liblttng-ust/lttng-context.c

   1 /*
   2  * lttng-context.c
   3  *
   4  * LTTng UST trace/channel/event context management.
   5  *
   6  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23
  24 #include <lttng/ust-events.h>
  25 #include <lttng/ust-tracer.h>
  26 #include <usterr-signal-safe.h>
  27 #include <helper.h>
  28 #include <string.h>
  29 #include <assert.h>
  30
  31 /*
  32  * The filter implementation requires that two consecutive "get" for the
  33  * same context performed by the same thread return the same result.
  34  */
  35
  36 /*
  37  * Static array of contexts, for $ctx filters.
  38  */
  39 struct lttng_ctx *lttng_static_ctx;
  40
  41 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  42 {
  43         unsigned int i;
  44
  45         for (i = 0; i < ctx->nr_fields; i++) {
  46                 /* Skip allocated (but non-initialized) contexts */
  47                 if (!ctx->fields[i].event_field.name)
  48                         continue;
  49                 if (!strcmp(ctx->fields[i].event_field.name, name))
  50                         return 1;
  51         }
  52         return 0;
  53 }
  54
  55 int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
  56 {
  57         unsigned int i;
  58
  59         if (!ctx)
  60                 return -1;
  61         for (i = 0; i < ctx->nr_fields; i++) {
  62                 /* Skip allocated (but non-initialized) contexts */
  63                 if (!ctx->fields[i].event_field.name)
  64                         continue;
  65                 if (!strcmp(ctx->fields[i].event_field.name, name))
  66                         return i;
  67         }
  68         return -1;
  69 }
  70
  71 /*
  72  * Note: as we append context information, the pointer location may change.
  73  */
  74 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  75 {
  76         struct lttng_ctx_field *field;
  77         struct lttng_ctx *ctx;
  78
  79         if (!*ctx_p) {
  80                 *ctx_p = zmalloc(sizeof(struct lttng_ctx));
  81                 if (!*ctx_p)
  82                         return NULL;
  83                 (*ctx_p)->largest_align = 1;
  84         }
  85         ctx = *ctx_p;
  86         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  87                 struct lttng_ctx_field *new_fields;
  88
  89                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  90                 new_fields = zmalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field));
  91                 if (!new_fields)
  92                         return NULL;
  93                 if (ctx->fields)
  94                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  95                 free(ctx->fields);
  96                 ctx->fields = new_fields;
  97         }
  98         field = &ctx->fields[ctx->nr_fields];
  99         ctx->nr_fields++;
 100         return field;
 101 }
 102
 103 /*
 104  * lttng_context_update() should be called at least once between context
 105  * modification and trace start.
 106  */
 107 void lttng_context_update(struct lttng_ctx *ctx)
 108 {
 109         int i;
 110         size_t largest_align = 8;       /* in bits */
 111
 112         for (i = 0; i < ctx->nr_fields; i++) {
 113                 struct lttng_type *type;
 114                 size_t field_align = 8;
 115
 116                 type = &ctx->fields[i].event_field.type;
 117                 switch (type->atype) {
 118                 case atype_integer:
 119                         field_align = type->u.basic.integer.alignment;
 120                         break;
 121                 case atype_array:
 122                 {
 123                         struct lttng_basic_type *btype;
 124
 125                         btype = &type->u.array.elem_type;
 126                         switch (btype->atype) {
 127                         case atype_integer:
 128                                 field_align = btype->u.basic.integer.alignment;
 129                                 break;
 130                         case atype_string:
 131                                 break;
 132
 133                         case atype_array:
 134                         case atype_sequence:
 135                         default:
 136                                 WARN_ON_ONCE(1);
 137                                 break;
 138                         }
 139                         break;
 140                 }
 141                 case atype_sequence:
 142                 {
 143                         struct lttng_basic_type *btype;
 144
 145                         btype = &type->u.sequence.length_type;
 146                         switch (btype->atype) {
 147                         case atype_integer:
 148                                 field_align = btype->u.basic.integer.alignment;
 149                                 break;
 150
 151                         case atype_string:
 152                         case atype_array:
 153                         case atype_sequence:
 154                         default:
 155                                 WARN_ON_ONCE(1);
 156                                 break;
 157                         }
 158
 159                         btype = &type->u.sequence.elem_type;
 160                         switch (btype->atype) {
 161                         case atype_integer:
 162                                 field_align = max_t(size_t,
 163                                         field_align,
 164                                         btype->u.basic.integer.alignment);
 165                                 break;
 166
 167                         case atype_string:
 168                                 break;
 169
 170                         case atype_array:
 171                         case atype_sequence:
 172                         default:
 173                                 WARN_ON_ONCE(1);
 174                                 break;
 175                         }
 176                         break;
 177                 }
 178                 case atype_string:
 179                         break;
 180
 181                 case atype_enum:
 182                 default:
 183                         WARN_ON_ONCE(1);
 184                         break;
 185                 }
 186                 largest_align = max_t(size_t, largest_align, field_align);
 187         }
 188         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 189 }
 190
 191 /*
 192  * Remove last context field.
 193  */
 194 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 195                                 struct lttng_ctx_field *field)
 196 {
 197         struct lttng_ctx *ctx;
 198
 199         ctx = *ctx_p;
 200         ctx->nr_fields--;
 201         assert(&ctx->fields[ctx->nr_fields] == field);
 202         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 203 }
 204
 205 void lttng_destroy_context(struct lttng_ctx *ctx)
 206 {
 207         int i;
 208
 209         if (!ctx)
 210                 return;
 211         for (i = 0; i < ctx->nr_fields; i++) {
 212                 if (ctx->fields[i].destroy)
 213                         ctx->fields[i].destroy(&ctx->fields[i]);
 214         }
 215         free(ctx->fields);
 216         free(ctx);
 217 }
 218
 219 void lttng_context_init(void)
 220 {
 221         int ret;
 222
 223         ret = lttng_add_pthread_id_to_ctx(&lttng_static_ctx);
 224         if (ret) {
 225                 WARN("Cannot add context lttng_add_pthread_id_to_ctx");
 226         }
 227         ret = lttng_add_vtid_to_ctx(&lttng_static_ctx);
 228         if (ret) {
 229                 WARN("Cannot add context lttng_add_vtid_to_ctx");
 230         }
 231         ret = lttng_add_vpid_to_ctx(&lttng_static_ctx);
 232         if (ret) {
 233                 WARN("Cannot add context lttng_add_vpid_to_ctx");
 234         }
 235         ret = lttng_add_procname_to_ctx(&lttng_static_ctx);
 236         if (ret) {
 237                 WARN("Cannot add context lttng_add_procname_to_ctx");
 238         }
 239 }
 240
 241 void lttng_context_exit(void)
 242 {
 243         lttng_destroy_context(lttng_static_ctx);
 244         lttng_static_ctx = NULL;
 245 }