Fix: Relay daemon ownership and reference counting

[lttng-tools.git] / src / bin / lttng-relayd / connection.h

diff --git a/src/bin/lttng-relayd/connection.h b/src/bin/lttng-relayd/connection.h
index 70fe4ba3da19c9a5f534911ac70b95abe610cd76..44386381325e531fb45ea45f233e6f7f3a2ef946 100644 (file)
--- a/src/bin/lttng-relayd/connection.h
+++ b/src/bin/lttng-relayd/connection.h
@@ -1,6 +1,10 @@
+#ifndef _CONNECTION_H
+#define _CONNECTION_H
+
 /*
  * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
  *                      David Goulet <dgoulet@efficios.com>
+ *               2015 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
  * 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
@@ -16,9 +20,6 @@
  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#ifndef _CONNECTION_H
-#define _CONNECTION_H
-
 #include <limits.h>
 #include <inttypes.h>
 #include <pthread.h>
@@ -32,6 +33,7 @@
 #include "session.h"
 
 enum connection_type {
+       RELAY_CONNECTION_UNKNOWN    = 0,
        RELAY_DATA                  = 1,
        RELAY_CONTROL               = 2,
        RELAY_VIEWER_COMMAND        = 3,
@@ -41,39 +43,60 @@ enum connection_type {
 /*
  * Internal structure to map a socket with the corresponding session.
  * A hashtable indexed on the socket FD is used for the lookups.
+ *
+ * Connections are assumed to be accessed from a single thread. Live
+ * connections between the relay and a live client are only accessed
+ * from the live worker thread.
+ *
+ * The connections between the consumerd/sessiond and the relayd are only
+ * handled by the "main" worker thread (as in, the worker thread in main.c).
+ *
+ * This is why there are no back references to connections from the
+ * sessions and session list.
  */
 struct relay_connection {
        struct lttcomm_sock *sock;
-       struct relay_session *session;
-       struct relay_viewer_session *viewer_session;
        struct cds_wfcq_node qnode;
-       struct lttng_ht_node_ulong sock_n;
-       struct rcu_head rcu_node;
+
        enum connection_type type;
-       /* Protocol version to use for this connection. */
+       /*
+        * session is only ever set for RELAY_CONTROL connection type.
+        */
+       struct relay_session *session;
+       /*
+        * viewer_session is only ever set for RELAY_VIEWER_COMMAND
+        * connection type.
+        */
+       struct relay_viewer_session *viewer_session;
+
+       /*
+        * Protocol version to use for this connection. Only valid for
+        * RELAY_CONTROL connection type.
+        */
        uint32_t major;
        uint32_t minor;
-       uint64_t session_id;
+
+       struct urcu_ref ref;
+       pthread_mutex_t reflock;
+
+       bool version_check_done;
 
        /*
-        * This contains streams that are received on that connection. It's used to
-        * store them until we get the streams sent command where they are removed
-        * and flagged ready for the viewer. This is ONLY used by the control
-        * thread thus any action on it should happen in that thread.
+        * Node member of connection within global socket hash table.
         */
-       struct cds_list_head recv_head;
-       unsigned int version_check_done:1;
-
-       /* Pointer to the sessions HT that this connection can use. */
-       struct lttng_ht *sessions_ht;
+       struct lttng_ht_node_ulong sock_n;
+       bool in_socket_ht;
+       struct lttng_ht *socket_ht;     /* HACK: Contained within this hash table. */
+       struct rcu_head rcu_node;       /* For call_rcu teardown. */
 };
 
-struct relay_connection *connection_find_by_sock(struct lttng_ht *ht,
+struct relay_connection *connection_create(struct lttcomm_sock *sock,
+               enum connection_type type);
+struct relay_connection *connection_get_by_sock(struct lttng_ht *relay_connections_ht,
                int sock);
-struct relay_connection *connection_create(void);
-void connection_init(struct relay_connection *conn);
-void connection_delete(struct lttng_ht *ht, struct relay_connection *conn);
-void connection_destroy(struct relay_connection *conn);
-void connection_free(struct relay_connection *conn);
+bool connection_get(struct relay_connection *connection);
+void connection_put(struct relay_connection *connection);
+void connection_ht_add(struct lttng_ht *relay_connections_ht,
+               struct relay_connection *conn);
 
 #endif /* _CONNECTION_H */