lib/frr_pthread.c

   1 /*
   2  * Utilities and interfaces for managing POSIX threads within FRR.
   3  * Copyright (C) 2017  Cumulus Networks, Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; see the file COPYING; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 #include <zebra.h>
  21 #include <pthread.h>
  22 #include <sched.h>
  23
  24 #include "frr_pthread.h"
  25 #include "memory.h"
  26 #include "hash.h"
  27
  28 DEFINE_MTYPE(LIB, FRR_PTHREAD, "FRR POSIX Thread");
  29 DEFINE_MTYPE(LIB, PTHREAD_PRIM, "POSIX synchronization primitives");
  30
  31 /* id for next created pthread */
  32 static _Atomic uint32_t next_id = 0;
  33
  34 /* default frr_pthread start/stop routine prototypes */
  35 static void *fpt_run(void *arg);
  36 static int fpt_halt(struct frr_pthread *fpt, void **res);
  37
  38 /* default frr_pthread attributes */
  39 struct frr_pthread_attr frr_pthread_attr_default = {
  40         .id = 0,
  41         .start = fpt_run,
  42         .stop = fpt_halt,
  43 };
  44
  45 /* hash table to keep track of all frr_pthreads */
  46 static struct hash *frr_pthread_hash;
  47 static pthread_mutex_t frr_pthread_hash_mtx = PTHREAD_MUTEX_INITIALIZER;
  48
  49 /* frr_pthread_hash->hash_cmp */
  50 static int frr_pthread_hash_cmp(const void *value1, const void *value2)
  51 {
  52         const struct frr_pthread *tq1 = value1;
  53         const struct frr_pthread *tq2 = value2;
  54
  55         return (tq1->attr.id == tq2->attr.id);
  56 }
  57
  58 /* frr_pthread_hash->hash_key */
  59 static unsigned int frr_pthread_hash_key(void *value)
  60 {
  61         return ((struct frr_pthread *)value)->attr.id;
  62 }
  63
  64 /* ------------------------------------------------------------------------ */
  65
  66 void frr_pthread_init()
  67 {
  68         pthread_mutex_lock(&frr_pthread_hash_mtx);
  69         {
  70                 frr_pthread_hash = hash_create(frr_pthread_hash_key,
  71                                                frr_pthread_hash_cmp, NULL);
  72         }
  73         pthread_mutex_unlock(&frr_pthread_hash_mtx);
  74 }
  75
  76 void frr_pthread_finish()
  77 {
  78         pthread_mutex_lock(&frr_pthread_hash_mtx);
  79         {
  80                 hash_clean(frr_pthread_hash,
  81                            (void (*)(void *))frr_pthread_destroy);
  82                 hash_free(frr_pthread_hash);
  83         }
  84         pthread_mutex_unlock(&frr_pthread_hash_mtx);
  85 }
  86
  87 struct frr_pthread *frr_pthread_new(struct frr_pthread_attr *attr,
  88                                     const char *name)
  89 {
  90         static struct frr_pthread holder = {};
  91         struct frr_pthread *fpt = NULL;
  92
  93         attr = attr ? attr : &frr_pthread_attr_default;
  94
  95         pthread_mutex_lock(&frr_pthread_hash_mtx);
  96         {
  97                 holder.attr.id = attr->id;
  98
  99                 if (!hash_lookup(frr_pthread_hash, &holder)) {
 100                         fpt = XCALLOC(MTYPE_FRR_PTHREAD,
 101                                       sizeof(struct frr_pthread));
 102                         /* initialize mutex */
 103                         pthread_mutex_init(&fpt->mtx, NULL);
 104                         /* create new thread master */
 105                         fpt->master = thread_master_create(name);
 106                         /* set attributes */
 107                         fpt->attr = *attr;
 108                         name = (name ? name : "Anonymous thread");
 109                         fpt->name = XSTRDUP(MTYPE_FRR_PTHREAD, name);
 110                         if (attr == &frr_pthread_attr_default)
 111                                 fpt->attr.id = frr_pthread_get_id();
 112                         /* initialize startup synchronization primitives */
 113                         fpt->running_cond_mtx = XCALLOC(
 114                                 MTYPE_PTHREAD_PRIM, sizeof(pthread_mutex_t));
 115                         fpt->running_cond = XCALLOC(MTYPE_PTHREAD_PRIM,
 116                                                     sizeof(pthread_cond_t));
 117                         pthread_mutex_init(fpt->running_cond_mtx, NULL);
 118                         pthread_cond_init(fpt->running_cond, NULL);
 119
 120                         /* insert into global thread hash */
 121                         hash_get(frr_pthread_hash, fpt, hash_alloc_intern);
 122                 }
 123         }
 124         pthread_mutex_unlock(&frr_pthread_hash_mtx);
 125
 126         return fpt;
 127 }
 128
 129 void frr_pthread_destroy(struct frr_pthread *fpt)
 130 {
 131         thread_master_free(fpt->master);
 132
 133         pthread_mutex_destroy(&fpt->mtx);
 134         pthread_mutex_destroy(fpt->running_cond_mtx);
 135         pthread_cond_destroy(fpt->running_cond);
 136         if (fpt->name)
 137                 XFREE(MTYPE_FRR_PTHREAD, fpt->name);
 138         XFREE(MTYPE_PTHREAD_PRIM, fpt->running_cond_mtx);
 139         XFREE(MTYPE_PTHREAD_PRIM, fpt->running_cond);
 140         XFREE(MTYPE_FRR_PTHREAD, fpt);
 141 }
 142
 143 void frr_pthread_set_name(struct frr_pthread *fpt, const char *name)
 144 {
 145         pthread_mutex_lock(&fpt->mtx);
 146         {
 147                 if (fpt->name)
 148                         XFREE(MTYPE_FRR_PTHREAD, fpt->name);
 149                 fpt->name = XSTRDUP(MTYPE_FRR_PTHREAD, name);
 150         }
 151         pthread_mutex_unlock(&fpt->mtx);
 152         thread_master_set_name(fpt->master, name);
 153 }
 154
 155 struct frr_pthread *frr_pthread_get(uint32_t id)
 156 {
 157         static struct frr_pthread holder = {};
 158         struct frr_pthread *fpt;
 159
 160         pthread_mutex_lock(&frr_pthread_hash_mtx);
 161         {
 162                 holder.attr.id = id;
 163                 fpt = hash_lookup(frr_pthread_hash, &holder);
 164         }
 165         pthread_mutex_unlock(&frr_pthread_hash_mtx);
 166
 167         return fpt;
 168 }
 169
 170 int frr_pthread_run(struct frr_pthread *fpt, const pthread_attr_t *attr)
 171 {
 172         int ret;
 173
 174         ret = pthread_create(&fpt->thread, attr, fpt->attr.start, fpt);
 175
 176         /*
 177          * Per pthread_create(3), the contents of fpt->thread are undefined if
 178          * pthread_create() did not succeed. Reset this value to zero.
 179          */
 180         if (ret < 0)
 181                 memset(&fpt->thread, 0x00, sizeof(fpt->thread));
 182
 183         return ret;
 184 }
 185
 186 void frr_pthread_wait_running(struct frr_pthread *fpt)
 187 {
 188         pthread_mutex_lock(fpt->running_cond_mtx);
 189         {
 190                 while (!fpt->running)
 191                         pthread_cond_wait(fpt->running_cond,
 192                                           fpt->running_cond_mtx);
 193         }
 194         pthread_mutex_unlock(fpt->running_cond_mtx);
 195 }
 196
 197 void frr_pthread_notify_running(struct frr_pthread *fpt)
 198 {
 199         pthread_mutex_lock(fpt->running_cond_mtx);
 200         {
 201                 fpt->running = true;
 202                 pthread_cond_signal(fpt->running_cond);
 203         }
 204         pthread_mutex_unlock(fpt->running_cond_mtx);
 205 }
 206
 207 int frr_pthread_stop(struct frr_pthread *fpt, void **result)
 208 {
 209         int ret = (*fpt->attr.stop)(fpt, result);
 210         memset(&fpt->thread, 0x00, sizeof(fpt->thread));
 211         return ret;
 212 }
 213
 214 /*
 215  * Callback for hash_iterate to stop all frr_pthread's.
 216  */
 217 static void frr_pthread_stop_all_iter(struct hash_backet *hb, void *arg)
 218 {
 219         struct frr_pthread *fpt = hb->data;
 220         frr_pthread_stop(fpt, NULL);
 221 }
 222
 223 void frr_pthread_stop_all()
 224 {
 225         pthread_mutex_lock(&frr_pthread_hash_mtx);
 226         {
 227                 hash_iterate(frr_pthread_hash, frr_pthread_stop_all_iter, NULL);
 228         }
 229         pthread_mutex_unlock(&frr_pthread_hash_mtx);
 230 }
 231
 232 uint32_t frr_pthread_get_id(void)
 233 {
 234         _Atomic uint32_t nxid;
 235         nxid = atomic_fetch_add_explicit(&next_id, 1, memory_order_seq_cst);
 236         /* just a sanity check, this should never happen */
 237         assert(nxid <= (UINT32_MAX - 1));
 238         return nxid;
 239 }
 240
 241 void frr_pthread_yield(void)
 242 {
 243         (void)sched_yield();
 244 }
 245
 246 /*
 247  * ----------------------------------------------------------------------------
 248  * Default Event Loop
 249  * ----------------------------------------------------------------------------
 250  */
 251
 252 /* dummy task for sleeper pipe */
 253 static int fpt_dummy(struct thread *thread)
 254 {
 255         return 0;
 256 }
 257
 258 /* poison pill task to end event loop */
 259 static int fpt_finish(struct thread *thread)
 260 {
 261         struct frr_pthread *fpt = THREAD_ARG(thread);
 262
 263         atomic_store_explicit(&fpt->running, false, memory_order_relaxed);
 264         return 0;
 265 }
 266
 267 /* stop function, called from other threads to halt this one */
 268 static int fpt_halt(struct frr_pthread *fpt, void **res)
 269 {
 270         thread_add_event(fpt->master, &fpt_finish, fpt, 0, NULL);
 271         pthread_join(fpt->thread, res);
 272         fpt = NULL;
 273
 274         return 0;
 275 }
 276
 277 /* entry pthread function & main event loop */
 278 static void *fpt_run(void *arg)
 279 {
 280         struct frr_pthread *fpt = arg;
 281         fpt->master->owner = pthread_self();
 282
 283         int sleeper[2];
 284         pipe(sleeper);
 285         thread_add_read(fpt->master, &fpt_dummy, NULL, sleeper[0], NULL);
 286
 287         fpt->master->handle_signals = false;
 288
 289         frr_pthread_notify_running(fpt);
 290
 291         struct thread task;
 292         while (atomic_load_explicit(&fpt->running, memory_order_relaxed)) {
 293                 if (thread_fetch(fpt->master, &task)) {
 294                         thread_call(&task);
 295                 }
 296         }
 297
 298         close(sleeper[1]);
 299         close(sleeper[0]);
 300
 301         return NULL;
 302 }