X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fnotification-thread.h;h=8b4c7af2b0326dec1126ea2767cc1ffcf0e9761c;hp=2aa76e71ca422bfd007dfcaec4786ebb1d7db549;hb=246611b0dffa58fbc0e2329ddf6f9dc9d9eff7ce;hpb=814b4934e2604a419bcb8eec57c0450dbb47e2c3 diff --git a/src/bin/lttng-sessiond/notification-thread.h b/src/bin/lttng-sessiond/notification-thread.h index 2aa76e71c..8b4c7af2b 100644 --- a/src/bin/lttng-sessiond/notification-thread.h +++ b/src/bin/lttng-sessiond/notification-thread.h @@ -1,31 +1,60 @@ /* - * Copyright (C) 2017 - Jérémie Galarneau + * Copyright (C) 2017 Jérémie Galarneau * - * 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 -#include -#include -#include -#include +#include "action-executor.h" +#include "thread.h" #include #include +#include +#include +#include #include +#include +#include +#include +#include + +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 { /* @@ -47,6 +76,8 @@ struct notification_thread_handle { int ust64_consumer; int kernel_consumer; } channel_monitoring_pipes; + /* Used to wait for the launch of the notification thread. */ + sem_t ready; }; /** @@ -55,19 +86,34 @@ 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 * struct lttng_trigger_list_nodes. The triggers in this list are - * those that have conditions that apply to this channel. + * those that have conditions that apply to a particular channel. * A channel entry is only created when a channel is added; the * list of triggers applying to such a channel is built at that * moment. * This hash table owns the list, but not the triggers themselves. * + * - session_triggers_ht: + * associates a session name to a list of + * struct lttng_trigger_list_nodes. The triggers in this list are + * those that have conditions that apply to a particular session. + * A session entry is only created when a session is created; the + * list of triggers applying to this new session is built at that + * moment. This happens at the time of creation of a session_info. + * Likewise, the list is destroyed at the time of the session_info's + * destruction. + * * - channel_state_ht: * associates a pair (channel key, channel domain) to its last * sampled state received from the consumer daemon @@ -88,36 +134,61 @@ struct notification_thread_handle { * associates a channel_key to a struct channel_info. The hash table * holds the ownership of the struct channel_info. * + * - sessions_ht: + * associates a session_name (hash) to a struct session_info. The + * hash table holds no ownership of the struct session_info; + * the session_info structure is owned by the session's various + * channels through their struct channel_info (ref-counting is used). + * * - triggers_ht: - * associated 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. + * 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: - * 6) connection of a notification client, - * 7) disconnection of a notification client, - * 8) subscription of a client to a conditions' notifications, - * 9) 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 is traversed to identify * triggers which apply to this new channel, - * - triggers identified are added to the channel_triggers_ht. + * - triggers identified are added to the channel_triggers_ht. * - add channel to channels_ht + * - if it is the first channel of a session, a session_info is created and + * added to the sessions_ht. A list of the triggers associated with that + * session is built, and it is added to session_triggers_ht. * * 2) Destruction of a tracing channel * - remove entry from channel_triggers_ht, releasing the list wrapper and * elements, * - remove entry from the channel_state_ht. * - remove channel from channels_ht + * - if it was the last known channel of a session, the session_info + * structure is torndown, which in return destroys the list of triggers + * applying to that session. * * 3) Registration of a trigger * - if the trigger's action is of type "notify", @@ -126,12 +197,18 @@ struct notification_thread_handle { * - add list of clients (even if it is empty) to the * 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. * * 4) Unregistration of a trigger * - if the trigger's action is of type "notify", * - 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 @@ -141,20 +218,38 @@ struct notification_thread_handle { * "notify", query the notification_trigger_clients_ht and send * a notification to the clients. * - * 6) Connection of a client - * - add client socket to the client_socket_ht. + * 6) Session rotation ongoing + * + * 7) Session rotation completed + * + * 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. * - * 7) Disconnection of a client + * 10) Connection of a client + * - add client socket to the client_socket_ht, + * - add client socket to the client_id_ht. + * + * 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. * - * 8) 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. * - * 9) 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. @@ -163,11 +258,58 @@ struct notification_thread_state { 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 *notification_trigger_clients_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. */ @@ -177,7 +319,7 @@ struct notification_thread_handle *notification_thread_handle_create( struct lttng_pipe *kernel_channel_monitor_pipe); void notification_thread_handle_destroy( struct notification_thread_handle *handle); - -void *thread_notification(void *data); +struct lttng_thread *launch_notification_thread( + struct notification_thread_handle *handle); #endif /* NOTIFICATION_THREAD_H */