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

   1 /* $OpenLDAP$ */
   2 /*
   3  * Copyright 1998-2002 The OpenLDAP Foundation, Redwood City, California, USA
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms are permitted only
   7  * as authorized by the OpenLDAP Public License.  A copy of this
   8  * license is available at http://www.OpenLDAP.org/license.html or
   9  * in file LICENSE in the top-level directory of the distribution.
  10  */
  11
  12 #include "portable.h"
  13
  14 #include <stdio.h>
  15
  16 #include <ac/stdarg.h>
  17 #include <ac/stdlib.h>
  18 #include <ac/string.h>
  19 #include <ac/time.h>
  20 #include <ac/errno.h>
  21
  22 #include "ldap-int.h"
  23 #include "ldap_pvt_thread.h"
  24 #include "ldap_queue.h"
  25
  26 #ifndef LDAP_THREAD_HAVE_TPOOL
  27
  28 enum ldap_int_thread_pool_state {
  29         LDAP_INT_THREAD_POOL_RUNNING,
  30         LDAP_INT_THREAD_POOL_FINISHING,
  31         LDAP_INT_THREAD_POOL_STOPPING
  32 };
  33
  34 typedef struct ldap_int_thread_key_s {
  35         void *ltk_key;
  36         void *ltk_data;
  37         ldap_pvt_thread_pool_keyfree_t *ltk_free;
  38 } ldap_int_thread_key_t;
  39
  40 /* Max number of thread-specific keys we store per thread.
  41  * We don't expect to use many...
  42  */
  43 #define MAXKEYS 32
  44
  45 typedef struct ldap_int_thread_ctx_s {
  46         union {
  47         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  48         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  49         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  50         } ltc_next;
  51         ldap_pvt_thread_start_t *ltc_start_routine;
  52         void *ltc_arg;
  53         ldap_pvt_thread_t ltc_thread_id;
  54         ldap_int_thread_key_t ltc_key[MAXKEYS];
  55 } ldap_int_thread_ctx_t;
  56
  57 struct ldap_int_thread_pool_s {
  58         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  59         ldap_pvt_thread_mutex_t ltp_mutex;
  60         ldap_pvt_thread_cond_t ltp_cond;
  61         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  62         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  63         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  64         long ltp_state;
  65         long ltp_max_count;
  66         long ltp_max_pending;
  67         long ltp_pending_count;
  68         long ltp_active_count;
  69         long ltp_open_count;
  70         long ltp_starting;
  71 };
  72
  73 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  74         ldap_int_thread_pool_list =
  75         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  76
  77 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  78
  79 static void *ldap_int_thread_pool_wrapper( void *pool );
  80
  81 int
  82 ldap_int_thread_pool_startup ( void )
  83 {
  84         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
  85 }
  86
  87 int
  88 ldap_int_thread_pool_shutdown ( void )
  89 {
  90         struct ldap_int_thread_pool_s *pool;
  91
  92         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
  93                 LDAP_STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
  94                 ldap_pvt_thread_pool_destroy( &pool, 0);
  95         }
  96         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
  97         return(0);
  98 }
  99
 100 int
 101 ldap_pvt_thread_pool_init (
 102         ldap_pvt_thread_pool_t *tpool,
 103         int max_threads,
 104         int max_pending )
 105 {
 106         ldap_pvt_thread_pool_t pool;
 107         int rc;
 108
 109         *tpool = NULL;
 110         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 111                 sizeof(struct ldap_int_thread_pool_s));
 112
 113         if (pool == NULL) return(-1);
 114
 115         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 116         if (rc != 0)
 117                 return(rc);
 118         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 119         if (rc != 0)
 120                 return(rc);
 121         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 122         pool->ltp_max_count = max_threads;
 123         pool->ltp_max_pending = max_pending;
 124         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 125         LDAP_SLIST_INIT(&pool->ltp_free_list);
 126         LDAP_SLIST_INIT(&pool->ltp_active_list);
 127         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 128         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 129         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 130
 131 #if 0
 132         /* THIS WILL NOT WORK on some systems.  If the process
 133          * forks after starting a thread, there is no guarantee
 134          * that the thread will survive the fork.  For example,
 135          * slapd forks in order to daemonize, and does so after
 136          * calling ldap_pvt_thread_pool_init.  On some systems,
 137          * this initial thread does not run in the child process,
 138          * but ltp_open_count == 1, so two things happen:
 139          * 1) the first client connection fails, and 2) when
 140          * slapd is kill'ed, it never terminates since it waits
 141          * for all worker threads to exit. */
 142
 143         /* start up one thread, just so there is one. no need to
 144          * lock the mutex right now, since no threads are running.
 145          */
 146         pool->ltp_open_count++;
 147
 148         ldap_pvt_thread_t thr;
 149         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 150
 151         if( rc != 0) {
 152                 /* couldn't start one?  then don't start any */
 153                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 154                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 155                         ldap_int_thread_pool_s, ltp_next);
 156                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 157                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 158                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 159                 LDAP_FREE(pool);
 160                 return(-1);
 161         }
 162 #endif
 163
 164         *tpool = pool;
 165         return(0);
 166 }
 167
 168 int
 169 ldap_pvt_thread_pool_submit (
 170         ldap_pvt_thread_pool_t *tpool,
 171         ldap_pvt_thread_start_t *start_routine, void *arg )
 172 {
 173         struct ldap_int_thread_pool_s *pool;
 174         ldap_int_thread_ctx_t *ctx;
 175         int need_thread = 0;
 176         ldap_pvt_thread_t thr;
 177
 178         if (tpool == NULL)
 179                 return(-1);
 180
 181         pool = *tpool;
 182
 183         if (pool == NULL)
 184                 return(-1);
 185
 186         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 187         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 188                 || (pool->ltp_max_pending > 0
 189                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 190         {
 191                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 192                 return(-1);
 193         }
 194         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 195         if (ctx) {
 196                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 197         } else {
 198                 int i;
 199                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 200                         sizeof(ldap_int_thread_ctx_t));
 201                 if (ctx == NULL) {
 202                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 203                         return(-1);
 204                 }
 205                 for ( i=0; i<MAXKEYS; i++ ) {
 206                         ctx->ltc_key[i].ltk_key = NULL;
 207                 }
 208         }
 209
 210         ctx->ltc_start_routine = start_routine;
 211         ctx->ltc_arg = arg;
 212
 213         pool->ltp_pending_count++;
 214         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 215         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 216         if ((pool->ltp_open_count <= 0
 217                         || pool->ltp_pending_count > 1
 218                         || pool->ltp_open_count == pool->ltp_active_count)
 219                 && (pool->ltp_max_count <= 0
 220                         || pool->ltp_open_count < pool->ltp_max_count))
 221         {
 222                 pool->ltp_open_count++;
 223                 pool->ltp_starting++;
 224                 need_thread = 1;
 225         }
 226         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 227
 228         if (need_thread) {
 229                 int rc = ldap_pvt_thread_create( &thr, 1,
 230                         ldap_int_thread_pool_wrapper, pool );
 231                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 232                 if (rc == 0) {
 233                         pool->ltp_starting--;
 234                 } else {
 235                         /* couldn't create thread.  back out of
 236                          * ltp_open_count and check for even worse things.
 237                          */
 238                         pool->ltp_open_count--;
 239                         pool->ltp_starting--;
 240                         if (pool->ltp_open_count == 0) {
 241                                 /* no open threads at all?!?
 242                                  */
 243                                 ldap_int_thread_ctx_t *ptr;
 244                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 245                                         if (ptr == ctx) break;
 246                                 if (ptr == ctx) {
 247                                         /* no open threads, context not handled, so
 248                                          * back out of ltp_pending_count, free the context,
 249                                          * report the error.
 250                                          */
 251                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 252                                                 ldap_int_thread_ctx_s, ltc_next.q);
 253                                         pool->ltp_pending_count++;
 254                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 255                                         LDAP_FREE(ctx);
 256                                         return(-1);
 257                                 }
 258                         }
 259                         /* there is another open thread, so this
 260                          * context will be handled eventually.
 261                          * continue on and signal that the context
 262                          * is waiting.
 263                          */
 264                 }
 265                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 266         }
 267
 268         return(0);
 269 }
 270
 271 int
 272 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 273 {
 274         struct ldap_int_thread_pool_s *pool;
 275
 276         if (tpool == NULL)
 277                 return(-1);
 278
 279         pool = *tpool;
 280
 281         if (pool == NULL)
 282                 return(-1);
 283
 284         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 285         pool->ltp_max_count = max_threads;
 286         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 287         return(0);
 288 }
 289
 290 int
 291 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 292 {
 293         struct ldap_int_thread_pool_s *pool;
 294         int count;
 295
 296         if (tpool == NULL)
 297                 return(-1);
 298
 299         pool = *tpool;
 300
 301         if (pool == NULL)
 302                 return(0);
 303
 304         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 305         count = pool->ltp_pending_count + pool->ltp_active_count;
 306         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 307         return(count);
 308 }
 309
 310 static void ldap_int_thread_pool_keyfree( ldap_int_thread_ctx_t *ctx )
 311 {
 312         int i;
 313         for ( i=0; i<MAXKEYS && ctx->ltc_key[i].ltk_key; i++ ) {
 314                 if (ctx->ltc_key[i].ltk_free)
 315                         ctx->ltc_key[i].ltk_free(
 316                                 ctx->ltc_key[i].ltk_key,
 317                                 ctx->ltc_key[i].ltk_data );
 318         }
 319 }
 320
 321 int
 322 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 323 {
 324         struct ldap_int_thread_pool_s *pool, *pptr;
 325         long waiting;
 326         ldap_int_thread_ctx_t *ctx;
 327
 328         if (tpool == NULL)
 329                 return(-1);
 330
 331         pool = *tpool;
 332
 333         if (pool == NULL) return(-1);
 334
 335         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 336         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 337                 if (pptr == pool) break;
 338         if (pptr == pool)
 339                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 340                         ldap_int_thread_pool_s, ltp_next);
 341         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 342
 343         if (pool != pptr) return(-1);
 344
 345         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 346         pool->ltp_state = run_pending
 347                 ? LDAP_INT_THREAD_POOL_FINISHING
 348                 : LDAP_INT_THREAD_POOL_STOPPING;
 349         waiting = pool->ltp_open_count;
 350
 351         /* broadcast could be used here, but only after
 352          * it is fixed in the NT thread implementation
 353          */
 354         while (--waiting >= 0) {
 355                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 356         }
 357         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 358
 359         do {
 360                 ldap_pvt_thread_yield();
 361                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 362                 waiting = pool->ltp_open_count;
 363                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 364         } while (waiting > 0);
 365
 366         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 367         {
 368                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 369                 ldap_int_thread_pool_keyfree( ctx );
 370                 LDAP_FREE(ctx);
 371         }
 372
 373         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 374         {
 375                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 376                 ldap_int_thread_pool_keyfree( ctx );
 377                 LDAP_FREE(ctx);
 378         }
 379
 380         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 381         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 382         LDAP_FREE(pool);
 383         return(0);
 384 }
 385
 386 static void *
 387 ldap_int_thread_pool_wrapper (
 388         void *xpool )
 389 {
 390         struct ldap_int_thread_pool_s *pool = xpool;
 391         ldap_int_thread_ctx_t *ctx;
 392
 393         if (pool == NULL)
 394                 return NULL;
 395
 396         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 397
 398         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 399                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 400                 if (ctx) {
 401                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 402                 } else {
 403                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 404                                 break;
 405                         if (pool->ltp_max_count > 0
 406                                 && pool->ltp_open_count > pool->ltp_max_count)
 407                         {
 408                                 /* too many threads running (can happen if the
 409                                  * maximum threads value is set during ongoing
 410                                  * operation using ldap_pvt_thread_pool_maxthreads)
 411                                  * so let this thread die.
 412                                  */
 413                                 break;
 414                         }
 415
 416                         /* we could check an idle timer here, and let the
 417                          * thread die if it has been inactive for a while.
 418                          * only die if there are other open threads (i.e.,
 419                          * always have at least one thread open).  the check
 420                          * should be like this:
 421                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 422                          *       check timer, leave thread (break;)
 423                          */
 424
 425                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 426                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 427
 428                         continue;
 429                 }
 430
 431                 pool->ltp_pending_count--;
 432                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 433                 pool->ltp_active_count++;
 434                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 435
 436                 ctx->ltc_thread_id = ldap_pvt_thread_self();
 437                 ctx->ltc_start_routine(ctx, ctx->ltc_arg);
 438
 439                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 440                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 441                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 442
 443                 ldap_pvt_thread_yield();
 444
 445                 /* if we use an idle timer, here's
 446                  * a good place to update it
 447                  */
 448
 449                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 450                 pool->ltp_active_count--;
 451                 ctx = LDAP_SLIST_FIRST(&pool->ltp_active_list);
 452                 if (ctx) {
 453                         LDAP_SLIST_REMOVE_HEAD(&pool->ltp_active_list, ltc_next.al);
 454                 }
 455         }
 456
 457         pool->ltp_open_count--;
 458         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 459
 460
 461         ldap_pvt_thread_exit(NULL);
 462         return(NULL);
 463 }
 464
 465 int ldap_pvt_thread_pool_getkey(
 466         void *xctx,
 467         void *key,
 468         void **data,
 469         ldap_pvt_thread_pool_keyfree_t **kfree )
 470 {
 471         ldap_int_thread_ctx_t *ctx = xctx;
 472         int i;
 473
 474         if ( !ctx || !data ) return EINVAL;
 475
 476         for ( i=0; i<MAXKEYS && ctx->ltc_key[i].ltk_key; i++ ) {
 477                 if ( ctx->ltc_key[i].ltk_key == key ) {
 478                         *data = ctx->ltc_key[i].ltk_data;
 479                         if ( kfree ) *kfree = ctx->ltc_key[i].ltk_free;
 480                         return 0;
 481                 }
 482         }
 483         return ENOENT;
 484 }
 485
 486 int ldap_pvt_thread_pool_setkey(
 487         void *xctx,
 488         void *key,
 489         void *data,
 490         ldap_pvt_thread_pool_keyfree_t *kfree )
 491 {
 492         ldap_int_thread_ctx_t *ctx = xctx;
 493         int i;
 494
 495         if ( !ctx || !key ) return EINVAL;
 496
 497         for ( i=0; i<MAXKEYS; i++ ) {
 498                 if ( !ctx->ltc_key[i].ltk_key || ctx->ltc_key[i].ltk_key == key ) {
 499                         ctx->ltc_key[i].ltk_key = key;
 500                         ctx->ltc_key[i].ltk_data = data;
 501                         ctx->ltc_key[i].ltk_free = kfree;
 502                         return 0;
 503                 }
 504         }
 505         return ENOMEM;
 506 }
 507
 508 /*
 509  * This is necessary if the caller does not have access to the
 510  * thread context handle (for example, a slapd plugin calling
 511  * slapi_search_internal()). No doubt it is more efficient to
 512  * for the application to keep track of the thread context
 513  * handles itself.
 514  */
 515 void *ldap_pvt_thread_pool_context( ldap_pvt_thread_pool_t *tpool )
 516 {
 517         ldap_pvt_thread_pool_t pool;
 518         ldap_pvt_thread_t tid;
 519         ldap_int_thread_ctx_t *ptr;
 520
 521         pool = *tpool;
 522         if (pool == NULL) {
 523                 return NULL;
 524         }
 525
 526         tid = ldap_pvt_thread_self();
 527
 528         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 529         LDAP_SLIST_FOREACH(ptr, &pool->ltp_active_list, ltc_next.al)
 530                 if (ptr != NULL && ptr->ltc_thread_id == tid) break;
 531         if (ptr != NULL && ptr->ltc_thread_id != tid) {
 532                 ptr = NULL;
 533         }
 534         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 535
 536         return ptr;
 537 }
 538
 539 #endif /* LDAP_HAVE_THREAD_POOL */