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

   1 /* $OpenLDAP$ */
   2 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   3  *
   4  * Copyright 1998-2004 The OpenLDAP Foundation.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted only as authorized by the OpenLDAP
   9  * Public License.
  10  *
  11  * A copy of this license is available in file LICENSE in the
  12  * top-level directory of the distribution or, alternatively, at
  13  * <http://www.OpenLDAP.org/license.html>.
  14  */
  15
  16 #include "portable.h"
  17
  18 #include <stdio.h>
  19
  20 #include <ac/stdarg.h>
  21 #include <ac/stdlib.h>
  22 #include <ac/string.h>
  23 #include <ac/time.h>
  24 #include <ac/errno.h>
  25
  26 #include "ldap-int.h"
  27 #include "ldap_pvt_thread.h"
  28 #include "ldap_queue.h"
  29
  30 #ifndef LDAP_THREAD_HAVE_TPOOL
  31
  32 enum ldap_int_thread_pool_state {
  33         LDAP_INT_THREAD_POOL_RUNNING,
  34         LDAP_INT_THREAD_POOL_FINISHING,
  35         LDAP_INT_THREAD_POOL_STOPPING
  36 };
  37
  38 typedef struct ldap_int_thread_key_s {
  39         void *ltk_key;
  40         void *ltk_data;
  41         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  42 } ldap_int_thread_key_t;
  43
  44 /* Max number of thread-specific keys we store per thread.
  45  * We don't expect to use many...
  46  */
  47 #define MAXKEYS 32
  48 #define LDAP_MAXTHR     1024    /* must be a power of 2 */
  49
  50 static ldap_pvt_thread_t tid_zero;
  51
  52 #ifdef HAVE_PTHREADS
  53 #define TID_EQ(a,b)     pthread_equal((a),(b))
  54 #else
  55 #define TID_EQ(a,b)     ((a) == (b))
  56 #endif
  57 static struct {
  58         ldap_pvt_thread_t id;
  59         ldap_int_thread_key_t *ctx;
  60 } thread_keys[LDAP_MAXTHR];
  61
  62
  63 typedef struct ldap_int_thread_ctx_s {
  64         union {
  65         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  66         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  67         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  68         } ltc_next;
  69         ldap_pvt_thread_start_t *ltc_start_routine;
  70         void *ltc_arg;
  71 } ldap_int_thread_ctx_t;
  72
  73 struct ldap_int_thread_pool_s {
  74         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  75         ldap_pvt_thread_mutex_t ltp_mutex;
  76         ldap_pvt_thread_cond_t ltp_cond;
  77         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  78         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  79         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  80         long ltp_state;
  81         long ltp_max_count;
  82         long ltp_max_pending;
  83         long ltp_pending_count;
  84         long ltp_active_count;
  85         long ltp_open_count;
  86         long ltp_starting;
  87 };
  88
  89 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  90         ldap_int_thread_pool_list =
  91         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  92
  93 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  94
  95 static void *ldap_int_thread_pool_wrapper( void *pool );
  96
  97 int
  98 ldap_int_thread_pool_startup ( void )
  99 {
 100         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 101 }
 102
 103 int
 104 ldap_int_thread_pool_shutdown ( void )
 105 {
 106         struct ldap_int_thread_pool_s *pool;
 107
 108         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 109                 LDAP_STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
 110                 ldap_pvt_thread_pool_destroy( &pool, 0);
 111         }
 112         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 113         return(0);
 114 }
 115
 116 int
 117 ldap_pvt_thread_pool_init (
 118         ldap_pvt_thread_pool_t *tpool,
 119         int max_threads,
 120         int max_pending )
 121 {
 122         ldap_pvt_thread_pool_t pool;
 123         int rc;
 124
 125         *tpool = NULL;
 126         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 127                 sizeof(struct ldap_int_thread_pool_s));
 128
 129         if (pool == NULL) return(-1);
 130
 131         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 132         if (rc != 0)
 133                 return(rc);
 134         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 135         if (rc != 0)
 136                 return(rc);
 137         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 138         pool->ltp_max_count = max_threads;
 139         pool->ltp_max_pending = max_pending;
 140         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 141         LDAP_SLIST_INIT(&pool->ltp_free_list);
 142         LDAP_SLIST_INIT(&pool->ltp_active_list);
 143         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 144         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 145         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 146
 147 #if 0
 148         /* THIS WILL NOT WORK on some systems.  If the process
 149          * forks after starting a thread, there is no guarantee
 150          * that the thread will survive the fork.  For example,
 151          * slapd forks in order to daemonize, and does so after
 152          * calling ldap_pvt_thread_pool_init.  On some systems,
 153          * this initial thread does not run in the child process,
 154          * but ltp_open_count == 1, so two things happen:
 155          * 1) the first client connection fails, and 2) when
 156          * slapd is kill'ed, it never terminates since it waits
 157          * for all worker threads to exit. */
 158
 159         /* start up one thread, just so there is one. no need to
 160          * lock the mutex right now, since no threads are running.
 161          */
 162         pool->ltp_open_count++;
 163
 164         ldap_pvt_thread_t thr;
 165         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 166
 167         if( rc != 0) {
 168                 /* couldn't start one?  then don't start any */
 169                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 170                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 171                         ldap_int_thread_pool_s, ltp_next);
 172                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 173                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 174                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 175                 LDAP_FREE(pool);
 176                 return(-1);
 177         }
 178 #endif
 179
 180         *tpool = pool;
 181         return(0);
 182 }
 183
 184 #define TID_HASH(tid, hash) do { int i; \
 185         unsigned char *ptr = (unsigned char *)&(tid); \
 186         for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
 187
 188 int
 189 ldap_pvt_thread_pool_submit (
 190         ldap_pvt_thread_pool_t *tpool,
 191         ldap_pvt_thread_start_t *start_routine, void *arg )
 192 {
 193         struct ldap_int_thread_pool_s *pool;
 194         ldap_int_thread_ctx_t *ctx;
 195         int need_thread = 0;
 196         ldap_pvt_thread_t thr;
 197
 198         if (tpool == NULL)
 199                 return(-1);
 200
 201         pool = *tpool;
 202
 203         if (pool == NULL)
 204                 return(-1);
 205
 206         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 207         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 208                 || (pool->ltp_max_pending > 0
 209                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 210         {
 211                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 212                 return(-1);
 213         }
 214         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 215         if (ctx) {
 216                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 217         } else {
 218                 int i;
 219                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 220                         sizeof(ldap_int_thread_ctx_t));
 221                 if (ctx == NULL) {
 222                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 223                         return(-1);
 224                 }
 225         }
 226
 227         ctx->ltc_start_routine = start_routine;
 228         ctx->ltc_arg = arg;
 229
 230         pool->ltp_pending_count++;
 231         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 232         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 233         if ((pool->ltp_open_count <= 0
 234 #if 0
 235                         || pool->ltp_pending_count > 1
 236 #endif
 237                         || pool->ltp_open_count == pool->ltp_active_count)
 238                 && (pool->ltp_max_count <= 0
 239                         || pool->ltp_open_count < pool->ltp_max_count))
 240         {
 241                 pool->ltp_open_count++;
 242                 pool->ltp_starting++;
 243                 need_thread = 1;
 244         }
 245         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 246
 247         if (need_thread) {
 248                 int rc;
 249
 250                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 251
 252                 rc = ldap_pvt_thread_create( &thr, 1,
 253                         ldap_int_thread_pool_wrapper, pool );
 254                 if (rc == 0) {
 255                         int hash;
 256                         pool->ltp_starting--;
 257
 258                         /* assign this thread ID to a key slot; start
 259                          * at the thread ID itself (mod LDAP_MAXTHR) and
 260                          * look for an empty slot.
 261                          */
 262                         TID_HASH(thr, hash);
 263                         for (rc = hash & (LDAP_MAXTHR-1);
 264                                 !TID_EQ(thread_keys[rc].id, tid_zero);
 265                                 rc = (rc+1) & (LDAP_MAXTHR-1));
 266                         thread_keys[rc].id = thr;
 267                 } else {
 268                         /* couldn't create thread.  back out of
 269                          * ltp_open_count and check for even worse things.
 270                          */
 271                         pool->ltp_open_count--;
 272                         pool->ltp_starting--;
 273                         if (pool->ltp_open_count == 0) {
 274                                 /* no open threads at all?!?
 275                                  */
 276                                 ldap_int_thread_ctx_t *ptr;
 277                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 278                                         if (ptr == ctx) break;
 279                                 if (ptr == ctx) {
 280                                         /* no open threads, context not handled, so
 281                                          * back out of ltp_pending_count, free the context,
 282                                          * report the error.
 283                                          */
 284                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 285                                                 ldap_int_thread_ctx_s, ltc_next.q);
 286                                         pool->ltp_pending_count++;
 287                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 288                                         LDAP_FREE(ctx);
 289                                         return(-1);
 290                                 }
 291                         }
 292                         /* there is another open thread, so this
 293                          * context will be handled eventually.
 294                          * continue on and signal that the context
 295                          * is waiting.
 296                          */
 297                 }
 298                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 299         }
 300
 301         return(0);
 302 }
 303
 304 int
 305 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 306 {
 307         struct ldap_int_thread_pool_s *pool;
 308
 309         if (tpool == NULL)
 310                 return(-1);
 311
 312         pool = *tpool;
 313
 314         if (pool == NULL)
 315                 return(-1);
 316
 317         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 318         pool->ltp_max_count = max_threads;
 319         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 320         return(0);
 321 }
 322
 323 int
 324 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 325 {
 326         struct ldap_int_thread_pool_s *pool;
 327         int count;
 328
 329         if (tpool == NULL)
 330                 return(-1);
 331
 332         pool = *tpool;
 333
 334         if (pool == NULL)
 335                 return(0);
 336
 337         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 338         count = pool->ltp_pending_count + pool->ltp_active_count;
 339         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 340         return(count);
 341 }
 342
 343 int
 344 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 345 {
 346         struct ldap_int_thread_pool_s *pool, *pptr;
 347         long waiting;
 348         ldap_int_thread_ctx_t *ctx;
 349
 350         if (tpool == NULL)
 351                 return(-1);
 352
 353         pool = *tpool;
 354
 355         if (pool == NULL) return(-1);
 356
 357         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 358         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 359                 if (pptr == pool) break;
 360         if (pptr == pool)
 361                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 362                         ldap_int_thread_pool_s, ltp_next);
 363         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 364
 365         if (pool != pptr) return(-1);
 366
 367         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 368         pool->ltp_state = run_pending
 369                 ? LDAP_INT_THREAD_POOL_FINISHING
 370                 : LDAP_INT_THREAD_POOL_STOPPING;
 371
 372         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 373         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 374
 375         do {
 376                 ldap_pvt_thread_yield();
 377                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 378                 waiting = pool->ltp_open_count;
 379                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 380         } while (waiting > 0);
 381
 382         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 383         {
 384                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 385                 LDAP_FREE(ctx);
 386         }
 387
 388         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 389         {
 390                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 391                 LDAP_FREE(ctx);
 392         }
 393
 394         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 395         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 396         LDAP_FREE(pool);
 397         return(0);
 398 }
 399
 400 static void *
 401 ldap_int_thread_pool_wrapper (
 402         void *xpool )
 403 {
 404         struct ldap_int_thread_pool_s *pool = xpool;
 405         ldap_int_thread_ctx_t *ctx;
 406         ldap_int_thread_key_t ltc_key[MAXKEYS];
 407         ldap_pvt_thread_t tid;
 408         int i, keyslot, hash;
 409
 410         if (pool == NULL)
 411                 return NULL;
 412
 413         for ( i=0; i<MAXKEYS; i++ ) {
 414                 ltc_key[i].ltk_key = NULL;
 415         }
 416
 417         tid = ldap_pvt_thread_self();
 418
 419         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 420
 421         /* store pointer to our keys */
 422         TID_HASH(tid, hash);
 423         for (i = hash & (LDAP_MAXTHR-1); !TID_EQ(thread_keys[i].id, tid);
 424                                 i = (i+1) & (LDAP_MAXTHR-1));
 425         thread_keys[i].ctx = ltc_key;
 426         keyslot = i;
 427
 428         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 429                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 430                 if (ctx) {
 431                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 432                 } else {
 433                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 434                                 break;
 435                         if (pool->ltp_max_count > 0
 436                                 && pool->ltp_open_count > pool->ltp_max_count)
 437                         {
 438                                 /* too many threads running (can happen if the
 439                                  * maximum threads value is set during ongoing
 440                                  * operation using ldap_pvt_thread_pool_maxthreads)
 441                                  * so let this thread die.
 442                                  */
 443                                 break;
 444                         }
 445
 446                         /* we could check an idle timer here, and let the
 447                          * thread die if it has been inactive for a while.
 448                          * only die if there are other open threads (i.e.,
 449                          * always have at least one thread open).  the check
 450                          * should be like this:
 451                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 452                          *       check timer, leave thread (break;)
 453                          */
 454
 455                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 456                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 457
 458                         continue;
 459                 }
 460
 461                 pool->ltp_pending_count--;
 462
 463                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 464                 pool->ltp_active_count++;
 465                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 466
 467                 ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
 468
 469                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 470                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 471                         ldap_int_thread_ctx_s, ltc_next.al);
 472                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 473                 pool->ltp_active_count--;
 474                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 475
 476                 ldap_pvt_thread_yield();
 477
 478                 /* if we use an idle timer, here's
 479                  * a good place to update it
 480                  */
 481
 482                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 483         }
 484
 485         for ( i=0; i<MAXKEYS && ltc_key[i].ltk_key; i++ ) {
 486                 if (ltc_key[i].ltk_free)
 487                         ltc_key[i].ltk_free(
 488                                 ltc_key[i].ltk_key,
 489                                 ltc_key[i].ltk_data );
 490         }
 491
 492         thread_keys[keyslot].ctx = NULL;
 493         thread_keys[keyslot].id = tid_zero;
 494
 495         pool->ltp_open_count--;
 496         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 497
 498         ldap_pvt_thread_exit(NULL);
 499         return(NULL);
 500 }
 501
 502 int ldap_pvt_thread_pool_getkey(
 503         void *xctx,
 504         void *key,
 505         void **data,
 506         ldap_pvt_thread_pool_keyfree_t **kfree )
 507 {
 508         ldap_int_thread_key_t *ctx = xctx;
 509         int i;
 510
 511         if ( !ctx || !data ) return EINVAL;
 512
 513         for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++ ) {
 514                 if ( ctx[i].ltk_key == key ) {
 515                         *data = ctx[i].ltk_data;
 516                         if ( kfree ) *kfree = ctx[i].ltk_free;
 517                         return 0;
 518                 }
 519         }
 520         return ENOENT;
 521 }
 522
 523 int ldap_pvt_thread_pool_setkey(
 524         void *xctx,
 525         void *key,
 526         void *data,
 527         ldap_pvt_thread_pool_keyfree_t *kfree )
 528 {
 529         ldap_int_thread_key_t *ctx = xctx;
 530         int i;
 531
 532         if ( !ctx || !key ) return EINVAL;
 533
 534         for ( i=0; i<MAXKEYS; i++ ) {
 535                 if ( !ctx[i].ltk_key || ctx[i].ltk_key == key ) {
 536                         ctx[i].ltk_key = key;
 537                         ctx[i].ltk_data = data;
 538                         ctx[i].ltk_free = kfree;
 539                         return 0;
 540                 }
 541         }
 542         return ENOMEM;
 543 }
 544
 545 /*
 546  * This is necessary if the caller does not have access to the
 547  * thread context handle (for example, a slapd plugin calling
 548  * slapi_search_internal()). No doubt it is more efficient to
 549  * for the application to keep track of the thread context
 550  * handles itself.
 551  */
 552 void *ldap_pvt_thread_pool_context( )
 553 {
 554         ldap_pvt_thread_t tid;
 555         int i, hash;
 556
 557         tid = ldap_pvt_thread_self();
 558
 559         TID_HASH( tid, hash );
 560         for (i = hash & (LDAP_MAXTHR-1); !TID_EQ(thread_keys[i].id, tid_zero) &&
 561                 !TID_EQ(thread_keys[i].id, tid); i = (i+1) & (LDAP_MAXTHR-1));
 562
 563         return thread_keys[i].ctx;
 564 }
 565
 566 #endif /* LDAP_THREAD_HAVE_TPOOL */