfree;
 527                         return 0;
 528                 }
 529         }
 530         return ENOMEM;
 531 }
 532
 533 /*
 534  * This is necessary if the caller does not have access to the
 535  * thread context handle (for example, a slapd plugin calling
 536  * slapi_search_internal()). No doubt it is more efficient to
 537  * for the application to keep track of the thread context
 538  * handles itself.
 539  */
 540 void *ldap_pvt_thread_pool_context( )
 541 {
 542         ldap_pvt_thread_t tid;
 543         int i, hash;
 544
 545         tid = ldap_pvt_thread_self();
 546
 547         TID_HASH( tid, hash );
 548         for (i = hash & (MAXTHREADS-1); thread_keys[i].id &&
 549                 thread_keys[i].id != tid; i = (i+1) & (MAXTHREADS-1));
 550
 551         return thread_keys[i].ctx;
 552 }
 553
 554 #endif /* LDAP_HAVE_THREAD_POOL */