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