lib/libthread_xu/thread/thr_list.c

   1 /*
   2  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
   3  * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice unmodified, this list of conditions, and the following
  11  *    disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  *
  27  * $DragonFly: src/lib/libthread_xu/thread/thr_list.c,v 1.7 2006/04/06 13:03:09 davidxu Exp $
  28  */
  29
  30 #include <sys/cdefs.h>
  31 #include <sys/types.h>
  32 #include <sys/queue.h>
  33
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <pthread.h>
  37
  38 #include "thr_private.h"
  39 #include "libc_private.h"
  40
  41 /* #define DEBUG_THREAD_LIST */
  42 #ifdef DEBUG_THREAD_LIST
  43 #define DBG_MSG         stdout_debug
  44 #else
  45 #define DBG_MSG(x...)
  46 #endif
  47
  48 /* List of all threads */
  49 struct thread_head _thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
  50
  51 /* List of threads needing GC */
  52 struct thread_head _thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
  53
  54 /* Number of active threads */
  55 int     _thread_active_threads = 1;
  56
  57 /* Garbage thread count. */
  58 int     _thr_gc_count;
  59
  60 umtx_t  _thr_list_lock;
  61
  62 /*
  63  * Define a high water mark for the maximum number of threads that
  64  * will be cached.  Once this level is reached, any extra threads
  65  * will be free()'d.
  66  */
  67 #define MAX_CACHED_THREADS      100
  68
  69 /*
  70  * We've got to keep track of everything that is allocated, not only
  71  * to have a speedy free list, but also so they can be deallocated
  72  * after a fork().
  73  */
  74 static TAILQ_HEAD(, pthread)    free_threadq;
  75 static umtx_t                   free_thread_lock;
  76 static umtx_t                   tcb_lock;
  77 static int                      free_thread_count = 0;
  78 static int                      inited = 0;
  79 static u_int64_t                next_uniqueid = 1;
  80
  81 LIST_HEAD(thread_hash_head, pthread);
  82 #define HASH_QUEUES     128
  83 static struct thread_hash_head  thr_hashtable[HASH_QUEUES];
  84 #define THREAD_HASH(thrd)       (((unsigned long)thrd >> 12) % HASH_QUEUES)
  85
  86 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
  87
  88 void
  89 _thr_list_init(void)
  90 {
  91         int i;
  92
  93         _thr_gc_count = 0;
  94         _thr_umtx_init(&_thr_list_lock);
  95         TAILQ_INIT(&_thread_list);
  96         TAILQ_INIT(&free_threadq);
  97         _thr_umtx_init(&free_thread_lock);
  98         _thr_umtx_init(&tcb_lock);
  99         if (inited) {
 100                 for (i = 0; i < HASH_QUEUES; ++i)
 101                         LIST_INIT(&thr_hashtable[i]);
 102         }
 103         inited = 1;
 104 }
 105
 106 void
 107 _thr_gc(struct pthread *curthread)
 108 {
 109         struct pthread *td, *td_next;
 110         TAILQ_HEAD(, pthread) worklist;
 111
 112         TAILQ_INIT(&worklist);
 113         THREAD_LIST_LOCK(curthread);
 114
 115         /* Check the threads waiting for GC. */
 116         for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) {
 117                 td_next = TAILQ_NEXT(td, gcle);
 118                 if (td->terminated == 0) {
 119                         /* make sure we are not still in userland */
 120                         continue;
 121                 }
 122                 _thr_stack_free(&td->attr);
 123                 if (((td->tlflags & TLFLAGS_DETACHED) != 0) &&
 124                     (td->refcount == 0)) {
 125                         THR_GCLIST_REMOVE(td);
 126                         /*
 127                          * The thread has detached and is no longer
 128                          * referenced.  It is safe to remove all
 129                          * remnants of the thread.
 130                          */
 131                         THR_LIST_REMOVE(td);
 132                         TAILQ_INSERT_HEAD(&worklist, td, gcle);
 133                 }
 134         }
 135         THREAD_LIST_UNLOCK(curthread);
 136
 137         while ((td = TAILQ_FIRST(&worklist)) != NULL) {
 138                 TAILQ_REMOVE(&worklist, td, gcle);
 139                 /*
 140                  * XXX we don't free initial thread, because there might
 141                  * have some code referencing initial thread.
 142                  */
 143                 if (td == _thr_initial) {
 144                         DBG_MSG("Initial thread won't be freed\n");
 145                         continue;
 146                 }
 147
 148                 _thr_free(curthread, td);
 149         }
 150 }
 151
 152 struct pthread *
 153 _thr_alloc(struct pthread *curthread)
 154 {
 155         struct pthread  *thread = NULL;
 156         struct tls_tcb  *tcb;
 157
 158         if (curthread != NULL) {
 159                 if (GC_NEEDED())
 160                         _thr_gc(curthread);
 161                 if (free_thread_count > 0) {
 162                         THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 163                         if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
 164                                 TAILQ_REMOVE(&free_threadq, thread, tle);
 165                                 free_thread_count--;
 166                         }
 167                         THR_LOCK_RELEASE(curthread, &free_thread_lock);
 168                 }
 169         }
 170         if (thread == NULL) {
 171                 thread = malloc(sizeof(struct pthread));
 172                 if (thread == NULL)
 173                         return (NULL);
 174         }
 175         if (curthread != NULL) {
 176                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 177                 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
 178                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 179         } else {
 180                 tcb = _tcb_ctor(thread, 1 /* initial tls */);
 181         }
 182         if (tcb != NULL) {
 183                 memset(thread, 0, sizeof(*thread));
 184                 thread->tcb = tcb;
 185         } else {
 186                 thr_destroy(curthread, thread);
 187                 thread = NULL;
 188         }
 189         return (thread);
 190 }
 191
 192 void
 193 _thr_free(struct pthread *curthread, struct pthread *thread)
 194 {
 195         DBG_MSG("Freeing thread %p\n", thread);
 196         if (thread->name) {
 197                 free(thread->name);
 198                 thread->name = NULL;
 199         }
 200         /*
 201          * Always free tcb, as we only know it is part of RTLD TLS
 202          * block, but don't know its detail and can not assume how
 203          * it works, so better to avoid caching it here.
 204          */
 205         if (curthread != NULL) {
 206                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 207                 _tcb_dtor(thread->tcb);
 208                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 209         } else {
 210                 _tcb_dtor(thread->tcb);
 211         }
 212         thread->tcb = NULL;
 213         if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
 214                 thr_destroy(curthread, thread);
 215         } else {
 216                 /*
 217                  * Add the thread to the free thread list, this also avoids
 218                  * pthread id is reused too quickly, may help some buggy apps.
 219                  */
 220                 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 221                 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
 222                 free_thread_count++;
 223                 THR_LOCK_RELEASE(curthread, &free_thread_lock);
 224         }
 225 }
 226
 227 static void
 228 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
 229 {
 230         free(thread);
 231 }
 232
 233 /*
 234  * Add an active thread:
 235  *
 236  *   o Assign the thread a unique id (which GDB uses to track
 237  *     threads.
 238  *   o Add the thread to the list of all threads and increment
 239  *     number of active threads.
 240  */
 241 void
 242 _thr_link(struct pthread *curthread, struct pthread *thread)
 243 {
 244         THREAD_LIST_LOCK(curthread);
 245         /*
 246          * Initialize the unique id (which GDB uses to track
 247          * threads), add the thread to the list of all threads,
 248          * and
 249          */
 250         thread->uniqueid = next_uniqueid++;
 251         THR_LIST_ADD(thread);
 252         _thread_active_threads++;
 253         THREAD_LIST_UNLOCK(curthread);
 254 }
 255
 256 /*
 257  * Remove an active thread.
 258  */
 259 void
 260 _thr_unlink(struct pthread *curthread, struct pthread *thread)
 261 {
 262         THREAD_LIST_LOCK(curthread);
 263         THR_LIST_REMOVE(thread);
 264         _thread_active_threads--;
 265         THREAD_LIST_UNLOCK(curthread);
 266 }
 267
 268 void
 269 _thr_hash_add(struct pthread *thread)
 270 {
 271         struct thread_hash_head *head;
 272
 273         head = &thr_hashtable[THREAD_HASH(thread)];
 274         LIST_INSERT_HEAD(head, thread, hle);
 275 }
 276
 277 void
 278 _thr_hash_remove(struct pthread *thread)
 279 {
 280         LIST_REMOVE(thread, hle);
 281 }
 282
 283 struct pthread *
 284 _thr_hash_find(struct pthread *thread)
 285 {
 286         struct pthread *td;
 287         struct thread_hash_head *head;
 288
 289         head = &thr_hashtable[THREAD_HASH(thread)];
 290         LIST_FOREACH(td, head, hle) {
 291                 if (td == thread)
 292                         return (thread);
 293         }
 294         return (NULL);
 295 }
 296
 297 /*
 298  * Find a thread in the linked list of active threads and add a reference
 299  * to it.  Threads with positive reference counts will not be deallocated
 300  * until all references are released.
 301  */
 302 int
 303 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
 304     int include_dead)
 305 {
 306         int ret;
 307
 308         if (thread == NULL)
 309                 /* Invalid thread: */
 310                 return (EINVAL);
 311
 312         THREAD_LIST_LOCK(curthread);
 313         if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
 314                 thread->refcount++;
 315         }
 316         THREAD_LIST_UNLOCK(curthread);
 317
 318         /* Return zero if the thread exists: */
 319         return (ret);
 320 }
 321
 322 void
 323 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
 324 {
 325         THREAD_LIST_LOCK(curthread);
 326         _thr_ref_delete_unlocked(curthread, thread);
 327         THREAD_LIST_UNLOCK(curthread);
 328 }
 329
 330 void
 331 _thr_ref_delete_unlocked(struct pthread *curthread __unused,
 332         struct pthread *thread)
 333 {
 334         if (thread != NULL) {
 335                 thread->refcount--;
 336                 if ((thread->refcount == 0) && thread->state == PS_DEAD &&
 337                     (thread->tlflags & TLFLAGS_DETACHED) != 0)
 338                         THR_GCLIST_ADD(thread);
 339         }
 340 }
 341
 342 int
 343 _thr_find_thread(struct pthread *curthread __unused, struct pthread *thread,
 344     int include_dead)
 345 {
 346         struct pthread *pthread;
 347
 348         if (thread == NULL)
 349                 /* Invalid thread: */
 350                 return (EINVAL);
 351
 352         pthread = _thr_hash_find(thread);
 353         if (pthread) {
 354                 if (include_dead == 0 && pthread->state == PS_DEAD) {
 355                         pthread = NULL;
 356                 }
 357         }
 358
 359         /* Return zero if the thread exists: */
 360         return ((pthread != NULL) ? 0 : ESRCH);
 361 }