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

   1 /* $OpenLDAP$ */
   2 /*
   3  * Copyright 1998-2000 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
  21 #include "ldap-int.h"
  22 #include "ldap_pvt_thread.h"
  23 #include "queue-compat.h"
  24
  25 #ifndef LDAP_THREAD_HAVE_TPOOL
  26
  27 enum ldap_int_thread_pool_state {
  28         LDAP_INT_THREAD_POOL_RUNNING,
  29         LDAP_INT_THREAD_POOL_FINISHING,
  30         LDAP_INT_THREAD_POOL_STOPPING
  31 };
  32
  33 typedef struct ldap_int_thread_ctx_s {
  34         union {
  35         SLIST_ENTRY(ldap_int_thread_ctx_s) l;
  36         STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
  37         } ltc_next;
  38         void *(*ltc_start_routine)( void *);
  39         void *ltc_arg;
  40 } ldap_int_thread_ctx_t;
  41
  42 struct ldap_int_thread_pool_s {
  43         STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  44         ldap_pvt_thread_mutex_t ltp_mutex;
  45         ldap_pvt_thread_cond_t ltp_cond;
  46         STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
  47         long ltp_state;
  48         long ltp_max_count;
  49         long ltp_max_pending;
  50         long ltp_pending_count;
  51         long ltp_active_count;
  52         long ltp_open_count;
  53         long ltp_starting;
  54 };
  55
  56 static STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
  57         ldap_int_thread_pool_list =
  58         STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
  59
  60 static SLIST_HEAD(tcl, ldap_int_thread_ctx_s)
  61         ldap_int_ctx_free_list =
  62         SLIST_HEAD_INITIALIZER(ldap_int_ctx_free_list);
  63
  64 static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
  65 static ldap_pvt_thread_mutex_t ldap_pvt_ctx_free_mutex;
  66
  67 static void *ldap_int_thread_pool_wrapper(
  68         struct ldap_int_thread_pool_s *pool );
  69
  70 int
  71 ldap_int_thread_pool_startup ( void )
  72 {
  73         int rc = ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
  74         if (rc == 0)
  75                 rc = ldap_pvt_thread_mutex_init(&ldap_pvt_ctx_free_mutex);
  76         return rc;
  77 }
  78
  79 int
  80 ldap_int_thread_pool_shutdown ( void )
  81 {
  82         ldap_int_thread_ctx_t *ctx;
  83         struct ldap_int_thread_pool_s *pool;
  84
  85         while ((pool = STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
  86                 STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
  87                 ldap_pvt_thread_pool_destroy( &pool, 0);
  88         }
  89         while ((ctx = SLIST_FIRST(&ldap_int_ctx_free_list))) {
  90                 SLIST_REMOVE_HEAD(&ldap_int_ctx_free_list, ltc_next.l);
  91                 free(ctx);
  92         }
  93         ldap_pvt_thread_mutex_destroy(&ldap_pvt_ctx_free_mutex);
  94         ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
  95         return(0);
  96 }
  97
  98 int
  99 ldap_pvt_thread_pool_init (
 100         ldap_pvt_thread_pool_t *tpool,
 101         int max_threads,
 102         int max_pending )
 103 {
 104         ldap_pvt_thread_pool_t pool;
 105         int rc;
 106
 107         *tpool = NULL;
 108         pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
 109                 sizeof(struct ldap_int_thread_pool_s));
 110
 111         if (pool == NULL) return(-1);
 112
 113         rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
 114         if (rc != 0)
 115                 return(rc);
 116         rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
 117         if (rc != 0)
 118                 return(rc);
 119         pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
 120         pool->ltp_max_count = max_threads;
 121         pool->ltp_max_pending = max_pending;
 122         STAILQ_INIT(&pool->ltp_pending_list);
 123         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 124         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,
 146                 (void *) ldap_int_thread_pool_wrapper, pool );
 147
 148         if( rc != 0) {
 149                 /* couldn't start one?  then don't start any */
 150                 ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 151                 STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
 152                         ldap_int_thread_element_s, ltp_next);
 153                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 154                 ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 155                 ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 156                 free(pool);
 157                 return(-1);
 158         }
 159 #endif
 160
 161         *tpool = pool;
 162         return(0);
 163 }
 164
 165 int
 166 ldap_pvt_thread_pool_submit (
 167         ldap_pvt_thread_pool_t *tpool,
 168         void *(*start_routine)( void * ), void *arg )
 169 {
 170         struct ldap_int_thread_pool_s *pool;
 171         ldap_int_thread_ctx_t *ctx;
 172         int need_thread = 0;
 173         ldap_pvt_thread_t thr;
 174
 175         if (tpool == NULL)
 176                 return(-1);
 177
 178         pool = *tpool;
 179
 180         if (pool == NULL)
 181                 return(-1);
 182
 183         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 184         if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
 185                 || (pool->ltp_max_pending > 0
 186                         && pool->ltp_pending_count >= pool->ltp_max_pending))
 187         {
 188                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 189                 return(-1);
 190         }
 191         ldap_pvt_thread_mutex_lock(&ldap_pvt_ctx_free_mutex);
 192         ctx = SLIST_FIRST(&ldap_int_ctx_free_list);
 193         if (ctx) {
 194                 SLIST_REMOVE_HEAD(&ldap_int_ctx_free_list, ltc_next.l);
 195                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_ctx_free_mutex);
 196         } else {
 197                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_ctx_free_mutex);
 198                 ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
 199                         sizeof(ldap_int_thread_ctx_t));
 200                 if (ctx == NULL) {
 201                         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 202                         return(-1);
 203                 }
 204         }
 205
 206         ctx->ltc_start_routine = start_routine;
 207         ctx->ltc_arg = arg;
 208
 209         pool->ltp_pending_count++;
 210         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                         (void *)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                                 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                                         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                                         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 int
 307 ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
 308 {
 309         struct ldap_int_thread_pool_s *pool, *pptr;
 310         long waiting;
 311         ldap_int_thread_ctx_t *ctx;
 312
 313         if (tpool == NULL)
 314                 return(-1);
 315
 316         pool = *tpool;
 317
 318         if (pool == NULL) return(-1);
 319
 320         ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
 321         STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
 322                 if (pptr == pool) break;
 323         if (pptr == pool)
 324                 STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
 325                         ldap_int_thread_pool_s, ltp_next);
 326         ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
 327
 328         if (pool != pptr) return(-1);
 329
 330         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 331         pool->ltp_state = run_pending
 332                 ? LDAP_INT_THREAD_POOL_FINISHING
 333                 : LDAP_INT_THREAD_POOL_STOPPING;
 334         waiting = pool->ltp_open_count;
 335
 336         /* broadcast could be used here, but only after
 337          * it is fixed in the NT thread implementation
 338          */
 339         while (--waiting >= 0) {
 340                 ldap_pvt_thread_cond_signal(&pool->ltp_cond);
 341         }
 342         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 343
 344         do {
 345                 ldap_pvt_thread_yield();
 346                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 347                 waiting = pool->ltp_open_count;
 348                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 349         } while (waiting > 0);
 350
 351         while ((ctx = STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
 352         {
 353                 STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 354                 free(ctx);
 355         }
 356
 357         ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
 358         ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
 359         free(pool);
 360         return(0);
 361 }
 362
 363 static void *
 364 ldap_int_thread_pool_wrapper (
 365         struct ldap_int_thread_pool_s *pool )
 366 {
 367         ldap_int_thread_ctx_t *ctx;
 368
 369         if (pool == NULL)
 370                 return NULL;
 371
 372         ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 373
 374         while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
 375                 ctx = STAILQ_FIRST(&pool->ltp_pending_list);
 376                 if (ctx) {
 377                         STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
 378                 } else {
 379                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
 380                                 break;
 381                         if (pool->ltp_max_count > 0
 382                                 && pool->ltp_open_count > pool->ltp_max_count)
 383                         {
 384                                 /* too many threads running (can happen if the
 385                                  * maximum threads value is set during ongoing
 386                                  * operation using ldap_pvt_thread_pool_maxthreads)
 387                                  * so let this thread die.
 388                                  */
 389                                 break;
 390                         }
 391
 392                         /* we could check an idle timer here, and let the
 393                          * thread die if it has been inactive for a while.
 394                          * only die if there are other open threads (i.e.,
 395                          * always have at least one thread open).  the check
 396                          * should be like this:
 397                          *   if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
 398                          *       check timer, leave thread (break;)
 399                          */
 400
 401                         if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
 402                                 ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
 403
 404                         continue;
 405                 }
 406
 407                 pool->ltp_pending_count--;
 408                 pool->ltp_active_count++;
 409                 ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 410
 411                 (ctx->ltc_start_routine)(ctx->ltc_arg);
 412                 ldap_pvt_thread_mutex_lock(&ldap_pvt_ctx_free_mutex);
 413                 SLIST_INSERT_HEAD(&ldap_int_ctx_free_list, ctx, ltc_next.l);
 414                 ldap_pvt_thread_mutex_unlock(&ldap_pvt_ctx_free_mutex);
 415                 ldap_pvt_thread_yield();
 416
 417                 /* if we use an idle timer, here's
 418                  * a good place to update it
 419                  */
 420
 421                 ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
 422                 pool->ltp_active_count--;
 423         }
 424
 425         pool->ltp_open_count--;
 426         ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
 427
 428         ldap_pvt_thread_exit(NULL);
 429         return(NULL);
 430 }
 431 #endif /* LDAP_HAVE_THREAD_POOL */