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 1998-2007 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_query ( ldap_pvt_thread_pool_t *tpool, ldap_pvt_thread_pool_param_t param, void *value )
 468 {
 469         struct ldap_int_thread_pool_s   *pool;
 470         int                             count = -1;
 471
 472         if ( tpool == NULL || value == NULL ) {
 473                 return -1;
 474         }
 475
 476         pool = *tpool;
 477
 478         if ( pool == NULL ) {
 479                 return 0;
 480         }
 481
 482         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 483         switch ( param ) {
 484         case LDAP_PVT_THREAD_POOL_PARAM_MAX:
 485                 count = pool->ltp_max_count;
 486                 break;
 487
 488         case LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING:
 489                 count = pool->ltp_max_pending;
 490                 break;
 491
 492         case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
 493                 count = pool->ltp_open_count;
 494                 break;
 495
 496         case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
 497                 count = pool->ltp_starting;
 498                 break;
 499
 500         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
 501                 count = pool->ltp_active_count;
 502                 break;
 503
 504         case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
 505                 count = pool->ltp_pending_count;
 506                 break;
 507
 508         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
 509                 count = pool->ltp_pending_count + pool->ltp_active_count;
 510                 break;
 511
 512         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX:
 513                 break;
 514
 515         case LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX:
 516                 break;
 517
 518         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX:
 519                 break;
 520
 521         case LDAP_PVT_THREAD_POOL_PARAM_STATE: {
 522                 static struct {
 523                         char                            *name;
 524                         ldap_int_thread_pool_state_t    state;
 525                 }               str2state[] = {
 526                         { "running",    LDAP_INT_THREAD_POOL_RUNNING },
 527                         { "finishing",  LDAP_INT_THREAD_POOL_FINISHING },
 528                         { "stopping",   LDAP_INT_THREAD_POOL_STOPPING },
 529                         { "pausing",    LDAP_INT_THREAD_POOL_PAUSING },
 530                         { NULL }
 531                 };
 532                 int             i;
 533
 534                 for ( i = 0; str2state[ i ].name != NULL; i++ ) {
 535                         if ( str2state[ i ].state == pool->ltp_state ) {
 536                                 break;
 537                         }
 538                 }
 539                 *((char **)value) = str2state[ i ].name;
 540                 if ( str2state[ i ].name != NULL ) {
 541                         count = -2;
 542                 }
 543                 } break;
 544         }
 545         ldap_pvt_thread_mutex_unlock( &pool->ltp_mutex );
 546
 547         if ( count > -1 ) {
 548                 *((int *)value) = count;
 549         }
 550
 551         return ( count == -1 ? -1 : 0 );
 552 }
 553
 554 /*
 555  * wrapper for ldap_pvt_thread_pool_query(), left around
 556  * for backwards compatibility
 557  */
 558 int
 559 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 560 {
 561         int     rc, count;
 562
 563         rc = ldap_pvt_thread_pool_query( tpool,
 564                 LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD, (void *)&count );
 565
 566         if ( rc == 0 ) {
 567                 return count;
 568         }
 569
 570         return rc;
 571 }
 572
 573 int
 574 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 575 {
 576         struct ldap_int_thread_pool_s *pool, *pptr;
 577         ldap_int_thread_ctx_t *ctx;
 578
 579         if (tpool == NULL)
 580                 return(-1);
 581
 582         pool = *tpool;
 583
 584         if (pool == NULL) return(-1);
 585
 586         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 587         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 588                 if (pptr == pool) break;
 589         if (pptr == pool)
 590                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 591                         ldap_int_thread_pool_s, ltp_next);
 592         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 593
 594         if (pool != pptr) return(-1);
 595
 596         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 597         pool->ltp_state = run_pending
 598                 ? LDAP_INT_THREAD_POOL_FINISHING
 599                 : LDAP_INT_THREAD_POOL_STOPPING;
 600
 601         if ( pool->ltp_open_count ) {
 602                 ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 603                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 604         }
 605         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 606
 607         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 608         {
 609                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 610                 LDAP_FREE(ctx);
 611         }
 612
 613         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 614         {
 615                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 616                 LDAP_FREE(ctx);
 617         }
 618
 619         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 620         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 621         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 622         LDAP_FREE(pool);
 623 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 624         if ( thread_pool_sem ) {
 625                 LDAP_FREE( thread_pool_sem );
 626         }
 627 #endif
 628         return(0);
 629 }
 630
 631 static void *
 632 ldap_int_thread_pool_wrapper (
 633         void *xpool )
 634 {
 635         struct ldap_int_thread_pool_s *pool = xpool;
 636         ldap_int_thread_ctx_t *ctx;
 637         ldap_int_thread_userctx_t uctx;
 638         int i, keyslot, hash;
 639
 640         if (pool == NULL)
 641                 return NULL;
 642
 643         for ( i=0; i<MAXKEYS; i++ ) {
 644                 uctx.ltu_key[i].ltk_key = NULL;
 645         }
 646
 647         uctx.ltu_id = ldap_pvt_thread_self();
 648
 649         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 650
 651         /* store pointer to our keys */
 652         TID_HASH(uctx.ltu_id, hash);
 653         for (i = hash & (LDAP_MAXTHR-1);
 654                                 !ldap_pvt_thread_equal(thread_keys[i].id, uctx.ltu_id);
 655                                 i = (i+1) & (LDAP_MAXTHR-1));
 656         thread_keys[i].ctx = &uctx;
 657         keyslot = i;
 658
 659         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 660                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 661                 if (ctx) {
 662                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 663                 } else {
 664                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 665                                 break;
 666                         if (pool->ltp_max_count > 0
 667                                 && pool->ltp_open_count > pool->ltp_max_count)
 668                         {
 669                                 /* too many threads running (can happen if the
 670                                  * maximum threads value is set during ongoing
 671                                  * operation using ldap_pvt_thread_pool_maxthreads)
 672                                  * so let this thread die.
 673                                  */
 674                                 break;
 675                         }
 676
 677                         /* we could check an idle timer here, and let the
 678                          * thread die if it has been inactive for a while.
 679                          * only die if there are other open threads (i.e.,
 680                          * always have at least one thread open).  the check
 681                          * should be like this:
 682                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 683                          *       check timer, leave thread (break;)
 684                          *
 685                          * Just use pthread_cond_timedwait if we want to
 686                          * check idle time.
 687                          */
 688
 689                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING
 690                                 || pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING)
 691                         {
 692                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 693                         }
 694
 695                         continue;
 696                 }
 697
 698                 pool->ltp_pending_count--;
 699
 700                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 701                 pool->ltp_active_count++;
 702                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 703
 704                 ctx->ltc_start_routine(&uctx, ctx->ltc_arg);
 705
 706 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 707                 ldap_lazy_sem_post( thread_pool_sem );
 708 #endif
 709                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 710                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 711                         ldap_int_thread_ctx_s, ltc_next.al);
 712                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 713                 pool->ltp_active_count--;
 714
 715                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 716                         if (pool->ltp_active_count < 2) {
 717                                 ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 718                         }
 719                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 720                 }
 721         }
 722
 723         ldap_pvt_thread_pool_context_reset(&uctx);
 724
 725         thread_keys[keyslot].ctx = NULL;
 726         thread_keys[keyslot].id = tid_zero;
 727
 728         pool->ltp_open_count--;
 729
 730         /* let pool_destroy know we're all done */
 731         if (pool->ltp_open_count < 1)
 732                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 733
 734         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 735
 736         ldap_pvt_thread_exit(NULL);
 737         return(NULL);
 738 }
 739
 740 int
 741 ldap_pvt_thread_pool_pause (
 742         ldap_pvt_thread_pool_t *tpool )
 743 {
 744         struct ldap_int_thread_pool_s *pool;
 745
 746         if (tpool == NULL)
 747                 return(-1);
 748
 749         pool = *tpool;
 750
 751         if (pool == NULL)
 752                 return(0);
 753
 754         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 755
 756         /* If someone else has already requested a pause, we have to wait */
 757         while (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 758                 pool->ltp_pending_count++;
 759                 pool->ltp_active_count--;
 760                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 761                 pool->ltp_pending_count--;
 762                 pool->ltp_active_count++;
 763         }
 764         /* Wait for everyone else to finish */
 765         pool->ltp_state = LDAP_INT_THREAD_POOL_PAUSING;
 766         while (pool->ltp_active_count > 1) {
 767                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 768         }
 769         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 770         return(0);
 771 }
 772
 773 int
 774 ldap_pvt_thread_pool_resume (
 775         ldap_pvt_thread_pool_t *tpool )
 776 {
 777         struct ldap_int_thread_pool_s *pool;
 778
 779         if (tpool == NULL)
 780                 return(-1);
 781
 782         pool = *tpool;
 783
 784         if (pool == NULL)
 785                 return(0);
 786
 787         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 788
 789         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 790         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 791         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 792         return(0);
 793 }
 794
 795 int ldap_pvt_thread_pool_getkey(
 796         void *xctx,
 797         void *key,
 798         void **data,
 799         ldap_pvt_thread_pool_keyfree_t **kfree )
 800 {
 801         ldap_int_thread_userctx_t *ctx = xctx;
 802         int i;
 803
 804         if ( !ctx || !data ) return EINVAL;
 805
 806         for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) {
 807                 if ( ctx->ltu_key[i].ltk_key == key ) {
 808                         *data = ctx->ltu_key[i].ltk_data;
 809                         if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free;
 810                         return 0;
 811                 }
 812         }
 813         return ENOENT;
 814 }
 815
 816 int ldap_pvt_thread_pool_setkey(
 817         void *xctx,
 818         void *key,
 819         void *data,
 820         ldap_pvt_thread_pool_keyfree_t *kfree )
 821 {
 822         ldap_int_thread_userctx_t *ctx = xctx;
 823         int i;
 824
 825         if ( !ctx || !key ) return EINVAL;
 826
 827         for ( i=0; i<MAXKEYS; i++ ) {
 828                 if ( !ctx->ltu_key[i].ltk_key || ctx->ltu_key[i].ltk_key == key ) {
 829                         ctx->ltu_key[i].ltk_key = key;
 830                         ctx->ltu_key[i].ltk_data = data;
 831                         ctx->ltu_key[i].ltk_free = kfree;
 832                         return 0;
 833                 }
 834         }
 835         return ENOMEM;
 836 }
 837
 838 /* Free all elements with this key, no matter which thread they're in.
 839  * May only be called while the pool is paused.
 840  */
 841 void ldap_pvt_thread_pool_purgekey( void *key )
 842 {
 843         int i, j;
 844         ldap_int_thread_userctx_t *ctx;
 845
 846         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 847                 if ( thread_keys[i].ctx ) {
 848                         ctx = thread_keys[i].ctx;
 849                         for ( j=0; j<MAXKEYS; j++ ) {
 850                                 if ( ctx->ltu_key[j].ltk_key == key ) {
 851                                         if (ctx->ltu_key[j].ltk_free)
 852                                                 ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key,
 853                                                 ctx->ltu_key[j].ltk_data );
 854                                         ctx->ltu_key[j].ltk_key = NULL;
 855                                         ctx->ltu_key[j].ltk_free = NULL;
 856                                         break;
 857                                 }
 858                         }
 859                 }
 860         }
 861 }
 862
 863 /*
 864  * This is necessary if the caller does not have access to the
 865  * thread context handle (for example, a slapd plugin calling
 866  * slapi_search_internal()). No doubt it is more efficient
 867  * for the application to keep track of the thread context
 868  * handles itself.
 869  */
 870 void *ldap_pvt_thread_pool_context( )
 871 {
 872         ldap_pvt_thread_t tid;
 873         int i, hash;
 874
 875         tid = ldap_pvt_thread_self();
 876         if ( ldap_pvt_thread_equal( tid, ldap_int_main_tid ))
 877                 return &ldap_int_main_thrctx;
 878
 879         TID_HASH( tid, hash );
 880         for (i = hash & (LDAP_MAXTHR-1);
 881                 !ldap_pvt_thread_equal(thread_keys[i].id, tid_zero) &&
 882                 !ldap_pvt_thread_equal(thread_keys[i].id, tid);
 883                 i = (i+1) & (LDAP_MAXTHR-1));
 884
 885         return thread_keys[i].ctx;
 886 }
 887
 888 void ldap_pvt_thread_pool_context_reset( void *vctx )
 889 {
 890         ldap_int_thread_userctx_t *ctx = vctx;
 891         int i;
 892
 893         for ( i=MAXKEYS-1; i>=0; i--) {
 894                 if ( !ctx->ltu_key[i].ltk_key )
 895                         continue;
 896                 if ( ctx->ltu_key[i].ltk_free )
 897                         ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key,
 898                         ctx->ltu_key[i].ltk_data );
 899                 ctx->ltu_key[i].ltk_key = NULL;
 900         }
 901 }
 902
 903 ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx )
 904 {
 905         ldap_int_thread_userctx_t *ctx = vctx;
 906
 907         return ctx->ltu_id;
 908 }
 909 #endif /* LDAP_THREAD_HAVE_TPOOL */