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

   1 /* $OpenLDAP$ */
   2 /*
   3  * Copyright 1998-2003 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;
  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         }
 206
 207         ctx->ltc_start_routine = start_routine;
 208         ctx->ltc_arg = arg;
 209
 210         pool->ltp_pending_count++;
 211         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 212         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 213         if ((pool->ltp_open_count <= 0
 214 #if 0
 215                         || pool->ltp_pending_count > 1
 216 #endif
 217                         || pool->ltp_open_count == pool->ltp_active_count)
 218                 && (pool->ltp_max_count <= 0
 219                         || pool->ltp_open_count < pool->ltp_max_count))
 220         {
 221                 pool->ltp_open_count++;
 222                 pool->ltp_starting++;
 223                 need_thread = 1;
 224         }
 225         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 226
 227         if (need_thread) {
 228                 int rc = ldap_pvt_thread_create( &thr, 1,
 229                         ldap_int_thread_pool_wrapper, pool );
 230                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 231                 if (rc == 0) {
 232                         pool->ltp_starting--;
 233                 } else {
 234                         /* couldn't create thread.  back out of
 235                          * ltp_open_count and check for even worse things.
 236                          */
 237                         pool->ltp_open_count--;
 238                         pool->ltp_starting--;
 239                         if (pool->ltp_open_count == 0) {
 240                                 /* no open threads at all?!?
 241                                  */
 242                                 ldap_int_thread_ctx_t *ptr;
 243                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 244                                         if (ptr == ctx) break;
 245                                 if (ptr == ctx) {
 246                                         /* no open threads, context not handled, so
 247                                          * back out of ltp_pending_count, free the context,
 248                                          * report the error.
 249                                          */
 250                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 251                                                 ldap_int_thread_ctx_s, ltc_next.q);
 252                                         pool->ltp_pending_count++;
 253                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 254                                         LDAP_FREE(ctx);
 255                                         return(-1);
 256                                 }
 257                         }
 258                         /* there is another open thread, so this
 259                          * context will be handled eventually.
 260                          * continue on and signal that the context
 261                          * is waiting.
 262                          */
 263                 }
 264                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 265         }
 266
 267         return(0);
 268 }
 269
 270 int
 271 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 272 {
 273         struct ldap_int_thread_pool_s *pool;
 274
 275         if (tpool == NULL)
 276                 return(-1);
 277
 278         pool = *tpool;
 279
 280         if (pool == NULL)
 281                 return(-1);
 282
 283         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 284         pool->ltp_max_count = max_threads;
 285         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 286         return(0);
 287 }
 288
 289 int
 290 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 291 {
 292         struct ldap_int_thread_pool_s *pool;
 293         int count;
 294
 295         if (tpool == NULL)
 296                 return(-1);
 297
 298         pool = *tpool;
 299
 300         if (pool == NULL)
 301                 return(0);
 302
 303         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 304         count = pool->ltp_pending_count + pool->ltp_active_count;
 305         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 306         return(count);
 307 }
 308
 309 int
 310 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 311 {
 312         struct ldap_int_thread_pool_s *pool, *pptr;
 313         long waiting;
 314         ldap_int_thread_ctx_t *ctx;
 315
 316         if (tpool == NULL)
 317                 return(-1);
 318
 319         pool = *tpool;
 320
 321         if (pool == NULL) return(-1);
 322
 323         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 324         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 325                 if (pptr == pool) break;
 326         if (pptr == pool)
 327                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 328                         ldap_int_thread_pool_s, ltp_next);
 329         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 330
 331         if (pool != pptr) return(-1);
 332
 333         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 334         pool->ltp_state = run_pending
 335                 ? LDAP_INT_THREAD_POOL_FINISHING
 336                 : LDAP_INT_THREAD_POOL_STOPPING;
 337
 338         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 339         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 340
 341         do {
 342                 ldap_pvt_thread_yield();
 343                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 344                 waiting = pool->ltp_open_count;
 345                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 346         } while (waiting > 0);
 347
 348         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 349         {
 350                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 351                 LDAP_FREE(ctx);
 352         }
 353
 354         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 355         {
 356                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 357                 LDAP_FREE(ctx);
 358         }
 359
 360         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 361         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 362         LDAP_FREE(pool);
 363         return(0);
 364 }
 365
 366 static void *
 367 ldap_int_thread_pool_wrapper (
 368         void *xpool )
 369 {
 370         struct ldap_int_thread_pool_s *pool = xpool;
 371         ldap_int_thread_ctx_t *ctx;
 372         ldap_int_thread_key_t ltc_key[MAXKEYS];
 373         int i;
 374
 375         if (pool == NULL)
 376                 return NULL;
 377
 378         for ( i=0; i<MAXKEYS; i++ ) {
 379                 ltc_key[i].ltk_key = NULL;
 380         }
 381
 382         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 383
 384         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 385                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 386                 if (ctx) {
 387                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 388                 } else {
 389                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 390                                 break;
 391                         if (pool->ltp_max_count > 0
 392                                 && pool->ltp_open_count > pool->ltp_max_count)
 393                         {
 394                                 /* too many threads running (can happen if the
 395                                  * maximum threads value is set during ongoing
 396                                  * operation using ldap_pvt_thread_pool_maxthreads)
 397                                  * so let this thread die.
 398                                  */
 399                                 break;
 400                         }
 401
 402                         /* we could check an idle timer here, and let the
 403                          * thread die if it has been inactive for a while.
 404                          * only die if there are other open threads (i.e.,
 405                          * always have at least one thread open).  the check
 406                          * should be like this:
 407                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 408                          *       check timer, leave thread (break;)
 409                          */
 410
 411                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 412                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 413
 414                         continue;
 415                 }
 416
 417                 pool->ltp_pending_count--;
 418
 419                 ctx->ltc_key = ltc_key;
 420                 ctx->ltc_thread_id = ldap_pvt_thread_self();
 421
 422                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 423                 pool->ltp_active_count++;
 424                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 425
 426                 ctx->ltc_start_routine(ctx, ctx->ltc_arg);
 427                 ctx->ltc_key = NULL;
 428
 429                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 430                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 431                         ldap_int_thread_ctx_s, ltc_next.al);
 432                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 433                 pool->ltp_active_count--;
 434                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 435
 436                 ldap_pvt_thread_yield();
 437
 438                 /* if we use an idle timer, here's
 439                  * a good place to update it
 440                  */
 441
 442                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 443         }
 444
 445         for ( i=0; i<MAXKEYS && ltc_key[i].ltk_key; i++ ) {
 446                 if (ltc_key[i].ltk_free)
 447                         ltc_key[i].ltk_free(
 448                                 ltc_key[i].ltk_key,
 449                                 ltc_key[i].ltk_data );
 450         }
 451
 452         pool->ltp_open_count--;
 453         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 454
 455         ldap_pvt_thread_exit(NULL);
 456         return(NULL);
 457 }
 458
 459 int ldap_pvt_thread_pool_getkey(
 460         void *xctx,
 461         void *key,
 462         void **data,
 463         ldap_pvt_thread_pool_keyfree_t **kfree )
 464 {
 465         ldap_int_thread_ctx_t *ctx = xctx;
 466         int i;
 467
 468         if ( !ctx || !data || !ctx->ltc_key ) return EINVAL;
 469
 470         for ( i=0; i<MAXKEYS && ctx->ltc_key[i].ltk_key; i++ ) {
 471                 if ( ctx->ltc_key[i].ltk_key == key ) {
 472                         *data = ctx->ltc_key[i].ltk_data;
 473                         if ( kfree ) *kfree = ctx->ltc_key[i].ltk_free;
 474                         return 0;
 475                 }
 476         }
 477         return ENOENT;
 478 }
 479
 480 int ldap_pvt_thread_pool_setkey(
 481         void *xctx,
 482         void *key,
 483         void *data,
 484         ldap_pvt_thread_pool_keyfree_t *kfree )
 485 {
 486         ldap_int_thread_ctx_t *ctx = xctx;
 487         int i;
 488
 489         if ( !ctx || !key || !ctx->ltc_key ) return EINVAL;
 490
 491         for ( i=0; i<MAXKEYS; i++ ) {
 492                 if ( !ctx->ltc_key[i].ltk_key || ctx->ltc_key[i].ltk_key == key ) {
 493                         ctx->ltc_key[i].ltk_key = key;
 494                         ctx->ltc_key[i].ltk_data = data;
 495                         ctx->ltc_key[i].ltk_free = kfree;
 496                         return 0;
 497                 }
 498         }
 499         return ENOMEM;
 500 }
 501
 502 /*
 503  * This is necessary if the caller does not have access to the
 504  * thread context handle (for example, a slapd plugin calling
 505  * slapi_search_internal()). No doubt it is more efficient to
 506  * for the application to keep track of the thread context
 507  * handles itself.
 508  */
 509 void *ldap_pvt_thread_pool_context( ldap_pvt_thread_pool_t *tpool )
 510 {
 511         ldap_pvt_thread_pool_t pool;
 512         ldap_pvt_thread_t tid;
 513         ldap_int_thread_ctx_t *ptr;
 514
 515         pool = *tpool;
 516         if (pool == NULL) {
 517                 return NULL;
 518         }
 519
 520         tid = ldap_pvt_thread_self();
 521
 522         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 523         LDAP_SLIST_FOREACH(ptr, &pool->ltp_active_list, ltc_next.al)
 524                 if (ptr != NULL && ptr->ltc_thread_id == tid) break;
 525         if (ptr != NULL && ptr->ltc_thread_id != tid) {
 526                 ptr = NULL;
 527         }
 528         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 529
 530         return ptr;
 531 }
 532
 533 #endif /* LDAP_HAVE_THREAD_POOL */