Fix: sessiond: rotation thread: fatal error when not finding a 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 da3805658cd28e1255292d6250ae6882f779a6d0..1a31d3f0bdfd5fe9240a8de968428a7ed6293924 100644 (file)
--- a/src/bin/lttng-sessiond/session.h
+++ b/src/bin/lttng-sessiond/session.h
@@ -1,18 +1,8 @@
 /*
- * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
  *
- * 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 _LTT_SESSION_H
@@ -78,7 +68,7 @@ struct ltt_session {
        char name[NAME_MAX];
        bool has_auto_generated_name;
        bool name_contains_creation_time;
-       char hostname[HOST_NAME_MAX]; /* Local hostname. */
+       char hostname[LTTNG_HOST_NAME_MAX]; /* Local hostname. */
        /* Path of the last closed chunk. */
        char last_chunk_path[LTTNG_PATH_MAX];
        time_t creation_time;
@@ -155,6 +145,10 @@ struct ltt_session {
         * Node in ltt_sessions_ht_by_id.
         */
        struct lttng_ht_node_u64 node;
+       /*
+        * Node in ltt_sessions_ht_by_name.
+        */
+       struct lttng_ht_node_str node_by_name;
        /*
         * Timer to check periodically if a relay and/or consumer has completed
         * the last rotation.
@@ -172,7 +166,8 @@ struct ltt_session {
         * Keep a state if this session was rotated after the last stop command.
         * We only allow one rotation after a stop. At destroy, we also need to
         * know if a rotation occurred since the last stop to rename the current
-        * chunk.
+        * chunk. After a stop followed by rotate, all subsequent clear
+        * (without prior start) will succeed, but will be effect-less.
         */
        bool rotated_after_last_stop;
        /*
@@ -181,6 +176,10 @@ struct ltt_session {
         * subsequent rotate (without prior start) will return an error.
         */
        bool cleared_after_last_stop;
+       /*
+        * True if the session has had an explicit non-quiet rotation.
+        */
+       bool rotated;
        /*
         * Condition and trigger for size-based rotations.
         */
@@ -200,13 +199,22 @@ struct ltt_session {
        char *base_path;
 };
 
-/* Prototypes */
 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
                struct ltt_session **out_session);
 void session_lock(struct ltt_session *session);
+void session_unlock(struct ltt_session *session);
+
+/*
+ * The session list lock covers more ground than its name implies. While
+ * it does protect against concurent mutations of the session list, it is
+ * also used as a multi-session lock when synchronizing newly-registered
+ * 'user space tracer' and 'agent' applications.
+ *
+ * In other words, it prevents tracer configurations from changing while they
+ * are being transmitted to the various applications.
+ */
 void session_lock_list(void);
 int session_trylock_list(void);
-void session_unlock(struct ltt_session *session);
 void session_unlock_list(void);
 
 void session_destroy(struct ltt_session *session);
@@ -236,7 +244,7 @@ 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);
+bool session_access_ok(struct ltt_session *session, uid_t uid);
 
 int session_reset_rotation_state(struct ltt_session *session,
                enum lttng_rotation_state result);
@@ -269,6 +277,20 @@ int session_close_trace_chunk(struct ltt_session *session,
                enum lttng_trace_chunk_command_type close_command,
                char *path);
 
+/* Open a packet in all channels of a given session. */
+enum lttng_error_code session_open_packets(struct ltt_session *session);
+
 bool session_output_supports_trace_chunks(const struct ltt_session *session);
 
+/*
+ * Sample the id of a session looked up via its name.
+ * Here the term "sampling" hint the caller that this return the id at a given
+ * point in time with no guarantee that the session for which the id was
+ * sampled still exist at that point.
+ *
+ * Return 0 when the session is not found,
+ * Return 1 when the session is found and set `id`.
+ */
+bool sample_session_id_by_name(const char *name, uint64_t *id);
+
 #endif /* _LTT_SESSION_H */