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

   1 /* $OpenLDAP$ */
   2 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   3  *
   4  * Copyright 1998-2007 The OpenLDAP Foundation.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted only as authorized by the OpenLDAP
   9  * Public License.
  10  *
  11  * A copy of this license is available in file LICENSE in the
  12  * top-level directory of the distribution or, alternatively, at
  13  * <http://www.OpenLDAP.org/license.html>.
  14  */
  15
  16 #include "portable.h"
  17
  18 #include <stdio.h>
  19
  20 #include <ac/stdarg.h>
  21 #include <ac/stdlib.h>
  22 #include <ac/string.h>
  23 #include <ac/time.h>
  24 #include <ac/errno.h>
  25
  26 #include "ldap-int.h"
  27 #include "ldap_pvt_thread.h" /* Get the thread interface */
  28 #include "ldap_queue.h"
  29 #define LDAP_THREAD_POOL_IMPLEMENTATION
  30 #include "ldap_thr_debug.h"  /* May rename symbols defined below */
  31
  32 #ifndef LDAP_THREAD_HAVE_TPOOL
  33
  34 typedef enum ldap_int_thread_pool_state_e {
  35         LDAP_INT_THREAD_POOL_RUNNING,
  36         LDAP_INT_THREAD_POOL_FINISHING,
  37         LDAP_INT_THREAD_POOL_STOPPING
  38 } ldap_int_thread_pool_state_t;
  39
  40 typedef struct ldap_int_thread_key_s {
  41         void *ltk_key;
  42         void *ltk_data;
  43         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  44 } ldap_int_thread_key_t;
  45
  46 /* Max number of thread-specific keys we store per thread.
  47  * We don't expect to use many...
  48  */
  49 #define MAXKEYS 32
  50 #define LDAP_MAXTHR     1024    /* must be a power of 2 */
  51
  52 typedef struct ldap_int_thread_userctx_s {
  53         ldap_pvt_thread_t ltu_id;
  54         ldap_int_thread_key_t ltu_key[MAXKEYS];
  55 } ldap_int_thread_userctx_t;
  56
  57 static ldap_pvt_thread_t tid_zero;
  58
  59 /* Thread ID -> context mapping (poor open-addressed hash table).
  60  * Protected by ldap_pvt_thread_pool_mutex except during pauses,
  61  * when it is read-only (used by pool_purgekey and pool_context).
  62  */
  63 static struct {
  64         ldap_pvt_thread_t id;
  65         ldap_int_thread_userctx_t *ctx;         /* set when id != tid_zero */
  66 #       define DELETED_THREAD_CTX (&ldap_int_main_thrctx + 1) /* dummy addr */
  67 } thread_keys[LDAP_MAXTHR];
  68
  69 #define TID_HASH(tid, hash) do { \
  70         unsigned const char *ptr_ = (unsigned const char *)&(tid); \
  71         unsigned i_; \
  72         for (i_ = 0, (hash) = ptr_[0]; ++i_ < sizeof(tid);) \
  73                 (hash) += ((hash) << 5) ^ ptr_[i_]; \
  74 } while(0)
  75
  76
  77 typedef struct ldap_int_thread_ctx_s {
  78         union {
  79         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  80         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  81         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  82         } ltc_next;
  83         ldap_pvt_thread_start_t *ltc_start_routine;
  84         void *ltc_arg;
  85 } ldap_int_thread_ctx_t;
  86
  87 struct ldap_int_thread_pool_s {
  88         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  89         ldap_pvt_thread_mutex_t ltp_mutex;
  90         ldap_pvt_thread_cond_t ltp_cond;
  91         ldap_pvt_thread_cond_t ltp_pcond;
  92         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  93         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  94         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  95         ldap_int_thread_pool_state_t ltp_state;
  96         int ltp_pause;
  97         long ltp_max_count;
  98         long ltp_max_pending;
  99         long ltp_pending_count;
 100         long ltp_active_count;
 101         long ltp_open_count;
 102         long ltp_starting;
 103 };
 104
 105 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
 106         ldap_int_thread_pool_list =
 107         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
 108
 109 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
 110
 111 static void *ldap_int_thread_pool_wrapper( void *pool );
 112
 113 static ldap_pvt_thread_t ldap_int_main_tid;
 114
 115 static ldap_int_thread_userctx_t ldap_int_main_thrctx;
 116
 117 int
 118 ldap_int_thread_pool_startup ( void )
 119 {
 120         ldap_int_main_tid = ldap_pvt_thread_self();
 121         ldap_int_main_thrctx.ltu_id = ldap_int_main_tid;
 122
 123         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
 124 }
 125
 126 int
 127 ldap_int_thread_pool_shutdown ( void )
 128 {
 129         struct ldap_int_thread_pool_s *pool;
 130
 131         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 132                 (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
 133         }
 134         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 135         return(0);
 136 }
 137
 138 typedef struct ldap_lazy_sem_t {
 139         ldap_pvt_thread_mutex_t ls_mutex;
 140         ldap_pvt_thread_cond_t  ls_cond;
 141         int ls_sem_value;
 142         /*
 143          * when more than ls_lazy_count number of resources
 144          * becmoes available, the thread wating for the resources will
 145          * be waken up in order to prevent frequent blocking/waking-up
 146          */
 147         unsigned int ls_lazy_count;
 148         /*
 149          * only one thread(listener) will wait on this semaphore
 150          * using a flag instead of a list
 151          */
 152         int ls_wait;
 153 } ldap_lazy_sem_t;
 154
 155 ldap_lazy_sem_t* thread_pool_sem = NULL;
 156
 157 int
 158 ldap_lazy_sem_init( unsigned int value, unsigned int lazyness )
 159 {
 160         thread_pool_sem = (ldap_lazy_sem_t*) LDAP_CALLOC(1,
 161                 sizeof( ldap_lazy_sem_t ));
 162
 163         if( thread_pool_sem == NULL ) return -1;
 164
 165         ldap_pvt_thread_mutex_init( &thread_pool_sem->ls_mutex );
 166         ldap_pvt_thread_cond_init( &thread_pool_sem->ls_cond );
 167         thread_pool_sem->ls_sem_value = value;
 168         thread_pool_sem->ls_lazy_count = lazyness;
 169         thread_pool_sem->ls_wait = 0;
 170
 171         return 0;
 172 }
 173
 174 /* FIXME: move to some approprite header */
 175 int ldap_lazy_sem_dec( ldap_lazy_sem_t* ls );
 176 int ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls );
 177
 178 /*
 179  * ldap_lazy_sem_wait is used if a caller is blockable(listener).
 180  * Otherwise use ldap_lazy_sem_dec (worker)
 181  */
 182 int
 183 ldap_lazy_sem_op_submit( ldap_lazy_sem_t* ls )
 184 {
 185         if ( ls == NULL ) return -1;
 186
 187         /* only worker thread has its thread ctx */
 188         if ( ldap_pvt_thread_pool_context() ) {
 189                 /* worker thread */
 190                 return ldap_lazy_sem_dec( ls );
 191         } else {
 192                 /* listener */
 193                 return ldap_lazy_sem_wait( ls );
 194         }
 195 }
 196
 197 /*
 198  * test if given semaphore's count is zero.
 199  * If 0, the caller is blocked
 200  * If not, the count is decremented.
 201  */
 202 int
 203 ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls )
 204 {
 205         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 206
 207 lazy_sem_retry:
 208         if ( ls->ls_sem_value <= 0 ) {
 209                 /* no more avaliable resources */
 210                 ls->ls_wait = 1;
 211                 ldap_pvt_thread_cond_wait( &ls->ls_cond, &ls->ls_mutex );
 212                 goto lazy_sem_retry;
 213         } else {
 214                 /* avaliable resources */
 215                 ls->ls_sem_value--;
 216         }
 217
 218         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 219
 220         return 0;
 221 }
 222
 223 /*
 224  * decrement the count without blocking
 225  * even when the count becomes less than or equal to 0
 226  */
 227 int
 228 ldap_lazy_sem_dec( ldap_lazy_sem_t* ls )
 229 {
 230         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 231
 232         ls->ls_sem_value--;
 233
 234         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 235
 236         return 0;
 237 }
 238
 239 /*
 240  * Increment the count by one and test if it is greater or
 241  * equal to lazyness. If it is, wake up a blocked thread.
 242  */
 243 int
 244 ldap_lazy_sem_post( ldap_lazy_sem_t* ls )
 245 {
 246         if( ls == NULL ) return (-1);
 247
 248         ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
 249
 250         ls->ls_sem_value++;
 251         if ( ls->ls_wait ) {
 252                 if ( ls->ls_sem_value >= ls->ls_lazy_count ) {
 253                         ls->ls_wait = 0;
 254                         ldap_pvt_thread_cond_signal( &ls->ls_cond );
 255                 }
 256         }
 257
 258         ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
 259
 260         return 0;
 261 }
 262
 263 int
 264 ldap_pvt_thread_pool_init (
 265         ldap_pvt_thread_pool_t *tpool,
 266         int max_threads,
 267         int max_pending )
 268 {
 269         ldap_pvt_thread_pool_t pool;
 270         int rc;
 271
 272         if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
 273                 max_threads = 0;
 274
 275         *tpool = NULL;
 276         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 277                 sizeof(struct ldap_int_thread_pool_s));
 278
 279         if (pool == NULL) return(-1);
 280
 281         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 282         if (rc != 0)
 283                 return(rc);
 284         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 285         if (rc != 0)
 286                 return(rc);
 287         rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
 288         if (rc != 0)
 289                 return(rc);
 290         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 291         pool->ltp_max_count = max_threads;
 292         pool->ltp_max_pending = max_pending;
 293         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 294         LDAP_SLIST_INIT(&pool->ltp_free_list);
 295         LDAP_SLIST_INIT(&pool->ltp_active_list);
 296         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 297         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 298         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 299
 300 #if 0
 301         /* THIS WILL NOT WORK on some systems.  If the process
 302          * forks after starting a thread, there is no guarantee
 303          * that the thread will survive the fork.  For example,
 304          * slapd forks in order to daemonize, and does so after
 305          * calling ldap_pvt_thread_pool_init.  On some systems,
 306          * this initial thread does not run in the child process,
 307          * but ltp_open_count == 1, so two things happen:
 308          * 1) the first client connection fails, and 2) when
 309          * slapd is kill'ed, it never terminates since it waits
 310          * for all worker threads to exit. */
 311
 312         /* start up one thread, just so there is one. no need to
 313          * lock the mutex right now, since no threads are running.
 314          */
 315         pool->ltp_open_count++;
 316
 317         ldap_pvt_thread_t thr;
 318         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 319
 320         if( rc != 0) {
 321                 /* couldn't start one?  then don't start any */
 322                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 323                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 324                         ldap_int_thread_pool_s, ltp_next);
 325                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 326                 ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 327                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 328                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 329                 LDAP_FREE(pool);
 330                 return(-1);
 331         }
 332 #endif
 333
 334         *tpool = pool;
 335         return(0);
 336 }
 337
 338
 339 int
 340 ldap_pvt_thread_pool_submit (
 341         ldap_pvt_thread_pool_t *tpool,
 342         ldap_pvt_thread_start_t *start_routine, void *arg )
 343 {
 344         struct ldap_int_thread_pool_s *pool;
 345         ldap_int_thread_ctx_t *ctx;
 346         int need_thread = 0;
 347         ldap_pvt_thread_t thr;
 348
 349         if (tpool == NULL)
 350                 return(-1);
 351
 352         pool = *tpool;
 353
 354         if (pool == NULL)
 355                 return(-1);
 356
 357         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 358         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 359                 || (pool->ltp_max_pending > 0
 360                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 361         {
 362                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 363                 return(-1);
 364         }
 365
 366         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 367         if (ctx) {
 368                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 369         } else {
 370                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 371                         sizeof(ldap_int_thread_ctx_t));
 372                 if (ctx == NULL) {
 373                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 374                         return(-1);
 375                 }
 376         }
 377
 378         ctx->ltc_start_routine = start_routine;
 379         ctx->ltc_arg = arg;
 380
 381         pool->ltp_pending_count++;
 382         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 383         if (pool->ltp_pause) {
 384                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 385                 return(0);
 386         }
 387         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 388         if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
 389                 && (pool->ltp_open_count <
 390                         (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR)))
 391         {
 392                 pool->ltp_open_count++;
 393                 pool->ltp_starting++;
 394                 need_thread = 1;
 395         }
 396
 397 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 398         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 399         ldap_lazy_sem_op_submit( thread_pool_sem );
 400         /* FIXME:  Another thread can now handle and release ctx, after
 401          * which a newly submitted op can reuse ctx.  Then it is wrong for
 402          * the "if (pool->ltp_open_count == 0)" code below to release ctx.
 403          */
 404 #endif
 405
 406         if (need_thread) {
 407                 if (0 != ldap_pvt_thread_create(
 408                         &thr, 1, ldap_int_thread_pool_wrapper, pool))
 409                 {
 410                         /* couldn't create thread.  back out of
 411                          * ltp_open_count and check for even worse things.
 412                          */
 413 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 414                         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 415 #endif
 416                         pool->ltp_starting--;
 417                         pool->ltp_open_count--;
 418                         if (pool->ltp_open_count == 0) {
 419                                 /* no open threads at all?!?
 420                                  */
 421                                 ldap_int_thread_ctx_t *ptr;
 422
 423                                 /* let pool_destroy know there are no more threads */
 424                                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 425
 426                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 427                                         if (ptr == ctx) break;
 428                                 if (ptr == ctx) {
 429                                         /* no open threads, context not handled, so
 430                                          * back out of ltp_pending_count, free the context,
 431                                          * report the error.
 432                                          */
 433                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 434                                                 ldap_int_thread_ctx_s, ltc_next.q);
 435                                         pool->ltp_pending_count--;
 436                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 437                                         LDAP_FREE(ctx);
 438                                         return(-1);
 439                                 }
 440                         }
 441 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 442                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 443 #endif
 444                         /* there is another open thread, so this
 445                          * context will be handled eventually.
 446                          * continue on, we have signalled that
 447                          * the context is waiting.
 448                          */
 449                 }
 450         }
 451
 452 #ifndef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 453         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 454 #endif
 455
 456         return(0);
 457 }
 458
 459 int
 460 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 461 {
 462         struct ldap_int_thread_pool_s *pool;
 463
 464         if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
 465                 max_threads = 0;
 466
 467         if (tpool == NULL)
 468                 return(-1);
 469
 470         pool = *tpool;
 471
 472         if (pool == NULL)
 473                 return(-1);
 474
 475         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 476         pool->ltp_max_count = max_threads;
 477         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 478         return(0);
 479 }
 480
 481 int
 482 ldap_pvt_thread_pool_query ( ldap_pvt_thread_pool_t *tpool, ldap_pvt_thread_pool_param_t param, void *value )
 483 {
 484         struct ldap_int_thread_pool_s   *pool;
 485         int                             count = -1;
 486
 487         if ( tpool == NULL || value == NULL ) {
 488                 return -1;
 489         }
 490
 491         pool = *tpool;
 492
 493         if ( pool == NULL ) {
 494                 return 0;
 495         }
 496
 497         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 498         switch ( param ) {
 499         case LDAP_PVT_THREAD_POOL_PARAM_MAX:
 500                 count = pool->ltp_max_count;
 501                 break;
 502
 503         case LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING:
 504                 count = pool->ltp_max_pending;
 505                 break;
 506
 507         case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
 508                 count = pool->ltp_open_count;
 509                 break;
 510
 511         case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
 512                 count = pool->ltp_starting;
 513                 break;
 514
 515         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
 516                 count = pool->ltp_active_count;
 517                 break;
 518
 519         case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
 520                 count = pool->ltp_pending_count;
 521                 break;
 522
 523         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
 524                 count = pool->ltp_pending_count + pool->ltp_active_count;
 525                 break;
 526
 527         case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX:
 528                 break;
 529
 530         case LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX:
 531                 break;
 532
 533         case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX:
 534                 break;
 535
 536         case LDAP_PVT_THREAD_POOL_PARAM_STATE: {
 537                 static struct {
 538                         char                            *name;
 539                         ldap_int_thread_pool_state_t    state;
 540                 }               str2state[] = {
 541                         { "running",    LDAP_INT_THREAD_POOL_RUNNING },
 542                         { "finishing",  LDAP_INT_THREAD_POOL_FINISHING },
 543                         { "stopping",   LDAP_INT_THREAD_POOL_STOPPING },
 544                         { NULL }
 545                 };
 546                 int             i;
 547
 548                 if ( pool->ltp_pause ) {
 549                         *((char **)value) = "pausing";
 550                 } else {
 551                         for ( i = 0; str2state[ i ].name != NULL; i++ ) {
 552                                 if ( str2state[ i ].state == pool->ltp_state ) {
 553                                         break;
 554                                 }
 555                         }
 556                         *((char **)value) = str2state[ i ].name;
 557                 }
 558                 if ( *((char **)value) != NULL ) {
 559                         count = -2;
 560                 }
 561                 } break;
 562         }
 563         ldap_pvt_thread_mutex_unlock( &pool->ltp_mutex );
 564
 565         if ( count > -1 ) {
 566                 *((int *)value) = count;
 567         }
 568
 569         return ( count == -1 ? -1 : 0 );
 570 }
 571
 572 /*
 573  * wrapper for ldap_pvt_thread_pool_query(), left around
 574  * for backwards compatibility
 575  */
 576 int
 577 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 578 {
 579         int     rc, count;
 580
 581         rc = ldap_pvt_thread_pool_query( tpool,
 582                 LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD, (void *)&count );
 583
 584         if ( rc == 0 ) {
 585                 return count;
 586         }
 587
 588         return rc;
 589 }
 590
 591 int
 592 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 593 {
 594         struct ldap_int_thread_pool_s *pool, *pptr;
 595         ldap_int_thread_ctx_t *ctx;
 596
 597         if (tpool == NULL)
 598                 return(-1);
 599
 600         pool = *tpool;
 601
 602         if (pool == NULL) return(-1);
 603
 604         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 605         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 606                 if (pptr == pool) break;
 607         if (pptr == pool)
 608                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 609                         ldap_int_thread_pool_s, ltp_next);
 610         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 611
 612         if (pool != pptr) return(-1);
 613
 614         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 615         pool->ltp_state = run_pending
 616                 ? LDAP_INT_THREAD_POOL_FINISHING
 617                 : LDAP_INT_THREAD_POOL_STOPPING;
 618
 619         while (pool->ltp_open_count) {
 620                 if (!pool->ltp_pause)
 621                         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 622                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 623         }
 624         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 625
 626         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 627         {
 628                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 629                 LDAP_FREE(ctx);
 630         }
 631
 632         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 633         {
 634                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 635                 LDAP_FREE(ctx);
 636         }
 637
 638         ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
 639         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 640         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 641         LDAP_FREE(pool);
 642 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 643         if ( thread_pool_sem ) {
 644                 LDAP_FREE( thread_pool_sem );
 645         }
 646 #endif
 647         return(0);
 648 }
 649
 650 static void *
 651 ldap_int_thread_pool_wrapper (
 652         void *xpool )
 653 {
 654         struct ldap_int_thread_pool_s *pool = xpool;
 655         ldap_int_thread_ctx_t *ctx;
 656         ldap_int_thread_userctx_t uctx;
 657         unsigned i, keyslot, hash;
 658
 659         if (pool == NULL)
 660                 return NULL;
 661
 662         for ( i=0; i<MAXKEYS; i++ ) {
 663                 uctx.ltu_key[i].ltk_key = NULL;
 664         }
 665
 666         uctx.ltu_id = ldap_pvt_thread_self();
 667         TID_HASH(uctx.ltu_id, hash);
 668
 669         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 670
 671         /* thread_keys[] is read-only when paused */
 672         while (pool->ltp_pause)
 673                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 674
 675         /* find a key slot to give this thread ID and store a
 676          * pointer to our keys there; start at the thread ID
 677          * itself (mod LDAP_MAXTHR) and look for an empty slot.
 678          */
 679         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 680         for (keyslot = hash & (LDAP_MAXTHR-1);
 681                 !ldap_pvt_thread_equal(thread_keys[keyslot].id, tid_zero);
 682                 keyslot = (keyslot+1) & (LDAP_MAXTHR-1));
 683         thread_keys[keyslot].id = uctx.ltu_id;
 684         thread_keys[keyslot].ctx = &uctx;
 685         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 686
 687         pool->ltp_starting--;
 688
 689         for (;;) {
 690                 while (pool->ltp_pause)
 691                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 692
 693                 if (pool->ltp_state == LDAP_INT_THREAD_POOL_STOPPING)
 694                         break;
 695
 696                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 697                 if (ctx == NULL) {
 698                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 699                                 break;
 700
 701                         if (pool->ltp_open_count >
 702                                 (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR))
 703                         {
 704                                 /* too many threads running (can happen if the
 705                                  * maximum threads value is set during ongoing
 706                                  * operation using ldap_pvt_thread_pool_maxthreads)
 707                                  * so let this thread die.
 708                                  */
 709                                 break;
 710                         }
 711
 712                         /* we could check an idle timer here, and let the
 713                          * thread die if it has been inactive for a while.
 714                          * only die if there are other open threads (i.e.,
 715                          * always have at least one thread open).  the check
 716                          * should be like this:
 717                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 718                          *       check timer, wait if ltp_pause, leave thread (break;)
 719                          *
 720                          * Just use pthread_cond_timedwait if we want to
 721                          * check idle time.
 722                          */
 723
 724                         assert(pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING);
 725                         ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 726                         continue;
 727                 }
 728
 729                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 730                 pool->ltp_pending_count--;
 731
 732                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 733                 pool->ltp_active_count++;
 734                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 735
 736                 ctx->ltc_start_routine(&uctx, ctx->ltc_arg);
 737
 738 #ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
 739                 ldap_lazy_sem_post( thread_pool_sem );
 740 #endif
 741                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 742                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 743                         ldap_int_thread_ctx_s, ltc_next.al);
 744                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 745                 pool->ltp_active_count--;
 746
 747                 /* let pool_pause know when it is the sole active thread */
 748                 if (pool->ltp_active_count < 2)
 749                         ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 750         }
 751
 752         ldap_pvt_thread_pool_context_reset(&uctx);
 753
 754         /* Needed if context_reset can let another thread request a pause */
 755         while (pool->ltp_pause)
 756                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 757
 758         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 759         thread_keys[keyslot].ctx = DELETED_THREAD_CTX;
 760         thread_keys[keyslot].id = tid_zero;
 761         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 762
 763         pool->ltp_open_count--;
 764
 765         /* let pool_destroy know we're all done */
 766         if (pool->ltp_open_count < 1)
 767                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 768
 769         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 770
 771         ldap_pvt_thread_exit(NULL);
 772         return(NULL);
 773 }
 774
 775 int
 776 ldap_pvt_thread_pool_pause (
 777         ldap_pvt_thread_pool_t *tpool )
 778 {
 779         struct ldap_int_thread_pool_s *pool;
 780
 781         if (tpool == NULL)
 782                 return(-1);
 783
 784         pool = *tpool;
 785
 786         if (pool == NULL)
 787                 return(0);
 788
 789         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 790
 791         /* If someone else has already requested a pause, we have to wait */
 792         while (pool->ltp_pause) {
 793                 pool->ltp_pending_count++;
 794                 pool->ltp_active_count--;
 795                 /* let the other pool_pause() know when it can proceed */
 796                 if (pool->ltp_active_count < 2)
 797                         ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
 798                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 799                 pool->ltp_pending_count--;
 800                 pool->ltp_active_count++;
 801         }
 802
 803         /* Wait for everyone else to pause or finish */
 804         pool->ltp_pause = 1;
 805         while (pool->ltp_active_count > 1) {
 806                 ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
 807         }
 808
 809         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 810         return(0);
 811 }
 812
 813 int
 814 ldap_pvt_thread_pool_resume (
 815         ldap_pvt_thread_pool_t *tpool )
 816 {
 817         struct ldap_int_thread_pool_s *pool;
 818
 819         if (tpool == NULL)
 820                 return(-1);
 821
 822         pool = *tpool;
 823
 824         if (pool == NULL)
 825                 return(0);
 826
 827         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 828         pool->ltp_pause = 0;
 829         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 830         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 831         return(0);
 832 }
 833
 834 int ldap_pvt_thread_pool_getkey(
 835         void *xctx,
 836         void *key,
 837         void **data,
 838         ldap_pvt_thread_pool_keyfree_t **kfree )
 839 {
 840         ldap_int_thread_userctx_t *ctx = xctx;
 841         int i;
 842
 843         if ( !ctx || !key || !data ) return EINVAL;
 844
 845         for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) {
 846                 if ( ctx->ltu_key[i].ltk_key == key ) {
 847                         *data = ctx->ltu_key[i].ltk_data;
 848                         if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free;
 849                         return 0;
 850                 }
 851         }
 852         return ENOENT;
 853 }
 854
 855 static void
 856 clear_key_idx( ldap_int_thread_userctx_t *ctx, int i )
 857 {
 858         for ( ; i < MAXKEYS-1 && ctx->ltu_key[i+1].ltk_key; i++ )
 859                 ctx->ltu_key[i] = ctx->ltu_key[i+1];
 860         ctx->ltu_key[i].ltk_key = NULL;
 861 }
 862
 863 int ldap_pvt_thread_pool_setkey(
 864         void *xctx,
 865         void *key,
 866         void *data,
 867         ldap_pvt_thread_pool_keyfree_t *kfree )
 868 {
 869         ldap_int_thread_userctx_t *ctx = xctx;
 870         int i, found;
 871
 872         if ( !ctx || !key ) return EINVAL;
 873
 874         for ( i=found=0; i<MAXKEYS; i++ ) {
 875                 if ( ctx->ltu_key[i].ltk_key == key ) {
 876                         found = 1;
 877                         break;
 878                 } else if ( !ctx->ltu_key[i].ltk_key ) {
 879                         break;
 880                 }
 881         }
 882
 883         if ( data || kfree ) {
 884                 if ( i>=MAXKEYS )
 885                         return ENOMEM;
 886                 ctx->ltu_key[i].ltk_key = key;
 887                 ctx->ltu_key[i].ltk_data = data;
 888                 ctx->ltu_key[i].ltk_free = kfree;
 889         } else if ( found ) {
 890                 clear_key_idx( ctx, i );
 891         }
 892
 893         return 0;
 894 }
 895
 896 /* Free all elements with this key, no matter which thread they're in.
 897  * May only be called while the pool is paused.
 898  */
 899 void ldap_pvt_thread_pool_purgekey( void *key )
 900 {
 901         int i, j;
 902         ldap_int_thread_userctx_t *ctx;
 903
 904         assert ( key != NULL );
 905
 906         for ( i=0; i<LDAP_MAXTHR; i++ ) {
 907                 ctx = thread_keys[i].ctx;
 908                 if ( ctx && ctx != DELETED_THREAD_CTX ) {
 909                         for ( j=0; j<MAXKEYS && ctx->ltu_key[j].ltk_key; j++ ) {
 910                                 if ( ctx->ltu_key[j].ltk_key == key ) {
 911                                         if (ctx->ltu_key[j].ltk_free)
 912                                                 ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key,
 913                                                 ctx->ltu_key[j].ltk_data );
 914                                         clear_key_idx( ctx, j );
 915                                         break;
 916                                 }
 917                         }
 918                 }
 919         }
 920 }
 921
 922 /*
 923  * This is necessary if the caller does not have access to the
 924  * thread context handle (for example, a slapd plugin calling
 925  * slapi_search_internal()). No doubt it is more efficient
 926  * for the application to keep track of the thread context
 927  * handles itself.
 928  */
 929 void *ldap_pvt_thread_pool_context( )
 930 {
 931         ldap_pvt_thread_t tid;
 932         unsigned i, hash;
 933         ldap_int_thread_userctx_t *ctx;
 934
 935         tid = ldap_pvt_thread_self();
 936         if ( ldap_pvt_thread_equal( tid, ldap_int_main_tid ))
 937                 return &ldap_int_main_thrctx;
 938
 939         TID_HASH( tid, hash );
 940         i = hash &= (LDAP_MAXTHR-1);
 941         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 942         do {
 943                 ctx = thread_keys[i].ctx;
 944                 if ( ctx != DELETED_THREAD_CTX )
 945                         if ( ldap_pvt_thread_equal(thread_keys[i].id, tid) || !ctx )
 946                                 goto done;
 947         } while ( (i = (i+1) & (LDAP_MAXTHR-1)) != hash );
 948         ctx = NULL;
 949  done:
 950         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 951
 952         return ctx;
 953 }
 954
 955 void ldap_pvt_thread_pool_context_reset( void *vctx )
 956 {
 957         ldap_int_thread_userctx_t *ctx = vctx;
 958         int i;
 959
 960         for ( i=MAXKEYS-1; i>=0; i--) {
 961                 if ( !ctx->ltu_key[i].ltk_key )
 962                         continue;
 963                 if ( ctx->ltu_key[i].ltk_free )
 964                         ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key,
 965                         ctx->ltu_key[i].ltk_data );
 966                 ctx->ltu_key[i].ltk_key = NULL;
 967         }
 968 }
 969
 970 ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx )
 971 {
 972         ldap_int_thread_userctx_t *ctx = vctx;
 973
 974         return ctx->ltu_id;
 975 }
 976 #endif /* LDAP_THREAD_HAVE_TPOOL */