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 #define MAXTHREADS      1024    /* must be a power of 2 */
  45
  46 static ldap_pvt_thread_t tid_zero;
  47
  48 #ifdef HAVE_PTHREADS
  49 #define TID_EQ(a,b)     pthread_equal((a),(b))
  50 #else
  51 #define TID_EQ(a,b)     ((a) == (b))
  52 #endif
  53 static struct {
  54         ldap_pvt_thread_t id;
  55         ldap_int_thread_key_t *ctx;
  56 } thread_keys[MAXTHREADS];
  57
  58
  59 typedef struct ldap_int_thread_ctx_s {
  60         union {
  61         LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  62         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  63         LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
  64         } ltc_next;
  65         ldap_pvt_thread_start_t *ltc_start_routine;
  66         void *ltc_arg;
  67 } ldap_int_thread_ctx_t;
  68
  69 struct ldap_int_thread_pool_s {
  70         LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  71         ldap_pvt_thread_mutex_t ltp_mutex;
  72         ldap_pvt_thread_cond_t ltp_cond;
  73         LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  74         LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
  75         LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_list;
  76         long ltp_state;
  77         long ltp_max_count;
  78         long ltp_max_pending;
  79         long ltp_pending_count;
  80         long ltp_active_count;
  81         long ltp_open_count;
  82         long ltp_starting;
  83 };
  84
  85 static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  86         ldap_int_thread_pool_list =
  87         LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  88
  89 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  90
  91 static void *ldap_int_thread_pool_wrapper( void *pool );
  92
  93 int
  94 ldap_int_thread_pool_startup ( void )
  95 {
  96         return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
  97 }
  98
  99 int
 100 ldap_int_thread_pool_shutdown ( void )
 101 {
 102         struct ldap_int_thread_pool_s *pool;
 103
 104         while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
 105                 LDAP_STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
 106                 ldap_pvt_thread_pool_destroy( &pool, 0);
 107         }
 108         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
 109         return(0);
 110 }
 111
 112 int
 113 ldap_pvt_thread_pool_init (
 114         ldap_pvt_thread_pool_t *tpool,
 115         int max_threads,
 116         int max_pending )
 117 {
 118         ldap_pvt_thread_pool_t pool;
 119         int rc;
 120
 121         *tpool = NULL;
 122         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 123                 sizeof(struct ldap_int_thread_pool_s));
 124
 125         if (pool == NULL) return(-1);
 126
 127         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 128         if (rc != 0)
 129                 return(rc);
 130         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 131         if (rc != 0)
 132                 return(rc);
 133         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 134         pool->ltp_max_count = max_threads;
 135         pool->ltp_max_pending = max_pending;
 136         LDAP_STAILQ_INIT(&pool->ltp_pending_list);
 137         LDAP_SLIST_INIT(&pool->ltp_free_list);
 138         LDAP_SLIST_INIT(&pool->ltp_active_list);
 139         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 140         LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
 141         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 142
 143 #if 0
 144         /* THIS WILL NOT WORK on some systems.  If the process
 145          * forks after starting a thread, there is no guarantee
 146          * that the thread will survive the fork.  For example,
 147          * slapd forks in order to daemonize, and does so after
 148          * calling ldap_pvt_thread_pool_init.  On some systems,
 149          * this initial thread does not run in the child process,
 150          * but ltp_open_count == 1, so two things happen:
 151          * 1) the first client connection fails, and 2) when
 152          * slapd is kill'ed, it never terminates since it waits
 153          * for all worker threads to exit. */
 154
 155         /* start up one thread, just so there is one. no need to
 156          * lock the mutex right now, since no threads are running.
 157          */
 158         pool->ltp_open_count++;
 159
 160         ldap_pvt_thread_t thr;
 161         rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
 162
 163         if( rc != 0) {
 164                 /* couldn't start one?  then don't start any */
 165                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 166                 LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 167                         ldap_int_thread_pool_s, ltp_next);
 168                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 169                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 170                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 171                 LDAP_FREE(pool);
 172                 return(-1);
 173         }
 174 #endif
 175
 176         *tpool = pool;
 177         return(0);
 178 }
 179
 180 #define TID_HASH(tid, hash) do { int i; \
 181         unsigned char *ptr = (unsigned char *)&(tid); \
 182         for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
 183
 184 int
 185 ldap_pvt_thread_pool_submit (
 186         ldap_pvt_thread_pool_t *tpool,
 187         ldap_pvt_thread_start_t *start_routine, void *arg )
 188 {
 189         struct ldap_int_thread_pool_s *pool;
 190         ldap_int_thread_ctx_t *ctx;
 191         int need_thread = 0;
 192         ldap_pvt_thread_t thr;
 193
 194         if (tpool == NULL)
 195                 return(-1);
 196
 197         pool = *tpool;
 198
 199         if (pool == NULL)
 200                 return(-1);
 201
 202         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 203         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 204                 || (pool->ltp_max_pending > 0
 205                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 206         {
 207                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 208                 return(-1);
 209         }
 210         ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
 211         if (ctx) {
 212                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 213         } else {
 214                 int i;
 215                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 216                         sizeof(ldap_int_thread_ctx_t));
 217                 if (ctx == NULL) {
 218                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 219                         return(-1);
 220                 }
 221         }
 222
 223         ctx->ltc_start_routine = start_routine;
 224         ctx->ltc_arg = arg;
 225
 226         pool->ltp_pending_count++;
 227         LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
 228         ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 229         if ((pool->ltp_open_count <= 0
 230 #if 0
 231                         || pool->ltp_pending_count > 1
 232 #endif
 233                         || pool->ltp_open_count == pool->ltp_active_count)
 234                 && (pool->ltp_max_count <= 0
 235                         || pool->ltp_open_count < pool->ltp_max_count))
 236         {
 237                 pool->ltp_open_count++;
 238                 pool->ltp_starting++;
 239                 need_thread = 1;
 240         }
 241         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 242
 243         if (need_thread) {
 244                 int rc;
 245
 246                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 247
 248                 rc = ldap_pvt_thread_create( &thr, 1,
 249                         ldap_int_thread_pool_wrapper, pool );
 250                 if (rc == 0) {
 251                         int hash;
 252                         pool->ltp_starting--;
 253
 254                         /* assign this thread ID to a key slot; start
 255                          * at the thread ID itself (mod MAXTHREADS) and
 256                          * look for an empty slot.
 257                          */
 258                         TID_HASH(thr, hash);
 259                         for (rc = hash & (MAXTHREADS-1);
 260                                 !TID_EQ(thread_keys[rc].id, tid_zero);
 261                                 rc = (rc+1) & (MAXTHREADS-1));
 262                         thread_keys[rc].id = thr;
 263                 } else {
 264                         /* couldn't create thread.  back out of
 265                          * ltp_open_count and check for even worse things.
 266                          */
 267                         pool->ltp_open_count--;
 268                         pool->ltp_starting--;
 269                         if (pool->ltp_open_count == 0) {
 270                                 /* no open threads at all?!?
 271                                  */
 272                                 ldap_int_thread_ctx_t *ptr;
 273                                 LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
 274                                         if (ptr == ctx) break;
 275                                 if (ptr == ctx) {
 276                                         /* no open threads, context not handled, so
 277                                          * back out of ltp_pending_count, free the context,
 278                                          * report the error.
 279                                          */
 280                                         LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
 281                                                 ldap_int_thread_ctx_s, ltc_next.q);
 282                                         pool->ltp_pending_count++;
 283                                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 284                                         LDAP_FREE(ctx);
 285                                         return(-1);
 286                                 }
 287                         }
 288                         /* there is another open thread, so this
 289                          * context will be handled eventually.
 290                          * continue on and signal that the context
 291                          * is waiting.
 292                          */
 293                 }
 294                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 295         }
 296
 297         return(0);
 298 }
 299
 300 int
 301 ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
 302 {
 303         struct ldap_int_thread_pool_s *pool;
 304
 305         if (tpool == NULL)
 306                 return(-1);
 307
 308         pool = *tpool;
 309
 310         if (pool == NULL)
 311                 return(-1);
 312
 313         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 314         pool->ltp_max_count = max_threads;
 315         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 316         return(0);
 317 }
 318
 319 int
 320 ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
 321 {
 322         struct ldap_int_thread_pool_s *pool;
 323         int count;
 324
 325         if (tpool == NULL)
 326                 return(-1);
 327
 328         pool = *tpool;
 329
 330         if (pool == NULL)
 331                 return(0);
 332
 333         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 334         count = pool->ltp_pending_count + pool->ltp_active_count;
 335         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 336         return(count);
 337 }
 338
 339 int
 340 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 341 {
 342         struct ldap_int_thread_pool_s *pool, *pptr;
 343         long waiting;
 344         ldap_int_thread_ctx_t *ctx;
 345
 346         if (tpool == NULL)
 347                 return(-1);
 348
 349         pool = *tpool;
 350
 351         if (pool == NULL) return(-1);
 352
 353         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 354         LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 355                 if (pptr == pool) break;
 356         if (pptr == pool)
 357                 LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 358                         ldap_int_thread_pool_s, ltp_next);
 359         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 360
 361         if (pool != pptr) return(-1);
 362
 363         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 364         pool->ltp_state = run_pending
 365                 ? LDAP_INT_THREAD_POOL_FINISHING
 366                 : LDAP_INT_THREAD_POOL_STOPPING;
 367
 368         ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
 369         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 370
 371         do {
 372                 ldap_pvt_thread_yield();
 373                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 374                 waiting = pool->ltp_open_count;
 375                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 376         } while (waiting > 0);
 377
 378         while ((ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 379         {
 380                 LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 381                 LDAP_FREE(ctx);
 382         }
 383
 384         while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
 385         {
 386                 LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
 387                 LDAP_FREE(ctx);
 388         }
 389
 390         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 391         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 392         LDAP_FREE(pool);
 393         return(0);
 394 }
 395
 396 static void *
 397 ldap_int_thread_pool_wrapper (
 398         void *xpool )
 399 {
 400         struct ldap_int_thread_pool_s *pool = xpool;
 401         ldap_int_thread_ctx_t *ctx;
 402         ldap_int_thread_key_t ltc_key[MAXKEYS];
 403         ldap_pvt_thread_t tid;
 404         int i, keyslot, hash;
 405
 406         if (pool == NULL)
 407                 return NULL;
 408
 409         for ( i=0; i<MAXKEYS; i++ ) {
 410                 ltc_key[i].ltk_key = NULL;
 411         }
 412
 413         tid = ldap_pvt_thread_self();
 414
 415         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 416
 417         /* store pointer to our keys */
 418         TID_HASH(tid, hash);
 419         for (i = hash & (MAXTHREADS-1); !TID_EQ(thread_keys[i].id, tid);
 420                                 i = (i+1) & (MAXTHREADS-1));
 421         thread_keys[i].ctx = ltc_key;
 422         keyslot = i;
 423
 424         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 425                 ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
 426                 if (ctx) {
 427                         LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 428                 } else {
 429                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 430                                 break;
 431                         if (pool->ltp_max_count > 0
 432                                 && pool->ltp_open_count > pool->ltp_max_count)
 433                         {
 434                                 /* too many threads running (can happen if the
 435                                  * maximum threads value is set during ongoing
 436                                  * operation using ldap_pvt_thread_pool_maxthreads)
 437                                  * so let this thread die.
 438                                  */
 439                                 break;
 440                         }
 441
 442                         /* we could check an idle timer here, and let the
 443                          * thread die if it has been inactive for a while.
 444                          * only die if there are other open threads (i.e.,
 445                          * always have at least one thread open).  the check
 446                          * should be like this:
 447                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 448                          *       check timer, leave thread (break;)
 449                          */
 450
 451                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 452                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 453
 454                         continue;
 455                 }
 456
 457                 pool->ltp_pending_count--;
 458
 459                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
 460                 pool->ltp_active_count++;
 461                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 462
 463                 ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
 464
 465                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 466                 LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
 467                         ldap_int_thread_ctx_s, ltc_next.al);
 468                 LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
 469                 pool->ltp_active_count--;
 470                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 471
 472                 ldap_pvt_thread_yield();
 473
 474                 /* if we use an idle timer, here's
 475                  * a good place to update it
 476                  */
 477
 478                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 479         }
 480
 481         for ( i=0; i<MAXKEYS && ltc_key[i].ltk_key; i++ ) {
 482                 if (ltc_key[i].ltk_free)
 483                         ltc_key[i].ltk_free(
 484                                 ltc_key[i].ltk_key,
 485                                 ltc_key[i].ltk_data );
 486         }
 487
 488         thread_keys[keyslot].ctx = NULL;
 489         thread_keys[keyslot].id = tid_zero;
 490
 491         pool->ltp_open_count--;
 492         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 493
 494         ldap_pvt_thread_exit(NULL);
 495         return(NULL);
 496 }
 497
 498 int ldap_pvt_thread_pool_getkey(
 499         void *xctx,
 500         void *key,
 501         void **data,
 502         ldap_pvt_thread_pool_keyfree_t **kfree )
 503 {
 504         ldap_int_thread_key_t *ctx = xctx;
 505         int i;
 506
 507         if ( !ctx || !data ) return EINVAL;
 508
 509         for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++ ) {
 510                 if ( ctx[i].ltk_key == key ) {
 511                         *data = ctx[i].ltk_data;
 512                         if ( kfree ) *kfree = ctx[i].ltk_free;
 513                         return 0;
 514                 }
 515         }
 516         return ENOENT;
 517 }
 518
 519 int ldap_pvt_thread_pool_setkey(
 520         void *xctx,
 521         void *key,
 522         void *data,
 523         ldap_pvt_thread_pool_keyfree_t *kfree )
 524 {
 525         ldap_int_thread_key_t *ctx = xctx;
 526         int i;
 527
 528         if ( !ctx || !key ) return EINVAL;
 529
 530         for ( i=0; i<MAXKEYS; i++ ) {
 531                 if ( !ctx[i].ltk_key || ctx[i].ltk_key == key ) {
 532                         ctx[i].ltk_key = key;
 533                         ctx[i].ltk_data = data;
 534                         ctx[i].ltk_free = kfree;
 535                         return 0;
 536                 }
 537         }
 538         return ENOMEM;
 539 }
 540
 541 /*
 542  * This is necessary if the caller does not have access to the
 543  * thread context handle (for example, a slapd plugin calling
 544  * slapi_search_internal()). No doubt it is more efficient to
 545  * for the application to keep track of the thread context
 546  * handles itself.
 547  */
 548 void *ldap_pvt_thread_pool_context( )
 549 {
 550         ldap_pvt_thread_t tid;
 551         int i, hash;
 552
 553         tid = ldap_pvt_thread_self();
 554
 555         TID_HASH( tid, hash );
 556         for (i = hash & (MAXTHREADS-1); !TID_EQ(thread_keys[i].id, tid_zero) &&
 557                 !TID_EQ(thread_keys[i].id, tid); i = (i+1) & (MAXTHREADS-1));
 558
 559         return thread_keys[i].ctx;
 560 }
 561
 562 #endif /* LDAP_THREAD_HAVE_TPOOL */