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 1998-2006 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 typedef struct ldap_int_thread_userctx_s {
  54         ldap_pvt_thread_t ltu_id;
  55         ldap_int_thread_key_t ltu_key[MAXKEYS];
  56 } ldap_int_thread_userctx_t;
  57
  58 static ldap_pvt_thread_t tid_zero;
  59
  60 static struct {
  61         ldap_pvt_thread_t id;
  62         ldap_int_thread_userctx_t *ctx;
  63 } thread_keys[LDAP_MAXTHR];
  64
  65
  66 typedef struct ldap_int_thread_ctx_s {
  67         union {
  68         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  69         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  70         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  71         } ltc_next;
  72         ldap_pvt_thread_start_t *ltc_start_routine;
  73         void *ltc_arg;
  74 } ldap_int_thread_ctx_t;
  75
  76 struct ldap_int_thread_pool_s {
  77         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  78         ldap_pvt_thread_mutex_t ltp_mutex;
  79         ldap_pvt_thread_cond_t ltp_cond;
  80         ldap_pvt_thread_cond_t ltp_pcond;
  81         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  82         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  83         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  84         ldap_int_thread_pool_state_t ltp_state;
  85         long ltp_max_count;
  86         long ltp_max_pending;
  87         long ltp_pending_count;
  88         long ltp_active_count;
  89         long ltp_open_count;
  90         long ltp_starting;
  91 };
  92
  93 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  94         ldap_int_thread_pool_list =
  95         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  96
  97 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  98
  99 static void *ldap_int_thread_pool_wrapper( void *pool );
 100
 101 static ldap_pvt_thread_t ldap_int_main_tid;
 102
 103 static ldap_int_thread_userctx_t ldap_int_main_thrctx;
 104
 105 int
 106 ldap_int_thread_pool_startup ( void )
 107 {
 108         ldap_int_main_tid = ldap_pvt_thread_self();
 109         ldap_int_main_thrctx.ltu_id = ldap_int_main_tid;
 110
 111         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 112 }
 113
 114 int
 115 ldap_int_thread_pool_shutdown ( void )
 116 {
 117         struct ldap_int_thread_pool_s *pool;
 118
 119         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 120                 (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
 121         }
 122         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 123         return(0);
 124 }
 125
 126 typedef struct ldap_lazy_sem_t {
 127         ldap_pvt_thread_mutex_t ls_mutex;
 128         ldap_pvt_thread_cond_t  ls_cond;
 129         int ls_sem_value;
 130         /*
 131          * when more than ls_lazy_count number of resources
 132          * becmoes available, the thread wating for the resources will
 133          * be waken up in order to prevent frequent blocking/waking-up
 134          */
 135         unsigned int ls_lazy_count;
 136         /*
 137          * only one thread(listener) will wait on this semaphore
 138          * using a flag instead of a list
 139          */
 140         int ls_wait;
 141 } ldap_lazy_sem_t;
 142
 143 ldap_lazy_sem_t* thread_pool_sem = NULL;
 144
 145 int
 146 ldap_lazy_sem_init( unsigned int value, unsigned int lazyness )
 147 {
 148         thread_pool_sem = (ldap_lazy_sem_t*) LDAP_CALLOC(1,
 149                 sizeof( ldap_lazy_sem_t ));
 150
 151         if( thread_pool_sem == NULL ) return -1;
 152
 153         ldap_pvt_thread_mutex_init( &thread_pool_sem->ls_mutex );
 154         ldap_pvt_thread_cond_init( &thread_pool_sem->ls_cond );
 155         thread_pool_sem->ls_sem_value = value;
 156         thread_pool_sem->ls_lazy_count = lazyness;
 157         thread_pool_sem->ls_wait = 0;
 158
 159         return 0;
 160 }
 161
 162 /* FIXME: move to some approprite header */
 163 int ldap_lazy_sem_dec( ldap_lazy_sem_t* ls );
 164 int ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls );
 165
 166 /*
 167  * ldap_lazy_sem_wait is used if a caller is blockable(listener).
 168  * Otherwise use ldap_lazy_sem_dec (worker)
 169  */
 170 int
 171 ldap_lazy_sem_op_submit( ldap_lazy_sem_t* ls )
 172 {
 173         if ( ls == NULL ) return -1;
 174
 175         /* only worker thread has its thread ctx */
 176         if ( ldap_pvt_thread_pool_context() ) {
 177                 /* worker thread */
 178                 return ldap_lazy_sem_dec( ls );
 179         } else {
 180                 /* listener */
 181                 return ldap_lazy_sem_wait( ls );
 182         }
 183 }
 184
 185 /*
 186  * test if given semaphore's count is zero.
 187  * If 0, the caller is blocked
 188  * If not, the count is decremented.
 189  */
 190 int
 191 ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls )
 192 {
 193         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 194
 195 lazy_sem_retry:
 196         if ( ls->ls_sem_value <= 0 ) {
 197                 /* no more avaliable resources */
 198                 ls->ls_wait = 1;
 199                 ldap_pvt_thread_cond_wait( &ls->ls_cond, &ls->ls_mutex );
 200                 goto lazy_sem_retry;
 201         } else {
 202                 /* avaliable resources */
 203                 ls->ls_sem_value--;
 204         }
 205
 206         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 207
 208         return 0;
 209 }
 210
 211 /*
 212  * decrement the count without blocking
 213  * even when the count becomes less than or equal to 0
 214  */
 215 int
 216 ldap_lazy_sem_dec( ldap_lazy_sem_t* ls )
 217 {
 218         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 219
 220         ls->ls_sem_value--;
 221
 222         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 223
 224         return 0;
 225 }
 226
 227 /*
 228  * Increment the count by one and test if it is greater or
 229  * equal to lazyness. If it is, wake up a blocked thread.
 230  */
 231 int
 232 ldap_lazy_sem_post( ldap_lazy_sem_t* ls )
 233 {
 234         if( ls == NULL ) return (-1);
 235
 236         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 237
 238         ls->ls_sem_value++;
 239         if ( ls->ls_wait ) {
 240                 if ( ls->ls_sem_value >= ls->ls_lazy_count ) {
 241                         ls->ls_wait = 0;
 242                         ldap_pvt_thread_cond_signal( &ls->ls_cond );
 243                 }
 244         }
 245
 246         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 247
 248         return 0;
 249 }
 250
 251 int
 252 ldap_pvt_thread_pool_init (
 253         ldap_pvt_thread_pool_t *tpool,
 254         int max_threads,
 255         int max_pending )
 256 {
 257         ldap_pvt_thread_pool_t pool;
 258         int rc;
 259
 260         *tpool = NULL;
 261         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 262                 sizeof(struct ldap_int_thread_pool_s));
 263
 264         if (pool == NULL) return(-1);
 265
 266         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 267         if (rc != 0)
 268                 return(rc);
 269         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 270         if (rc != 0)
 271                 return(rc);
 272         rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
 273         if (rc != 0)
 274                 return(rc);
 275         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 276         pool->ltp_max_count = max_threads;
 277         pool->ltp_max_pending = max_pending;
 278         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 279         LDAP_SLIST_INIT(&pool->ltp_free_list);
 280         LDAP_SLIST_INIT(&pool->ltp_active_list);
 281         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 282         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 283         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 284
 285 #if 0
 286         /* THIS WILL NOT WORK on some systems.  If the process
 287          * forks after starting a thread, there is no guarantee
 288          * that the thread will survive the fork.  For example,
 289          * slapd forks in order to daemonize, and does so after
 290          * calling ldap_pvt_thread_pool_init.  On some systems,
 291          * this initial thread does not run in the child process,
 292          * but ltp_open_count == 1, so two things happen:
 293          * 1) the first client connection fails, and 2) when
 294          * slapd is kill'ed, it never terminates since it waits
 295          * for all worker threads to exit. */
 296
 297         /* start up one thread, just so there is one. no need to
 298          * lock the mutex right now, since no threads are running.
 299          */
 300         pool->ltp_open_count++;
 301
 302         ldap_pvt_thread_t thr;
 303         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 304
 305         if( rc != 0) {
 306                 /* couldn't start one?  then don't start any */
 307                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 308                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 309                         ldap_int_thread_pool_s, ltp_next);
 310                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 311                 ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 312                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 313                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 314                 LDAP_FREE(pool);
 315                 return(-1);
 316         }
 317 #endif
 318
 319         *tpool = pool;
 320         return(0);
 321 }
 322
 323 #define TID_HASH(tid, hash) do { unsigned i; \
 324         unsigned char *ptr = (unsigned char *)&(tid); \
 325         for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
 326
 327 int
 328 ldap_pvt_thread_pool_submit (
 329         ldap_pvt_thread_pool_t *tpool,
 330         ldap_pvt_thread_start_t *start_routine, void *arg )
 331 {
 332         struct ldap_int_thread_pool_s *pool;
 333         ldap_int_thread_ctx_t *ctx;
 334         int need_thread = 0;
 335         ldap_pvt_thread_t thr;
 336
 337         if (tpool == NULL)
 338                 return(-1);
 339
 340         pool = *tpool;
 341
 342         if (pool == NULL)
 343                 return(-1);
 344
 345         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 346         if ((pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING &&
 347                 pool->ltp_state != LDAP_INT_THREAD_POOL_PAUSING)
 348                 || (pool->ltp_max_pending > 0
 349                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 350         {
 351                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 352                 return(-1);
 353         }
 354         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 355         if (ctx) {
 356                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 357         } else {
 358                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 359                         sizeof(ldap_int_thread_ctx_t));
 360                 if (ctx == NULL) {
 361                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 362                         return(-1);
 363                 }
 364         }
 365
 366         ctx->ltc_start_routine = start_routine;
 367         ctx->ltc_arg = arg;
 368
 369         pool->ltp_pending_count++;
 370         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 371         if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 372                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 373                 return(0);
 374         }
 375         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 376         if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
 377                 && (pool->ltp_open_count < pool->ltp_max_count ||
 378                         pool->ltp_max_count <= 0 ))
 379         {
 380                 pool->ltp_open_count++;
 381                 pool->ltp_starting++;
 382                 need_thread = 1;
 383         }
 384         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 385
 386 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 387         ldap_lazy_sem_op_submit( thread_pool_sem );
 388 #endif
 389
 390         if (need_thread) {
 391                 int rc;
 392
 393                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 394
 395                 rc = ldap_pvt_thread_create( &thr, 1,
 396                         ldap_int_thread_pool_wrapper, pool );
 397                 if (rc == 0) {
 398                         int hash;
 399                         pool->ltp_starting--;
 400
 401                         /* assign this thread ID to a key slot; start
 402                          * at the thread ID itself (mod LDAP_MAXTHR) and
 403                          * look for an empty slot.
 404                          */
 405                         TID_HASH(thr, hash);
 406                         for (rc = hash & (LDAP_MAXTHR-1);
 407                                 !ldap_pvt_thread_equal(thread_keys[rc].id, tid_zero);
 408                                 rc = (rc+1) & (LDAP_MAXTHR-1));
 409                         thread_keys[rc].id = thr;
 410                 } else {
 411                         /* couldn't create thread.  back out of
 412                          * ltp_open_count and check for even worse things.
 413                          */
 414                         pool->ltp_open_count--;
 415                         pool->ltp_starting--;
 416                         if (pool->ltp_open_count == 0) {
 417                                 /* no open threads at all?!?
 418                                  */
 419                                 ldap_int_thread_ctx_t *ptr;
 420                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 421                                         if (ptr == ctx) break;
 422                                 if (ptr == ctx) {
 423                                         /* no open threads, context not handled, so
 424                                          * back out of ltp_pending_count, free the context,
 425                                          * report the error.
 426                                          */
 427                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 428                                                 ldap_int_thread_ctx_s, ltc_next.q);
 429                                         pool->ltp_pending_count++;
 430                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 431                                         LDAP_FREE(ctx);
 432                                         return(-1);
 433                                 }
 434                         }
 435                         /* there is another open thread, so this
 436                          * context will be handled eventually.
 437                          * continue on and signal that the context
 438                          * is waiting.
 439                          */
 440                 }
 441                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 442         }
 443
 444         return(0);
 445 }
 446
 447 int
 448 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 449 {
 450         struct ldap_int_thread_pool_s *pool;
 451
 452         if (tpool == NULL)
 453                 return(-1);
 454
 455         pool = *tpool;
 456
 457         if (pool == NULL)
 458                 return(-1);
 459
 460         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 461         pool->ltp_max_count = max_threads;
 462         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 463         return(0);
 464 }
 465
 466 int
 467 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 468 {
 469         struct ldap_int_thread_pool_s *pool;
 470         int count;
 471
 472         if (tpool == NULL)
 473                 return(-1);
 474
 475         pool = *tpool;
 476
 477         if (pool == NULL)
 478                 return(0);
 479
 480         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 481         count = pool->ltp_pending_count + pool->ltp_active_count;
 482         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 483         return(count);
 484 }
 485
 486 int
 487 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 488 {
 489         struct ldap_int_thread_pool_s *pool, *pptr;
 490         ldap_int_thread_ctx_t *ctx;
 491
 492         if (tpool == NULL)
 493                 return(-1);
 494
 495         pool = *tpool;
 496
 497         if (pool == NULL) return(-1);
 498
 499         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 500         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 501                 if (pptr == pool) break;
 502         if (pptr == pool)
 503                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 504                         ldap_int_thread_pool_s, ltp_next);
 505         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 506
 507         if (pool != pptr) return(-1);
 508
 509         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 510         pool->ltp_state = run_pending
 511                 ? LDAP_INT_THREAD_POOL_FINISHING
 512                 : LDAP_INT_THREAD_POOL_STOPPING;
 513
 514         if ( pool->ltp_open_count ) {
 515                 ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 516                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 517         }
 518         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 519
 520         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 521         {
 522                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 523                 LDAP_FREE(ctx);
 524         }
 525
 526         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 527         {
 528                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 529                 LDAP_FREE(ctx);
 530         }
 531
 532         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 533         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 534         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 535         LDAP_FREE(pool);
 536 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 537         if ( thread_pool_sem ) {
 538                 LDAP_FREE( thread_pool_sem );
 539         }
 540 #endif
 541         return(0);
 542 }
 543
 544 static void *
 545 ldap_int_thread_pool_wrapper (
 546         void *xpool )
 547 {
 548         struct ldap_int_thread_pool_s *pool = xpool;
 549         ldap_int_thread_ctx_t *ctx;
 550         ldap_int_thread_userctx_t uctx;
 551         int i, keyslot, hash;
 552
 553         if (pool == NULL)
 554                 return NULL;
 555
 556         for ( i=0; i<MAXKEYS; i++ ) {
 557                 uctx.ltu_key[i].ltk_key = NULL;
 558         }
 559
 560         uctx.ltu_id = ldap_pvt_thread_self();
 561
 562         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 563
 564         /* store pointer to our keys */
 565         TID_HASH(uctx.ltu_id, hash);
 566         for (i = hash & (LDAP_MAXTHR-1);
 567                                 !ldap_pvt_thread_equal(thread_keys[i].id, uctx.ltu_id);
 568                                 i = (i+1) & (LDAP_MAXTHR-1));
 569         thread_keys[i].ctx = &uctx;
 570         keyslot = i;
 571
 572         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 573                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 574                 if (ctx) {
 575                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 576                 } else {
 577                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 578                                 break;
 579                         if (pool->ltp_max_count > 0
 580                                 && pool->ltp_open_count > pool->ltp_max_count)
 581                         {
 582                                 /* too many threads running (can happen if the
 583                                  * maximum threads value is set during ongoing
 584                                  * operation using ldap_pvt_thread_pool_maxthreads)
 585                                  * so let this thread die.
 586                                  */
 587                                 break;
 588                         }
 589
 590                         /* we could check an idle timer here, and let the
 591                          * thread die if it has been inactive for a while.
 592                          * only die if there are other open threads (i.e.,
 593                          * always have at least one thread open).  the check
 594                          * should be like this:
 595                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 596                          *       check timer, leave thread (break;)
 597                          *
 598                          * Just use pthread_cond_timedwait if we want to
 599                          * check idle time.
 600                          */
 601
 602                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING
 603                                 || pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING)
 604                         {
 605                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 606                         }
 607
 608                         continue;
 609                 }
 610
 611                 pool->ltp_pending_count--;
 612
 613                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 614                 pool->ltp_active_count++;
 615                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 616
 617                 ctx->ltc_start_routine(&uctx, ctx->ltc_arg);
 618
 619 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 620                 ldap_lazy_sem_post( thread_pool_sem );
 621 #endif
 622                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 623                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 624                         ldap_int_thread_ctx_s, ltc_next.al);
 625                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 626                 pool->ltp_active_count--;
 627
 628                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 629                         if (pool->ltp_active_count < 2) {
 630                                 ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 631                         }
 632                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 633                 }
 634         }
 635
 636         for ( i=0; i<MAXKEYS && uctx.ltu_key[i].ltk_key; i++ ) {
 637                 if (uctx.ltu_key[i].ltk_free)
 638                         uctx.ltu_key[i].ltk_free(
 639                                 uctx.ltu_key[i].ltk_key,
 640                                 uctx.ltu_key[i].ltk_data );
 641         }
 642
 643         thread_keys[keyslot].ctx = NULL;
 644         thread_keys[keyslot].id = tid_zero;
 645
 646         pool->ltp_open_count--;
 647
 648         /* let pool_destroy know we're all done */
 649         if (pool->ltp_open_count < 1)
 650                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 651
 652         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 653
 654         ldap_pvt_thread_exit(NULL);
 655         return(NULL);
 656 }
 657
 658 int
 659 ldap_pvt_thread_pool_pause (
 660         ldap_pvt_thread_pool_t *tpool )
 661 {
 662         struct ldap_int_thread_pool_s *pool;
 663
 664         if (tpool == NULL)
 665                 return(-1);
 666
 667         pool = *tpool;
 668
 669         if (pool == NULL)
 670                 return(0);
 671
 672         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 673
 674         /* If someone else has already requested a pause, we have to wait */
 675         while (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 676                 pool->ltp_pending_count++;
 677                 pool->ltp_active_count--;
 678                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 679                 pool->ltp_pending_count--;
 680                 pool->ltp_active_count++;
 681         }
 682         /* Wait for everyone else to finish */
 683         pool->ltp_state = LDAP_INT_THREAD_POOL_PAUSING;
 684         while (pool->ltp_active_count > 1) {
 685                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 686         }
 687         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 688         return(0);
 689 }
 690
 691 int
 692 ldap_pvt_thread_pool_resume (
 693         ldap_pvt_thread_pool_t *tpool )
 694 {
 695         struct ldap_int_thread_pool_s *pool;
 696
 697         if (tpool == NULL)
 698                 return(-1);
 699
 700         pool = *tpool;
 701
 702         if (pool == NULL)
 703                 return(0);
 704
 705         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 706
 707         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 708         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 709         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 710         return(0);
 711 }
 712
 713 int ldap_pvt_thread_pool_getkey(
 714         void *xctx,
 715         void *key,
 716         void **data,
 717         ldap_pvt_thread_pool_keyfree_t **kfree )
 718 {
 719         ldap_int_thread_userctx_t *ctx = xctx;
 720         int i;
 721
 722         if ( !ctx || !data ) return EINVAL;
 723
 724         for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) {
 725                 if ( ctx->ltu_key[i].ltk_key == key ) {
 726                         *data = ctx->ltu_key[i].ltk_data;
 727                         if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free;
 728                         return 0;
 729                 }
 730         }
 731         return ENOENT;
 732 }
 733
 734 int ldap_pvt_thread_pool_setkey(
 735         void *xctx,
 736         void *key,
 737         void *data,
 738         ldap_pvt_thread_pool_keyfree_t *kfree )
 739 {
 740         ldap_int_thread_userctx_t *ctx = xctx;
 741         int i;
 742
 743         if ( !ctx || !key ) return EINVAL;
 744
 745         for ( i=0; i<MAXKEYS; i++ ) {
 746                 if ( !ctx->ltu_key[i].ltk_key || ctx->ltu_key[i].ltk_key == key ) {
 747                         ctx->ltu_key[i].ltk_key = key;
 748                         ctx->ltu_key[i].ltk_data = data;
 749                         ctx->ltu_key[i].ltk_free = kfree;
 750                         return 0;
 751                 }
 752         }
 753         return ENOMEM;
 754 }
 755
 756 /* Free all elements with this key, no matter which thread they're in.
 757  * May only be called while the pool is paused.
 758  */
 759 void ldap_pvt_thread_pool_purgekey( void *key )
 760 {
 761         int i, j;
 762         ldap_int_thread_userctx_t *ctx;
 763
 764         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 765                 if ( thread_keys[i].ctx ) {
 766                         ctx = thread_keys[i].ctx;
 767                         for ( j=0; j<MAXKEYS; j++ ) {
 768                                 if ( ctx->ltu_key[j].ltk_key == key ) {
 769                                         if (ctx->ltu_key[j].ltk_free)
 770                                                 ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key,
 771                                                 ctx->ltu_key[j].ltk_data );
 772                                         ctx->ltu_key[j].ltk_key = NULL;
 773                                         ctx->ltu_key[j].ltk_free = NULL;
 774                                         break;
 775                                 }
 776                         }
 777                 }
 778         }
 779 }
 780
 781 /*
 782  * This is necessary if the caller does not have access to the
 783  * thread context handle (for example, a slapd plugin calling
 784  * slapi_search_internal()). No doubt it is more efficient to
 785  * for the application to keep track of the thread context
 786  * handles itself.
 787  */
 788 void *ldap_pvt_thread_pool_context( )
 789 {
 790         ldap_pvt_thread_t tid;
 791         int i, hash;
 792
 793         tid = ldap_pvt_thread_self();
 794         if ( ldap_pvt_thread_equal( tid, ldap_int_main_tid ))
 795                 return &ldap_int_main_thrctx;
 796
 797         TID_HASH( tid, hash );
 798         for (i = hash & (LDAP_MAXTHR-1);
 799                 !ldap_pvt_thread_equal(thread_keys[i].id, tid_zero) &&
 800                 !ldap_pvt_thread_equal(thread_keys[i].id, tid);
 801                 i = (i+1) & (LDAP_MAXTHR-1));
 802
 803         return thread_keys[i].ctx;
 804 }
 805
 806 void ldap_pvt_thread_pool_context_reset( void *vctx )
 807 {
 808         ldap_int_thread_userctx_t *ctx = vctx;
 809         int i;
 810
 811         for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++) {
 812                 if ( ctx->ltu_key[i].ltk_free )
 813                         ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key,
 814                         ctx->ltu_key[i].ltk_data );
 815                 ctx->ltu_key[i].ltk_key = NULL;
 816         }
 817 }
 818
 819 ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx )
 820 {
 821         ldap_int_thread_userctx_t *ctx = vctx;
 822
 823         return ctx->ltu_id;
 824 }
 825 #endif /* LDAP_THREAD_HAVE_TPOOL */