git.sur5r.net Git - openldap/blob - 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         } ltc_next;
  50         ldap_pvt_thread_start_t *ltc_start_routine;
  51         void *ltc_arg;
  52         ldap_int_thread_key_t ltc_key[MAXKEYS];
  53 } ldap_int_thread_ctx_t;
  54
  55 struct ldap_int_thread_pool_s {
  56         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  57         ldap_pvt_thread_mutex_t ltp_mutex;
  58         ldap_pvt_thread_cond_t ltp_cond;
  59         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  60         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  61         long ltp_state;
  62         long ltp_max_count;
  63         long ltp_max_pending;
  64         long ltp_pending_count;
  65         long ltp_active_count;
  66         long ltp_open_count;
  67         long ltp_starting;
  68 };
  69
  70 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  71         ldap_int_thread_pool_list =
  72         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  73
  74 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  75
  76 static void *ldap_int_thread_pool_wrapper( void *pool );
  77
  78 int
  79 ldap_int_thread_pool_startup ( void )
  80 {
  81         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
  82 }
  83
  84 int
  85 ldap_int_thread_pool_shutdown ( void )
  86 {
  87         struct ldap_int_thread_pool_s *pool;
  88
  89         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
  90                 LDAP_STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
  91                 ldap_pvt_thread_pool_destroy( &pool, 0);
  92         }
  93         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
  94         return(0);
  95 }
  96
  97 int
  98 ldap_pvt_thread_pool_init (
  99         ldap_pvt_thread_pool_t *tpool,
 100         int max_threads,
 101         int max_pending )
 102 {
 103         ldap_pvt_thread_pool_t pool;
 104         int rc;
 105
 106         *tpool = NULL;
 107         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 108                 sizeof(struct ldap_int_thread_pool_s));
 109
 110         if (pool == NULL) return(-1);
 111
 112         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 113         if (rc != 0)
 114                 return(rc);
 115         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 116         if (rc != 0)
 117                 return(rc);
 118         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 119         pool->ltp_max_count = max_threads;
 120         pool->ltp_max_pending = max_pending;
 121         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 122         LDAP_SLIST_INIT(&pool->ltp_free_list);
 123         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 124         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 125         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 126
 127 #if 0
 128         /* THIS WILL NOT WORK on some systems.  If the process
 129          * forks after starting a thread, there is no guarantee
 130          * that the thread will survive the fork.  For example,
 131          * slapd forks in order to daemonize, and does so after
 132          * calling ldap_pvt_thread_pool_init.  On some systems,
 133          * this initial thread does not run in the child process,
 134          * but ltp_open_count == 1, so two things happen:
 135          * 1) the first client connection fails, and 2) when
 136          * slapd is kill'ed, it never terminates since it waits
 137          * for all worker threads to exit. */
 138
 139         /* start up one thread, just so there is one. no need to
 140          * lock the mutex right now, since no threads are running.
 141          */
 142         pool->ltp_open_count++;
 143
 144         ldap_pvt_thread_t thr;
 145         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 146
 147         if( rc != 0) {
 148                 /* couldn't start one?  then don't start any */
 149                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 150                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 151                         ldap_int_thread_pool_s, ltp_next);
 152                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 153                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 154                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 155                 LDAP_FREE(pool);
 156                 return(-1);
 157         }
 158 #endif
 159
 160         *tpool = pool;
 161         return(0);
 162 }
 163
 164 int
 165 ldap_pvt_thread_pool_submit (
 166         ldap_pvt_thread_pool_t *tpool,
 167         ldap_pvt_thread_start_t *start_routine, void *arg )
 168 {
 169         struct ldap_int_thread_pool_s *pool;
 170         ldap_int_thread_ctx_t *ctx;
 171         int need_thread = 0;
 172         ldap_pvt_thread_t thr;
 173
 174         if (tpool == NULL)
 175                 return(-1);
 176
 177         pool = *tpool;
 178
 179         if (pool == NULL)
 180                 return(-1);
 181
 182         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 183         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 184                 || (pool->ltp_max_pending > 0
 185                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 186         {
 187                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 188                 return(-1);
 189         }
 190         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 191         if (ctx) {
 192                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 193         } else {
 194                 int i;
 195                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 196                         sizeof(ldap_int_thread_ctx_t));
 197                 if (ctx == NULL) {
 198                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 199                         return(-1);
 200                 }
 201                 for ( i=0; i<MAXKEYS; i++ ) {
 202                         ctx->ltc_key[i].ltk_key = NULL;
 203                 }
 204         }
 205
 206         ctx->ltc_start_routine = start_routine;
 207         ctx->ltc_arg = arg;
 208
 209         pool->ltp_pending_count++;
 210         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 211         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 212         if ((pool->ltp_open_count <= 0
 213                         || pool->ltp_pending_count > 1
 214                         || pool->ltp_open_count == pool->ltp_active_count)
 215                 && (pool->ltp_max_count <= 0
 216                         || pool->ltp_open_count < pool->ltp_max_count))
 217         {
 218                 pool->ltp_open_count++;
 219                 pool->ltp_starting++;
 220                 need_thread = 1;
 221         }
 222         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 223
 224         if (need_thread) {
 225                 int rc = ldap_pvt_thread_create( &thr, 1,
 226                         ldap_int_thread_pool_wrapper, pool );
 227                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 228                 if (rc == 0) {
 229                         pool->ltp_starting--;
 230                 } else {
 231                         /* couldn't create thread.  back out of
 232                          * ltp_open_count and check for even worse things.
 233                          */
 234                         pool->ltp_open_count--;
 235                         pool->ltp_starting--;
 236                         if (pool->ltp_open_count == 0) {
 237                                 /* no open threads at all?!?
 238                                  */
 239                                 ldap_int_thread_ctx_t *ptr;
 240                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 241                                         if (ptr == ctx) break;
 242                                 if (ptr == ctx) {
 243                                         /* no open threads, context not handled, so
 244                                          * back out of ltp_pending_count, free the context,
 245                                          * report the error.
 246                                          */
 247                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 248                                                 ldap_int_thread_ctx_s, ltc_next.q);
 249                                         pool->ltp_pending_count++;
 250                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 251                                         LDAP_FREE(ctx);
 252                                         return(-1);
 253                                 }
 254                         }
 255                         /* there is another open thread, so this
 256                          * context will be handled eventually.
 257                          * continue on and signal that the context
 258                          * is waiting.
 259                          */
 260                 }
 261                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 262         }
 263
 264         return(0);
 265 }
 266
 267 int
 268 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 269 {
 270         struct ldap_int_thread_pool_s *pool;
 271
 272         if (tpool == NULL)
 273                 return(-1);
 274
 275         pool = *tpool;
 276
 277         if (pool == NULL)
 278                 return(-1);
 279
 280         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 281         pool->ltp_max_count = max_threads;
 282         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 283         return(0);
 284 }
 285
 286 int
 287 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 288 {
 289         struct ldap_int_thread_pool_s *pool;
 290         int count;
 291
 292         if (tpool == NULL)
 293                 return(-1);
 294
 295         pool = *tpool;
 296
 297         if (pool == NULL)
 298                 return(0);
 299
 300         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 301         count = pool->ltp_pending_count + pool->ltp_active_count;
 302         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 303         return(count);
 304 }
 305
 306 static void ldap_int_thread_pool_keyfree( ldap_int_thread_ctx_t *ctx )
 307 {
 308         int i;
 309         for ( i=0; i<MAXKEYS && ctx->ltc_key[i].ltk_key; i++ ) {
 310                 if (ctx->ltc_key[i].ltk_free)
 311                         ctx->ltc_key[i].ltk_free(
 312                                 ctx->ltc_key[i].ltk_key,
 313                                 ctx->ltc_key[i].ltk_data );
 314         }
 315 }
 316
 317 int
 318 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 319 {
 320         struct ldap_int_thread_pool_s *pool, *pptr;
 321         long waiting;
 322         ldap_int_thread_ctx_t *ctx;
 323
 324         if (tpool == NULL)
 325                 return(-1);
 326
 327         pool = *tpool;
 328
 329         if (pool == NULL) return(-1);
 330
 331         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 332         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 333                 if (pptr == pool) break;
 334         if (pptr == pool)
 335                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 336                         ldap_int_thread_pool_s, ltp_next);
 337         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 338
 339         if (pool != pptr) return(-1);
 340
 341         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 342         pool->ltp_state = run_pending
 343                 ? LDAP_INT_THREAD_POOL_FINISHING
 344                 : LDAP_INT_THREAD_POOL_STOPPING;
 345         waiting = pool->ltp_open_count;
 346
 347         /* broadcast could be used here, but only after
 348          * it is fixed in the NT thread implementation
 349          */
 350         while (--waiting >= 0) {
 351                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 352         }
 353         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 354
 355         do {
 356                 ldap_pvt_thread_yield();
 357                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 358                 waiting = pool->ltp_open_count;
 359                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 360         } while (waiting > 0);
 361
 362         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 363         {
 364                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 365                 ldap_int_thread_pool_keyfree( ctx );
 366                 LDAP_FREE(ctx);
 367         }
 368
 369         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 370         {
 371                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 372                 ldap_int_thread_pool_keyfree( ctx );
 373                 LDAP_FREE(ctx);
 374         }
 375
 376         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 377         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 378         LDAP_FREE(pool);
 379         return(0);
 380 }
 381
 382 static void *
 383 ldap_int_thread_pool_wrapper (
 384         void *xpool )
 385 {
 386         struct ldap_int_thread_pool_s *pool = xpool;
 387         ldap_int_thread_ctx_t *ctx;
 388
 389         if (pool == NULL)
 390                 return NULL;
 391
 392         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 393
 394         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 395                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 396                 if (ctx) {
 397                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 398                 } else {
 399                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 400                                 break;
 401                         if (pool->ltp_max_count > 0
 402                                 && pool->ltp_open_count > pool->ltp_max_count)
 403                         {
 404                                 /* too many threads running (can happen if the
 405                                  * maximum threads value is set during ongoing
 406                                  * operation using ldap_pvt_thread_pool_maxthreads)
 407                                  * so let this thread die.
 408                                  */
 409                                 break;
 410                         }
 411
 412                         /* we could check an idle timer here, and let the
 413                          * thread die if it has been inactive for a while.
 414                          * only die if there are other open threads (i.e.,
 415                          * always have at least one thread open).  the check
 416                          * should be like this:
 417                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 418                          *       check timer, leave thread (break;)
 419                          */
 420
 421                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 422                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 423
 424                         continue;
 425                 }
 426
 427                 pool->ltp_pending_count--;
 428                 pool->ltp_active_count++;
 429                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 430
 431                 ctx->ltc_start_routine(ctx, ctx->ltc_arg);
 432
 433                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 434                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 435                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 436
 437                 ldap_pvt_thread_yield();
 438
 439                 /* if we use an idle timer, here's
 440                  * a good place to update it
 441                  */
 442
 443                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 444                 pool->ltp_active_count--;
 445         }
 446
 447         pool->ltp_open_count--;
 448         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 449
 450
 451         ldap_pvt_thread_exit(NULL);
 452         return(NULL);
 453 }
 454
 455 int ldap_pvt_thread_pool_getkey(
 456         void *xctx,
 457         void *key,
 458         void **data,
 459         ldap_pvt_thread_pool_keyfree_t **kfree )
 460 {
 461         ldap_int_thread_ctx_t *ctx = xctx;
 462         int i;
 463
 464         if ( !ctx || !data ) return EINVAL;
 465
 466         for ( i=0; i<MAXKEYS && ctx->ltc_key[i].ltk_key; i++ ) {
 467                 if ( ctx->ltc_key[i].ltk_key == key ) {
 468                         *data = ctx->ltc_key[i].ltk_data;
 469                         if ( kfree ) *kfree = ctx->ltc_key[i].ltk_free;
 470                         return 0;
 471                 }
 472         }
 473         return ENOENT;
 474 }
 475
 476 int ldap_pvt_thread_pool_setkey(
 477         void *xctx,
 478         void *key,
 479         void *data,
 480         ldap_pvt_thread_pool_keyfree_t *kfree )
 481 {
 482         ldap_int_thread_ctx_t *ctx = xctx;
 483         int i;
 484
 485         if ( !ctx || !key ) return EINVAL;
 486
 487         for ( i=0; i<MAXKEYS; i++ ) {
 488                 if ( !ctx->ltc_key[i].ltk_key || ctx->ltc_key[i].ltk_key == key ) {
 489                         ctx->ltc_key[i].ltk_key = key;
 490                         ctx->ltc_key[i].ltk_data = data;
 491                         ctx->ltc_key[i].ltk_free = kfree;
 492                         return 0;
 493                 }
 494         }
 495         return ENOMEM;
 496 }
 497 #endif /* LDAP_HAVE_THREAD_POOL */