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 <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24
  25 #include <lttngerr.h>
  26
  27 #include "session.h"
  28
  29 /*
  30  * NOTES:
  31  *
  32  * No ltt_session.lock is taken here because those data structure are widely
  33  * spread across the lttng-tools code base so before caling functions below
  34  * that can read/write a session, the caller MUST acquire the session lock
  35  * using lock_session() and unlock_session().
  36  */
  37
  38 /*
  39  * Init tracing session list.
  40  *
  41  * Please see session.h for more explanation and correct usage of the list.
  42  */
  43 static struct ltt_session_list ltt_session_list = {
  44         .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
  45         .lock = PTHREAD_MUTEX_INITIALIZER,
  46         .count = 0,
  47 };
  48
  49 /*
  50  * Add a ltt_session structure to the global list.
  51  *
  52  * The caller MUST acquire the session list lock before.
  53  */
  54 static void add_session_list(struct ltt_session *ls)
  55 {
  56         cds_list_add(&ls->list, &ltt_session_list.head);
  57         ltt_session_list.count++;
  58 }
  59
  60 /*
  61  * Delete a ltt_session structure to the global list.
  62  *
  63  * The caller MUST acquire the session list lock before.
  64  */
  65 static void del_session_list(struct ltt_session *ls)
  66 {
  67         cds_list_del(&ls->list);
  68         /* Sanity check */
  69         if (ltt_session_list.count > 0) {
  70                 ltt_session_list.count--;
  71         }
  72 }
  73
  74 /*
  75  * Return a pointer to the session list.
  76  */
  77 struct ltt_session_list *get_session_list(void)
  78 {
  79         return &ltt_session_list;
  80 }
  81
  82 /*
  83  * Acquire session list lock
  84  */
  85 void lock_session_list(void)
  86 {
  87         pthread_mutex_lock(&ltt_session_list.lock);
  88 }
  89
  90 /*
  91  * Release session list lock
  92  */
  93 void unlock_session_list(void)
  94 {
  95         pthread_mutex_unlock(&ltt_session_list.lock);
  96 }
  97
  98 /*
  99  * Acquire session lock
 100  */
 101 void lock_session(struct ltt_session *session)
 102 {
 103         pthread_mutex_lock(&session->lock);
 104 }
 105
 106 /*
 107  * Release session lock
 108  */
 109 void unlock_session(struct ltt_session *session)
 110 {
 111         pthread_mutex_unlock(&session->lock);
 112 }
 113
 114 /*
 115  * Return a ltt_session structure ptr that matches name.
 116  * If no session found, NULL is returned.
 117  */
 118 struct ltt_session *find_session_by_name(char *name)
 119 {
 120         int found = 0;
 121         struct ltt_session *iter;
 122
 123         lock_session_list();
 124         cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
 125                 if (strncmp(iter->name, name, NAME_MAX) == 0) {
 126                         found = 1;
 127                         break;
 128                 }
 129         }
 130         unlock_session_list();
 131
 132         if (!found) {
 133                 iter = NULL;
 134         }
 135
 136         return iter;
 137 }
 138
 139 /*
 140  * Delete session from the session list and free the memory.
 141  *
 142  * Return -1 if no session is found.  On success, return 1;
 143  */
 144 int destroy_session(char *name)
 145 {
 146         int found = -1;
 147         struct ltt_session *iter, *tmp;
 148
 149         lock_session_list();
 150         cds_list_for_each_entry_safe(iter, tmp, &ltt_session_list.head, list) {
 151                 if (strcmp(iter->name, name) == 0) {
 152                         DBG("Destroying session %s", iter->name);
 153                         del_session_list(iter);
 154                         free(iter->name);
 155                         free(iter->path);
 156                         pthread_mutex_destroy(&iter->lock);
 157                         free(iter);
 158                         found = 1;
 159                         break;
 160                 }
 161         }
 162         unlock_session_list();
 163
 164         return found;
 165 }
 166
 167 /*
 168  * Create a brand new session and add it to the session list.
 169  */
 170 int create_session(char *name, char *path)
 171 {
 172         int ret;
 173         struct ltt_session *new_session;
 174
 175         new_session = find_session_by_name(name);
 176         if (new_session != NULL) {
 177                 ret = -EEXIST;
 178                 goto error_exist;
 179         }
 180
 181         /* Allocate session data structure */
 182         new_session = malloc(sizeof(struct ltt_session));
 183         if (new_session == NULL) {
 184                 perror("malloc");
 185                 ret = -ENOMEM;
 186                 goto error_malloc;
 187         }
 188
 189         /* Define session name */
 190         if (name != NULL) {
 191                 if (asprintf(&new_session->name, "%s", name) < 0) {
 192                         ret = -ENOMEM;
 193                         goto error_asprintf;
 194                 }
 195         } else {
 196                 ERR("No session name given");
 197                 ret = -1;
 198                 goto error;
 199         }
 200
 201         /* Define session system path */
 202         if (path != NULL) {
 203                 if (asprintf(&new_session->path, "%s", path) < 0) {
 204                         ret = -ENOMEM;
 205                         goto error_asprintf;
 206                 }
 207         } else {
 208                 ERR("No session path given");
 209                 ret = -1;
 210                 goto error;
 211         }
 212
 213         /* Init kernel session */
 214         new_session->kernel_session = NULL;
 215
 216         /* Init list */
 217         CDS_INIT_LIST_HEAD(&new_session->ust_traces);
 218
 219         /* Set trace list counter */
 220         new_session->ust_trace_count = 0;
 221
 222         /* Add new session to the session list */
 223         lock_session_list();
 224         add_session_list(new_session);
 225         unlock_session_list();
 226
 227         /* Init lock */
 228         pthread_mutex_init(&new_session->lock, NULL);
 229
 230         DBG("Tracing session %s created in %s", new_session->name, new_session->path);
 231
 232         return 0;
 233
 234 error:
 235 error_asprintf:
 236         if (new_session != NULL) {
 237                 free(new_session);
 238         }
 239
 240 error_exist:
 241 error_malloc:
 242         return ret;
 243 }