/*
* lttng-context-provider.c
*
* LTTng UST application context provider.
*
* Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; only
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <sys/types.h>
#include <unistd.h>
#include <lttng/ust-context-provider.h>
#include "lttng-tracer-core.h"
#include "jhash.h"
#include <helper.h>
#define CONTEXT_PROVIDER_HT_BITS 12
#define CONTEXT_PROVIDER_HT_SIZE (1U << CONTEXT_PROVIDER_HT_BITS)
struct context_provider_ht {
struct cds_hlist_head table[CONTEXT_PROVIDER_HT_SIZE];
};
static struct context_provider_ht context_provider_ht;
static struct lttng_ust_context_provider *
lookup_provider_by_name(const char *name)
{
struct cds_hlist_head *head;
struct cds_hlist_node *node;
struct lttng_ust_context_provider *provider;
uint32_t hash;
const char *end;
size_t len;
/* Lookup using everything before first ':' as key. */
end = strchr(name, ':');
if (end)
len = end - name;
else
len = strlen(name);
hash = jhash(name, len, 0);
head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)];
cds_hlist_for_each_entry(provider, node, head, node) {
if (!strncmp(provider->name, name, len))
return provider;
}
return NULL;
}
int lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider)
{
struct cds_hlist_head *head;
size_t name_len = strlen(provider->name);
uint32_t hash;
int ret = 0;
/* Provider name starts with "$app.". */
if (strncmp("$app.", provider->name, strlen("$app.") != 0))
return -EINVAL;
/* Provider name cannot contain a column character. */
if (strchr(provider->name, ':'))
return -EINVAL;
if (ust_lock()) {
ret = -EBUSY;
goto end;
}
if (lookup_provider_by_name(provider->name)) {
ret = -EBUSY;
goto end;
}
hash = jhash(provider->name, name_len, 0);
head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)];
cds_hlist_add_head(&provider->node, head);
lttng_ust_context_set_session_provider(provider->name,
provider->get_size, provider->record,
provider->get_value);
end:
ust_unlock();
return ret;
}
void lttng_ust_context_provider_unregister(struct lttng_ust_context_provider *provider)
{
if (ust_lock())
goto end;
lttng_ust_context_set_session_provider(provider->name,
lttng_ust_dummy_get_size, lttng_ust_dummy_record,
lttng_ust_dummy_get_value);
cds_hlist_del(&provider->node);
end:
ust_unlock();
}
/*
* Called with ust mutex held.
* Add application context to array of context, even if the application
* context is not currently loaded by application. It will then use the
* dummy callbacks in that case.
* Always performed before tracing is started, since it modifies
* metadata describing the context.
*/
int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
struct lttng_ctx **ctx)
{
struct lttng_ust_context_provider *provider;
struct lttng_ctx_field new_field;
int ret;
if (*ctx && lttng_find_context(*ctx, name))
return -EEXIST;
/*
* For application context, add it by expanding
* ctx array.
*/
memset(&new_field, 0, sizeof(new_field));
new_field.field_name = strdup(name);
if (!new_field.field_name)
return -ENOMEM;
new_field.event_field.name = new_field.field_name;
new_field.event_field.type.atype = atype_dynamic;
/*
* If provider is not found, we add the context anyway, but
* it will provide a dummy context.
*/
provider = lookup_provider_by_name(name);
if (provider) {
new_field.get_size = provider->get_size;
new_field.record = provider->record;
new_field.get_value = provider->get_value;
} else {
new_field.get_size = lttng_ust_dummy_get_size;
new_field.record = lttng_ust_dummy_record;
new_field.get_value = lttng_ust_dummy_get_value;
}
ret = lttng_context_add_rcu(ctx, &new_field);
if (ret) {
free(new_field.field_name);
return ret;
}
return 0;
}