/*

 * 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;

}