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 1.2 2005/03/24 12:38:39 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 /*
  49  * Define a high water mark for the maximum number of threads that
  50  * will be cached.  Once this level is reached, any extra threads
  51  * will be free()'d.
  52  */
  53 #define MAX_CACHED_THREADS      100
  54
  55 /*
  56  * We've got to keep track of everything that is allocated, not only
  57  * to have a speedy free list, but also so they can be deallocated
  58  * after a fork().
  59  */
  60 static TAILQ_HEAD(, pthread)    free_threadq;
  61 static umtx_t                   free_thread_lock;
  62 static umtx_t                   tcb_lock;
  63 static int                      free_thread_count = 0;
  64 static int                      inited = 0;
  65 static u_int64_t                next_uniqueid = 1;
  66
  67 LIST_HEAD(thread_hash_head, pthread);
  68 #define HASH_QUEUES     128
  69 static struct thread_hash_head  thr_hashtable[HASH_QUEUES];
  70 #define THREAD_HASH(thrd)       (((unsigned long)thrd >> 12) % HASH_QUEUES)
  71
  72 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
  73
  74 void
  75 _thr_list_init(void)
  76 {
  77         int i;
  78
  79         _gc_count = 0;
  80         _thr_umtx_init(&_thr_list_lock);
  81         TAILQ_INIT(&_thread_list);
  82         TAILQ_INIT(&free_threadq);
  83         _thr_umtx_init(&free_thread_lock);
  84         _thr_umtx_init(&tcb_lock);
  85         if (inited) {
  86                 for (i = 0; i < HASH_QUEUES; ++i)
  87                         LIST_INIT(&thr_hashtable[i]);
  88         }
  89         inited = 1;
  90 }
  91
  92 void
  93 _thr_gc(struct pthread *curthread)
  94 {
  95         struct pthread *td, *td_next;
  96         TAILQ_HEAD(, pthread) worklist;
  97
  98         TAILQ_INIT(&worklist);
  99         THREAD_LIST_LOCK(curthread);
 100
 101         /* Check the threads waiting for GC. */
 102         for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) {
 103                 td_next = TAILQ_NEXT(td, gcle);
 104                 if (td->terminated == 0) {
 105                         /* make sure we are not still in userland */
 106                         continue;
 107                 }
 108                 _thr_stack_free(&td->attr);
 109                 if (((td->tlflags & TLFLAGS_DETACHED) != 0) &&
 110                     (td->refcount == 0)) {
 111                         THR_GCLIST_REMOVE(td);
 112                         /*
 113                          * The thread has detached and is no longer
 114                          * referenced.  It is safe to remove all
 115                          * remnants of the thread.
 116                          */
 117                         THR_LIST_REMOVE(td);
 118                         TAILQ_INSERT_HEAD(&worklist, td, gcle);
 119                 }
 120         }
 121         THREAD_LIST_UNLOCK(curthread);
 122
 123         while ((td = TAILQ_FIRST(&worklist)) != NULL) {
 124                 TAILQ_REMOVE(&worklist, td, gcle);
 125                 /*
 126                  * XXX we don't free initial thread, because there might
 127                  * have some code referencing initial thread.
 128                  */
 129                 if (td == _thr_initial) {
 130                         DBG_MSG("Initial thread won't be freed\n");
 131                         continue;
 132                 }
 133
 134                 DBG_MSG("Freeing thread %p\n", td);
 135                 _thr_free(curthread, td);
 136         }
 137 }
 138
 139 struct pthread *
 140 _thr_alloc(struct pthread *curthread)
 141 {
 142         struct pthread  *thread = NULL;
 143         struct tcb      *tcb;
 144
 145         if (curthread != NULL) {
 146                 if (GC_NEEDED())
 147                         _thr_gc(curthread);
 148                 if (free_thread_count > 0) {
 149                         THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 150                         if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
 151                                 TAILQ_REMOVE(&free_threadq, thread, tle);
 152                                 free_thread_count--;
 153                         }
 154                         THR_LOCK_RELEASE(curthread, &free_thread_lock);
 155                 }
 156         }
 157         if (thread == NULL) {
 158                 thread = malloc(sizeof(struct pthread));
 159                 if (thread == NULL)
 160                         return (NULL);
 161         }
 162         if (curthread != NULL) {
 163                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 164                 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
 165                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 166         } else {
 167                 tcb = _tcb_ctor(thread, 1 /* initial tls */);
 168         }
 169         if (tcb != NULL) {
 170                 memset(thread, 0, sizeof(*thread));
 171                 thread->tcb = tcb;
 172         } else {
 173                 thr_destroy(curthread, thread);
 174                 thread = NULL;
 175         }
 176         return (thread);
 177 }
 178
 179 void
 180 _thr_free(struct pthread *curthread, struct pthread *thread)
 181 {
 182         DBG_MSG("Freeing thread %p\n", thread);
 183         if (thread->name) {
 184                 free(thread->name);
 185                 thread->name = NULL;
 186         }
 187         /*
 188          * Always free tcb, as we only know it is part of RTLD TLS
 189          * block, but don't know its detail and can not assume how
 190          * it works, so better to avoid caching it here.
 191          */
 192         if (curthread != NULL) {
 193                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 194                 _tcb_dtor(thread->tcb);
 195                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 196         } else {
 197                 _tcb_dtor(thread->tcb);
 198         }
 199         thread->tcb = NULL;
 200         if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
 201                 thr_destroy(curthread, thread);
 202         } else {
 203                 /*
 204                  * Add the thread to the free thread list, this also avoids
 205                  * pthread id is reused too quickly, may help some buggy apps.
 206                  */
 207                 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 208                 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
 209                 free_thread_count++;
 210                 THR_LOCK_RELEASE(curthread, &free_thread_lock);
 211         }
 212 }
 213
 214 static void
 215 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
 216 {
 217         free(thread);
 218 }
 219
 220 /*
 221  * Add an active thread:
 222  *
 223  *   o Assign the thread a unique id (which GDB uses to track
 224  *     threads.
 225  *   o Add the thread to the list of all threads and increment
 226  *     number of active threads.
 227  */
 228 void
 229 _thr_link(struct pthread *curthread, struct pthread *thread)
 230 {
 231         THREAD_LIST_LOCK(curthread);
 232         /*
 233          * Initialize the unique id (which GDB uses to track
 234          * threads), add the thread to the list of all threads,
 235          * and
 236          */
 237         thread->uniqueid = next_uniqueid++;
 238         THR_LIST_ADD(thread);
 239         if (thread->attr.flags & PTHREAD_DETACHED)
 240                 thread->tlflags |= TLFLAGS_DETACHED;
 241         _thread_active_threads++;
 242         THREAD_LIST_UNLOCK(curthread);
 243 }
 244
 245 /*
 246  * Remove an active thread.
 247  */
 248 void
 249 _thr_unlink(struct pthread *curthread, struct pthread *thread)
 250 {
 251         THREAD_LIST_LOCK(curthread);
 252         THR_LIST_REMOVE(thread);
 253         _thread_active_threads--;
 254         THREAD_LIST_UNLOCK(curthread);
 255 }
 256
 257 void
 258 _thr_hash_add(struct pthread *thread)
 259 {
 260         struct thread_hash_head *head;
 261
 262         head = &thr_hashtable[THREAD_HASH(thread)];
 263         LIST_INSERT_HEAD(head, thread, hle);
 264 }
 265
 266 void
 267 _thr_hash_remove(struct pthread *thread)
 268 {
 269         LIST_REMOVE(thread, hle);
 270 }
 271
 272 struct pthread *
 273 _thr_hash_find(struct pthread *thread)
 274 {
 275         struct pthread *td;
 276         struct thread_hash_head *head;
 277
 278         head = &thr_hashtable[THREAD_HASH(thread)];
 279         LIST_FOREACH(td, head, hle) {
 280                 if (td == thread)
 281                         return (thread);
 282         }
 283         return (NULL);
 284 }
 285
 286 /*
 287  * Find a thread in the linked list of active threads and add a reference
 288  * to it.  Threads with positive reference counts will not be deallocated
 289  * until all references are released.
 290  */
 291 int
 292 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
 293     int include_dead)
 294 {
 295         int ret;
 296
 297         if (thread == NULL)
 298                 /* Invalid thread: */
 299                 return (EINVAL);
 300
 301         THREAD_LIST_LOCK(curthread);
 302         if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
 303                 thread->refcount++;
 304         }
 305         THREAD_LIST_UNLOCK(curthread);
 306
 307         /* Return zero if the thread exists: */
 308         return (ret);
 309 }
 310
 311 void
 312 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
 313 {
 314         if (thread != NULL) {
 315                 THREAD_LIST_LOCK(curthread);
 316                 thread->refcount--;
 317                 if ((thread->refcount == 0) &&
 318                     (thread->tlflags & TLFLAGS_GC_SAFE) != 0)
 319                         THR_GCLIST_ADD(thread);
 320                 THREAD_LIST_UNLOCK(curthread);
 321         }
 322 }
 323
 324 int
 325 _thr_find_thread(struct pthread *curthread, struct pthread *thread,
 326     int include_dead)
 327 {
 328         struct pthread *pthread;
 329
 330         if (thread == NULL)
 331                 /* Invalid thread: */
 332                 return (EINVAL);
 333
 334         pthread = _thr_hash_find(thread);
 335         if (pthread) {
 336                 if (include_dead == 0 && pthread->state == PS_DEAD) {
 337                         pthread = NULL;
 338                 }
 339         }
 340
 341         /* Return zero if the thread exists: */
 342         return ((pthread != NULL) ? 0 : ESRCH);
 343 }