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ab0ee2ca | 1 | /* |
ab5be9fa | 2 | * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
ab0ee2ca | 3 | * |
ab5be9fa | 4 | * SPDX-License-Identifier: GPL-2.0-only |
ab0ee2ca | 5 | * |
ab0ee2ca JG |
6 | */ |
7 | ||
8 | #ifndef NOTIFICATION_THREAD_H | |
9 | #define NOTIFICATION_THREAD_H | |
10 | ||
c9e313bc SM |
11 | #include "action-executor.hpp" |
12 | #include "thread.hpp" | |
28f23191 | 13 | |
c9e313bc SM |
14 | #include <common/compat/poll.hpp> |
15 | #include <common/hashtable/hashtable.hpp> | |
16 | #include <common/pipe.hpp> | |
28f23191 | 17 | |
d02d7404 | 18 | #include <lttng/domain.h> |
28f23191 JG |
19 | #include <lttng/trigger/trigger.h> |
20 | ||
ab0ee2ca | 21 | #include <pthread.h> |
90936dcf | 22 | #include <semaphore.h> |
f2b3ef9f JG |
23 | #include <urcu.h> |
24 | #include <urcu/list.h> | |
25 | #include <urcu/rculfhash.h> | |
ab0ee2ca | 26 | |
e665dfbc | 27 | using notification_client_id = uint64_t; |
ac1889bf | 28 | |
d02d7404 JR |
29 | /* |
30 | * The notification thread holds no ownership of the tracer event source pipe | |
31 | * file descriptor. The tracer management logic must remove the event source | |
32 | * from the notification thread (see external commands) before releasing | |
33 | * this file descriptor. | |
34 | */ | |
35 | struct notification_event_tracer_event_source_element { | |
36 | int fd; | |
37 | /* | |
38 | * A tracer event source can be removed from the notification thread's | |
39 | * poll set before the end of its lifetime (for instance, when an error | |
40 | * or hang-up is detected on its file descriptor). This is done to | |
41 | * allow the notification thread to ignore follow-up events on this | |
42 | * file descriptors. | |
43 | * | |
44 | * Under such circumstances, the notification thread still expects | |
45 | * the normal clean-up to occur through the 'REMOVE_TRACER_EVENT_SOURCE' | |
46 | * command. | |
47 | */ | |
48 | bool is_fd_in_poll_set; | |
49 | enum lttng_domain_type domain; | |
50 | struct cds_list_head node; | |
51 | }; | |
52 | ||
e7c93cf9 JR |
53 | struct notification_trigger_tokens_ht_element { |
54 | uint64_t token; | |
55 | /* Weak reference to the trigger. */ | |
56 | struct lttng_trigger *trigger; | |
57 | struct cds_lfht_node node; | |
58 | /* call_rcu delayed reclaim. */ | |
59 | struct rcu_head rcu_node; | |
60 | }; | |
61 | ||
ab0ee2ca JG |
62 | struct notification_thread_handle { |
63 | /* | |
64 | * Queue of struct notification command. | |
814b4934 | 65 | * event_pipe must be WRITE(2) to signal that a new command |
ab0ee2ca JG |
66 | * has been enqueued. |
67 | */ | |
68 | struct { | |
f370852f | 69 | int event_fd; |
ab0ee2ca JG |
70 | struct cds_list_head list; |
71 | pthread_mutex_t lock; | |
72 | } cmd_queue; | |
73 | /* | |
74 | * Read side of pipes used to receive channel status info collected | |
75 | * by the various consumer daemons. | |
76 | */ | |
77 | struct { | |
78 | int ust32_consumer; | |
79 | int ust64_consumer; | |
80 | int kernel_consumer; | |
81 | } channel_monitoring_pipes; | |
c8a9de5a JG |
82 | /* Used to wait for the launch of the notification thread. */ |
83 | sem_t ready; | |
ab0ee2ca JG |
84 | }; |
85 | ||
74df9916 JG |
86 | /** |
87 | * This thread maintains an internal state associating clients and triggers. | |
88 | * | |
89 | * In order to speed-up and simplify queries, hash tables providing the | |
90 | * following associations are maintained: | |
91 | * | |
ac1889bf JG |
92 | * - client_socket_ht: associate a client's socket (fd) to its |
93 | * "struct notification_client". | |
94 | * This hash table owns the "struct notification_client" which must | |
95 | * thus be disposed-of on removal from the hash table. | |
96 | * | |
97 | * - client_id_ht: associate a client's id to its "struct notification_client" | |
98 | * This hash table holds a _weak_ reference to the | |
99 | * "struct notification_client". | |
74df9916 JG |
100 | * |
101 | * - channel_triggers_ht: | |
102 | * associates a channel key to a list of | |
103 | * struct lttng_trigger_list_nodes. The triggers in this list are | |
ea9a44f0 | 104 | * those that have conditions that apply to a particular channel. |
74df9916 JG |
105 | * A channel entry is only created when a channel is added; the |
106 | * list of triggers applying to such a channel is built at that | |
107 | * moment. | |
108 | * This hash table owns the list, but not the triggers themselves. | |
109 | * | |
ea9a44f0 JG |
110 | * - session_triggers_ht: |
111 | * associates a session name to a list of | |
112 | * struct lttng_trigger_list_nodes. The triggers in this list are | |
113 | * those that have conditions that apply to a particular session. | |
114 | * A session entry is only created when a session is created; the | |
115 | * list of triggers applying to this new session is built at that | |
116 | * moment. This happens at the time of creation of a session_info. | |
117 | * Likewise, the list is destroyed at the time of the session_info's | |
118 | * destruction. | |
119 | * | |
74df9916 JG |
120 | * - channel_state_ht: |
121 | * associates a pair (channel key, channel domain) to its last | |
122 | * sampled state received from the consumer daemon | |
123 | * (struct channel_state). | |
124 | * This previous sample is kept to implement edge-triggered | |
125 | * conditions as we need to detect the state transitions. | |
126 | * This hash table owns the channel state. | |
127 | * | |
128 | * - notification_trigger_clients_ht: | |
129 | * associates notification-emitting triggers to clients | |
130 | * (struct notification_client_list) subscribed to those | |
131 | * conditions. | |
132 | * The condition's hash and match functions are used directly since | |
133 | * all triggers in this hash table have the "notify" action. | |
134 | * This hash table holds no ownership. | |
135 | * | |
136 | * - channels_ht: | |
137 | * associates a channel_key to a struct channel_info. The hash table | |
138 | * holds the ownership of the struct channel_info. | |
139 | * | |
8abe313a JG |
140 | * - sessions_ht: |
141 | * associates a session_name (hash) to a struct session_info. The | |
142 | * hash table holds no ownership of the struct session_info; | |
143 | * the session_info structure is owned by the session's various | |
144 | * channels through their struct channel_info (ref-counting is used). | |
145 | * | |
74df9916 | 146 | * - triggers_ht: |
242388e4 | 147 | * associates a trigger to a struct lttng_trigger_ht_element. |
74df9916 JG |
148 | * The hash table holds the ownership of the |
149 | * lttng_trigger_ht_elements along with the triggers themselves. | |
242388e4 JR |
150 | * - triggers_by_name_uid_ht: |
151 | * associates a trigger (name, uid) tuple to | |
152 | * a struct lttng_trigger_ht_element. | |
153 | * The hash table does not hold any ownership and is used strictly | |
154 | * for lookup on registration. | |
d02d7404 JR |
155 | * - tracer_event_sources_list: |
156 | * A list of tracer event source (read side fd) of type | |
28f23191 JG |
157 | * struct notification_event_tracer_event_source_element. |
158 | * | |
74df9916 JG |
159 | * |
160 | * The thread reacts to the following internal events: | |
161 | * 1) creation of a tracing channel, | |
162 | * 2) destruction of a tracing channel, | |
139a8d25 JG |
163 | * 3) creation of a tracing session, |
164 | * 4) destruction of a tracing session, | |
165 | * 5) registration of a trigger, | |
166 | * 6) unregistration of a trigger, | |
167 | * 7) reception of a channel monitor sample from the consumer daemon, | |
168 | * 8) Session rotation ongoing, | |
169 | * 9) Session rotation completed, | |
170 | * 10) registration of a tracer event source, | |
171 | * 11) unregistration of a tracer event source, | |
74df9916 JG |
172 | * |
173 | * Events specific to notification-emitting triggers: | |
d02d7404 JR |
174 | * 9) connection of a notification client, |
175 | * 10) disconnection of a notification client, | |
176 | * 11) subscription of a client to a conditions' notifications, | |
177 | * 12) unsubscription of a client from a conditions' notifications, | |
74df9916 JG |
178 | * |
179 | * | |
180 | * 1) Creation of a tracing channel | |
181 | * - notification_trigger_clients_ht is traversed to identify | |
182 | * triggers which apply to this new channel, | |
8abe313a | 183 | * - triggers identified are added to the channel_triggers_ht. |
74df9916 | 184 | * - add channel to channels_ht |
ea9a44f0 JG |
185 | * - if it is the first channel of a session, a session_info is created and |
186 | * added to the sessions_ht. A list of the triggers associated with that | |
187 | * session is built, and it is added to session_triggers_ht. | |
74df9916 JG |
188 | * |
189 | * 2) Destruction of a tracing channel | |
190 | * - remove entry from channel_triggers_ht, releasing the list wrapper and | |
191 | * elements, | |
192 | * - remove entry from the channel_state_ht. | |
193 | * - remove channel from channels_ht | |
ea9a44f0 JG |
194 | * - if it was the last known channel of a session, the session_info |
195 | * structure is torndown, which in return destroys the list of triggers | |
196 | * applying to that session. | |
74df9916 JG |
197 | * |
198 | * 3) Registration of a trigger | |
199 | * - if the trigger's action is of type "notify", | |
200 | * - traverse the list of conditions of every client to build a list of | |
201 | * clients which have to be notified when this trigger's condition is met, | |
202 | * - add list of clients (even if it is empty) to the | |
203 | * notification_trigger_clients_ht, | |
204 | * - add trigger to channel_triggers_ht (if applicable), | |
ea9a44f0 | 205 | * - add trigger to session_triggers_ht (if applicable), |
242388e4 | 206 | * - add trigger to triggers_by_name_uid_ht |
74df9916 | 207 | * - add trigger to triggers_ht |
2ae99f0b JG |
208 | * - evaluate the trigger's condition right away to react if that condition |
209 | * is true from the beginning. | |
74df9916 JG |
210 | * |
211 | * 4) Unregistration of a trigger | |
212 | * - if the trigger's action is of type "notify", | |
213 | * - remove the trigger from the notification_trigger_clients_ht, | |
214 | * - remove trigger from channel_triggers_ht (if applicable), | |
ea9a44f0 | 215 | * - remove trigger from session_triggers_ht (if applicable), |
242388e4 | 216 | * - remove trigger from triggers_by_name_uid_ht |
74df9916 JG |
217 | * - remove trigger from triggers_ht |
218 | * | |
219 | * 5) Reception of a channel monitor sample from the consumer daemon | |
220 | * - evaluate the conditions associated with the triggers found in | |
221 | * the channel_triggers_ht, | |
222 | * - if a condition evaluates to "true" and the condition is of type | |
223 | * "notify", query the notification_trigger_clients_ht and send | |
224 | * a notification to the clients. | |
225 | * | |
51eab943 JG |
226 | * 6) Session rotation ongoing |
227 | * | |
228 | * 7) Session rotation completed | |
229 | * | |
d02d7404 JR |
230 | * 8) Registration of a tracer event source |
231 | * - Add the tracer event source of the application to | |
232 | * tracer_event_sources_list, | |
233 | * - Add the trace event source to the pollset. | |
234 | * | |
235 | * 8) Unregistration of a tracer event source | |
236 | * - Remove the tracer event source of the application from | |
237 | * tracer_event_sources_list, | |
238 | * - Remove the trace event source from the pollset. | |
239 | * | |
240 | * 10) Connection of a client | |
ac1889bf JG |
241 | * - add client socket to the client_socket_ht, |
242 | * - add client socket to the client_id_ht. | |
74df9916 | 243 | * |
d02d7404 | 244 | * 11) Disconnection of a client |
ac1889bf | 245 | * - remove client socket from the client_id_ht, |
74df9916 JG |
246 | * - remove client socket from the client_socket_ht, |
247 | * - traverse all conditions to which the client is subscribed and remove | |
248 | * the client from the notification_trigger_clients_ht. | |
249 | * | |
d02d7404 | 250 | * 12) Subscription of a client to a condition's notifications |
74df9916 JG |
251 | * - Add the condition to the client's list of subscribed conditions, |
252 | * - Look-up notification_trigger_clients_ht and add the client to | |
253 | * list of clients. | |
2ae99f0b JG |
254 | * - Evaluate the condition for the client that subscribed if the trigger |
255 | * was already registered. | |
74df9916 | 256 | * |
d02d7404 | 257 | * 13) Unsubscription of a client to a condition's notifications |
74df9916 JG |
258 | * - Remove the condition from the client's list of subscribed conditions, |
259 | * - Look-up notification_trigger_clients_ht and remove the client | |
260 | * from the list of clients. | |
261 | */ | |
ab0ee2ca JG |
262 | struct notification_thread_state { |
263 | int notification_channel_socket; | |
264 | struct lttng_poll_event events; | |
265 | struct cds_lfht *client_socket_ht; | |
ac1889bf | 266 | struct cds_lfht *client_id_ht; |
ab0ee2ca | 267 | struct cds_lfht *channel_triggers_ht; |
ea9a44f0 | 268 | struct cds_lfht *session_triggers_ht; |
ab0ee2ca JG |
269 | struct cds_lfht *channel_state_ht; |
270 | struct cds_lfht *notification_trigger_clients_ht; | |
271 | struct cds_lfht *channels_ht; | |
8abe313a | 272 | struct cds_lfht *sessions_ht; |
ab0ee2ca | 273 | struct cds_lfht *triggers_ht; |
242388e4 | 274 | struct cds_lfht *triggers_by_name_uid_ht; |
e7c93cf9 | 275 | struct cds_lfht *trigger_tokens_ht; |
242388e4 | 276 | struct { |
e6887944 | 277 | uint64_t next_tracer_token; |
242388e4 JR |
278 | uint64_t name_offset; |
279 | } trigger_id; | |
d02d7404 JR |
280 | /* |
281 | * Read side of the pipes used to receive tracer events. As their name | |
282 | * implies, tracer event source activity originate from either | |
283 | * registered applications (user space tracer) or from the kernel | |
284 | * tracer. | |
285 | * | |
286 | * The list is not protected by a lock since add and remove operations | |
287 | * are currently done only by the notification thread through in | |
288 | * response to blocking commands. | |
289 | */ | |
290 | struct cds_list_head tracer_event_sources_list; | |
ac1889bf | 291 | notification_client_id next_notification_client_id; |
f2b3ef9f | 292 | struct action_executor *executor; |
8b524060 FD |
293 | |
294 | /* | |
295 | * Indicates the thread to break for the poll event processing loop and | |
296 | * call _poll_wait() again. | |
297 | * | |
298 | * This is necessary because some events on one fd might trigger the | |
299 | * consumption of another fd. | |
300 | * For example, a single _poll_wait() call can return notification | |
301 | * thread commands and events from the tracer event source (event | |
302 | * notifier). | |
303 | * Picture a scenario where we receive two events: | |
304 | * the first one is a _REMOVE_TRACER_EVENT_SOURCE command, and | |
305 | * the second is an POLLIN on the tracer event source fd. | |
306 | * | |
307 | * The _REMOVE_TRACER_EVENT_SOURCE will read all the data of the | |
308 | * removed tracer event source. | |
309 | * | |
310 | * The second event is now invalid has we consumed all the data for | |
311 | * which we received the POLLIN. | |
312 | * | |
313 | * For this reason, we need to break for the event processing loop and | |
314 | * call _poll_wait() again to get a clean view of the activity on the | |
315 | * fds. | |
316 | */ | |
317 | bool restart_poll; | |
ab0ee2ca JG |
318 | }; |
319 | ||
320 | /* notification_thread_data takes ownership of the channel monitor pipes. */ | |
28f23191 JG |
321 | struct notification_thread_handle * |
322 | notification_thread_handle_create(struct lttng_pipe *ust32_channel_monitor_pipe, | |
323 | struct lttng_pipe *ust64_channel_monitor_pipe, | |
324 | struct lttng_pipe *kernel_channel_monitor_pipe); | |
325 | void notification_thread_handle_destroy(struct notification_thread_handle *handle); | |
326 | struct lttng_thread *launch_notification_thread(struct notification_thread_handle *handle); | |
ab0ee2ca JG |
327 | |
328 | #endif /* NOTIFICATION_THREAD_H */ |