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

   1 /* $OpenLDAP$ */
   2 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   3  *
   4  * Copyright 1998-2007 The OpenLDAP Foundation.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted only as authorized by the OpenLDAP
   9  * Public License.
  10  *
  11  * A copy of this license is available in file LICENSE in the
  12  * top-level directory of the distribution or, alternatively, at
  13  * <http://www.OpenLDAP.org/license.html>.
  14  */
  15
  16 #include "portable.h"
  17
  18 #include <stdio.h>
  19
  20 #include <ac/stdarg.h>
  21 #include <ac/stdlib.h>
  22 #include <ac/string.h>
  23 #include <ac/time.h>
  24 #include <ac/errno.h>
  25
  26 #include "ldap-int.h"
  27 #include "ldap_pvt_thread.h" /* Get the thread interface */
  28 #include "ldap_queue.h"
  29 #define LDAP_THREAD_POOL_IMPLEMENTATION
  30 #include "ldap_thr_debug.h"  /* May rename symbols defined below */
  31
  32 #ifndef LDAP_THREAD_HAVE_TPOOL
  33
  34 typedef enum ldap_int_thread_pool_state_e {
  35         LDAP_INT_THREAD_POOL_RUNNING,
  36         LDAP_INT_THREAD_POOL_FINISHING,
  37         LDAP_INT_THREAD_POOL_STOPPING,
  38         LDAP_INT_THREAD_POOL_PAUSING
  39 } ldap_int_thread_pool_state_t;
  40
  41 typedef struct ldap_int_thread_key_s {
  42         void *ltk_key;
  43         void *ltk_data;
  44         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  45 } ldap_int_thread_key_t;
  46
  47 /* Max number of thread-specific keys we store per thread.
  48  * We don't expect to use many...
  49  */
  50 #define MAXKEYS 32
  51 #define LDAP_MAXTHR     1024    /* must be a power of 2 */
  52
  53 typedef struct ldap_int_thread_userctx_s {
  54         ldap_pvt_thread_t ltu_id;
  55         ldap_int_thread_key_t ltu_key[MAXKEYS];
  56 } ldap_int_thread_userctx_t;
  57
  58 static ldap_pvt_thread_t tid_zero;
  59
  60 static struct {
  61         ldap_pvt_thread_t id;
  62         ldap_int_thread_userctx_t *ctx;
  63 } thread_keys[LDAP_MAXTHR];
  64
  65
  66 typedef struct ldap_int_thread_ctx_s {
  67         union {
  68         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  69         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  70         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  71         } ltc_next;
  72         ldap_pvt_thread_start_t *ltc_start_routine;
  73         void *ltc_arg;
  74 } ldap_int_thread_ctx_t;
  75
  76 struct ldap_int_thread_pool_s {
  77         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  78         ldap_pvt_thread_mutex_t ltp_mutex;
  79         ldap_pvt_thread_cond_t ltp_cond;
  80         ldap_pvt_thread_cond_t ltp_pcond;
  81         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  82         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  83         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  84         ldap_int_thread_pool_state_t ltp_state;
  85         long ltp_max_count;
  86         long ltp_max_pending;
  87         long ltp_pending_count;
  88         long ltp_active_count;
  89         long ltp_open_count;
  90         long ltp_starting;
  91 };
  92
  93 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  94         ldap_int_thread_pool_list =
  95         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  96
  97 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  98
  99 static void *ldap_int_thread_pool_wrapper( void *pool );
 100
 101 static ldap_pvt_thread_t ldap_int_main_tid;
 102
 103 static ldap_int_thread_userctx_t ldap_int_main_thrctx;
 104
 105 int
 106 ldap_int_thread_pool_startup ( void )
 107 {
 108         ldap_int_main_tid = ldap_pvt_thread_self();
 109         ldap_int_main_thrctx.ltu_id = ldap_int_main_tid;
 110
 111         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 112 }
 113
 114 int
 115 ldap_int_thread_pool_shutdown ( void )
 116 {
 117         struct ldap_int_thread_pool_s *pool;
 118
 119         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 120                 (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
 121         }
 122         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 123         return(0);
 124 }
 125
 126 typedef struct ldap_lazy_sem_t {
 127         ldap_pvt_thread_mutex_t ls_mutex;
 128         ldap_pvt_thread_cond_t  ls_cond;
 129         int ls_sem_value;
 130         /*
 131          * when more than ls_lazy_count number of resources
 132          * becmoes available, the thread wating for the resources will
 133          * be waken up in order to prevent frequent blocking/waking-up
 134          */
 135         unsigned int ls_lazy_count;
 136         /*
 137          * only one thread(listener) will wait on this semaphore
 138          * using a flag instead of a list
 139          */
 140         int ls_wait;
 141 } ldap_lazy_sem_t;
 142
 143 ldap_lazy_sem_t* thread_pool_sem = NULL;
 144
 145 int
 146 ldap_lazy_sem_init( unsigned int value, unsigned int lazyness )
 147 {
 148         thread_pool_sem = (ldap_lazy_sem_t*) LDAP_CALLOC(1,
 149                 sizeof( ldap_lazy_sem_t ));
 150
 151         if( thread_pool_sem == NULL ) return -1;
 152
 153         ldap_pvt_thread_mutex_init( &thread_pool_sem->ls_mutex );
 154         ldap_pvt_thread_cond_init( &thread_pool_sem->ls_cond );
 155         thread_pool_sem->ls_sem_value = value;
 156         thread_pool_sem->ls_lazy_count = lazyness;
 157         thread_pool_sem->ls_wait = 0;
 158
 159         return 0;
 160 }
 161
 162 /* FIXME: move to some approprite header */
 163 int ldap_lazy_sem_dec( ldap_lazy_sem_t* ls );
 164 int ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls );
 165
 166 /*
 167  * ldap_lazy_sem_wait is used if a caller is blockable(listener).
 168  * Otherwise use ldap_lazy_sem_dec (worker)
 169  */
 170 int
 171 ldap_lazy_sem_op_submit( ldap_lazy_sem_t* ls )
 172 {
 173         if ( ls == NULL ) return -1;
 174
 175         /* only worker thread has its thread ctx */
 176         if ( ldap_pvt_thread_pool_context() ) {
 177                 /* worker thread */
 178                 return ldap_lazy_sem_dec( ls );
 179         } else {
 180                 /* listener */
 181                 return ldap_lazy_sem_wait( ls );
 182         }
 183 }
 184
 185 /*
 186  * test if given semaphore's count is zero.
 187  * If 0, the caller is blocked
 188  * If not, the count is decremented.
 189  */
 190 int
 191 ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls )
 192 {
 193         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 194
 195 lazy_sem_retry:
 196         if ( ls->ls_sem_value <= 0 ) {
 197                 /* no more avaliable resources */
 198                 ls->ls_wait = 1;
 199                 ldap_pvt_thread_cond_wait( &ls->ls_cond, &ls->ls_mutex );
 200                 goto lazy_sem_retry;
 201         } else {
 202                 /* avaliable resources */
 203                 ls->ls_sem_value--;
 204         }
 205
 206         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 207
 208         return 0;
 209 }
 210
 211 /*
 212  * decrement the count without blocking
 213  * even when the count becomes less than or equal to 0
 214  */
 215 int
 216 ldap_lazy_sem_dec( ldap_lazy_sem_t* ls )
 217 {
 218         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 219
 220         ls->ls_sem_value--;
 221
 222         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 223
 224         return 0;
 225 }
 226
 227 /*
 228  * Increment the count by one and test if it is greater or
 229  * equal to lazyness. If it is, wake up a blocked thread.
 230  */
 231 int
 232 ldap_lazy_sem_post( ldap_lazy_sem_t* ls )
 233 {
 234         if( ls == NULL ) return (-1);
 235
 236         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 237
 238         ls->ls_sem_value++;
 239         if ( ls->ls_wait ) {
 240                 if ( ls->ls_sem_value >= ls->ls_lazy_count ) {
 241                         ls->ls_wait = 0;
 242                         ldap_pvt_thread_cond_signal( &ls->ls_cond );
 243                 }
 244         }
 245
 246         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 247
 248         return 0;
 249 }
 250
 251 int
 252 ldap_pvt_thread_pool_init (
 253         ldap_pvt_thread_pool_t *tpool,
 254         int max_threads,
 255         int max_pending )
 256 {
 257         ldap_pvt_thread_pool_t pool;
 258         int rc;
 259
 260         *tpool = NULL;
 261         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 262                 sizeof(struct ldap_int_thread_pool_s));
 263
 264         if (pool == NULL) return(-1);
 265
 266         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 267         if (rc != 0)
 268                 return(rc);
 269         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 270         if (rc != 0)
 271                 return(rc);
 272         rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
 273         if (rc != 0)
 274                 return(rc);
 275         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 276         pool->ltp_max_count = max_threads;
 277         pool->ltp_max_pending = max_pending;
 278         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 279         LDAP_SLIST_INIT(&pool->ltp_free_list);
 280         LDAP_SLIST_INIT(&pool->ltp_active_list);
 281         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 282         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 283         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 284
 285 #if 0
 286         /* THIS WILL NOT WORK on some systems.  If the process
 287          * forks after starting a thread, there is no guarantee
 288          * that the thread will survive the fork.  For example,
 289          * slapd forks in order to daemonize, and does so after
 290          * calling ldap_pvt_thread_pool_init.  On some systems,
 291          * this initial thread does not run in the child process,
 292          * but ltp_open_count == 1, so two things happen:
 293          * 1) the first client connection fails, and 2) when
 294          * slapd is kill'ed, it never terminates since it waits
 295          * for all worker threads to exit. */
 296
 297         /* start up one thread, just so there is one. no need to
 298          * lock the mutex right now, since no threads are running.
 299          */
 300         pool->ltp_open_count++;
 301
 302         ldap_pvt_thread_t thr;
 303         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 304
 305         if( rc != 0) {
 306                 /* couldn't start one?  then don't start any */
 307                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 308                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 309                         ldap_int_thread_pool_s, ltp_next);
 310                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 311                 ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 312                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 313                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 314                 LDAP_FREE(pool);
 315                 return(-1);
 316         }
 317 #endif
 318
 319         *tpool = pool;
 320         return(0);
 321 }
 322
 323 #define TID_HASH(tid, hash) do { unsigned i; \
 324         unsigned char *ptr = (unsigned char *)&(tid); \
 325         for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
 326
 327 int
 328 ldap_pvt_thread_pool_submit (
 329         ldap_pvt_thread_pool_t *tpool,
 330         ldap_pvt_thread_start_t *start_routine, void *arg )
 331 {
 332         struct ldap_int_thread_pool_s *pool;
 333         ldap_int_thread_ctx_t *ctx;
 334         int need_thread = 0;
 335         ldap_pvt_thread_t thr;
 336
 337         if (tpool == NULL)
 338                 return(-1);
 339
 340         pool = *tpool;
 341
 342         if (pool == NULL)
 343                 return(-1);
 344
 345         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 346         if ((pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING &&
 347                 pool->ltp_state != LDAP_INT_THREAD_POOL_PAUSING)
 348                 || (pool->ltp_max_pending > 0
 349                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 350         {
 351                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 352                 return(-1);
 353         }
 354         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 355         if (ctx) {
 356                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 357         } else {
 358                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 359                         sizeof(ldap_int_thread_ctx_t));
 360                 if (ctx == NULL) {
 361                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 362                         return(-1);
 363                 }
 364         }
 365
 366         ctx->ltc_start_routine = start_routine;
 367         ctx->ltc_arg = arg;
 368
 369         pool->ltp_pending_count++;
 370         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 371         if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 372                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 373                 return(0);
 374         }
 375         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 376         if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
 377                 && (pool->ltp_open_count < pool->ltp_max_count ||
 378                         pool->ltp_max_count <= 0 ))
 379         {
 380                 pool->ltp_open_count++;
 381                 pool->ltp_starting++;
 382                 need_thread = 1;
 383         }
 384         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 385
 386 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 387         ldap_lazy_sem_op_submit( thread_pool_sem );
 388 #endif
 389
 390         if (need_thread) {
 391                 int rc;
 392
 393                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 394
 395                 rc = ldap_pvt_thread_create( &thr, 1,
 396                         ldap_int_thread_pool_wrapper, pool );
 397                 if (rc == 0) {
 398                         int hash;
 399                         pool->ltp_starting--;
 400
 401                         /* assign this thread ID to a key slot; start
 402                          * at the thread ID itself (mod LDAP_MAXTHR) and
 403                          * look for an empty slot.
 404                          */
 405                         TID_HASH(thr, hash);
 406                         for (rc = hash & (LDAP_MAXTHR-1);
 407                                 !ldap_pvt_thread_equal(thread_keys[rc].id, tid_zero);
 408                                 rc = (rc+1) & (LDAP_MAXTHR-1));
 409                         thread_keys[rc].id = thr;
 410                 } else {
 411                         /* couldn't create thread.  back out of
 412                          * ltp_open_count and check for even worse things.
 413                          */
 414                         pool->ltp_open_count--;
 415                         pool->ltp_starting--;
 416                         if (pool->ltp_open_count == 0) {
 417                                 /* no open threads at all?!?
 418                                  */
 419                                 ldap_int_thread_ctx_t *ptr;
 420
 421                                 /* let pool_destroy know there are no more threads */
 422                                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 423
 424                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 425                                         if (ptr == ctx) break;
 426                                 if (ptr == ctx) {
 427                                         /* no open threads, context not handled, so
 428                                          * back out of ltp_pending_count, free the context,
 429                                          * report the error.
 430                                          */
 431                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 432                                                 ldap_int_thread_ctx_s, ltc_next.q);
 433                                         pool->ltp_pending_count--;
 434                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 435                                         LDAP_FREE(ctx);
 436                                         return(-1);
 437                                 }
 438                         }
 439                         /* there is another open thread, so this
 440                          * context will be handled eventually.
 441                          * continue on and signal that the context
 442                          * is waiting.
 443                          */
 444                 }
 445                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 446         }
 447
 448         return(0);
 449 }
 450
 451 int
 452 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 453 {
 454         struct ldap_int_thread_pool_s *pool;
 455
 456         if (tpool == NULL)
 457                 return(-1);
 458
 459         pool = *tpool;
 460
 461         if (pool == NULL)
 462                 return(-1);
 463
 464         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 465         pool->ltp_max_count = max_threads;
 466         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 467         return(0);
 468 }
 469
 470 int
 471 ldap_pvt_thread_pool_query ( ldap_pvt_thread_pool_t *tpool, ldap_pvt_thread_pool_param_t param, void *value )
 472 {
 473         struct ldap_int_thread_pool_s   *pool;
 474         int                             count = -1;
 475
 476         if ( tpool == NULL || value == NULL ) {
 477                 return -1;
 478         }
 479
 480         pool = *tpool;
 481
 482         if ( pool == NULL ) {
 483                 return 0;
 484         }
 485
 486         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 487         switch ( param ) {
 488         case LDAP_PVT_THREAD_POOL_PARAM_MAX:
 489                 count = pool->ltp_max_count;
 490                 break;
 491
 492         case LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING:
 493                 count = pool->ltp_max_pending;
 494                 break;
 495
 496         case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
 497                 count = pool->ltp_open_count;
 498                 break;
 499
 500         case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
 501                 count = pool->ltp_starting;
 502                 break;
 503
 504         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
 505                 count = pool->ltp_active_count;
 506                 break;
 507
 508         case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
 509                 count = pool->ltp_pending_count;
 510                 break;
 511
 512         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
 513                 count = pool->ltp_pending_count + pool->ltp_active_count;
 514                 break;
 515
 516         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX:
 517                 break;
 518
 519         case LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX:
 520                 break;
 521
 522         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX:
 523                 break;
 524
 525         case LDAP_PVT_THREAD_POOL_PARAM_STATE: {
 526                 static struct {
 527                         char                            *name;
 528                         ldap_int_thread_pool_state_t    state;
 529                 }               str2state[] = {
 530                         { "running",    LDAP_INT_THREAD_POOL_RUNNING },
 531                         { "finishing",  LDAP_INT_THREAD_POOL_FINISHING },
 532                         { "stopping",   LDAP_INT_THREAD_POOL_STOPPING },
 533                         { "pausing",    LDAP_INT_THREAD_POOL_PAUSING },
 534                         { NULL }
 535                 };
 536                 int             i;
 537
 538                 for ( i = 0; str2state[ i ].name != NULL; i++ ) {
 539                         if ( str2state[ i ].state == pool->ltp_state ) {
 540                                 break;
 541                         }
 542                 }
 543                 *((char **)value) = str2state[ i ].name;
 544                 if ( str2state[ i ].name != NULL ) {
 545                         count = -2;
 546                 }
 547                 } break;
 548         }
 549         ldap_pvt_thread_mutex_unlock( &pool->ltp_mutex );
 550
 551         if ( count > -1 ) {
 552                 *((int *)value) = count;
 553         }
 554
 555         return ( count == -1 ? -1 : 0 );
 556 }
 557
 558 /*
 559  * wrapper for ldap_pvt_thread_pool_query(), left around
 560  * for backwards compatibility
 561  */
 562 int
 563 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 564 {
 565         int     rc, count;
 566
 567         rc = ldap_pvt_thread_pool_query( tpool,
 568                 LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD, (void *)&count );
 569
 570         if ( rc == 0 ) {
 571                 return count;
 572         }
 573
 574         return rc;
 575 }
 576
 577 int
 578 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 579 {
 580         struct ldap_int_thread_pool_s *pool, *pptr;
 581         ldap_int_thread_ctx_t *ctx;
 582
 583         if (tpool == NULL)
 584                 return(-1);
 585
 586         pool = *tpool;
 587
 588         if (pool == NULL) return(-1);
 589
 590         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 591         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 592                 if (pptr == pool) break;
 593         if (pptr == pool)
 594                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 595                         ldap_int_thread_pool_s, ltp_next);
 596         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 597
 598         if (pool != pptr) return(-1);
 599
 600         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 601         pool->ltp_state = run_pending
 602                 ? LDAP_INT_THREAD_POOL_FINISHING
 603                 : LDAP_INT_THREAD_POOL_STOPPING;
 604
 605         if ( pool->ltp_open_count ) {
 606                 ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 607                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 608         }
 609         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 610
 611         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 612         {
 613                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 614                 LDAP_FREE(ctx);
 615         }
 616
 617         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 618         {
 619                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 620                 LDAP_FREE(ctx);
 621         }
 622
 623         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 624         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 625         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 626         LDAP_FREE(pool);
 627 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 628         if ( thread_pool_sem ) {
 629                 LDAP_FREE( thread_pool_sem );
 630         }
 631 #endif
 632         return(0);
 633 }
 634
 635 static void *
 636 ldap_int_thread_pool_wrapper (
 637         void *xpool )
 638 {
 639         struct ldap_int_thread_pool_s *pool = xpool;
 640         ldap_int_thread_ctx_t *ctx;
 641         ldap_int_thread_userctx_t uctx;
 642         int i, keyslot, hash;
 643
 644         if (pool == NULL)
 645                 return NULL;
 646
 647         for ( i=0; i<MAXKEYS; i++ ) {
 648                 uctx.ltu_key[i].ltk_key = NULL;
 649         }
 650
 651         uctx.ltu_id = ldap_pvt_thread_self();
 652
 653         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 654
 655         /* store pointer to our keys */
 656         TID_HASH(uctx.ltu_id, hash);
 657         for (i = hash & (LDAP_MAXTHR-1);
 658                                 !ldap_pvt_thread_equal(thread_keys[i].id, uctx.ltu_id);
 659                                 i = (i+1) & (LDAP_MAXTHR-1));
 660         thread_keys[i].ctx = &uctx;
 661         keyslot = i;
 662
 663         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 664                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 665                 if (ctx) {
 666                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 667                 } else {
 668                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 669                                 break;
 670                         if (pool->ltp_max_count > 0
 671                                 && pool->ltp_open_count > pool->ltp_max_count)
 672                         {
 673                                 /* too many threads running (can happen if the
 674                                  * maximum threads value is set during ongoing
 675                                  * operation using ldap_pvt_thread_pool_maxthreads)
 676                                  * so let this thread die.
 677                                  */
 678                                 break;
 679                         }
 680
 681                         /* we could check an idle timer here, and let the
 682                          * thread die if it has been inactive for a while.
 683                          * only die if there are other open threads (i.e.,
 684                          * always have at least one thread open).  the check
 685                          * should be like this:
 686                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 687                          *       check timer, leave thread (break;)
 688                          *
 689                          * Just use pthread_cond_timedwait if we want to
 690                          * check idle time.
 691                          */
 692
 693                         assert(pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING
 694                                    || pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING);
 695                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 696                         continue;
 697                 }
 698
 699                 pool->ltp_pending_count--;
 700
 701                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 702                 pool->ltp_active_count++;
 703                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 704
 705                 ctx->ltc_start_routine(&uctx, ctx->ltc_arg);
 706
 707 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 708                 ldap_lazy_sem_post( thread_pool_sem );
 709 #endif
 710                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 711                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 712                         ldap_int_thread_ctx_s, ltc_next.al);
 713                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 714                 pool->ltp_active_count--;
 715
 716                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 717                         if (pool->ltp_active_count < 2) {
 718                                 ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 719                         }
 720                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 721                 }
 722         }
 723
 724         ldap_pvt_thread_pool_context_reset(&uctx);
 725
 726         thread_keys[keyslot].ctx = NULL;
 727         thread_keys[keyslot].id = tid_zero;
 728
 729         pool->ltp_open_count--;
 730
 731         /* let pool_destroy know we're all done */
 732         if (pool->ltp_open_count < 1)
 733                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 734
 735         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 736
 737         ldap_pvt_thread_exit(NULL);
 738         return(NULL);
 739 }
 740
 741 int
 742 ldap_pvt_thread_pool_pause (
 743         ldap_pvt_thread_pool_t *tpool )
 744 {
 745         struct ldap_int_thread_pool_s *pool;
 746
 747         if (tpool == NULL)
 748                 return(-1);
 749
 750         pool = *tpool;
 751
 752         if (pool == NULL)
 753                 return(0);
 754
 755         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 756
 757         /* If someone else has already requested a pause, we have to wait */
 758         while (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
 759                 pool->ltp_pending_count++;
 760                 pool->ltp_active_count--;
 761                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 762                 pool->ltp_pending_count--;
 763                 pool->ltp_active_count++;
 764         }
 765         /* Wait for everyone else to finish */
 766         pool->ltp_state = LDAP_INT_THREAD_POOL_PAUSING;
 767         while (pool->ltp_active_count > 1) {
 768                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 769         }
 770         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 771         return(0);
 772 }
 773
 774 int
 775 ldap_pvt_thread_pool_resume (
 776         ldap_pvt_thread_pool_t *tpool )
 777 {
 778         struct ldap_int_thread_pool_s *pool;
 779
 780         if (tpool == NULL)
 781                 return(-1);
 782
 783         pool = *tpool;
 784
 785         if (pool == NULL)
 786                 return(0);
 787
 788         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 789
 790         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 791         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 792         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 793         return(0);
 794 }
 795
 796 int ldap_pvt_thread_pool_getkey(
 797         void *xctx,
 798         void *key,
 799         void **data,
 800         ldap_pvt_thread_pool_keyfree_t **kfree )
 801 {
 802         ldap_int_thread_userctx_t *ctx = xctx;
 803         int i;
 804
 805         if ( !ctx || !data ) return EINVAL;
 806
 807         for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) {
 808                 if ( ctx->ltu_key[i].ltk_key == key ) {
 809                         *data = ctx->ltu_key[i].ltk_data;
 810                         if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free;
 811                         return 0;
 812                 }
 813         }
 814         return ENOENT;
 815 }
 816
 817 int ldap_pvt_thread_pool_setkey(
 818         void *xctx,
 819         void *key,
 820         void *data,
 821         ldap_pvt_thread_pool_keyfree_t *kfree )
 822 {
 823         ldap_int_thread_userctx_t *ctx = xctx;
 824         int i;
 825
 826         if ( !ctx || !key ) return EINVAL;
 827
 828         for ( i=0; i<MAXKEYS; i++ ) {
 829                 if (( data && !ctx->ltu_key[i].ltk_key ) || ctx->ltu_key[i].ltk_key == key ) {
 830                         if ( data || kfree ) {
 831                                 ctx->ltu_key[i].ltk_key = key;
 832                                 ctx->ltu_key[i].ltk_data = data;
 833                                 ctx->ltu_key[i].ltk_free = kfree;
 834                         } else {
 835                                 int j;
 836                                 for ( j=i+1; j<MAXKEYS; j++ )
 837                                         if ( !ctx->ltu_key[j].ltk_key ) break;
 838                                 j--;
 839                                 if ( j != i ) {
 840                                         ctx->ltu_key[i].ltk_key = ctx->ltu_key[j].ltk_key;
 841                                         ctx->ltu_key[i].ltk_data = ctx->ltu_key[j].ltk_data;
 842                                         ctx->ltu_key[i].ltk_free = ctx->ltu_key[j].ltk_free;
 843                                 }
 844                                 ctx->ltu_key[j].ltk_key = NULL;
 845                                 ctx->ltu_key[j].ltk_data = NULL;
 846                                 ctx->ltu_key[j].ltk_free = NULL;
 847                         }
 848                         return 0;
 849                 }
 850         }
 851         return ENOMEM;
 852 }
 853
 854 /* Free all elements with this key, no matter which thread they're in.
 855  * May only be called while the pool is paused.
 856  */
 857 void ldap_pvt_thread_pool_purgekey( void *key )
 858 {
 859         int i, j;
 860         ldap_int_thread_userctx_t *ctx;
 861
 862         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 863                 if ( thread_keys[i].ctx ) {
 864                         ctx = thread_keys[i].ctx;
 865                         for ( j=0; j<MAXKEYS; j++ ) {
 866                                 if ( ctx->ltu_key[j].ltk_key == key ) {
 867                                         if (ctx->ltu_key[j].ltk_free)
 868                                                 ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key,
 869                                                 ctx->ltu_key[j].ltk_data );
 870                                         ctx->ltu_key[j].ltk_key = NULL;
 871                                         ctx->ltu_key[j].ltk_free = NULL;
 872                                         break;
 873                                 }
 874                         }
 875                 }
 876         }
 877 }
 878
 879 /*
 880  * This is necessary if the caller does not have access to the
 881  * thread context handle (for example, a slapd plugin calling
 882  * slapi_search_internal()). No doubt it is more efficient
 883  * for the application to keep track of the thread context
 884  * handles itself.
 885  */
 886 void *ldap_pvt_thread_pool_context( )
 887 {
 888         ldap_pvt_thread_t tid;
 889         int i, hash;
 890
 891         tid = ldap_pvt_thread_self();
 892         if ( ldap_pvt_thread_equal( tid, ldap_int_main_tid ))
 893                 return &ldap_int_main_thrctx;
 894
 895         TID_HASH( tid, hash );
 896         for (i = hash & (LDAP_MAXTHR-1);
 897                 !ldap_pvt_thread_equal(thread_keys[i].id, tid_zero) &&
 898                 !ldap_pvt_thread_equal(thread_keys[i].id, tid);
 899                 i = (i+1) & (LDAP_MAXTHR-1));
 900
 901         return thread_keys[i].ctx;
 902 }
 903
 904 void ldap_pvt_thread_pool_context_reset( void *vctx )
 905 {
 906         ldap_int_thread_userctx_t *ctx = vctx;
 907         int i;
 908
 909         for ( i=MAXKEYS-1; i>=0; i--) {
 910                 if ( !ctx->ltu_key[i].ltk_key )
 911                         continue;
 912                 if ( ctx->ltu_key[i].ltk_free )
 913                         ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key,
 914                         ctx->ltu_key[i].ltk_data );
 915                 ctx->ltu_key[i].ltk_key = NULL;
 916         }
 917 }
 918
 919 ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx )
 920 {
 921         ldap_int_thread_userctx_t *ctx = vctx;
 922
 923         return ctx->ltu_id;
 924 }
 925 #endif /* LDAP_THREAD_HAVE_TPOOL */