Docs: clarify the meaning of the snapshot_mode flag in ltt_session

[lttng-tools.git] / src / bin / lttng-sessiond / session.h

diff --git a/src/bin/lttng-sessiond/session.h b/src/bin/lttng-sessiond/session.h
index b1ca2504e6d86b722fef2bc0c4c3b7ae048e7872..82e409521c440c621f06d5d46a86d8cc380e6d6c 100644 (file)
--- a/src/bin/lttng-sessiond/session.h
+++ b/src/bin/lttng-sessiond/session.h
@@ -47,6 +47,11 @@ struct ltt_session_list {
         * iterate or/and do any actions on that list.
         */
        pthread_mutex_t lock;
+       /*
+        * This condition variable is signaled on every removal from
+        * the session list.
+        */
+       pthread_cond_t removal_cond;
 
        /*
         * Session unique ID generator. The session list lock MUST be
@@ -67,6 +72,7 @@ struct ltt_session {
        char hostname[HOST_NAME_MAX]; /* Local hostname. */
        struct ltt_kernel_session *kernel_session;
        struct ltt_ust_session *ust_session;
+       struct urcu_ref ref;
        /*
         * Protect any read/write on this session data structure. This lock must be
         * acquired *before* using any public functions declared below. Use
@@ -75,6 +81,10 @@ struct ltt_session {
        pthread_mutex_t lock;
        struct cds_list_head list;
        uint64_t id;            /* session unique identifier */
+       /* Indicates if the session has been added to the session list and ht.*/
+       bool published;
+       /* Indicates if a destroy command has been applied to this session. */
+       bool destroyed;
        /* UID/GID of the user owning the session */
        uid_t uid;
        gid_t gid;
@@ -104,9 +114,11 @@ struct ltt_session {
        /* Indicate if the session has to output the traces or not. */
        unsigned int output_traces;
        /*
-        * This session is in snapshot mode. This means that every channel enabled
-        * will be set in overwrite mode and mmap. It is considered exclusively for
-        * snapshot purposes.
+        * This session is in snapshot mode. This means that channels enabled
+        * will be set in overwrite mode by default and must be in mmap
+        * output mode. Note that snapshots can be taken on a session that
+        * is not in "snapshot_mode". This parameter only affects channel
+        * creation defaults.
         */
        unsigned int snapshot_mode;
        /*
@@ -205,7 +217,6 @@ struct ltt_session {
 
 /* Prototypes */
 int session_create(char *name, uid_t uid, gid_t gid);
-int session_destroy(struct ltt_session *session);
 
 void session_lock(struct ltt_session *session);
 void session_lock_list(void);
@@ -213,6 +224,11 @@ int session_trylock_list(void);
 void session_unlock(struct ltt_session *session);
 void session_unlock_list(void);
 
+void session_destroy(struct ltt_session *session);
+
+bool session_get(struct ltt_session *session);
+void session_put(struct ltt_session *session);
+
 enum consumer_dst_type session_get_consumer_destination_type(
                const struct ltt_session *session);
 const char *session_get_net_consumer_hostname(
@@ -225,7 +241,9 @@ struct lttng_trace_archive_location *session_get_trace_archive_location(
 
 struct ltt_session *session_find_by_name(const char *name);
 struct ltt_session *session_find_by_id(uint64_t id);
+
 struct ltt_session_list *session_get_list(void);
+void session_list_wait_empty(void);
 
 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);