ltt-sessiond/session.c

   1 /*
   2  * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; only version 2
   7  * of the License.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <limits.h>
  21 #include <pthread.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <time.h>
  26 #include <urcu/list.h>
  27
  28 #include "lttngerr.h"
  29 #include "session.h"
  30
  31 /*
  32  * NOTES:
  33  *
  34  * No ltt_session.lock is taken here because those data structure are widely
  35  * spread across the lttng-tools code base so before caling functions below
  36  * that can read/write a session, the caller MUST acquire the session lock
  37  * using lock_session() and unlock_session().
  38  */
  39
  40 /*
  41  * Init tracing session list.
  42  *
  43  * Please see session.h for more explanation and correct usage of the list.
  44  */
  45 static struct ltt_session_list ltt_session_list = {
  46         .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
  47         .lock = PTHREAD_MUTEX_INITIALIZER,
  48         .count = 0,
  49 };
  50
  51 /*
  52  *  add_session_list
  53  *
  54  *  Add a ltt_session structure to the global list.
  55  *
  56  *  The caller MUST acquire the session list lock before.
  57  */
  58 static void add_session_list(struct ltt_session *ls)
  59 {
  60         cds_list_add(&ls->list, &ltt_session_list.head);
  61         ltt_session_list.count++;
  62 }
  63
  64 /*
  65  *  del_session_list
  66  *
  67  *  Delete a ltt_session structure to the global list.
  68  *
  69  *  The caller MUST acquire the session list lock before.
  70  */
  71 static void del_session_list(struct ltt_session *ls)
  72 {
  73         cds_list_del(&ls->list);
  74         /* Sanity check */
  75         if (ltt_session_list.count > 0) {
  76                 ltt_session_list.count--;
  77         }
  78 }
  79
  80 /*
  81  *  get_session_list
  82  *
  83  *  Return a pointer to the session list.
  84  */
  85 struct ltt_session_list *get_session_list(void)
  86 {
  87         return &ltt_session_list;
  88 }
  89
  90 /*
  91  * Acquire session list lock
  92  */
  93 void lock_session_list(void)
  94 {
  95         pthread_mutex_lock(&ltt_session_list.lock);
  96 }
  97
  98 /*
  99  * Release session list lock
 100  */
 101 void unlock_session_list(void)
 102 {
 103         pthread_mutex_unlock(&ltt_session_list.lock);
 104 }
 105
 106 /*
 107  * Acquire session lock
 108  */
 109 void lock_session(struct ltt_session *session)
 110 {
 111         pthread_mutex_lock(&session->lock);
 112 }
 113
 114 /*
 115  * Release session lock
 116  */
 117 void unlock_session(struct ltt_session *session)
 118 {
 119         pthread_mutex_unlock(&session->lock);
 120 }
 121
 122 /*
 123  *      find_session_by_name
 124  *
 125  *      Return a ltt_session structure ptr that matches name.
 126  *      If no session found, NULL is returned.
 127  */
 128 struct ltt_session *find_session_by_name(char *name)
 129 {
 130         int found = 0;
 131         struct ltt_session *iter;
 132
 133         lock_session_list();
 134         cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
 135                 if (strncmp(iter->name, name, NAME_MAX) == 0) {
 136                         found = 1;
 137                         break;
 138                 }
 139         }
 140         unlock_session_list();
 141
 142         if (!found) {
 143                 iter = NULL;
 144         }
 145
 146         return iter;
 147 }
 148
 149 /*
 150  *      destroy_session
 151  *
 152  *  Delete session from the session list and free the memory.
 153  *
 154  *  Return -1 if no session is found.  On success, return 1;
 155  */
 156 int destroy_session(char *name)
 157 {
 158         int found = -1;
 159         struct ltt_session *iter, *tmp;
 160
 161         lock_session_list();
 162         cds_list_for_each_entry_safe(iter, tmp, &ltt_session_list.head, list) {
 163                 if (strcmp(iter->name, name) == 0) {
 164                         DBG("Destroying session %s", iter->name);
 165                         del_session_list(iter);
 166                         free(iter->name);
 167                         free(iter->path);
 168                         pthread_mutex_destroy(&iter->lock);
 169                         free(iter);
 170                         found = 1;
 171                         break;
 172                 }
 173         }
 174         unlock_session_list();
 175
 176         return found;
 177 }
 178
 179 /*
 180  *      create_session
 181  *
 182  *      Create a brand new session and add it to the session list.
 183  */
 184 int create_session(char *name, char *path)
 185 {
 186         int ret;
 187         struct ltt_session *new_session;
 188
 189         new_session = find_session_by_name(name);
 190         if (new_session != NULL) {
 191                 ret = -EEXIST;
 192                 goto error_exist;
 193         }
 194
 195         /* Allocate session data structure */
 196         new_session = malloc(sizeof(struct ltt_session));
 197         if (new_session == NULL) {
 198                 perror("malloc");
 199                 ret = -ENOMEM;
 200                 goto error_malloc;
 201         }
 202
 203         /* Define session name */
 204         if (name != NULL) {
 205                 if (asprintf(&new_session->name, "%s", name) < 0) {
 206                         ret = -ENOMEM;
 207                         goto error_asprintf;
 208                 }
 209         } else {
 210                 ERR("No session name given");
 211                 ret = -1;
 212                 goto error;
 213         }
 214
 215         /* Define session system path */
 216         if (path != NULL) {
 217                 if (asprintf(&new_session->path, "%s", path) < 0) {
 218                         ret = -ENOMEM;
 219                         goto error_asprintf;
 220                 }
 221         } else {
 222                 ERR("No session path given");
 223                 ret = -1;
 224                 goto error;
 225         }
 226
 227         /* Init kernel session */
 228         new_session->kernel_session = NULL;
 229
 230         /* Init list */
 231         CDS_INIT_LIST_HEAD(&new_session->ust_traces);
 232
 233         /* Set trace list counter */
 234         new_session->ust_trace_count = 0;
 235
 236         /* Add new session to the session list */
 237         lock_session_list();
 238         add_session_list(new_session);
 239         unlock_session_list();
 240
 241         /* Init lock */
 242         pthread_mutex_init(&new_session->lock, NULL);
 243
 244         DBG("Tracing session %s created in %s", new_session->name, new_session->path);
 245
 246         return 0;
 247
 248 error:
 249 error_asprintf:
 250         if (new_session != NULL) {
 251                 free(new_session);
 252         }
 253
 254 error_exist:
 255 error_malloc:
 256         return ret;
 257 }