+++ /dev/null
-/*
- * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#ifndef NOTIFICATION_THREAD_H
-#define NOTIFICATION_THREAD_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 {
- /*
- * Queue of struct notification command.
- * event_pipe must be WRITE(2) to signal that a new command
- * has been enqueued.
- */
- struct {
- struct lttng_pipe *event_pipe;
- struct cds_list_head list;
- pthread_mutex_t lock;
- } cmd_queue;
- /*
- * Read side of pipes used to receive channel status info collected
- * by the various consumer daemons.
- */
- struct {
- int ust32_consumer;
- int ust64_consumer;
- int kernel_consumer;
- } channel_monitoring_pipes;
- /* Used to wait for the launch of the notification thread. */
- sem_t ready;
-};
-
-/**
- * This thread maintains an internal state associating clients and triggers.
- *
- * 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 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 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
- * (struct channel_state).
- * This previous sample is kept to implement edge-triggered
- * conditions as we need to detect the state transitions.
- * This hash table owns the channel state.
- *
- * - notification_trigger_clients_ht:
- * associates notification-emitting triggers to clients
- * (struct notification_client_list) subscribed to those
- * conditions.
- * The condition's hash and match functions are used directly since
- * all triggers in this hash table have the "notify" action.
- * This hash table holds no ownership.
- *
- * - channels_ht:
- * 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:
- * 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,
- * 8) registration of a tracer event source,
- * 9) unregistration of a tracer event source,
- *
- * Events specific to notification-emitting triggers:
- * 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.
- * - 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",
- * - traverse the list of conditions of every client to build a list of
- * clients which have to be notified when this trigger's condition is met,
- * - 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
- * - evaluate the conditions associated with the triggers found in
- * the channel_triggers_ht,
- * - if a condition evaluates to "true" and the condition is of type
- * "notify", query the notification_trigger_clients_ht and send
- * a notification to the clients.
- *
- * 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.
- *
- * 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.
- *
- * 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.
- *
- * 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.
- */
-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. */
-struct notification_thread_handle *notification_thread_handle_create(
- struct lttng_pipe *ust32_channel_monitor_pipe,
- struct lttng_pipe *ust64_channel_monitor_pipe,
- struct lttng_pipe *kernel_channel_monitor_pipe);
-void notification_thread_handle_destroy(
- struct notification_thread_handle *handle);
-struct lttng_thread *launch_notification_thread(
- struct notification_thread_handle *handle);
-
-#endif /* NOTIFICATION_THREAD_H */
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