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

   1 /* $OpenLDAP$ */
   2 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   3  *
   4  * Copyright 1998-2006 The OpenLDAP Foundation.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted only as authorized by the OpenLDAP
   9  * Public License.
  10  *
  11  * A copy of this license is available in file LICENSE in the
  12  * top-level directory of the distribution or, alternatively, at
  13  * <http://www.OpenLDAP.org/license.html>.
  14  */
  15
  16 #include "portable.h"
  17
  18 #include <stdio.h>
  19
  20 #include <ac/stdarg.h>
  21 #include <ac/stdlib.h>
  22 #include <ac/string.h>
  23 #include <ac/time.h>
  24 #include <ac/errno.h>
  25
  26 #include "ldap-int.h"
  27 #include "ldap_pvt_thread.h" /* Get the thread interface */
  28 #include "ldap_queue.h"
  29 #define LDAP_THREAD_POOL_IMPLEMENTATION
  30 #include "ldap_thr_debug.h"  /* May rename symbols defined below */
  31
  32 #ifndef LDAP_THREAD_HAVE_TPOOL
  33
  34 typedef enum ldap_int_thread_pool_state_e {
  35         LDAP_INT_THREAD_POOL_RUNNING,
  36         LDAP_INT_THREAD_POOL_FINISHING,
  37         LDAP_INT_THREAD_POOL_STOPPING,
  38         LDAP_INT_THREAD_POOL_PAUSING
  39 } ldap_int_thread_pool_state_t;
  40
  41 typedef struct ldap_int_thread_key_s {
  42         void *ltk_key;
  43         void *ltk_data;
  44         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  45 } ldap_int_thread_key_t;
  46
  47 /* Max number of thread-specific keys we store per thread.
  48  * We don't expect to use many...
  49  */
  50 #define MAXKEYS 32
  51 #define LDAP_MAXTHR     1024    /* must be a power of 2 */
  52
  53 static ldap_pvt_thread_t tid_zero;
  54
  55 static struct {
  56         ldap_pvt_thread_t id;
  57         ldap_int_thread_key_t *ctx;
  58 } thread_keys[LDAP_MAXTHR];
  59
  60
  61 typedef struct ldap_int_thread_ctx_s {
  62         union {
  63         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  64         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  65         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  66         } ltc_next;
  67         ldap_pvt_thread_start_t *ltc_start_routine;
  68         void *ltc_arg;
  69 } ldap_int_thread_ctx_t;
  70
  71 struct ldap_int_thread_pool_s {
  72         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  73         ldap_pvt_thread_mutex_t ltp_mutex;
  74         ldap_pvt_thread_cond_t ltp_cond;
  75         ldap_pvt_thread_cond_t ltp_pcond;
  76         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  77         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  78         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  79         ldap_int_thread_pool_state_t ltp_state;
  80         long ltp_max_count;
  81         long ltp_max_pending;
  82         long ltp_pending_count;
  83         long ltp_active_count;
  84         long ltp_open_count;
  85         long ltp_starting;
  86 };
  87
  88 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  89         ldap_int_thread_pool_list =
  90         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  91
  92 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  93
  94 static void *ldap_int_thread_pool_wrapper( void *pool );
  95
  96 static ldap_pvt_thread_t ldap_int_main_tid;
  97
  98 static ldap_int_thread_key_t ldap_int_main_thrctx[LDAP_MAXTHR];
  99
 100 int
 101 ldap_int_thread_pool_startup ( void )
 102 {
 103         ldap_int_main_tid = ldap_pvt_thread_self();
 104
 105         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 106 }
 107
 108 int
 109 ldap_int_thread_pool_shutdown ( void )
 110 {
 111         struct ldap_int_thread_pool_s *pool;
 112
 113         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 114                 LDAP_STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
 115                 (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
 116         }
 117         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 118         return(0);
 119 }
 120
 121 typedef struct ldap_lazy_sem_t {
 122         ldap_pvt_thread_mutex_t ls_mutex;
 123         ldap_pvt_thread_cond_t  ls_cond;
 124         int ls_sem_value;
 125         /*
 126          * when more than ls_lazy_count number of resources
 127          * becmoes available, the thread wating for the resources will
 128          * be waken up in order to prevent frequent blocking/waking-up
 129          */
 130         unsigned int ls_lazy_count;
 131         /*
 132          * only one thread(listener) will wait on this semaphore
 133          * using a flag instead of a list
 134          */
 135         int ls_wait;
 136 } ldap_lazy_sem_t;
 137
 138 ldap_lazy_sem_t* thread_pool_sem = NULL;
 139
 140 int
 141 ldap_lazy_sem_init( unsigned int value, unsigned int lazyness )
 142 {
 143         thread_pool_sem = (ldap_lazy_sem_t*) LDAP_CALLOC(1,
 144                 sizeof( ldap_lazy_sem_t ));
 145
 146         if( thread_pool_sem == NULL ) return -1;
 147
 148         ldap_pvt_thread_mutex_init( &thread_pool_sem->ls_mutex );
 149         ldap_pvt_thread_cond_init( &thread_pool_sem->ls_cond );
 150         thread_pool_sem->ls_sem_value = value;
 151         thread_pool_sem->ls_lazy_count = lazyness;
 152         thread_pool_sem->ls_wait = 0;
 153
 154         return 0;
 155 }
 156
 157 /* FIXME: move to some approprite header */
 158 int ldap_lazy_sem_dec( ldap_lazy_sem_t* ls );
 159 int ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls );
 160
 161 /*
 162  * ldap_lazy_sem_wait is used if a caller is blockable(listener).
 163  * Otherwise use ldap_lazy_sem_dec (worker)
 164  */
 165 int
 166 ldap_lazy_sem_op_submit( ldap_lazy_sem_t* ls )
 167 {
 168         if ( ls == NULL ) return -1;
 169
 170         /* only worker thread has its thread ctx */
 171         if ( ldap_pvt_thread_pool_context() ) {
 172                 /* worker thread */
 173                 return ldap_lazy_sem_dec( ls );
 174         } else {
 175                 /* listener */
 176                 return ldap_lazy_sem_wait( ls );
 177         }
 178 }
 179
 180 /*
 181  * test if given semaphore's count is zero.
 182  * If 0, the caller is blocked
 183  * If not, the count is decremented.
 184  */
 185 int
 186 ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls )
 187 {
 188         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 189
 190 lazy_sem_retry:
 191         if ( ls->ls_sem_value <= 0 ) {
 192                 /* no more avaliable resources */
 193                 ls->ls_wait = 1;
 194                 ldap_pvt_thread_cond_wait( &ls->ls_cond, &ls->ls_mutex );
 195                 goto lazy_sem_retry;
 196         } else {
 197                 /* avaliable resources */
 198                 ls->ls_sem_value--;
 199         }
 200
 201         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 202
 203         return 0;
 204 }
 205
 206 /*
 207  * decrement the count without blocking
 208  * even when the count becomes less than or equal to 0
 209  */
 210 int
 211 ldap_lazy_sem_dec( ldap_lazy_sem_t* ls )
 212 {
 213         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 214
 215         ls->ls_sem_value--;
 216
 217         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 218
 219         return 0;
 220 }
 221
 222 /*
 223  * Increment the count by one and test if it is greater or
 224  * equal to lazyness. If it is, wake up a blocked thread.
 225  */
 226 int
 227 ldap_lazy_sem_post( ldap_lazy_sem_t* ls )
 228 {
 229         if( ls == NULL ) return (-1);
 230
 231         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 232
 233         ls->ls_sem_value++;
 234         if ( ls->ls_wait ) {
 235                 if ( ls->ls_sem_value >= ls->ls_lazy_count ) {
 236                         ls->ls_wait = 0;
 237                         ldap_pvt_thread_cond_signal( &ls->ls_cond );
 238                 }
 239         }
 240
 241         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 242
 243         return 0;
 244 }
 245
 246 int
 247 ldap_pvt_thread_pool_init (
 248         ldap_pvt_thread_pool_t *tpool,
 249         int max_threads,
 250         int max_pending )
 251 {
 252         ldap_pvt_thread_pool_t pool;
 253         int rc;
 254
 255         *tpool = NULL;
 256         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 257                 sizeof(struct ldap_int_thread_pool_s));
 258
 259         if (pool == NULL) return(-1);
 260
 261         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 262         if (rc != 0)
 263                 return(rc);
 264         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 265         if (rc != 0)
 266                 return(rc);
 267         rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
 268         if (rc != 0)
 269                 return(rc);
 270         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 271         pool->ltp_max_count = max_threads;
 272         pool->ltp_max_pending = max_pending;
 273         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 274         LDAP_SLIST_INIT(&pool->ltp_free_list);
 275         LDAP_SLIST_INIT(&pool->ltp_active_list);
 276         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 277         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 278         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 279
 280 #if 0
 281         /* THIS WILL NOT WORK on some systems.  If the process
 282          * forks after starting a thread, there is no guarantee
 283          * that the thread will survive the fork.  For example,
 284          * slapd forks in order to daemonize, and does so after
 285          * calling ldap_pvt_thread_pool_init.  On some systems,
 286          * this initial thread does not run in the child process,
 287          * but ltp_open_count == 1, so two things happen:
 288          * 1) the first client connection fails, and 2) when
 289          * slapd is kill'ed, it never terminates since it waits
 290          * for all worker threads to exit. */
 291
 292         /* start up one thread, just so there is one. no need to
 293          * lock the mutex right now, since no threads are running.
 294          */
 295         pool->ltp_open_count++;
 296
 297         ldap_pvt_thread_t thr;
 298         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 299
 300         if( rc != 0) {
 301                 /* couldn't start one?  then don't start any */
 302                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 303                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 304                         ldap_int_thread_pool_s, ltp_next);
 305                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 306                 ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 307                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 308                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 309                 LDAP_FREE(pool);
 310                 return(-1);
 311         }
 312 #endif
 313
 314         *tpool = pool;
 315         return(0);
 316 }
 317
 318 #define TID_HASH(tid, hash) do { unsigned i; \
 319         unsigned char *ptr = (unsigned char *)&(tid); \
 320         for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
 321
 322 int
 323 ldap_pvt_thread_pool_submit (
 324         ldap_pvt_thread_pool_t *tpool,
 325         ldap_pvt_thread_start_t *start_routine, void *arg )
 326 {
 327         struct ldap_int_thread_pool_s *pool;
 328         ldap_int_thread_ctx_t *ctx;
 329         int need_thread = 0;
 330         ldap_pvt_thread_t thr;
 331
 332         if (tpool == NULL)
 333                 return(-1);
 334
 335         pool = *tpool;
 336
 337         if (pool == NULL)
 338                 return(-1);
 339
 340         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 341         if ((pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING &&
 342                 pool->ltp_state != LDAP_INT_THREAD_POOL_PAUSING)
 343                 || (pool->ltp_max_pending > 0
 344                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 345         {
 346                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 347                 return(-1);
 348         }
 349         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 350         if (ctx) {
 351                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 352         } else {
 353                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 354                         sizeof(ldap_int_thread_ctx_t));
 355                 if (ctx == NULL) {
 356                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 357                         return(-1);
 358                 }
 359         }
 360
 361         ctx->ltc_start_routine = start_routine;
 362         ctx->ltc_arg = arg;
 363
 364         pool->ltp_pending_count++;
 365         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 366         if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 367                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 368                 return(0);
 369         }
 370         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 371         if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
 372                 && (pool->ltp_open_count < pool->ltp_max_count ||
 373                         pool->ltp_max_count <= 0 ))
 374         {
 375                 pool->ltp_open_count++;
 376                 pool->ltp_starting++;
 377                 need_thread = 1;
 378         }
 379         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 380
 381 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 382         ldap_lazy_sem_op_submit( thread_pool_sem );
 383 #endif
 384
 385         if (need_thread) {
 386                 int rc;
 387
 388                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 389
 390                 rc = ldap_pvt_thread_create( &thr, 1,
 391                         ldap_int_thread_pool_wrapper, pool );
 392                 if (rc == 0) {
 393                         int hash;
 394                         pool->ltp_starting--;
 395
 396                         /* assign this thread ID to a key slot; start
 397                          * at the thread ID itself (mod LDAP_MAXTHR) and
 398                          * look for an empty slot.
 399                          */
 400                         TID_HASH(thr, hash);
 401                         for (rc = hash & (LDAP_MAXTHR-1);
 402                                 !ldap_pvt_thread_equal(thread_keys[rc].id, tid_zero);
 403                                 rc = (rc+1) & (LDAP_MAXTHR-1));
 404                         thread_keys[rc].id = thr;
 405                 } else {
 406                         /* couldn't create thread.  back out of
 407                          * ltp_open_count and check for even worse things.
 408                          */
 409                         pool->ltp_open_count--;
 410                         pool->ltp_starting--;
 411                         if (pool->ltp_open_count == 0) {
 412                                 /* no open threads at all?!?
 413                                  */
 414                                 ldap_int_thread_ctx_t *ptr;
 415                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 416                                         if (ptr == ctx) break;
 417                                 if (ptr == ctx) {
 418                                         /* no open threads, context not handled, so
 419                                          * back out of ltp_pending_count, free the context,
 420                                          * report the error.
 421                                          */
 422                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 423                                                 ldap_int_thread_ctx_s, ltc_next.q);
 424                                         pool->ltp_pending_count++;
 425                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 426                                         LDAP_FREE(ctx);
 427                                         return(-1);
 428                                 }
 429                         }
 430                         /* there is another open thread, so this
 431                          * context will be handled eventually.
 432                          * continue on and signal that the context
 433                          * is waiting.
 434                          */
 435                 }
 436                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 437         }
 438
 439         return(0);
 440 }
 441
 442 int
 443 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 444 {
 445         struct ldap_int_thread_pool_s *pool;
 446
 447         if (tpool == NULL)
 448                 return(-1);
 449
 450         pool = *tpool;
 451
 452         if (pool == NULL)
 453                 return(-1);
 454
 455         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 456         pool->ltp_max_count = max_threads;
 457         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 458         return(0);
 459 }
 460
 461 int
 462 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 463 {
 464         struct ldap_int_thread_pool_s *pool;
 465         int count;
 466
 467         if (tpool == NULL)
 468                 return(-1);
 469
 470         pool = *tpool;
 471
 472         if (pool == NULL)
 473                 return(0);
 474
 475         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 476         count = pool->ltp_pending_count + pool->ltp_active_count;
 477         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 478         return(count);
 479 }
 480
 481 int
 482 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 483 {
 484         struct ldap_int_thread_pool_s *pool, *pptr;
 485         long waiting;
 486         ldap_int_thread_ctx_t *ctx;
 487
 488         if (tpool == NULL)
 489                 return(-1);
 490
 491         pool = *tpool;
 492
 493         if (pool == NULL) return(-1);
 494
 495         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 496         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 497                 if (pptr == pool) break;
 498         if (pptr == pool)
 499                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 500                         ldap_int_thread_pool_s, ltp_next);
 501         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 502
 503         if (pool != pptr) return(-1);
 504
 505         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 506         pool->ltp_state = run_pending
 507                 ? LDAP_INT_THREAD_POOL_FINISHING
 508                 : LDAP_INT_THREAD_POOL_STOPPING;
 509
 510         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 511         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 512
 513         do {
 514                 ldap_pvt_thread_yield();
 515                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 516                 waiting = pool->ltp_open_count;
 517                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 518         } while (waiting > 0);
 519
 520         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 521         {
 522                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 523                 LDAP_FREE(ctx);
 524         }
 525
 526         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 527         {
 528                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 529                 LDAP_FREE(ctx);
 530         }
 531
 532         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 533         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 534         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 535         LDAP_FREE(pool);
 536 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 537         if ( thread_pool_sem ) {
 538                 LDAP_FREE( thread_pool_sem );
 539         }
 540 #endif
 541         return(0);
 542 }
 543
 544 static void *
 545 ldap_int_thread_pool_wrapper (
 546         void *xpool )
 547 {
 548         struct ldap_int_thread_pool_s *pool = xpool;
 549         ldap_int_thread_ctx_t *ctx;
 550         ldap_int_thread_key_t ltc_key[MAXKEYS];
 551         ldap_pvt_thread_t tid;
 552         int i, keyslot, hash;
 553
 554         if (pool == NULL)
 555                 return NULL;
 556
 557         for ( i=0; i<MAXKEYS; i++ ) {
 558                 ltc_key[i].ltk_key = NULL;
 559         }
 560
 561         tid = ldap_pvt_thread_self();
 562
 563         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 564
 565         /* store pointer to our keys */
 566         TID_HASH(tid, hash);
 567         for (i = hash & (LDAP_MAXTHR-1);
 568                                 !ldap_pvt_thread_equal(thread_keys[i].id, tid);
 569                                 i = (i+1) & (LDAP_MAXTHR-1));
 570         thread_keys[i].ctx = ltc_key;
 571         keyslot = i;
 572
 573         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 574                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 575                 if (ctx) {
 576                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 577                 } else {
 578                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 579                                 break;
 580                         if (pool->ltp_max_count > 0
 581                                 && pool->ltp_open_count > pool->ltp_max_count)
 582                         {
 583                                 /* too many threads running (can happen if the
 584                                  * maximum threads value is set during ongoing
 585                                  * operation using ldap_pvt_thread_pool_maxthreads)
 586                                  * so let this thread die.
 587                                  */
 588                                 break;
 589                         }
 590
 591                         /* we could check an idle timer here, and let the
 592                          * thread die if it has been inactive for a while.
 593                          * only die if there are other open threads (i.e.,
 594                          * always have at least one thread open).  the check
 595                          * should be like this:
 596                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 597                          *       check timer, leave thread (break;)
 598                          */
 599
 600                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING
 601                                 || pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING)
 602                         {
 603                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 604                         }
 605
 606                         continue;
 607                 }
 608
 609                 pool->ltp_pending_count--;
 610
 611                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 612                 pool->ltp_active_count++;
 613                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 614
 615                 ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
 616
 617 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 618                 ldap_lazy_sem_post( thread_pool_sem );
 619 #endif
 620                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 621                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 622                         ldap_int_thread_ctx_s, ltc_next.al);
 623                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 624                 pool->ltp_active_count--;
 625
 626                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 627                         if (pool->ltp_active_count < 2) {
 628                                 ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 629                         }
 630                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 631                 }
 632                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 633
 634                 ldap_pvt_thread_yield();
 635
 636                 /* if we use an idle timer, here's
 637                  * a good place to update it
 638                  */
 639
 640                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 641         }
 642
 643         for ( i=0; i<MAXKEYS && ltc_key[i].ltk_key; i++ ) {
 644                 if (ltc_key[i].ltk_free)
 645                         ltc_key[i].ltk_free(
 646                                 ltc_key[i].ltk_key,
 647                                 ltc_key[i].ltk_data );
 648         }
 649
 650         thread_keys[keyslot].ctx = NULL;
 651         thread_keys[keyslot].id = tid_zero;
 652
 653         pool->ltp_open_count--;
 654         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 655
 656         ldap_pvt_thread_exit(NULL);
 657         return(NULL);
 658 }
 659
 660 int
 661 ldap_pvt_thread_pool_pause (
 662         ldap_pvt_thread_pool_t *tpool )
 663 {
 664         struct ldap_int_thread_pool_s *pool;
 665
 666         if (tpool == NULL)
 667                 return(-1);
 668
 669         pool = *tpool;
 670
 671         if (pool == NULL)
 672                 return(0);
 673
 674         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 675
 676         /* If someone else has already requested a pause, we have to wait */
 677         while (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 678                 pool->ltp_pending_count++;
 679                 pool->ltp_active_count--;
 680                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 681                 pool->ltp_pending_count--;
 682                 pool->ltp_active_count++;
 683         }
 684         /* Wait for everyone else to finish */
 685         pool->ltp_state = LDAP_INT_THREAD_POOL_PAUSING;
 686         while (pool->ltp_active_count > 1) {
 687                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 688         }
 689         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 690         return(0);
 691 }
 692
 693 int
 694 ldap_pvt_thread_pool_resume (
 695         ldap_pvt_thread_pool_t *tpool )
 696 {
 697         struct ldap_int_thread_pool_s *pool;
 698
 699         if (tpool == NULL)
 700                 return(-1);
 701
 702         pool = *tpool;
 703
 704         if (pool == NULL)
 705                 return(0);
 706
 707         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 708
 709         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 710         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 711         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 712         return(0);
 713 }
 714
 715 int ldap_pvt_thread_pool_getkey(
 716         void *xctx,
 717         void *key,
 718         void **data,
 719         ldap_pvt_thread_pool_keyfree_t **kfree )
 720 {
 721         ldap_int_thread_key_t *ctx = xctx;
 722         int i;
 723
 724         if ( !ctx || !data ) return EINVAL;
 725
 726         for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++ ) {
 727                 if ( ctx[i].ltk_key == key ) {
 728                         *data = ctx[i].ltk_data;
 729                         if ( kfree ) *kfree = ctx[i].ltk_free;
 730                         return 0;
 731                 }
 732         }
 733         return ENOENT;
 734 }
 735
 736 int ldap_pvt_thread_pool_setkey(
 737         void *xctx,
 738         void *key,
 739         void *data,
 740         ldap_pvt_thread_pool_keyfree_t *kfree )
 741 {
 742         ldap_int_thread_key_t *ctx = xctx;
 743         int i;
 744
 745         if ( !ctx || !key ) return EINVAL;
 746
 747         for ( i=0; i<MAXKEYS; i++ ) {
 748                 if ( !ctx[i].ltk_key || ctx[i].ltk_key == key ) {
 749                         ctx[i].ltk_key = key;
 750                         ctx[i].ltk_data = data;
 751                         ctx[i].ltk_free = kfree;
 752                         return 0;
 753                 }
 754         }
 755         return ENOMEM;
 756 }
 757
 758 /* Free all elements with this key, no matter which thread they're in.
 759  * May only be called while the pool is paused.
 760  */
 761 void ldap_pvt_thread_pool_purgekey( void *key )
 762 {
 763         int i, j;
 764         ldap_int_thread_key_t *ctx;
 765
 766         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 767                 if ( thread_keys[i].ctx ) {
 768                         ctx = thread_keys[i].ctx;
 769                         for ( j=0; j<MAXKEYS; j++ ) {
 770                                 if ( ctx[j].ltk_key == key ) {
 771                                         if (ctx[j].ltk_free)
 772                                                 ctx[j].ltk_free( ctx[j].ltk_key, ctx[j].ltk_data );
 773                                         ctx[j].ltk_key = NULL;
 774                                         ctx[j].ltk_free = NULL;
 775                                         break;
 776                                 }
 777                         }
 778                 }
 779         }
 780 }
 781
 782 /*
 783  * This is necessary if the caller does not have access to the
 784  * thread context handle (for example, a slapd plugin calling
 785  * slapi_search_internal()). No doubt it is more efficient to
 786  * for the application to keep track of the thread context
 787  * handles itself.
 788  */
 789 void *ldap_pvt_thread_pool_context( )
 790 {
 791         ldap_pvt_thread_t tid;
 792         int i, hash;
 793
 794         tid = ldap_pvt_thread_self();
 795         if ( ldap_pvt_thread_equal( tid, ldap_int_main_tid ))
 796                 return ldap_int_main_thrctx;
 797
 798         TID_HASH( tid, hash );
 799         for (i = hash & (LDAP_MAXTHR-1);
 800                 !ldap_pvt_thread_equal(thread_keys[i].id, tid_zero) &&
 801                 !ldap_pvt_thread_equal(thread_keys[i].id, tid);
 802                 i = (i+1) & (LDAP_MAXTHR-1));
 803
 804         return thread_keys[i].ctx;
 805 }
 806
 807 void ldap_pvt_thread_pool_context_reset( void *vctx )
 808 {
 809         ldap_int_thread_key_t *ctx = vctx;
 810         int i;
 811
 812         for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++) {
 813                 if ( ctx[i].ltk_free )
 814                         ctx[i].ltk_free( ctx[i].ltk_key, ctx[i].ltk_data );
 815                 ctx[i].ltk_key = NULL;
 816         }
 817 }
 818 #endif /* LDAP_THREAD_HAVE_TPOOL */