src/bin/lttng-relayd/viewer-session.hpp

   1 #ifndef _VIEWER_SESSION_H
   2 #define _VIEWER_SESSION_H
   3
   4 /*
   5  * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
   6  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   7  * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-only
  10  *
  11  */
  12
  13 #include "lttng-viewer-abi.hpp"
  14 #include "session.hpp"
  15
  16 #include <common/hashtable/hashtable.hpp>
  17 #include <common/trace-chunk.hpp>
  18
  19 #include <inttypes.h>
  20 #include <limits.h>
  21 #include <pthread.h>
  22 #include <urcu/list.h>
  23 #include <urcu/ref.h>
  24
  25 struct relay_viewer_session {
  26         /*
  27          * The id of the relay viewer session. Uses the associated connection's socket FD.
  28          */
  29         uint64_t id;
  30         /*
  31          * Session list. Updates are protected by the session_list_lock.
  32          * Traversals are protected by RCU.
  33          * This list limits the design to having the sessions in at most
  34          * one viewer session.
  35          */
  36         struct cds_list_head session_list; /* RCU list. */
  37         pthread_mutex_t session_list_lock; /* Protects list updates. */
  38         /*
  39          * Unannounced stream list. Updates are protected by the
  40          * unannounced_stream_list_lock. This lock nests inside
  41          * the following locks (in order): relay session, ctf_trace,
  42          * and relay stream.
  43          *
  44          * Traversals are protected by RCU.
  45          */
  46         struct cds_list_head unannounced_stream_list;
  47         pthread_mutex_t unannounced_stream_list_lock;
  48         /*
  49          * Node in the global viewer sessions hashtable.
  50          */
  51         struct lttng_ht_node_u64 viewer_session_n;
  52         /*
  53          * The viewer session's current trace chunk is initially set, when
  54          * a viewer attaches to the viewer session, to a copy the corresponding
  55          * relay_session's current trace chunk.
  56          *
  57          * A live session always attempts to "catch-up" to the newest available
  58          * trace chunk. This means that when a viewer reaches the end of a
  59          * trace chunk, the viewer session may not transition to the "next" one:
  60          * it jumps to the most recent trace chunk available (the one being
  61          * produced by the relay_session). Hence, if the producer performs
  62          * multiple rotations before a viewer completes the consumption of a
  63          * trace chunk, it will skip over those "intermediary" trace chunks.
  64          *
  65          * A viewer session updates its current trace chunk when:
  66          *   1) new viewer streams are created,
  67          *   2) a new index is requested,
  68          *   3) metadata is requested.
  69          *
  70          * Hence, as a general principle, the viewer session will reference the
  71          * most recent trace chunk available _even if its streams do not point to
  72          * it_. It indicates which trace chunk viewer streams should transition
  73          * to when the end of their current trace chunk is reached.
  74          *
  75          * Note that a viewer session's trace chunk points to the session's
  76          * output directory. The sub-directories in which the various stream files
  77          * are created are considered as being a part of their name.
  78          */
  79         struct lttng_trace_chunk *current_trace_chunk;
  80 };
  81
  82 struct relay_viewer_session *viewer_session_create();
  83 void viewer_session_destroy(struct relay_viewer_session *vsession);
  84 void viewer_session_close(struct relay_viewer_session *vsession);
  85
  86 enum lttng_viewer_attach_return_code viewer_session_attach(struct relay_viewer_session *vsession,
  87                                                            struct relay_session *session);
  88 int viewer_session_is_attached(struct relay_viewer_session *vsession,
  89                                struct relay_session *session);
  90 void viewer_session_close_one_session(struct relay_viewer_session *vsession,
  91                                       struct relay_session *session);
  92 int viewer_session_set_trace_chunk_copy(struct relay_viewer_session *vsession,
  93                                         struct lttng_trace_chunk *relay_session_trace_chunk);
  94
  95 #endif /* _VIEWER_SESSION_H */