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

   1 /* $OpenLDAP$ */
   2 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   3  *
   4  * Copyright 1998-2008 The OpenLDAP Foundation.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted only as authorized by the OpenLDAP
   9  * Public License.
  10  *
  11  * A copy of this license is available in file LICENSE in the
  12  * top-level directory of the distribution or, alternatively, at
  13  * <http://www.OpenLDAP.org/license.html>.
  14  */
  15
  16 #include "portable.h"
  17
  18 #include <stdio.h>
  19
  20 #include <ac/stdarg.h>
  21 #include <ac/stdlib.h>
  22 #include <ac/string.h>
  23 #include <ac/time.h>
  24 #include <ac/errno.h>
  25
  26 #include "ldap-int.h"
  27 #include "ldap_pvt_thread.h" /* Get the thread interface */
  28 #include "ldap_queue.h"
  29 #define LDAP_THREAD_POOL_IMPLEMENTATION
  30 #include "ldap_thr_debug.h"  /* May rename symbols defined below */
  31
  32 #ifndef LDAP_THREAD_HAVE_TPOOL
  33
  34 typedef enum ldap_int_thread_pool_state_e {
  35         LDAP_INT_THREAD_POOL_RUNNING,
  36         LDAP_INT_THREAD_POOL_FINISHING,
  37         LDAP_INT_THREAD_POOL_STOPPING
  38 } ldap_int_thread_pool_state_t;
  39
  40 /* Thread-specific key with data and optional free function */
  41 typedef struct ldap_int_tpool_key_s {
  42         void *ltk_key;
  43         void *ltk_data;
  44         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  45 } ldap_int_tpool_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
  52 /* Max number of threads */
  53 #define LDAP_MAXTHR     1024    /* must be a power of 2 */
  54
  55 /* Context: thread ID and thread-specific key/data pairs */
  56 typedef struct ldap_int_thread_userctx_s {
  57         ldap_pvt_thread_t ltu_id;
  58         ldap_int_tpool_key_t ltu_key[MAXKEYS];
  59 } ldap_int_thread_userctx_t;
  60
  61
  62 /* Simple {thread ID -> context} hash table; key=ctx->ltu_id.
  63  * Protected by ldap_pvt_thread_pool_mutex except during pauses,
  64  * when it is read-only (used by pool_purgekey and pool_context).
  65  * Protected by tpool->ltp_mutex during pauses.
  66  */
  67 static struct {
  68         ldap_int_thread_userctx_t *ctx;
  69         /* ctx is valid when not NULL or DELETED_THREAD_CTX */
  70 #       define DELETED_THREAD_CTX (&ldap_int_main_thrctx + 1) /* dummy addr */
  71 } thread_keys[LDAP_MAXTHR];
  72
  73 #define TID_HASH(tid, hash) do { \
  74         unsigned const char *ptr_ = (unsigned const char *)&(tid); \
  75         unsigned i_; \
  76         for (i_ = 0, (hash) = ptr_[0]; ++i_ < sizeof(tid);) \
  77                 (hash) += ((hash) << 5) ^ ptr_[i_]; \
  78 } while(0)
  79
  80
  81 /* Task for a thread to perform */
  82 typedef struct ldap_int_thread_task_s {
  83         union {
  84                 LDAP_STAILQ_ENTRY(ldap_int_thread_task_s) q;
  85                 LDAP_SLIST_ENTRY(ldap_int_thread_task_s) l;
  86         } ltt_next;
  87         ldap_pvt_thread_start_t *ltt_start_routine;
  88         void *ltt_arg;
  89 } ldap_int_thread_task_t;
  90
  91 struct ldap_int_thread_pool_s {
  92         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  93
  94         /* protect members below, and protect thread_keys[] during pauses */
  95         ldap_pvt_thread_mutex_t ltp_mutex;
  96
  97         /* not paused and something to do for pool_<wrapper/pause/destroy>() */
  98         ldap_pvt_thread_cond_t ltp_cond;
  99
 100         /* ltp_active_count <= 1 && ltp_pause */
 101         ldap_pvt_thread_cond_t ltp_pcond;
 102
 103         /* pending tasks, and unused task objects */
 104         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_task_s) ltp_pending_list;
 105         LDAP_SLIST_HEAD(tcl, ldap_int_thread_task_s) ltp_free_list;
 106
 107         ldap_int_thread_pool_state_t ltp_state;
 108
 109         /* some active request needs to be the sole active request */
 110         int ltp_pause;
 111
 112         long ltp_max_count;                     /* max number of threads in pool, or 0 */
 113         long ltp_max_pending;           /* max pending or paused requests, or 0 */
 114         long ltp_pending_count;         /* pending or paused requests */
 115         long ltp_active_count;          /* active, not paused requests */
 116         long ltp_open_count;            /* number of threads */
 117         long ltp_starting;                      /* currenlty starting threads */
 118 };
 119
 120 static int ldap_int_has_thread_pool = 0;
 121 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
 122         ldap_int_thread_pool_list =
 123         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
 124
 125 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
 126
 127 static void *ldap_int_thread_pool_wrapper( void *pool );
 128
 129 static ldap_pvt_thread_key_t    ldap_tpool_key;
 130
 131 /* Context of the main thread */
 132 static ldap_int_thread_userctx_t ldap_int_main_thrctx;
 133
 134 int
 135 ldap_int_thread_pool_startup ( void )
 136 {
 137         ldap_int_main_thrctx.ltu_id = ldap_pvt_thread_self();
 138         ldap_pvt_thread_key_create( &ldap_tpool_key );
 139         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 140 }
 141
 142 int
 143 ldap_int_thread_pool_shutdown ( void )
 144 {
 145         struct ldap_int_thread_pool_s *pool;
 146
 147         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 148                 (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
 149         }
 150         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 151         ldap_pvt_thread_key_destroy( ldap_tpool_key );
 152         return(0);
 153 }
 154
 155
 156 /* Create a thread pool */
 157 int
 158 ldap_pvt_thread_pool_init (
 159         ldap_pvt_thread_pool_t *tpool,
 160         int max_threads,
 161         int max_pending )
 162 {
 163         ldap_pvt_thread_pool_t pool;
 164         int rc;
 165
 166         /* multiple pools are currently not supported (ITS#4943) */
 167         assert(!ldap_int_has_thread_pool);
 168
 169         if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
 170                 max_threads = 0;
 171         if (max_pending < 0)
 172                 max_pending = 0;
 173
 174         *tpool = NULL;
 175         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 176                 sizeof(struct ldap_int_thread_pool_s));
 177
 178         if (pool == NULL) return(-1);
 179
 180         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 181         if (rc != 0)
 182                 return(rc);
 183         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 184         if (rc != 0)
 185                 return(rc);
 186         rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
 187         if (rc != 0)
 188                 return(rc);
 189
 190         ldap_int_has_thread_pool = 1;
 191         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 192         pool->ltp_max_count = max_threads;
 193         pool->ltp_max_pending = max_pending;
 194         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 195         LDAP_SLIST_INIT(&pool->ltp_free_list);
 196         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 197         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 198         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 199
 200 #if 0
 201         /* THIS WILL NOT WORK on some systems.  If the process
 202          * forks after starting a thread, there is no guarantee
 203          * that the thread will survive the fork.  For example,
 204          * slapd forks in order to daemonize, and does so after
 205          * calling ldap_pvt_thread_pool_init.  On some systems,
 206          * this initial thread does not run in the child process,
 207          * but ltp_open_count == 1, so two things happen:
 208          * 1) the first client connection fails, and 2) when
 209          * slapd is kill'ed, it never terminates since it waits
 210          * for all worker threads to exit. */
 211
 212         /* start up one thread, just so there is one. no need to
 213          * lock the mutex right now, since no threads are running.
 214          */
 215         pool->ltp_open_count++;
 216
 217         ldap_pvt_thread_t thr;
 218         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 219
 220         if( rc != 0) {
 221                 /* couldn't start one?  then don't start any */
 222                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 223                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 224                         ldap_int_thread_pool_s, ltp_next);
 225                 ldap_int_has_thread_pool = 0;
 226                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 227                 ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 228                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 229                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 230                 LDAP_FREE(pool);
 231                 return(-1);
 232         }
 233 #endif
 234
 235         *tpool = pool;
 236         return(0);
 237 }
 238
 239
 240 /* Submit a task to be performed by the thread pool */
 241 int
 242 ldap_pvt_thread_pool_submit (
 243         ldap_pvt_thread_pool_t *tpool,
 244         ldap_pvt_thread_start_t *start_routine, void *arg )
 245 {
 246         struct ldap_int_thread_pool_s *pool;
 247         ldap_int_thread_task_t *task;
 248         ldap_pvt_thread_t thr;
 249
 250         if (tpool == NULL)
 251                 return(-1);
 252
 253         pool = *tpool;
 254
 255         if (pool == NULL)
 256                 return(-1);
 257
 258         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 259         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 260                 || (pool->ltp_max_pending
 261                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 262         {
 263                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 264                 return(-1);
 265         }
 266
 267         task = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 268         if (task) {
 269                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltt_next.l);
 270         } else {
 271                 task = (ldap_int_thread_task_t *) LDAP_MALLOC(sizeof(*task));
 272                 if (task == NULL) {
 273                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 274                         return(-1);
 275                 }
 276         }
 277
 278         task->ltt_start_routine = start_routine;
 279         task->ltt_arg = arg;
 280
 281         pool->ltp_pending_count++;
 282         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, task, ltt_next.q);
 283         if (pool->ltp_pause) {
 284                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 285                 return(0);
 286         }
 287         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 288         if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
 289                 && (pool->ltp_open_count <
 290                         (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR)))
 291         {
 292                 pool->ltp_open_count++;
 293                 pool->ltp_starting++;
 294                 if (0 != ldap_pvt_thread_create(
 295                         &thr, 1, ldap_int_thread_pool_wrapper, pool))
 296                 {
 297                         /* couldn't create thread.  back out of
 298                          * ltp_open_count and check for even worse things.
 299                          */
 300                         pool->ltp_starting--;
 301                         pool->ltp_open_count--;
 302                         if (pool->ltp_open_count == 0) {
 303                                 /* no open threads at all?!?
 304                                  */
 305                                 ldap_int_thread_task_t *ptr;
 306
 307                                 /* let pool_destroy know there are no more threads */
 308                                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 309
 310                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltt_next.q)
 311                                         if (ptr == task) break;
 312                                 if (ptr == task) {
 313                                         /* no open threads, task not handled, so
 314                                          * back out of ltp_pending_count, free the task,
 315                                          * report the error.
 316                                          */
 317                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, task,
 318                                                 ldap_int_thread_task_s, ltt_next.q);
 319                                         pool->ltp_pending_count--;
 320                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 321                                         LDAP_FREE(task);
 322                                         return(-1);
 323                                 }
 324                         }
 325                         /* there is another open thread, so this
 326                          * task will be handled eventually.
 327                          * continue on, we have signalled that
 328                          * the task is waiting.
 329                          */
 330                 }
 331         }
 332
 333         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 334         return(0);
 335 }
 336
 337 /* Set max #threads.  value <= 0 means max supported #threads (LDAP_MAXTHR) */
 338 int
 339 ldap_pvt_thread_pool_maxthreads(
 340         ldap_pvt_thread_pool_t *tpool,
 341         int max_threads )
 342 {
 343         struct ldap_int_thread_pool_s *pool;
 344
 345         if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
 346                 max_threads = 0;
 347
 348         if (tpool == NULL)
 349                 return(-1);
 350
 351         pool = *tpool;
 352
 353         if (pool == NULL)
 354                 return(-1);
 355
 356         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 357         pool->ltp_max_count = max_threads;
 358         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 359         return(0);
 360 }
 361
 362 /* Inspect the pool */
 363 int
 364 ldap_pvt_thread_pool_query(
 365         ldap_pvt_thread_pool_t *tpool,
 366         ldap_pvt_thread_pool_param_t param,
 367         void *value )
 368 {
 369         struct ldap_int_thread_pool_s   *pool;
 370         int                             count = -1;
 371
 372         if ( tpool == NULL || value == NULL ) {
 373                 return -1;
 374         }
 375
 376         pool = *tpool;
 377
 378         if ( pool == NULL ) {
 379                 return 0;
 380         }
 381
 382         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 383         switch ( param ) {
 384         case LDAP_PVT_THREAD_POOL_PARAM_MAX:
 385                 count = pool->ltp_max_count;
 386                 break;
 387
 388         case LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING:
 389                 count = pool->ltp_max_pending;
 390                 break;
 391
 392         case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
 393                 count = pool->ltp_open_count;
 394                 break;
 395
 396         case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
 397                 count = pool->ltp_starting;
 398                 break;
 399
 400         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
 401                 count = pool->ltp_active_count;
 402                 break;
 403
 404         case LDAP_PVT_THREAD_POOL_PARAM_PAUSING:
 405                 count = pool->ltp_pause;
 406                 break;
 407
 408         case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
 409                 count = pool->ltp_pending_count;
 410                 break;
 411
 412         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
 413                 count = pool->ltp_pending_count + pool->ltp_active_count;
 414                 break;
 415
 416         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX:
 417                 break;
 418
 419         case LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX:
 420                 break;
 421
 422         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX:
 423                 break;
 424
 425         case LDAP_PVT_THREAD_POOL_PARAM_STATE: {
 426                 static struct {
 427                         char                            *name;
 428                         ldap_int_thread_pool_state_t    state;
 429                 }               str2state[] = {
 430                         { "running",    LDAP_INT_THREAD_POOL_RUNNING },
 431                         { "finishing",  LDAP_INT_THREAD_POOL_FINISHING },
 432                         { "stopping",   LDAP_INT_THREAD_POOL_STOPPING },
 433                         { NULL }
 434                 };
 435                 int             i;
 436
 437                 if ( pool->ltp_pause ) {
 438                         *((char **)value) = "pausing";
 439                 } else {
 440                         for ( i = 0; str2state[ i ].name != NULL; i++ ) {
 441                                 if ( str2state[ i ].state == pool->ltp_state ) {
 442                                         break;
 443                                 }
 444                         }
 445                         *((char **)value) = str2state[ i ].name;
 446                 }
 447                 if ( *((char **)value) != NULL ) {
 448                         count = -2;
 449                 }
 450                 } break;
 451
 452         case LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN:
 453                 break;
 454         }
 455         ldap_pvt_thread_mutex_unlock( &pool->ltp_mutex );
 456
 457         if ( count > -1 ) {
 458                 *((int *)value) = count;
 459         }
 460
 461         return ( count == -1 ? -1 : 0 );
 462 }
 463
 464 /*
 465  * wrapper for ldap_pvt_thread_pool_query(), left around
 466  * for backwards compatibility
 467  */
 468 int
 469 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 470 {
 471         int     rc, count;
 472
 473         rc = ldap_pvt_thread_pool_query( tpool,
 474                 LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD, (void *)&count );
 475
 476         if ( rc == 0 ) {
 477                 return count;
 478         }
 479
 480         return rc;
 481 }
 482
 483 /* Destroy the pool after making its threads finish */
 484 int
 485 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 486 {
 487         struct ldap_int_thread_pool_s *pool, *pptr;
 488         ldap_int_thread_task_t *task;
 489
 490         if (tpool == NULL)
 491                 return(-1);
 492
 493         pool = *tpool;
 494
 495         if (pool == NULL) return(-1);
 496
 497         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 498         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 499                 if (pptr == pool) break;
 500         if (pptr == pool)
 501                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 502                         ldap_int_thread_pool_s, ltp_next);
 503         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 504
 505         if (pool != pptr) return(-1);
 506
 507         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 508         pool->ltp_state = run_pending
 509                 ? LDAP_INT_THREAD_POOL_FINISHING
 510                 : LDAP_INT_THREAD_POOL_STOPPING;
 511
 512         while (pool->ltp_open_count) {
 513                 if (!pool->ltp_pause)
 514                         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 515                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 516         }
 517         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 518
 519         while ((task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 520         {
 521                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
 522                 LDAP_FREE(task);
 523         }
 524
 525         while ((task = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 526         {
 527                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltt_next.l);
 528                 LDAP_FREE(task);
 529         }
 530
 531         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 532         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 533         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 534         LDAP_FREE(pool);
 535         *tpool = NULL;
 536         ldap_int_has_thread_pool = 0;
 537         return(0);
 538 }
 539
 540 /* Thread loop.  Accept and handle submitted tasks. */
 541 static void *
 542 ldap_int_thread_pool_wrapper (
 543         void *xpool )
 544 {
 545         struct ldap_int_thread_pool_s *pool = xpool;
 546         ldap_int_thread_task_t *task;
 547         ldap_int_thread_userctx_t ctx, *kctx;
 548         unsigned i, keyslot, hash;
 549
 550         assert(pool != NULL);
 551
 552         for ( i=0; i<MAXKEYS; i++ ) {
 553                 ctx.ltu_key[i].ltk_key = NULL;
 554         }
 555
 556         ctx.ltu_id = ldap_pvt_thread_self();
 557         TID_HASH(ctx.ltu_id, hash);
 558
 559         ldap_pvt_thread_key_setdata( ldap_tpool_key, &ctx );
 560
 561         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 562
 563         /* thread_keys[] is read-only when paused */
 564         while (pool->ltp_pause)
 565                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 566
 567         /* find a key slot to give this thread ID and store a
 568          * pointer to our keys there; start at the thread ID
 569          * itself (mod LDAP_MAXTHR) and look for an empty slot.
 570          */
 571         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 572         for (keyslot = hash & (LDAP_MAXTHR-1);
 573                 (kctx = thread_keys[keyslot].ctx) && kctx != DELETED_THREAD_CTX;
 574                 keyslot = (keyslot+1) & (LDAP_MAXTHR-1));
 575         thread_keys[keyslot].ctx = &ctx;
 576         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 577
 578         pool->ltp_starting--;
 579
 580         for (;;) {
 581                 while (pool->ltp_pause)
 582                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 583
 584                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_STOPPING)
 585                         break;
 586
 587                 task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 588                 if (task == NULL) {
 589                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 590                                 break;
 591
 592                         if (pool->ltp_open_count >
 593                                 (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR))
 594                         {
 595                                 /* too many threads running (can happen if the
 596                                  * maximum threads value is set during ongoing
 597                                  * operation using ldap_pvt_thread_pool_maxthreads)
 598                                  * so let this thread die.
 599                                  */
 600                                 break;
 601                         }
 602
 603                         /* we could check an idle timer here, and let the
 604                          * thread die if it has been inactive for a while.
 605                          * only die if there are other open threads (i.e.,
 606                          * always have at least one thread open).  the check
 607                          * should be like this:
 608                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 609                          *       check timer, wait if ltp_pause, leave thread (break;)
 610                          *
 611                          * Just use pthread_cond_timedwait if we want to
 612                          * check idle time.
 613                          */
 614
 615                         assert(pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING);
 616                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 617                         continue;
 618                 }
 619
 620                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
 621                 pool->ltp_pending_count--;
 622                 pool->ltp_active_count++;
 623                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 624
 625                 task->ltt_start_routine(&ctx, task->ltt_arg);
 626
 627                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 628                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, task, ltt_next.l);
 629                 pool->ltp_active_count--;
 630                 /* let pool_pause know when it is the sole active thread */
 631                 if (pool->ltp_active_count < 2)
 632                         ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 633         }
 634
 635         /* The ltp_mutex lock protects ctx->ltu_key from pool_purgekey()
 636          * during this call, since it prevents new pauses. */
 637         ldap_pvt_thread_pool_context_reset(&ctx);
 638
 639         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 640         thread_keys[keyslot].ctx = DELETED_THREAD_CTX;
 641         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 642
 643         pool->ltp_open_count--;
 644         /* let pool_destroy know we're all done */
 645         if (pool->ltp_open_count < 1)
 646                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 647
 648         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 649
 650         ldap_pvt_thread_exit(NULL);
 651         return(NULL);
 652 }
 653
 654 /* Pause the pool.  Return when all other threads are paused. */
 655 int
 656 ldap_pvt_thread_pool_pause (
 657         ldap_pvt_thread_pool_t *tpool )
 658 {
 659         struct ldap_int_thread_pool_s *pool;
 660
 661         if (tpool == NULL)
 662                 return(-1);
 663
 664         pool = *tpool;
 665
 666         if (pool == NULL)
 667                 return(0);
 668
 669         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 670
 671         /* If someone else has already requested a pause, we have to wait */
 672         if (pool->ltp_pause) {
 673                 pool->ltp_pending_count++;
 674                 pool->ltp_active_count--;
 675                 /* let the other pool_pause() know when it can proceed */
 676                 if (pool->ltp_active_count < 2)
 677                         ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 678                 do {
 679                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 680                 } while (pool->ltp_pause);
 681                 pool->ltp_pending_count--;
 682                 pool->ltp_active_count++;
 683         }
 684
 685         /* Wait for everyone else to pause or finish */
 686         pool->ltp_pause = 1;
 687         while (pool->ltp_active_count > 1) {
 688                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 689         }
 690
 691         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 692         return(0);
 693 }
 694
 695 /* End a pause */
 696 int
 697 ldap_pvt_thread_pool_resume (
 698         ldap_pvt_thread_pool_t *tpool )
 699 {
 700         struct ldap_int_thread_pool_s *pool;
 701
 702         if (tpool == NULL)
 703                 return(-1);
 704
 705         pool = *tpool;
 706
 707         if (pool == NULL)
 708                 return(0);
 709
 710         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 711         pool->ltp_pause = 0;
 712         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 713                 ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 714         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 715         return(0);
 716 }
 717
 718 /*
 719  * Get the key's data and optionally free function in the given context.
 720  */
 721 int ldap_pvt_thread_pool_getkey(
 722         void *xctx,
 723         void *key,
 724         void **data,
 725         ldap_pvt_thread_pool_keyfree_t **kfree )
 726 {
 727         ldap_int_thread_userctx_t *ctx = xctx;
 728         int i;
 729
 730         if ( !ctx || !key || !data ) return EINVAL;
 731
 732         for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) {
 733                 if ( ctx->ltu_key[i].ltk_key == key ) {
 734                         *data = ctx->ltu_key[i].ltk_data;
 735                         if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free;
 736                         return 0;
 737                 }
 738         }
 739         return ENOENT;
 740 }
 741
 742 static void
 743 clear_key_idx( ldap_int_thread_userctx_t *ctx, int i )
 744 {
 745         for ( ; i < MAXKEYS-1 && ctx->ltu_key[i+1].ltk_key; i++ )
 746                 ctx->ltu_key[i] = ctx->ltu_key[i+1];
 747         ctx->ltu_key[i].ltk_key = NULL;
 748 }
 749
 750 /*
 751  * Set or remove data for the key in the given context.
 752  * key can be any unique pointer.
 753  * kfree() is an optional function to free the data (but not the key):
 754  *   pool_context_reset() and pool_purgekey() call kfree(key, data),
 755  *   but pool_setkey() does not.  For pool_setkey() it is the caller's
 756  *   responsibility to free any existing data with the same key.
 757  *   kfree() must not call functions taking a tpool argument.
 758  */
 759 int ldap_pvt_thread_pool_setkey(
 760         void *xctx,
 761         void *key,
 762         void *data,
 763         ldap_pvt_thread_pool_keyfree_t *kfree,
 764         void **olddatap,
 765         ldap_pvt_thread_pool_keyfree_t **oldkfreep )
 766 {
 767         ldap_int_thread_userctx_t *ctx = xctx;
 768         int i, found;
 769
 770         if ( !ctx || !key ) return EINVAL;
 771
 772         for ( i=found=0; i<MAXKEYS; i++ ) {
 773                 if ( ctx->ltu_key[i].ltk_key == key ) {
 774                         found = 1;
 775                         break;
 776                 } else if ( !ctx->ltu_key[i].ltk_key ) {
 777                         break;
 778                 }
 779         }
 780
 781         if ( olddatap ) {
 782                 if ( found ) {
 783                         *olddatap = ctx->ltu_key[i].ltk_data;
 784                 } else {
 785                         *olddatap = NULL;
 786                 }
 787         }
 788
 789         if ( oldkfreep ) {
 790                 if ( found ) {
 791                         *oldkfreep = ctx->ltu_key[i].ltk_free;
 792                 } else {
 793                         *oldkfreep = 0;
 794                 }
 795         }
 796
 797         if ( data || kfree ) {
 798                 if ( i>=MAXKEYS )
 799                         return ENOMEM;
 800                 ctx->ltu_key[i].ltk_key = key;
 801                 ctx->ltu_key[i].ltk_data = data;
 802                 ctx->ltu_key[i].ltk_free = kfree;
 803         } else if ( found ) {
 804                 clear_key_idx( ctx, i );
 805         }
 806
 807         return 0;
 808 }
 809
 810 /* Free all elements with this key, no matter which thread they're in.
 811  * May only be called while the pool is paused.
 812  */
 813 void ldap_pvt_thread_pool_purgekey( void *key )
 814 {
 815         int i, j;
 816         ldap_int_thread_userctx_t *ctx;
 817
 818         assert ( key != NULL );
 819
 820         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 821                 ctx = thread_keys[i].ctx;
 822                 if ( ctx && ctx != DELETED_THREAD_CTX ) {
 823                         for ( j=0; j<MAXKEYS && ctx->ltu_key[j].ltk_key; j++ ) {
 824                                 if ( ctx->ltu_key[j].ltk_key == key ) {
 825                                         if (ctx->ltu_key[j].ltk_free)
 826                                                 ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key,
 827                                                 ctx->ltu_key[j].ltk_data );
 828                                         clear_key_idx( ctx, j );
 829                                         break;
 830                                 }
 831                         }
 832                 }
 833         }
 834 }
 835
 836 /*
 837  * Find the context of the current thread.
 838  * This is necessary if the caller does not have access to the
 839  * thread context handle (for example, a slapd plugin calling
 840  * slapi_search_internal()). No doubt it is more efficient
 841  * for the application to keep track of the thread context
 842  * handles itself.
 843  */
 844 void *ldap_pvt_thread_pool_context( )
 845 {
 846         void *ctx = NULL;
 847
 848         ldap_pvt_thread_key_getdata( ldap_tpool_key, &ctx );
 849         return ctx ? ctx : &ldap_int_main_thrctx;
 850 }
 851
 852 /*
 853  * Free the context's keys.
 854  * Must not call functions taking a tpool argument (because this
 855  * thread already holds ltp_mutex when called from pool_wrapper()).
 856  */
 857 void ldap_pvt_thread_pool_context_reset( void *vctx )
 858 {
 859         ldap_int_thread_userctx_t *ctx = vctx;
 860         int i;
 861
 862         for ( i=MAXKEYS-1; i>=0; i--) {
 863                 if ( !ctx->ltu_key[i].ltk_key )
 864                         continue;
 865                 if ( ctx->ltu_key[i].ltk_free )
 866                         ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key,
 867                         ctx->ltu_key[i].ltk_data );
 868                 ctx->ltu_key[i].ltk_key = NULL;
 869         }
 870 }
 871
 872 ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx )
 873 {
 874         ldap_int_thread_userctx_t *ctx = vctx;
 875
 876         return ctx->ltu_id;
 877 }
 878 #endif /* LDAP_THREAD_HAVE_TPOOL */