lib/fuse_loop_mt.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU LGPLv2.
   6   See the file COPYING.LIB.
   7 */
   8
   9 #include "fuse_lowlevel.h"
  10 #include "fuse_misc.h"
  11 #include "fuse_kernel.h"
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <signal.h>
  18 #include <semaphore.h>
  19 #include <errno.h>
  20 #include <sys/time.h>
  21
  22 /* Environment var controlling the thread stack size */
  23 #define ENVNAME_THREAD_STACK "FUSE_THREAD_STACK"
  24
  25 struct fuse_worker {
  26         struct fuse_worker *prev;
  27         struct fuse_worker *next;
  28         pthread_t thread_id;
  29         size_t bufsize;
  30         char *buf;
  31         struct fuse_mt *mt;
  32 };
  33
  34 struct fuse_mt {
  35         pthread_mutex_t lock;
  36         int numworker;
  37         int numavail;
  38         struct fuse_session *se;
  39         struct fuse_chan *prevch;
  40         struct fuse_worker main;
  41         sem_t finish;
  42         int exit;
  43         int error;
  44 };
  45
  46 static void list_add_worker(struct fuse_worker *w, struct fuse_worker *next)
  47 {
  48         struct fuse_worker *prev = next->prev;
  49         w->next = next;
  50         w->prev = prev;
  51         prev->next = w;
  52         next->prev = w;
  53 }
  54
  55 static void list_del_worker(struct fuse_worker *w)
  56 {
  57         struct fuse_worker *prev = w->prev;
  58         struct fuse_worker *next = w->next;
  59         prev->next = next;
  60         next->prev = prev;
  61 }
  62
  63 static int fuse_start_thread(struct fuse_mt *mt);
  64
  65 static void *fuse_do_work(void *data)
  66 {
  67         struct fuse_worker *w = (struct fuse_worker *) data;
  68         struct fuse_mt *mt = w->mt;
  69
  70         while (!fuse_session_exited(mt->se)) {
  71                 int isforget = 0;
  72                 struct fuse_chan *ch = mt->prevch;
  73                 int res = fuse_chan_recv(&ch, w->buf, w->bufsize);
  74                 if (res == -EINTR)
  75                         continue;
  76                 if (res <= 0) {
  77                         if (res < 0) {
  78                                 fuse_session_exit(mt->se);
  79                                 mt->error = -1;
  80                         }
  81                         break;
  82                 }
  83
  84                 pthread_mutex_lock(&mt->lock);
  85                 if (mt->exit) {
  86                         pthread_mutex_unlock(&mt->lock);
  87                         return NULL;
  88                 }
  89
  90                 /*
  91                  * This disgusting hack is needed so that zillions of threads
  92                  * are not created on a burst of FORGET messages
  93                  */
  94                 if (((struct fuse_in_header *) w->buf)->opcode == FUSE_FORGET)
  95                         isforget = 1;
  96
  97                 if (!isforget)
  98                         mt->numavail--;
  99                 if (mt->numavail == 0)
 100                         fuse_start_thread(mt);
 101                 pthread_mutex_unlock(&mt->lock);
 102
 103                 fuse_session_process(mt->se, w->buf, res, ch);
 104
 105                 pthread_mutex_lock(&mt->lock);
 106                 if (!isforget)
 107                         mt->numavail++;
 108                 if (mt->numavail > 10) {
 109                         if (mt->exit) {
 110                                 pthread_mutex_unlock(&mt->lock);
 111                                 return NULL;
 112                         }
 113                         list_del_worker(w);
 114                         mt->numavail--;
 115                         mt->numworker--;
 116                         pthread_mutex_unlock(&mt->lock);
 117
 118                         pthread_detach(w->thread_id);
 119                         free(w->buf);
 120                         free(w);
 121                         return NULL;
 122                 }
 123                 pthread_mutex_unlock(&mt->lock);
 124         }
 125
 126         sem_post(&mt->finish);
 127         pause();
 128
 129         return NULL;
 130 }
 131
 132 static int fuse_start_thread(struct fuse_mt *mt)
 133 {
 134         sigset_t oldset;
 135         sigset_t newset;
 136         int res;
 137         pthread_attr_t attr;
 138         char *stack_size;
 139         struct fuse_worker *w = malloc(sizeof(struct fuse_worker));
 140         if (!w) {
 141                 fprintf(stderr, "fuse: failed to allocate worker structure\n");
 142                 return -1;
 143         }
 144         memset(w, 0, sizeof(struct fuse_worker));
 145         w->bufsize = fuse_chan_bufsize(mt->prevch);
 146         w->buf = malloc(w->bufsize);
 147         w->mt = mt;
 148         if (!w->buf) {
 149                 fprintf(stderr, "fuse: failed to allocate read buffer\n");
 150                 free(w);
 151                 return -1;
 152         }
 153
 154         /* Override default stack size */
 155         pthread_attr_init(&attr);
 156         stack_size = getenv(ENVNAME_THREAD_STACK);
 157         if (stack_size && pthread_attr_setstacksize(&attr, atoi(stack_size)))
 158                 fprintf(stderr, "fuse: invalid stack size: %s\n", stack_size);
 159
 160         /* Disallow signal reception in worker threads */
 161         sigemptyset(&newset);
 162         sigaddset(&newset, SIGTERM);
 163         sigaddset(&newset, SIGINT);
 164         sigaddset(&newset, SIGHUP);
 165         sigaddset(&newset, SIGQUIT);
 166         pthread_sigmask(SIG_BLOCK, &newset, &oldset);
 167         res = pthread_create(&w->thread_id, &attr, fuse_do_work, w);
 168         pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 169         pthread_attr_destroy(&attr);
 170         if (res != 0) {
 171                 fprintf(stderr, "fuse: error creating thread: %s\n",
 172                         strerror(res));
 173                 free(w->buf);
 174                 free(w);
 175                 return -1;
 176         }
 177         list_add_worker(w, &mt->main);
 178         mt->numavail ++;
 179         mt->numworker ++;
 180
 181         return 0;
 182 }
 183
 184 static void fuse_join_worker(struct fuse_mt *mt, struct fuse_worker *w)
 185 {
 186         pthread_join(w->thread_id, NULL);
 187         pthread_mutex_lock(&mt->lock);
 188         list_del_worker(w);
 189         pthread_mutex_unlock(&mt->lock);
 190         free(w->buf);
 191         free(w);
 192 }
 193
 194 int fuse_session_loop_mt(struct fuse_session *se)
 195 {
 196         int err;
 197         struct fuse_mt mt;
 198         struct fuse_worker *w;
 199
 200         memset(&mt, 0, sizeof(struct fuse_mt));
 201         mt.se = se;
 202         mt.prevch = fuse_session_next_chan(se, NULL);
 203         mt.error = 0;
 204         mt.numworker = 0;
 205         mt.numavail = 0;
 206         mt.main.thread_id = pthread_self();
 207         mt.main.prev = mt.main.next = &mt.main;
 208         sem_init(&mt.finish, 0, 0);
 209         fuse_mutex_init(&mt.lock);
 210
 211         pthread_mutex_lock(&mt.lock);
 212         err = fuse_start_thread(&mt);
 213         pthread_mutex_unlock(&mt.lock);
 214         if (!err) {
 215                 /* sem_wait() is interruptible */
 216                 while (!fuse_session_exited(se))
 217                         sem_wait(&mt.finish);
 218
 219                 for (w = mt.main.next; w != &mt.main; w = w->next)
 220                         pthread_cancel(w->thread_id);
 221                 mt.exit = 1;
 222                 pthread_mutex_unlock(&mt.lock);
 223
 224                 while (mt.main.next != &mt.main)
 225                         fuse_join_worker(&mt, mt.main.next);
 226
 227                 err = mt.error;
 228         }
 229
 230         pthread_mutex_destroy(&mt.lock);
 231         sem_destroy(&mt.finish);
 232         fuse_session_reset(se);
 233         return err;
 234 }