Implement libcounter

[lttng-ust.git] / liblttng-ust / ust-core.c

/*
 * ust-core.c
 *
 * Copyright (C) 2011 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
 */

#define _LGPL_SOURCE
#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include <lttng/ust-events.h>
#include <usterr-signal-safe.h>
#include "lttng-tracer-core.h"
#include "jhash.h"

static CDS_LIST_HEAD(lttng_transport_list);
static CDS_LIST_HEAD(lttng_counter_transport_list);

struct lttng_transport *lttng_transport_find(const char *name)
{
	struct lttng_transport *transport;

	cds_list_for_each_entry(transport, &lttng_transport_list, node) {
		if (!strcmp(transport->name, name))
			return transport;
	}
	return NULL;
}

struct lttng_counter_transport *lttng_counter_transport_find(const char *name)
{
	struct lttng_counter_transport *transport;

	cds_list_for_each_entry(transport, &lttng_counter_transport_list, node) {
		if (!strcmp(transport->name, name))
			return transport;
	}
	return NULL;
}

/**
 * lttng_transport_register - LTT transport registration
 * @transport: transport structure
 *
 * Registers a transport which can be used as output to extract the data out of
 * LTTng. Called with ust_lock held.
 */
void lttng_transport_register(struct lttng_transport *transport)
{
	cds_list_add_tail(&transport->node, &lttng_transport_list);
}

/**
 * lttng_transport_unregister - LTT transport unregistration
 * @transport: transport structure
 * Called with ust_lock held.
 */
void lttng_transport_unregister(struct lttng_transport *transport)
{
	cds_list_del(&transport->node);
}

/**
 * lttng_counter_transport_register - LTTng counter transport registration
 * @transport: transport structure
 *
 * Registers a counter transport which can be used as output to extract
 * the data out of LTTng. Called with ust_lock held.
 */
void lttng_counter_transport_register(struct lttng_counter_transport *transport)
{
	cds_list_add_tail(&transport->node, &lttng_counter_transport_list);
}

/**
 * lttng_counter_transport_unregister - LTTng counter transport unregistration
 * @transport: transport structure
 * Called with ust_lock held.
 */
void lttng_counter_transport_unregister(struct lttng_counter_transport *transport)
{
	cds_list_del(&transport->node);
}

/*
 * Needed by comm layer.
 */
struct lttng_enum *lttng_ust_enum_get_from_desc(struct lttng_session *session,
		const struct lttng_enum_desc *enum_desc)
{
	struct lttng_enum *_enum;
	struct cds_hlist_head *head;
	struct cds_hlist_node *node;
	size_t name_len = strlen(enum_desc->name);
	uint32_t hash;

	hash = jhash(enum_desc->name, name_len, 0);
	head = &session->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
	cds_hlist_for_each_entry(_enum, node, head, hlist) {
		assert(_enum->desc);
		if (_enum->desc == enum_desc)
			return _enum;
	}
	return NULL;
}

size_t lttng_ust_dummy_get_size(struct lttng_ctx_field *field, size_t offset)
{
	size_t size = 0;

	size += lib_ring_buffer_align(offset, lttng_alignof(char));
	size += sizeof(char);		/* tag */
	return size;
}

void lttng_ust_dummy_record(struct lttng_ctx_field *field,
		 struct lttng_ust_lib_ring_buffer_ctx *ctx,
		 struct lttng_channel *chan)
{
	char sel_char = (char) LTTNG_UST_DYNAMIC_TYPE_NONE;

	lib_ring_buffer_align_ctx(ctx, lttng_alignof(sel_char));
	chan->ops->event_write(ctx, &sel_char, sizeof(sel_char));
}

void lttng_ust_dummy_get_value(struct lttng_ctx_field *field,
		struct lttng_ctx_value *value)
{
	value->sel = LTTNG_UST_DYNAMIC_TYPE_NONE;
}

int lttng_context_is_app(const char *name)
{
	if (strncmp(name, "$app.", strlen("$app.")) != 0) {
		return 0;
	}
	return 1;
}