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 1998-2008 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" /* Get the thread interface */
  28 #include "ldap_queue.h"
  29 #define LDAP_THREAD_POOL_IMPLEMENTATION
  30 #include "ldap_thr_debug.h"  /* May rename symbols defined below */
  31
  32 #ifndef LDAP_THREAD_HAVE_TPOOL
  33
  34 typedef enum ldap_int_thread_pool_state_e {
  35         LDAP_INT_THREAD_POOL_RUNNING,
  36         LDAP_INT_THREAD_POOL_FINISHING,
  37         LDAP_INT_THREAD_POOL_STOPPING,
  38         LDAP_INT_THREAD_POOL_PAUSING
  39 } ldap_int_thread_pool_state_t;
  40
  41 typedef struct ldap_int_thread_key_s {
  42         void *ltk_key;
  43         void *ltk_data;
  44         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  45 } ldap_int_thread_key_t;
  46
  47 /* Max number of thread-specific keys we store per thread.
  48  * We don't expect to use many...
  49  */
  50 #define MAXKEYS 32
  51 #define LDAP_MAXTHR     1024    /* must be a power of 2 */
  52
  53 static ldap_pvt_thread_t tid_zero;
  54
  55 static struct {
  56         ldap_pvt_thread_t id;
  57         ldap_int_thread_key_t *ctx;
  58 } thread_keys[LDAP_MAXTHR];
  59
  60
  61 typedef struct ldap_int_thread_ctx_s {
  62         union {
  63         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  64         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  65         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  66         } ltc_next;
  67         ldap_pvt_thread_start_t *ltc_start_routine;
  68         void *ltc_arg;
  69 } ldap_int_thread_ctx_t;
  70
  71 struct ldap_int_thread_pool_s {
  72         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  73         ldap_pvt_thread_mutex_t ltp_mutex;
  74         ldap_pvt_thread_cond_t ltp_cond;
  75         ldap_pvt_thread_cond_t ltp_pcond;
  76         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  77         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  78         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  79         ldap_int_thread_pool_state_t ltp_state;
  80         long ltp_max_count;
  81         long ltp_max_pending;
  82         long ltp_pending_count;
  83         long ltp_active_count;
  84         long ltp_open_count;
  85         long ltp_starting;
  86 };
  87
  88 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  89         ldap_int_thread_pool_list =
  90         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  91
  92 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  93
  94 static void *ldap_int_thread_pool_wrapper( void *pool );
  95
  96 static ldap_pvt_thread_t ldap_int_main_tid;
  97
  98 static ldap_int_thread_key_t ldap_int_main_thrctx[LDAP_MAXTHR];
  99
 100 int
 101 ldap_int_thread_pool_startup ( void )
 102 {
 103         ldap_int_main_tid = ldap_pvt_thread_self();
 104
 105         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 106 }
 107
 108 int
 109 ldap_int_thread_pool_shutdown ( void )
 110 {
 111         struct ldap_int_thread_pool_s *pool;
 112
 113         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 114                 (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
 115         }
 116         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 117         return(0);
 118 }
 119
 120 int
 121 ldap_pvt_thread_pool_init (
 122         ldap_pvt_thread_pool_t *tpool,
 123         int max_threads,
 124         int max_pending )
 125 {
 126         ldap_pvt_thread_pool_t pool;
 127         int rc;
 128
 129         *tpool = NULL;
 130         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 131                 sizeof(struct ldap_int_thread_pool_s));
 132
 133         if (pool == NULL) return(-1);
 134
 135         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 136         if (rc != 0)
 137                 return(rc);
 138         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 139         if (rc != 0)
 140                 return(rc);
 141         rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
 142         if (rc != 0)
 143                 return(rc);
 144         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 145         pool->ltp_max_count = max_threads;
 146         pool->ltp_max_pending = max_pending;
 147         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 148         LDAP_SLIST_INIT(&pool->ltp_free_list);
 149         LDAP_SLIST_INIT(&pool->ltp_active_list);
 150         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 151         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 152         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 153
 154 #if 0
 155         /* THIS WILL NOT WORK on some systems.  If the process
 156          * forks after starting a thread, there is no guarantee
 157          * that the thread will survive the fork.  For example,
 158          * slapd forks in order to daemonize, and does so after
 159          * calling ldap_pvt_thread_pool_init.  On some systems,
 160          * this initial thread does not run in the child process,
 161          * but ltp_open_count == 1, so two things happen:
 162          * 1) the first client connection fails, and 2) when
 163          * slapd is kill'ed, it never terminates since it waits
 164          * for all worker threads to exit. */
 165
 166         /* start up one thread, just so there is one. no need to
 167          * lock the mutex right now, since no threads are running.
 168          */
 169         pool->ltp_open_count++;
 170
 171         ldap_pvt_thread_t thr;
 172         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 173
 174         if( rc != 0) {
 175                 /* couldn't start one?  then don't start any */
 176                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 177                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 178                         ldap_int_thread_pool_s, ltp_next);
 179                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 180                 ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 181                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 182                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 183                 LDAP_FREE(pool);
 184                 return(-1);
 185         }
 186 #endif
 187
 188         *tpool = pool;
 189         return(0);
 190 }
 191
 192 #define TID_HASH(tid, hash) do { unsigned i; \
 193         unsigned char *ptr = (unsigned char *)&(tid); \
 194         for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
 195
 196 int
 197 ldap_pvt_thread_pool_submit (
 198         ldap_pvt_thread_pool_t *tpool,
 199         ldap_pvt_thread_start_t *start_routine, void *arg )
 200 {
 201         struct ldap_int_thread_pool_s *pool;
 202         ldap_int_thread_ctx_t *ctx;
 203         int need_thread = 0;
 204         ldap_pvt_thread_t thr;
 205
 206         if (tpool == NULL)
 207                 return(-1);
 208
 209         pool = *tpool;
 210
 211         if (pool == NULL)
 212                 return(-1);
 213
 214         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 215         if ((pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING &&
 216                 pool->ltp_state != LDAP_INT_THREAD_POOL_PAUSING)
 217                 || (pool->ltp_max_pending > 0
 218                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 219         {
 220                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 221                 return(-1);
 222         }
 223         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 224         if (ctx) {
 225                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 226         } else {
 227                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 228                         sizeof(ldap_int_thread_ctx_t));
 229                 if (ctx == NULL) {
 230                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 231                         return(-1);
 232                 }
 233         }
 234
 235         ctx->ltc_start_routine = start_routine;
 236         ctx->ltc_arg = arg;
 237
 238         pool->ltp_pending_count++;
 239         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 240         if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 241                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 242                 return(0);
 243         }
 244         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 245         if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
 246                 && (pool->ltp_open_count < pool->ltp_max_count ||
 247                         pool->ltp_max_count <= 0 ))
 248         {
 249                 pool->ltp_open_count++;
 250                 pool->ltp_starting++;
 251                 need_thread = 1;
 252         }
 253         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 254
 255         if (need_thread) {
 256                 int rc;
 257
 258                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 259
 260                 rc = ldap_pvt_thread_create( &thr, 1,
 261                         ldap_int_thread_pool_wrapper, pool );
 262                 if (rc == 0) {
 263                         int hash;
 264                         pool->ltp_starting--;
 265
 266                         /* assign this thread ID to a key slot; start
 267                          * at the thread ID itself (mod LDAP_MAXTHR) and
 268                          * look for an empty slot.
 269                          */
 270                         TID_HASH(thr, hash);
 271                         for (rc = hash & (LDAP_MAXTHR-1);
 272                                 !ldap_pvt_thread_equal(thread_keys[rc].id, tid_zero);
 273                                 rc = (rc+1) & (LDAP_MAXTHR-1));
 274                         thread_keys[rc].id = thr;
 275                 } else {
 276                         /* couldn't create thread.  back out of
 277                          * ltp_open_count and check for even worse things.
 278                          */
 279                         pool->ltp_open_count--;
 280                         pool->ltp_starting--;
 281                         if (pool->ltp_open_count == 0) {
 282                                 /* no open threads at all?!?
 283                                  */
 284                                 ldap_int_thread_ctx_t *ptr;
 285                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 286                                         if (ptr == ctx) break;
 287                                 if (ptr == ctx) {
 288                                         /* no open threads, context not handled, so
 289                                          * back out of ltp_pending_count, free the context,
 290                                          * report the error.
 291                                          */
 292                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 293                                                 ldap_int_thread_ctx_s, ltc_next.q);
 294                                         pool->ltp_pending_count++;
 295                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 296                                         LDAP_FREE(ctx);
 297                                         return(-1);
 298                                 }
 299                         }
 300                         /* there is another open thread, so this
 301                          * context will be handled eventually.
 302                          * continue on and signal that the context
 303                          * is waiting.
 304                          */
 305                 }
 306                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 307         }
 308
 309         return(0);
 310 }
 311
 312 int
 313 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 314 {
 315         struct ldap_int_thread_pool_s *pool;
 316
 317         if (tpool == NULL)
 318                 return(-1);
 319
 320         pool = *tpool;
 321
 322         if (pool == NULL)
 323                 return(-1);
 324
 325         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 326         pool->ltp_max_count = max_threads;
 327         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 328         return(0);
 329 }
 330
 331 int
 332 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 333 {
 334         struct ldap_int_thread_pool_s *pool;
 335         int count;
 336
 337         if (tpool == NULL)
 338                 return(-1);
 339
 340         pool = *tpool;
 341
 342         if (pool == NULL)
 343                 return(0);
 344
 345         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 346         count = pool->ltp_pending_count + pool->ltp_active_count;
 347         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 348         return(count);
 349 }
 350
 351 int
 352 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 353 {
 354         struct ldap_int_thread_pool_s *pool, *pptr;
 355         ldap_int_thread_ctx_t *ctx;
 356
 357         if (tpool == NULL)
 358                 return(-1);
 359
 360         pool = *tpool;
 361
 362         if (pool == NULL) return(-1);
 363
 364         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 365         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 366                 if (pptr == pool) break;
 367         if (pptr == pool)
 368                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 369                         ldap_int_thread_pool_s, ltp_next);
 370         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 371
 372         if (pool != pptr) return(-1);
 373
 374         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 375         pool->ltp_state = run_pending
 376                 ? LDAP_INT_THREAD_POOL_FINISHING
 377                 : LDAP_INT_THREAD_POOL_STOPPING;
 378
 379         if ( pool->ltp_open_count ) {
 380                 ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 381                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 382         }
 383         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 384
 385         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 386         {
 387                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 388                 LDAP_FREE(ctx);
 389         }
 390
 391         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 392         {
 393                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 394                 LDAP_FREE(ctx);
 395         }
 396
 397         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 398         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 399         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 400         LDAP_FREE(pool);
 401         return(0);
 402 }
 403
 404 static void *
 405 ldap_int_thread_pool_wrapper (
 406         void *xpool )
 407 {
 408         struct ldap_int_thread_pool_s *pool = xpool;
 409         ldap_int_thread_ctx_t *ctx;
 410         ldap_int_thread_key_t ltc_key[MAXKEYS];
 411         ldap_pvt_thread_t tid;
 412         int i, keyslot, hash;
 413
 414         if (pool == NULL)
 415                 return NULL;
 416
 417         for ( i=0; i<MAXKEYS; i++ ) {
 418                 ltc_key[i].ltk_key = NULL;
 419         }
 420
 421         tid = ldap_pvt_thread_self();
 422
 423         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 424
 425         /* store pointer to our keys */
 426         TID_HASH(tid, hash);
 427         for (i = hash & (LDAP_MAXTHR-1);
 428                                 !ldap_pvt_thread_equal(thread_keys[i].id, tid);
 429                                 i = (i+1) & (LDAP_MAXTHR-1));
 430         thread_keys[i].ctx = ltc_key;
 431         keyslot = i;
 432
 433         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 434                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 435                 if (ctx) {
 436                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 437                 } else {
 438                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 439                                 break;
 440                         if (pool->ltp_max_count > 0
 441                                 && pool->ltp_open_count > pool->ltp_max_count)
 442                         {
 443                                 /* too many threads running (can happen if the
 444                                  * maximum threads value is set during ongoing
 445                                  * operation using ldap_pvt_thread_pool_maxthreads)
 446                                  * so let this thread die.
 447                                  */
 448                                 break;
 449                         }
 450
 451                         /* we could check an idle timer here, and let the
 452                          * thread die if it has been inactive for a while.
 453                          * only die if there are other open threads (i.e.,
 454                          * always have at least one thread open).  the check
 455                          * should be like this:
 456                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 457                          *       check timer, leave thread (break;)
 458                          *
 459                          * Just use pthread_cond_timedwait if we want to
 460                          * check idle time.
 461                          */
 462
 463                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING
 464                                 || pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING)
 465                         {
 466                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 467                         }
 468
 469                         continue;
 470                 }
 471
 472                 pool->ltp_pending_count--;
 473
 474                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 475                 pool->ltp_active_count++;
 476                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 477
 478                 ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
 479
 480                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 481                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 482                         ldap_int_thread_ctx_s, ltc_next.al);
 483                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 484                 pool->ltp_active_count--;
 485
 486                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 487                         if (pool->ltp_active_count < 2) {
 488                                 ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 489                         }
 490                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 491                 }
 492         }
 493
 494         ldap_pvt_thread_pool_context_reset( ltc_key );
 495
 496         thread_keys[keyslot].ctx = NULL;
 497         thread_keys[keyslot].id = tid_zero;
 498
 499         pool->ltp_open_count--;
 500
 501         /* let pool_destroy know we're all done */
 502         if (pool->ltp_open_count < 1)
 503                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 504
 505         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 506
 507         ldap_pvt_thread_exit(NULL);
 508         return(NULL);
 509 }
 510
 511 int
 512 ldap_pvt_thread_pool_pause (
 513         ldap_pvt_thread_pool_t *tpool )
 514 {
 515         struct ldap_int_thread_pool_s *pool;
 516
 517         if (tpool == NULL)
 518                 return(-1);
 519
 520         pool = *tpool;
 521
 522         if (pool == NULL)
 523                 return(0);
 524
 525         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 526
 527         /* If someone else has already requested a pause, we have to wait */
 528         while (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 529                 pool->ltp_pending_count++;
 530                 pool->ltp_active_count--;
 531                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 532                 pool->ltp_pending_count--;
 533                 pool->ltp_active_count++;
 534         }
 535         /* Wait for everyone else to finish */
 536         pool->ltp_state = LDAP_INT_THREAD_POOL_PAUSING;
 537         while (pool->ltp_active_count > 1) {
 538                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 539         }
 540         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 541         return(0);
 542 }
 543
 544 int
 545 ldap_pvt_thread_pool_resume (
 546         ldap_pvt_thread_pool_t *tpool )
 547 {
 548         struct ldap_int_thread_pool_s *pool;
 549
 550         if (tpool == NULL)
 551                 return(-1);
 552
 553         pool = *tpool;
 554
 555         if (pool == NULL)
 556                 return(0);
 557
 558         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 559
 560         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 561         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 562         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 563         return(0);
 564 }
 565
 566 int ldap_pvt_thread_pool_getkey(
 567         void *xctx,
 568         void *key,
 569         void **data,
 570         ldap_pvt_thread_pool_keyfree_t **kfree )
 571 {
 572         ldap_int_thread_key_t *ctx = xctx;
 573         int i;
 574
 575         if ( !ctx || !data ) return EINVAL;
 576
 577         for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++ ) {
 578                 if ( ctx[i].ltk_key == key ) {
 579                         *data = ctx[i].ltk_data;
 580                         if ( kfree ) *kfree = ctx[i].ltk_free;
 581                         return 0;
 582                 }
 583         }
 584         return ENOENT;
 585 }
 586
 587 int ldap_pvt_thread_pool_setkey(
 588         void *xctx,
 589         void *key,
 590         void *data,
 591         ldap_pvt_thread_pool_keyfree_t *kfree )
 592 {
 593         ldap_int_thread_key_t *ctx = xctx;
 594         int i;
 595
 596         if ( !ctx || !key ) return EINVAL;
 597
 598         for ( i=0; i<MAXKEYS; i++ ) {
 599                 if (( data && !ctx[i].ltk_key ) || ctx[i].ltk_key == key ) {
 600                         if ( data || kfree ) {
 601                                 ctx[i].ltk_key = key;
 602                                 ctx[i].ltk_data = data;
 603                                 ctx[i].ltk_free = kfree;
 604                         } else {
 605                                 int j;
 606                                 for ( j=i+1; j<MAXKEYS; j++ )
 607                                         if ( !ctx[j].ltk_key ) break;
 608                                 j--;
 609                                 if ( j != i ) {
 610                                         ctx[i].ltk_key = ctx[j].ltk_key;
 611                                         ctx[i].ltk_data = ctx[j].ltk_data;
 612                                         ctx[i].ltk_free = ctx[j].ltk_free;
 613                                 }
 614                                 ctx[j].ltk_key = NULL;
 615                                 ctx[j].ltk_data = NULL;
 616                                 ctx[j].ltk_free = NULL;
 617                         }
 618                         return 0;
 619                 }
 620         }
 621         return ENOMEM;
 622 }
 623
 624 /* Free all elements with this key, no matter which thread they're in.
 625  * May only be called while the pool is paused.
 626  */
 627 void ldap_pvt_thread_pool_purgekey( void *key )
 628 {
 629         int i, j;
 630         ldap_int_thread_key_t *ctx;
 631
 632         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 633                 if ( thread_keys[i].ctx ) {
 634                         ctx = thread_keys[i].ctx;
 635                         for ( j=0; j<MAXKEYS; j++ ) {
 636                                 if ( ctx[j].ltk_key == key ) {
 637                                         if (ctx[j].ltk_free)
 638                                                 ctx[j].ltk_free( ctx[j].ltk_key, ctx[j].ltk_data );
 639                                         ctx[j].ltk_key = NULL;
 640                                         ctx[j].ltk_free = NULL;
 641                                         break;
 642                                 }
 643                         }
 644                 }
 645         }
 646 }
 647
 648 /*
 649  * This is necessary if the caller does not have access to the
 650  * thread context handle (for example, a slapd plugin calling
 651  * slapi_search_internal()). No doubt it is more efficient to
 652  * for the application to keep track of the thread context
 653  * handles itself.
 654  */
 655 void *ldap_pvt_thread_pool_context( )
 656 {
 657         ldap_pvt_thread_t tid;
 658         int i, hash;
 659
 660         tid = ldap_pvt_thread_self();
 661         if ( ldap_pvt_thread_equal( tid, ldap_int_main_tid ))
 662                 return ldap_int_main_thrctx;
 663
 664         TID_HASH( tid, hash );
 665         for (i = hash & (LDAP_MAXTHR-1);
 666                 !ldap_pvt_thread_equal(thread_keys[i].id, tid_zero) &&
 667                 !ldap_pvt_thread_equal(thread_keys[i].id, tid);
 668                 i = (i+1) & (LDAP_MAXTHR-1));
 669
 670         return thread_keys[i].ctx;
 671 }
 672
 673 void ldap_pvt_thread_pool_context_reset( void *vctx )
 674 {
 675         ldap_int_thread_key_t *ctx = vctx;
 676         int i;
 677
 678         for ( i=MAXKEYS-1; i>=0; i--) {
 679                 if ( ctx[i].ltk_key == NULL )
 680                         continue;
 681                 if ( ctx[i].ltk_free )
 682                         ctx[i].ltk_free( ctx[i].ltk_key, ctx[i].ltk_data );
 683                 ctx[i].ltk_key = NULL;
 684         }
 685 }
 686 #endif /* LDAP_THREAD_HAVE_TPOOL */