/*
- * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
*
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License, version 2 only, as
- * published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
*
- * This program 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 General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 51
- * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef NOTIFICATION_THREAD_H
#define NOTIFICATION_THREAD_H
-#include <urcu/list.h>
-#include <urcu.h>
-#include <urcu/rculfhash.h>
-#include <lttng/trigger/trigger.h>
-#include <common/pipe.h>
+#include "action-executor.h"
+#include "thread.h"
#include <common/compat/poll.h>
#include <common/hashtable/hashtable.h>
+#include <common/pipe.h>
+#include <lttng/trigger/trigger.h>
+#include <lttng/domain.h>
#include <pthread.h>
#include <semaphore.h>
+#include <urcu.h>
+#include <urcu/list.h>
+#include <urcu/rculfhash.h>
+
+typedef uint64_t notification_client_id;
+
+/*
+ * The notification thread holds no ownership of the tracer event source pipe
+ * file descriptor. The tracer management logic must remove the event source
+ * from the notification thread (see external commands) before releasing
+ * this file descriptor.
+ */
+struct notification_event_tracer_event_source_element {
+ int fd;
+ /*
+ * A tracer event source can be removed from the notification thread's
+ * poll set before the end of its lifetime (for instance, when an error
+ * or hang-up is detected on its file descriptor). This is done to
+ * allow the notification thread to ignore follow-up events on this
+ * file descriptors.
+ *
+ * Under such circumstances, the notification thread still expects
+ * the normal clean-up to occur through the 'REMOVE_TRACER_EVENT_SOURCE'
+ * command.
+ */
+ bool is_fd_in_poll_set;
+ enum lttng_domain_type domain;
+ struct cds_list_head node;
+};
+
+struct notification_trigger_tokens_ht_element {
+ uint64_t token;
+ /* Weak reference to the trigger. */
+ struct lttng_trigger *trigger;
+ struct cds_lfht_node node;
+ /* call_rcu delayed reclaim. */
+ struct rcu_head rcu_node;
+};
struct notification_thread_handle {
/*
* In order to speed-up and simplify queries, hash tables providing the
* following associations are maintained:
*
- * - client_socket_ht: associate a client's socket (fd) to its "struct client"
- * This hash table owns the "struct client" which must thus be
- * disposed-of on removal from the hash table.
+ * - client_socket_ht: associate a client's socket (fd) to its
+ * "struct notification_client".
+ * This hash table owns the "struct notification_client" which must
+ * thus be disposed-of on removal from the hash table.
+ *
+ * - client_id_ht: associate a client's id to its "struct notification_client"
+ * This hash table holds a _weak_ reference to the
+ * "struct notification_client".
*
* - channel_triggers_ht:
* associates a channel key to a list of
* channels through their struct channel_info (ref-counting is used).
*
* - triggers_ht:
- * associates a condition to a struct lttng_trigger_ht_element.
+ * associates a trigger to a struct lttng_trigger_ht_element.
* The hash table holds the ownership of the
* lttng_trigger_ht_elements along with the triggers themselves.
+ * - triggers_by_name_uid_ht:
+ * associates a trigger (name, uid) tuple to
+ * a struct lttng_trigger_ht_element.
+ * The hash table does not hold any ownership and is used strictly
+ * for lookup on registration.
+ * - tracer_event_sources_list:
+ * A list of tracer event source (read side fd) of type
+* struct notification_event_tracer_event_source_element.
+*
*
* The thread reacts to the following internal events:
* 1) creation of a tracing channel,
* 2) destruction of a tracing channel,
* 3) registration of a trigger,
* 4) unregistration of a trigger,
- * 5) reception of a channel monitor sample from the consumer daemon.
- * 6) Session rotation ongoing
- * 7) Session rotation completed
+ * 5) reception of a channel monitor sample from the consumer daemon,
+ * 6) Session rotation ongoing,
+ * 7) Session rotation completed,
+ * 8) registration of a tracer event source,
+ * 9) unregistration of a tracer event source,
*
* Events specific to notification-emitting triggers:
- * 8) connection of a notification client,
- * 9) disconnection of a notification client,
- * 10) subscription of a client to a conditions' notifications,
- * 11) unsubscription of a client from a conditions' notifications,
+ * 9) connection of a notification client,
+ * 10) disconnection of a notification client,
+ * 11) subscription of a client to a conditions' notifications,
+ * 12) unsubscription of a client from a conditions' notifications,
*
*
* 1) Creation of a tracing channel
* notification_trigger_clients_ht,
* - add trigger to channel_triggers_ht (if applicable),
* - add trigger to session_triggers_ht (if applicable),
+ * - add trigger to triggers_by_name_uid_ht
* - add trigger to triggers_ht
* - evaluate the trigger's condition right away to react if that condition
* is true from the beginning.
* - remove the trigger from the notification_trigger_clients_ht,
* - remove trigger from channel_triggers_ht (if applicable),
* - remove trigger from session_triggers_ht (if applicable),
+ * - remove trigger from triggers_by_name_uid_ht
* - remove trigger from triggers_ht
*
* 5) Reception of a channel monitor sample from the consumer daemon
*
* 7) Session rotation completed
*
- * 8) Connection of a client
- * - add client socket to the client_socket_ht.
+ * 8) Registration of a tracer event source
+ * - Add the tracer event source of the application to
+ * tracer_event_sources_list,
+ * - Add the trace event source to the pollset.
+ *
+ * 8) Unregistration of a tracer event source
+ * - Remove the tracer event source of the application from
+ * tracer_event_sources_list,
+ * - Remove the trace event source from the pollset.
+ *
+ * 10) Connection of a client
+ * - add client socket to the client_socket_ht,
+ * - add client socket to the client_id_ht.
*
- * 9) Disconnection of a client
+ * 11) Disconnection of a client
+ * - remove client socket from the client_id_ht,
* - remove client socket from the client_socket_ht,
* - traverse all conditions to which the client is subscribed and remove
* the client from the notification_trigger_clients_ht.
*
- * 10) Subscription of a client to a condition's notifications
+ * 12) Subscription of a client to a condition's notifications
* - Add the condition to the client's list of subscribed conditions,
* - Look-up notification_trigger_clients_ht and add the client to
* list of clients.
* - Evaluate the condition for the client that subscribed if the trigger
* was already registered.
*
- * 11) Unsubscription of a client to a condition's notifications
+ * 13) Unsubscription of a client to a condition's notifications
* - Remove the condition from the client's list of subscribed conditions,
* - Look-up notification_trigger_clients_ht and remove the client
* from the list of clients.
int notification_channel_socket;
struct lttng_poll_event events;
struct cds_lfht *client_socket_ht;
+ struct cds_lfht *client_id_ht;
struct cds_lfht *channel_triggers_ht;
struct cds_lfht *session_triggers_ht;
struct cds_lfht *channel_state_ht;
struct cds_lfht *channels_ht;
struct cds_lfht *sessions_ht;
struct cds_lfht *triggers_ht;
+ struct cds_lfht *triggers_by_name_uid_ht;
+ struct cds_lfht *trigger_tokens_ht;
+ struct {
+ uint64_t next_tracer_token;
+ uint64_t name_offset;
+ } trigger_id;
+ /*
+ * Read side of the pipes used to receive tracer events. As their name
+ * implies, tracer event source activity originate from either
+ * registered applications (user space tracer) or from the kernel
+ * tracer.
+ *
+ * The list is not protected by a lock since add and remove operations
+ * are currently done only by the notification thread through in
+ * response to blocking commands.
+ */
+ struct cds_list_head tracer_event_sources_list;
+ notification_client_id next_notification_client_id;
+ struct action_executor *executor;
+
+ /*
+ * Indicates the thread to break for the poll event processing loop and
+ * call _poll_wait() again.
+ *
+ * This is necessary because some events on one fd might trigger the
+ * consumption of another fd.
+ * For example, a single _poll_wait() call can return notification
+ * thread commands and events from the tracer event source (event
+ * notifier).
+ * Picture a scenario where we receive two events:
+ * the first one is a _REMOVE_TRACER_EVENT_SOURCE command, and
+ * the second is an POLLIN on the tracer event source fd.
+ *
+ * The _REMOVE_TRACER_EVENT_SOURCE will read all the data of the
+ * removed tracer event source.
+ *
+ * The second event is now invalid has we consumed all the data for
+ * which we received the POLLIN.
+ *
+ * For this reason, we need to break for the event processing loop and
+ * call _poll_wait() again to get a clean view of the activity on the
+ * fds.
+ */
+ bool restart_poll;
};
/* notification_thread_data takes ownership of the channel monitor pipes. */
struct lttng_pipe *kernel_channel_monitor_pipe);
void notification_thread_handle_destroy(
struct notification_thread_handle *handle);
-bool launch_notification_thread(struct notification_thread_handle *handle);
+struct lttng_thread *launch_notification_thread(
+ struct notification_thread_handle *handle);
#endif /* NOTIFICATION_THREAD_H */
projects / lttng-tools.git / blobdiff