| 1 | /* |
| 2 | * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com> |
| 3 | * David Goulet <dgoulet@efficios.com> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License, version 2 only, as |
| 7 | * published by the Free Software Foundation. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 12 | * more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License along with |
| 15 | * this program; if not, write to the Free Software Foundation, Inc., 51 |
| 16 | * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 17 | */ |
| 18 | |
| 19 | #define _GNU_SOURCE |
| 20 | #include <common/common.h> |
| 21 | |
| 22 | #include "ctf-trace.h" |
| 23 | #include "session.h" |
| 24 | #include "stream.h" |
| 25 | |
| 26 | /* Global session id used in the session creation. */ |
| 27 | static uint64_t last_relay_session_id; |
| 28 | |
| 29 | static void rcu_destroy_session(struct rcu_head *head) |
| 30 | { |
| 31 | struct relay_session *session = |
| 32 | caa_container_of(head, struct relay_session, rcu_node); |
| 33 | |
| 34 | free(session); |
| 35 | } |
| 36 | |
| 37 | /* |
| 38 | * Create a new session by assigning a new session ID. |
| 39 | * |
| 40 | * Return allocated session or else NULL. |
| 41 | */ |
| 42 | struct relay_session *session_create(void) |
| 43 | { |
| 44 | struct relay_session *session; |
| 45 | |
| 46 | session = zmalloc(sizeof(*session)); |
| 47 | if (!session) { |
| 48 | PERROR("relay session zmalloc"); |
| 49 | goto error; |
| 50 | } |
| 51 | |
| 52 | session->ctf_traces_ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING); |
| 53 | if (!session->ctf_traces_ht) { |
| 54 | free(session); |
| 55 | session = NULL; |
| 56 | goto error; |
| 57 | } |
| 58 | |
| 59 | pthread_mutex_init(&session->viewer_ready_lock, NULL); |
| 60 | session->id = ++last_relay_session_id; |
| 61 | lttng_ht_node_init_u64(&session->session_n, session->id); |
| 62 | |
| 63 | error: |
| 64 | return session; |
| 65 | } |
| 66 | |
| 67 | /* |
| 68 | * Lookup a session within the given hash table and session id. RCU read side |
| 69 | * lock MUST be acquired before calling this and as long as the caller has a |
| 70 | * reference to the object. |
| 71 | * |
| 72 | * Return session or NULL if not found. |
| 73 | */ |
| 74 | struct relay_session *session_find_by_id(struct lttng_ht *ht, uint64_t id) |
| 75 | { |
| 76 | struct relay_session *session = NULL; |
| 77 | struct lttng_ht_node_u64 *node; |
| 78 | struct lttng_ht_iter iter; |
| 79 | |
| 80 | assert(ht); |
| 81 | |
| 82 | lttng_ht_lookup(ht, &id, &iter); |
| 83 | node = lttng_ht_iter_get_node_u64(&iter); |
| 84 | if (!node) { |
| 85 | DBG("Session find by ID %" PRIu64 " id NOT found", id); |
| 86 | goto end; |
| 87 | } |
| 88 | session = caa_container_of(node, struct relay_session, session_n); |
| 89 | DBG("Session find by ID %" PRIu64 " id found", id); |
| 90 | |
| 91 | end: |
| 92 | return session; |
| 93 | } |
| 94 | |
| 95 | /* |
| 96 | * Delete session from the given hash table. |
| 97 | * |
| 98 | * Return lttng ht del error code being 0 on success and 1 on failure. |
| 99 | */ |
| 100 | int session_delete(struct lttng_ht *ht, struct relay_session *session) |
| 101 | { |
| 102 | struct lttng_ht_iter iter; |
| 103 | |
| 104 | assert(ht); |
| 105 | assert(session); |
| 106 | |
| 107 | iter.iter.node = &session->session_n.node; |
| 108 | return lttng_ht_del(ht, &iter); |
| 109 | } |
| 110 | |
| 111 | /* |
| 112 | * The caller MUST be from the viewer thread since the viewer refcount is |
| 113 | * decremented. With this calue down to 0, it will try to destroy the session. |
| 114 | */ |
| 115 | void session_viewer_try_destroy(struct lttng_ht *ht, |
| 116 | struct relay_session *session) |
| 117 | { |
| 118 | unsigned long ret_ref; |
| 119 | |
| 120 | assert(session); |
| 121 | |
| 122 | ret_ref = uatomic_add_return(&session->viewer_refcount, -1); |
| 123 | if (ret_ref == 0) { |
| 124 | session_try_destroy(ht, session); |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | /* |
| 129 | * Should only be called from the main streaming thread since it does not touch |
| 130 | * the viewer refcount. If this refcount is down to 0, destroy the session only |
| 131 | * and only if the session deletion succeeds. This is done because the viewer |
| 132 | * *and* the streaming thread can both concurently try to destroy the session |
| 133 | * thus the first come first serve. |
| 134 | */ |
| 135 | void session_try_destroy(struct lttng_ht *ht, struct relay_session *session) |
| 136 | { |
| 137 | int ret = 0; |
| 138 | unsigned long ret_ref; |
| 139 | |
| 140 | assert(session); |
| 141 | |
| 142 | ret_ref = uatomic_read(&session->viewer_refcount); |
| 143 | if (ret_ref == 0 && session->close_flag) { |
| 144 | if (ht) { |
| 145 | ret = session_delete(ht, session); |
| 146 | } |
| 147 | if (!ret) { |
| 148 | /* Only destroy the session if the deletion was successful. */ |
| 149 | session_destroy(session); |
| 150 | } |
| 151 | } |
| 152 | } |
| 153 | |
| 154 | /* |
| 155 | * Destroy a session object. |
| 156 | */ |
| 157 | void session_destroy(struct relay_session *session) |
| 158 | { |
| 159 | struct ctf_trace *ctf_trace; |
| 160 | struct lttng_ht_iter iter; |
| 161 | |
| 162 | assert(session); |
| 163 | |
| 164 | DBG("Relay destroying session %" PRIu64, session->id); |
| 165 | |
| 166 | /* |
| 167 | * Empty the ctf trace hash table which will destroy the stream contained |
| 168 | * in that table. |
| 169 | */ |
| 170 | rcu_read_lock(); |
| 171 | cds_lfht_for_each_entry(session->ctf_traces_ht->ht, &iter.iter, ctf_trace, |
| 172 | node.node) { |
| 173 | ctf_trace_delete(session->ctf_traces_ht, ctf_trace); |
| 174 | ctf_trace_destroy(ctf_trace); |
| 175 | } |
| 176 | lttng_ht_destroy(session->ctf_traces_ht); |
| 177 | rcu_read_unlock(); |
| 178 | |
| 179 | call_rcu(&session->rcu_node, rcu_destroy_session); |
| 180 | } |