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_state_t;
  39
  40 typedef struct ldap_int_thread_key_s {
  41         void *ltk_key;
  42         void *ltk_data;
  43         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  44 } ldap_int_thread_key_t;
  45
  46 /* Max number of thread-specific keys we store per thread.
  47  * We don't expect to use many...
  48  */
  49 #define MAXKEYS 32
  50 #define LDAP_MAXTHR     1024    /* must be a power of 2 */
  51
  52 typedef struct ldap_int_thread_userctx_s {
  53         ldap_pvt_thread_t ltu_id;
  54         ldap_int_thread_key_t ltu_key[MAXKEYS];
  55 } ldap_int_thread_userctx_t;
  56
  57 static ldap_pvt_thread_t tid_zero;
  58
  59 /* Thread ID -> context mapping (poor open-addressed hash table).
  60  * Protected by ldap_pvt_thread_pool_mutex except during pauses,
  61  * when it is read-only (used by pool_purgekey and pool_context).
  62  */
  63 static struct {
  64         ldap_pvt_thread_t id;
  65         ldap_int_thread_userctx_t *ctx;         /* set when id != tid_zero */
  66 #       define DELETED_THREAD_CTX (&ldap_int_main_thrctx + 1) /* dummy addr */
  67 } thread_keys[LDAP_MAXTHR];
  68
  69 #define TID_HASH(tid, hash) do { \
  70         unsigned const char *ptr_ = (unsigned const char *)&(tid); \
  71         unsigned i_; \
  72         for (i_ = 0, (hash) = ptr_[0]; ++i_ < sizeof(tid);) \
  73                 (hash) += ((hash) << 5) ^ ptr_[i_]; \
  74 } while(0)
  75
  76
  77 typedef struct ldap_int_thread_ctx_s {
  78         union {
  79         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  80         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  81         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  82         } ltc_next;
  83         ldap_pvt_thread_start_t *ltc_start_routine;
  84         void *ltc_arg;
  85 } ldap_int_thread_ctx_t;
  86
  87 struct ldap_int_thread_pool_s {
  88         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  89         ldap_pvt_thread_mutex_t ltp_mutex;
  90         ldap_pvt_thread_cond_t ltp_cond;
  91         ldap_pvt_thread_cond_t ltp_pcond;
  92         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  93         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  94         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  95         ldap_int_thread_pool_state_t ltp_state;
  96         int ltp_pause;
  97         long ltp_max_count;
  98         long ltp_max_pending;
  99         long ltp_pending_count;
 100         long ltp_active_count;
 101         long ltp_open_count;
 102         long ltp_starting;
 103 };
 104
 105 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
 106         ldap_int_thread_pool_list =
 107         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
 108
 109 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
 110
 111 static void *ldap_int_thread_pool_wrapper( void *pool );
 112
 113 static ldap_pvt_thread_t ldap_int_main_tid;
 114
 115 static ldap_int_thread_userctx_t ldap_int_main_thrctx;
 116
 117 int
 118 ldap_int_thread_pool_startup ( void )
 119 {
 120         ldap_int_main_tid = ldap_pvt_thread_self();
 121         ldap_int_main_thrctx.ltu_id = ldap_int_main_tid;
 122
 123         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 124 }
 125
 126 int
 127 ldap_int_thread_pool_shutdown ( void )
 128 {
 129         struct ldap_int_thread_pool_s *pool;
 130
 131         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 132                 (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
 133         }
 134         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 135         return(0);
 136 }
 137
 138 typedef struct ldap_lazy_sem_t {
 139         ldap_pvt_thread_mutex_t ls_mutex;
 140         ldap_pvt_thread_cond_t  ls_cond;
 141         int ls_sem_value;
 142         /*
 143          * when more than ls_lazy_count number of resources
 144          * becmoes available, the thread wating for the resources will
 145          * be waken up in order to prevent frequent blocking/waking-up
 146          */
 147         unsigned int ls_lazy_count;
 148         /*
 149          * only one thread(listener) will wait on this semaphore
 150          * using a flag instead of a list
 151          */
 152         int ls_wait;
 153 } ldap_lazy_sem_t;
 154
 155 ldap_lazy_sem_t* thread_pool_sem = NULL;
 156
 157 int
 158 ldap_lazy_sem_init( unsigned int value, unsigned int lazyness )
 159 {
 160         thread_pool_sem = (ldap_lazy_sem_t*) LDAP_CALLOC(1,
 161                 sizeof( ldap_lazy_sem_t ));
 162
 163         if( thread_pool_sem == NULL ) return -1;
 164
 165         ldap_pvt_thread_mutex_init( &thread_pool_sem->ls_mutex );
 166         ldap_pvt_thread_cond_init( &thread_pool_sem->ls_cond );
 167         thread_pool_sem->ls_sem_value = value;
 168         thread_pool_sem->ls_lazy_count = lazyness;
 169         thread_pool_sem->ls_wait = 0;
 170
 171         return 0;
 172 }
 173
 174 /* FIXME: move to some approprite header */
 175 int ldap_lazy_sem_dec( ldap_lazy_sem_t* ls );
 176 int ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls );
 177
 178 /*
 179  * ldap_lazy_sem_wait is used if a caller is blockable(listener).
 180  * Otherwise use ldap_lazy_sem_dec (worker)
 181  */
 182 int
 183 ldap_lazy_sem_op_submit( ldap_lazy_sem_t* ls )
 184 {
 185         if ( ls == NULL ) return -1;
 186
 187         /* only worker thread has its thread ctx */
 188         if ( ldap_pvt_thread_pool_context() ) {
 189                 /* worker thread */
 190                 return ldap_lazy_sem_dec( ls );
 191         } else {
 192                 /* listener */
 193                 return ldap_lazy_sem_wait( ls );
 194         }
 195 }
 196
 197 /*
 198  * test if given semaphore's count is zero.
 199  * If 0, the caller is blocked
 200  * If not, the count is decremented.
 201  */
 202 int
 203 ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls )
 204 {
 205         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 206
 207 lazy_sem_retry:
 208         if ( ls->ls_sem_value <= 0 ) {
 209                 /* no more avaliable resources */
 210                 ls->ls_wait = 1;
 211                 ldap_pvt_thread_cond_wait( &ls->ls_cond, &ls->ls_mutex );
 212                 goto lazy_sem_retry;
 213         } else {
 214                 /* avaliable resources */
 215                 ls->ls_sem_value--;
 216         }
 217
 218         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 219
 220         return 0;
 221 }
 222
 223 /*
 224  * decrement the count without blocking
 225  * even when the count becomes less than or equal to 0
 226  */
 227 int
 228 ldap_lazy_sem_dec( ldap_lazy_sem_t* ls )
 229 {
 230         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 231
 232         ls->ls_sem_value--;
 233
 234         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 235
 236         return 0;
 237 }
 238
 239 /*
 240  * Increment the count by one and test if it is greater or
 241  * equal to lazyness. If it is, wake up a blocked thread.
 242  */
 243 int
 244 ldap_lazy_sem_post( ldap_lazy_sem_t* ls )
 245 {
 246         if( ls == NULL ) return (-1);
 247
 248         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 249
 250         ls->ls_sem_value++;
 251         if ( ls->ls_wait ) {
 252                 if ( ls->ls_sem_value >= ls->ls_lazy_count ) {
 253                         ls->ls_wait = 0;
 254                         ldap_pvt_thread_cond_signal( &ls->ls_cond );
 255                 }
 256         }
 257
 258         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 259
 260         return 0;
 261 }
 262
 263 int
 264 ldap_pvt_thread_pool_init (
 265         ldap_pvt_thread_pool_t *tpool,
 266         int max_threads,
 267         int max_pending )
 268 {
 269         ldap_pvt_thread_pool_t pool;
 270         int rc;
 271
 272         if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
 273                 max_threads = 0;
 274
 275         *tpool = NULL;
 276         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 277                 sizeof(struct ldap_int_thread_pool_s));
 278
 279         if (pool == NULL) return(-1);
 280
 281         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 282         if (rc != 0)
 283                 return(rc);
 284         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 285         if (rc != 0)
 286                 return(rc);
 287         rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
 288         if (rc != 0)
 289                 return(rc);
 290         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 291         pool->ltp_max_count = max_threads;
 292         pool->ltp_max_pending = max_pending;
 293         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 294         LDAP_SLIST_INIT(&pool->ltp_free_list);
 295         LDAP_SLIST_INIT(&pool->ltp_active_list);
 296         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 297         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 298         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 299
 300 #if 0
 301         /* THIS WILL NOT WORK on some systems.  If the process
 302          * forks after starting a thread, there is no guarantee
 303          * that the thread will survive the fork.  For example,
 304          * slapd forks in order to daemonize, and does so after
 305          * calling ldap_pvt_thread_pool_init.  On some systems,
 306          * this initial thread does not run in the child process,
 307          * but ltp_open_count == 1, so two things happen:
 308          * 1) the first client connection fails, and 2) when
 309          * slapd is kill'ed, it never terminates since it waits
 310          * for all worker threads to exit. */
 311
 312         /* start up one thread, just so there is one. no need to
 313          * lock the mutex right now, since no threads are running.
 314          */
 315         pool->ltp_open_count++;
 316
 317         ldap_pvt_thread_t thr;
 318         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 319
 320         if( rc != 0) {
 321                 /* couldn't start one?  then don't start any */
 322                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 323                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 324                         ldap_int_thread_pool_s, ltp_next);
 325                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 326                 ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 327                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 328                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 329                 LDAP_FREE(pool);
 330                 return(-1);
 331         }
 332 #endif
 333
 334         *tpool = pool;
 335         return(0);
 336 }
 337
 338
 339 int
 340 ldap_pvt_thread_pool_submit (
 341         ldap_pvt_thread_pool_t *tpool,
 342         ldap_pvt_thread_start_t *start_routine, void *arg )
 343 {
 344         struct ldap_int_thread_pool_s *pool;
 345         ldap_int_thread_ctx_t *ctx;
 346         int need_thread = 0;
 347         ldap_pvt_thread_t thr;
 348
 349         if (tpool == NULL)
 350                 return(-1);
 351
 352         pool = *tpool;
 353
 354         if (pool == NULL)
 355                 return(-1);
 356
 357         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 358         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 359                 || (pool->ltp_max_pending > 0
 360                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 361         {
 362                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 363                 return(-1);
 364         }
 365
 366         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 367         if (ctx) {
 368                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 369         } else {
 370                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 371                         sizeof(ldap_int_thread_ctx_t));
 372                 if (ctx == NULL) {
 373                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 374                         return(-1);
 375                 }
 376         }
 377
 378         ctx->ltc_start_routine = start_routine;
 379         ctx->ltc_arg = arg;
 380
 381         pool->ltp_pending_count++;
 382         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 383         if (pool->ltp_pause) {
 384                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 385                 return(0);
 386         }
 387         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 388         if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
 389                 && (pool->ltp_open_count <
 390                         (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR)))
 391         {
 392                 pool->ltp_open_count++;
 393                 pool->ltp_starting++;
 394                 need_thread = 1;
 395         }
 396         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 397
 398 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 399         ldap_lazy_sem_op_submit( thread_pool_sem );
 400 #endif
 401
 402         if (need_thread) {
 403                 int rc;
 404
 405                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 406
 407                 rc = ldap_pvt_thread_create( &thr, 1,
 408                         ldap_int_thread_pool_wrapper, pool );
 409                 pool->ltp_starting--;
 410                 if (rc != 0) {
 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                         if (pool->ltp_open_count == 0) {
 416                                 /* no open threads at all?!?
 417                                  */
 418                                 ldap_int_thread_ctx_t *ptr;
 419
 420                                 /* let pool_destroy know there are no more threads */
 421                                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 422
 423                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 424                                         if (ptr == ctx) break;
 425                                 if (ptr == ctx) {
 426                                         /* no open threads, context not handled, so
 427                                          * back out of ltp_pending_count, free the context,
 428                                          * report the error.
 429                                          */
 430                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 431                                                 ldap_int_thread_ctx_s, ltc_next.q);
 432                                         pool->ltp_pending_count--;
 433                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 434                                         LDAP_FREE(ctx);
 435                                         return(-1);
 436                                 }
 437                         }
 438                         /* there is another open thread, so this
 439                          * context will be handled eventually.
 440                          * continue on, we have signalled that
 441                          * the context is waiting.
 442                          */
 443                 }
 444                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 445         }
 446
 447         return(0);
 448 }
 449
 450 int
 451 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 452 {
 453         struct ldap_int_thread_pool_s *pool;
 454
 455         if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
 456                 max_threads = 0;
 457
 458         if (tpool == NULL)
 459                 return(-1);
 460
 461         pool = *tpool;
 462
 463         if (pool == NULL)
 464                 return(-1);
 465
 466         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 467         pool->ltp_max_count = max_threads;
 468         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 469         return(0);
 470 }
 471
 472 int
 473 ldap_pvt_thread_pool_query ( ldap_pvt_thread_pool_t *tpool, ldap_pvt_thread_pool_param_t param, void *value )
 474 {
 475         struct ldap_int_thread_pool_s   *pool;
 476         int                             count = -1;
 477
 478         if ( tpool == NULL || value == NULL ) {
 479                 return -1;
 480         }
 481
 482         pool = *tpool;
 483
 484         if ( pool == NULL ) {
 485                 return 0;
 486         }
 487
 488         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 489         switch ( param ) {
 490         case LDAP_PVT_THREAD_POOL_PARAM_MAX:
 491                 count = pool->ltp_max_count;
 492                 break;
 493
 494         case LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING:
 495                 count = pool->ltp_max_pending;
 496                 break;
 497
 498         case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
 499                 count = pool->ltp_open_count;
 500                 break;
 501
 502         case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
 503                 count = pool->ltp_starting;
 504                 break;
 505
 506         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
 507                 count = pool->ltp_active_count;
 508                 break;
 509
 510         case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
 511                 count = pool->ltp_pending_count;
 512                 break;
 513
 514         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
 515                 count = pool->ltp_pending_count + pool->ltp_active_count;
 516                 break;
 517
 518         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX:
 519                 break;
 520
 521         case LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX:
 522                 break;
 523
 524         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX:
 525                 break;
 526
 527         case LDAP_PVT_THREAD_POOL_PARAM_STATE: {
 528                 static struct {
 529                         char                            *name;
 530                         ldap_int_thread_pool_state_t    state;
 531                 }               str2state[] = {
 532                         { "running",    LDAP_INT_THREAD_POOL_RUNNING },
 533                         { "finishing",  LDAP_INT_THREAD_POOL_FINISHING },
 534                         { "stopping",   LDAP_INT_THREAD_POOL_STOPPING },
 535                         { NULL }
 536                 };
 537                 int             i;
 538
 539                 if ( pool->ltp_pause ) {
 540                         *((char **)value) = "pausing";
 541                 } else {
 542                         for ( i = 0; str2state[ i ].name != NULL; i++ ) {
 543                                 if ( str2state[ i ].state == pool->ltp_state ) {
 544                                         break;
 545                                 }
 546                         }
 547                         *((char **)value) = str2state[ i ].name;
 548                 }
 549                 if ( *((char **)value) != NULL ) {
 550                         count = -2;
 551                 }
 552                 } break;
 553         }
 554         ldap_pvt_thread_mutex_unlock( &pool->ltp_mutex );
 555
 556         if ( count > -1 ) {
 557                 *((int *)value) = count;
 558         }
 559
 560         return ( count == -1 ? -1 : 0 );
 561 }
 562
 563 /*
 564  * wrapper for ldap_pvt_thread_pool_query(), left around
 565  * for backwards compatibility
 566  */
 567 int
 568 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 569 {
 570         int     rc, count;
 571
 572         rc = ldap_pvt_thread_pool_query( tpool,
 573                 LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD, (void *)&count );
 574
 575         if ( rc == 0 ) {
 576                 return count;
 577         }
 578
 579         return rc;
 580 }
 581
 582 int
 583 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 584 {
 585         struct ldap_int_thread_pool_s *pool, *pptr;
 586         ldap_int_thread_ctx_t *ctx;
 587
 588         if (tpool == NULL)
 589                 return(-1);
 590
 591         pool = *tpool;
 592
 593         if (pool == NULL) return(-1);
 594
 595         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 596         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 597                 if (pptr == pool) break;
 598         if (pptr == pool)
 599                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 600                         ldap_int_thread_pool_s, ltp_next);
 601         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 602
 603         if (pool != pptr) return(-1);
 604
 605         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 606         pool->ltp_state = run_pending
 607                 ? LDAP_INT_THREAD_POOL_FINISHING
 608                 : LDAP_INT_THREAD_POOL_STOPPING;
 609
 610         while (pool->ltp_open_count) {
 611                 if (!pool->ltp_pause)
 612                         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 613                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 614         }
 615         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 616
 617         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 618         {
 619                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 620                 LDAP_FREE(ctx);
 621         }
 622
 623         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 624         {
 625                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 626                 LDAP_FREE(ctx);
 627         }
 628
 629         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 630         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 631         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 632         LDAP_FREE(pool);
 633 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 634         if ( thread_pool_sem ) {
 635                 LDAP_FREE( thread_pool_sem );
 636         }
 637 #endif
 638         return(0);
 639 }
 640
 641 static void *
 642 ldap_int_thread_pool_wrapper (
 643         void *xpool )
 644 {
 645         struct ldap_int_thread_pool_s *pool = xpool;
 646         ldap_int_thread_ctx_t *ctx;
 647         ldap_int_thread_userctx_t uctx;
 648         unsigned i, keyslot, hash;
 649
 650         if (pool == NULL)
 651                 return NULL;
 652
 653         for ( i=0; i<MAXKEYS; i++ ) {
 654                 uctx.ltu_key[i].ltk_key = NULL;
 655         }
 656
 657         uctx.ltu_id = ldap_pvt_thread_self();
 658         TID_HASH(uctx.ltu_id, hash);
 659
 660         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 661
 662         /* thread_keys[] is read-only when paused */
 663         while (pool->ltp_pause)
 664                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 665
 666         /* find a key slot to give this thread ID and store a
 667          * pointer to our keys there; start at the thread ID
 668          * itself (mod LDAP_MAXTHR) and look for an empty slot.
 669          */
 670         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 671         for (keyslot = hash & (LDAP_MAXTHR-1);
 672                 !ldap_pvt_thread_equal(thread_keys[keyslot].id, tid_zero);
 673                 keyslot = (keyslot+1) & (LDAP_MAXTHR-1));
 674         thread_keys[keyslot].id = uctx.ltu_id;
 675         thread_keys[keyslot].ctx = &uctx;
 676         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 677
 678         for (;;) {
 679                 while (pool->ltp_pause)
 680                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 681
 682                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_STOPPING)
 683                         break;
 684
 685                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 686                 if (ctx == NULL) {
 687                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 688                                 break;
 689
 690                         if (pool->ltp_open_count >
 691                                 (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR))
 692                         {
 693                                 /* too many threads running (can happen if the
 694                                  * maximum threads value is set during ongoing
 695                                  * operation using ldap_pvt_thread_pool_maxthreads)
 696                                  * so let this thread die.
 697                                  */
 698                                 break;
 699                         }
 700
 701                         /* we could check an idle timer here, and let the
 702                          * thread die if it has been inactive for a while.
 703                          * only die if there are other open threads (i.e.,
 704                          * always have at least one thread open).  the check
 705                          * should be like this:
 706                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 707                          *       check timer, wait if ltp_pause, leave thread (break;)
 708                          *
 709                          * Just use pthread_cond_timedwait if we want to
 710                          * check idle time.
 711                          */
 712
 713                         assert(pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING);
 714                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 715                         continue;
 716                 }
 717
 718                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 719                 pool->ltp_pending_count--;
 720
 721                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 722                 pool->ltp_active_count++;
 723                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 724
 725                 ctx->ltc_start_routine(&uctx, ctx->ltc_arg);
 726
 727 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 728                 ldap_lazy_sem_post( thread_pool_sem );
 729 #endif
 730                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 731                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 732                         ldap_int_thread_ctx_s, ltc_next.al);
 733                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 734                 pool->ltp_active_count--;
 735
 736                 /* let pool_pause know when it is the sole active thread */
 737                 if (pool->ltp_active_count < 2)
 738                         ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 739         }
 740
 741         ldap_pvt_thread_pool_context_reset(&uctx);
 742
 743         /* Needed if context_reset can let another thread request a pause */
 744         while (pool->ltp_pause)
 745                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 746
 747         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 748         thread_keys[keyslot].ctx = DELETED_THREAD_CTX;
 749         thread_keys[keyslot].id = tid_zero;
 750         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 751
 752         pool->ltp_open_count--;
 753
 754         /* let pool_destroy know we're all done */
 755         if (pool->ltp_open_count < 1)
 756                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 757
 758         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 759
 760         ldap_pvt_thread_exit(NULL);
 761         return(NULL);
 762 }
 763
 764 int
 765 ldap_pvt_thread_pool_pause (
 766         ldap_pvt_thread_pool_t *tpool )
 767 {
 768         struct ldap_int_thread_pool_s *pool;
 769
 770         if (tpool == NULL)
 771                 return(-1);
 772
 773         pool = *tpool;
 774
 775         if (pool == NULL)
 776                 return(0);
 777
 778         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 779
 780         /* If someone else has already requested a pause, we have to wait */
 781         while (pool->ltp_pause) {
 782                 pool->ltp_pending_count++;
 783                 pool->ltp_active_count--;
 784                 /* let the other pool_pause() know when it can proceed */
 785                 if (pool->ltp_active_count < 2)
 786                         ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 787                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 788                 pool->ltp_pending_count--;
 789                 pool->ltp_active_count++;
 790         }
 791
 792         /* Wait for everyone else to pause or finish */
 793         pool->ltp_pause = 1;
 794         while (pool->ltp_active_count > 1) {
 795                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 796         }
 797
 798         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 799         return(0);
 800 }
 801
 802 int
 803 ldap_pvt_thread_pool_resume (
 804         ldap_pvt_thread_pool_t *tpool )
 805 {
 806         struct ldap_int_thread_pool_s *pool;
 807
 808         if (tpool == NULL)
 809                 return(-1);
 810
 811         pool = *tpool;
 812
 813         if (pool == NULL)
 814                 return(0);
 815
 816         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 817         pool->ltp_pause = 0;
 818         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 819         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 820         return(0);
 821 }
 822
 823 int ldap_pvt_thread_pool_getkey(
 824         void *xctx,
 825         void *key,
 826         void **data,
 827         ldap_pvt_thread_pool_keyfree_t **kfree )
 828 {
 829         ldap_int_thread_userctx_t *ctx = xctx;
 830         int i;
 831
 832         if ( !ctx || !key || !data ) return EINVAL;
 833
 834         for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) {
 835                 if ( ctx->ltu_key[i].ltk_key == key ) {
 836                         *data = ctx->ltu_key[i].ltk_data;
 837                         if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free;
 838                         return 0;
 839                 }
 840         }
 841         return ENOENT;
 842 }
 843
 844 static void
 845 clear_key_idx( ldap_int_thread_userctx_t *ctx, int i )
 846 {
 847         int j = i;
 848         while ( ++j < MAXKEYS && ctx->ltu_key[j].ltk_key );
 849         if ( --j != i ) {
 850                 ctx->ltu_key[i] = ctx->ltu_key[j];
 851                 i = j;
 852         }
 853         ctx->ltu_key[i].ltk_key = NULL;
 854 }
 855
 856 int ldap_pvt_thread_pool_setkey(
 857         void *xctx,
 858         void *key,
 859         void *data,
 860         ldap_pvt_thread_pool_keyfree_t *kfree )
 861 {
 862         ldap_int_thread_userctx_t *ctx = xctx;
 863         int i, found;
 864
 865         if ( !ctx || !key ) return EINVAL;
 866
 867         for ( i=found=0; i<MAXKEYS; i++ ) {
 868                 if ( ctx->ltu_key[i].ltk_key == key ) {
 869                         found = 1;
 870                         break;
 871                 } else if ( !ctx->ltu_key[i].ltk_key ) {
 872                         break;
 873                 }
 874         }
 875
 876         if ( data || kfree ) {
 877                 if ( i>=MAXKEYS )
 878                         return ENOMEM;
 879                 ctx->ltu_key[i].ltk_key = key;
 880                 ctx->ltu_key[i].ltk_data = data;
 881                 ctx->ltu_key[i].ltk_free = kfree;
 882         } else if ( found ) {
 883                 clear_key_idx( ctx, i );
 884         }
 885
 886         return 0;
 887 }
 888
 889 /* Free all elements with this key, no matter which thread they're in.
 890  * May only be called while the pool is paused.
 891  */
 892 void ldap_pvt_thread_pool_purgekey( void *key )
 893 {
 894         int i, j;
 895         ldap_int_thread_userctx_t *ctx;
 896
 897         assert ( key != NULL );
 898
 899         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 900                 ctx = thread_keys[i].ctx;
 901                 if ( ctx && ctx != DELETED_THREAD_CTX ) {
 902                         for ( j=0; j<MAXKEYS && ctx->ltu_key[j].ltk_key; j++ ) {
 903                                 if ( ctx->ltu_key[j].ltk_key == key ) {
 904                                         if (ctx->ltu_key[j].ltk_free)
 905                                                 ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key,
 906                                                 ctx->ltu_key[j].ltk_data );
 907                                         clear_key_idx( ctx, j );
 908                                         break;
 909                                 }
 910                         }
 911                 }
 912         }
 913 }
 914
 915 /*
 916  * This is necessary if the caller does not have access to the
 917  * thread context handle (for example, a slapd plugin calling
 918  * slapi_search_internal()). No doubt it is more efficient
 919  * for the application to keep track of the thread context
 920  * handles itself.
 921  */
 922 void *ldap_pvt_thread_pool_context( )
 923 {
 924         ldap_pvt_thread_t tid;
 925         unsigned i, hash;
 926         ldap_int_thread_userctx_t *ctx;
 927
 928         tid = ldap_pvt_thread_self();
 929         if ( ldap_pvt_thread_equal( tid, ldap_int_main_tid ))
 930                 return &ldap_int_main_thrctx;
 931
 932         TID_HASH( tid, hash );
 933         i = hash &= (LDAP_MAXTHR-1);
 934         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 935         do {
 936                 ctx = thread_keys[i].ctx;
 937                 if ( ctx != DELETED_THREAD_CTX )
 938                         if ( ldap_pvt_thread_equal(thread_keys[i].id, tid) || !ctx )
 939                                 goto done;
 940         } while ( (i = (i+1) & (LDAP_MAXTHR-1)) != hash );
 941         ctx = NULL;
 942  done:
 943         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 944
 945         return ctx;
 946 }
 947
 948 void ldap_pvt_thread_pool_context_reset( void *vctx )
 949 {
 950         ldap_int_thread_userctx_t *ctx = vctx;
 951         int i;
 952
 953         for ( i=MAXKEYS-1; i>=0; i--) {
 954                 if ( !ctx->ltu_key[i].ltk_key )
 955                         continue;
 956                 if ( ctx->ltu_key[i].ltk_free )
 957                         ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key,
 958                         ctx->ltu_key[i].ltk_data );
 959                 ctx->ltu_key[i].ltk_key = NULL;
 960         }
 961 }
 962
 963 ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx )
 964 {
 965         ldap_int_thread_userctx_t *ctx = vctx;
 966
 967         return ctx->ltu_id;
 968 }
 969 #endif /* LDAP_THREAD_HAVE_TPOOL */