lib/graph/connection.c

   1 /*
   2  * Copyright 2017-2018 Philippe Proulx <pproulx@efficios.com>
   3  * Copyright 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy
   6  * of this software and associated documentation files (the "Software"), to deal
   7  * in the Software without restriction, including without limitation the rights
   8  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9  * copies of the Software, and to permit persons to whom the Software is
  10  * furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 #define BT_LOG_TAG "CONNECTION"
  25 #include <babeltrace2/lib-logging-internal.h>
  26
  27 #include <babeltrace2/assert-internal.h>
  28 #include <babeltrace2/assert-pre-internal.h>
  29 #include <babeltrace2/graph/message-iterator-internal.h>
  30 #include <babeltrace2/graph/component-internal.h>
  31 #include <babeltrace2/graph/connection-internal.h>
  32 #include <babeltrace2/graph/connection-const.h>
  33 #include <babeltrace2/graph/graph-internal.h>
  34 #include <babeltrace2/graph/port-internal.h>
  35 #include <babeltrace2/object-internal.h>
  36 #include <babeltrace2/compiler-internal.h>
  37 #include <stdlib.h>
  38 #include <glib.h>
  39
  40 static
  41 void destroy_connection(struct bt_object *obj)
  42 {
  43         struct bt_connection *connection = container_of(obj,
  44                         struct bt_connection, base);
  45
  46         BT_LIB_LOGD("Destroying connection: %!+x", connection);
  47
  48         /*
  49          * Make sure that each message iterator which was created for
  50          * this connection is finalized before we destroy it. Once a
  51          * message iterator is finalized, all its method return NULL or
  52          * the BT_MESSAGE_ITERATOR_STATUS_CANCELED status.
  53          *
  54          * Because connections are destroyed before components within a
  55          * graph, this ensures that message iterators are always
  56          * finalized before their upstream component.
  57          *
  58          * Ending the connection does exactly this. We pass `false` to
  59          * bt_connection_end() here to avoid removing this connection
  60          * from the graph: if we're here, we're already in the graph's
  61          * destructor.
  62          */
  63         bt_connection_end(connection, false);
  64         g_ptr_array_free(connection->iterators, TRUE);
  65         connection->iterators = NULL;
  66
  67         /*
  68          * No bt_object_put_ref on ports as a connection only holds _weak_
  69          * references to them.
  70          */
  71         g_free(connection);
  72 }
  73
  74 static
  75 void try_remove_connection_from_graph(struct bt_connection *connection)
  76 {
  77         void *graph = (void *) bt_object_borrow_parent(&connection->base);
  78
  79         if (connection->base.ref_count > 0 ||
  80                         connection->downstream_port ||
  81                         connection->upstream_port ||
  82                         connection->iterators->len > 0) {
  83                 return;
  84         }
  85
  86         /*
  87          * At this point we know that:
  88          *
  89          * 1. The connection is ended (ports were disconnected).
  90          * 2. All the message iterators that this connection
  91          *    created, if any, are finalized.
  92          * 3. The connection's reference count is 0, so only the
  93          *    parent (graph) owns this connection after this call.
  94          *
  95          * In other words, no other object than the graph knows this
  96          * connection.
  97          *
  98          * It is safe to remove the connection from the graph, therefore
  99          * destroying it.
 100          */
 101         BT_LIB_LOGD("Removing self from graph's connections: "
 102                 "%![graph-]+g, %![conn-]+x", graph, connection);
 103         bt_graph_remove_connection(graph, connection);
 104 }
 105
 106 static
 107 void parent_is_owner(struct bt_object *obj)
 108 {
 109         struct bt_connection *connection = container_of(obj,
 110                         struct bt_connection, base);
 111
 112         try_remove_connection_from_graph(connection);
 113 }
 114
 115 BT_HIDDEN
 116 struct bt_connection *bt_connection_create(struct bt_graph *graph,
 117                 struct bt_port *upstream_port,
 118                 struct bt_port *downstream_port)
 119 {
 120         struct bt_connection *connection = NULL;
 121
 122         BT_LIB_LOGD("Creating connection: "
 123                 "%![graph-]+g, %![up-port-]+p, %![down-port-]+p",
 124                 graph, upstream_port, downstream_port);
 125         connection = g_new0(struct bt_connection, 1);
 126         if (!connection) {
 127                 BT_LOGE_STR("Failed to allocate one connection.");
 128                 goto end;
 129         }
 130
 131         bt_object_init_shared_with_parent(&connection->base,
 132                 destroy_connection);
 133         bt_object_set_parent_is_owner_listener_func(&connection->base,
 134                 parent_is_owner);
 135         connection->iterators = g_ptr_array_new();
 136         if (!connection->iterators) {
 137                 BT_LOGE_STR("Failed to allocate a GPtrArray.");
 138                 BT_OBJECT_PUT_REF_AND_RESET(connection);
 139                 goto end;
 140         }
 141
 142         /* Weak references are taken, see comment in header. */
 143         connection->upstream_port = upstream_port;
 144         connection->downstream_port = downstream_port;
 145         BT_LIB_LOGD("Setting upstream port's connection: %!+p", upstream_port);
 146         bt_port_set_connection(upstream_port, connection);
 147         BT_LIB_LOGD("Setting downstream port's connection: %!+p",
 148                 downstream_port);
 149         bt_port_set_connection(downstream_port, connection);
 150         bt_object_set_parent(&connection->base, &graph->base);
 151         BT_LIB_LOGD("Created connection: %!+x", connection);
 152
 153 end:
 154         return connection;
 155 }
 156
 157 BT_HIDDEN
 158 void bt_connection_end(struct bt_connection *conn, bool try_remove_from_graph)
 159 {
 160         struct bt_port *downstream_port = conn->downstream_port;
 161         struct bt_port *upstream_port = conn->upstream_port;
 162         size_t i;
 163
 164         BT_LIB_LOGD("Ending connection: %!+x, try-remove-from-graph=%d",
 165                 conn, try_remove_from_graph);
 166
 167         /*
 168          * Any of the following message callback functions could
 169          * remove one of the connection's ports from its component. To
 170          * make sure that at least logging in called functions works
 171          * with existing objects, get a local reference on both ports.
 172          */
 173         bt_object_get_ref(downstream_port);
 174         bt_object_get_ref(upstream_port);
 175
 176         if (downstream_port) {
 177                 BT_LIB_LOGD("Disconnecting connection's downstream port: %!+p",
 178                         downstream_port);
 179                 bt_port_set_connection(downstream_port, NULL);
 180                 conn->downstream_port = NULL;
 181         }
 182
 183         if (upstream_port) {
 184                 BT_LIB_LOGD("Disconnecting connection's upstream port: %!+p",
 185                         upstream_port);
 186                 bt_port_set_connection(upstream_port, NULL);
 187                 conn->upstream_port = NULL;
 188         }
 189
 190         /*
 191          * It is safe to put the local port references now that we don't
 192          * need them anymore. This could indeed destroy them.
 193          */
 194         bt_object_put_ref(downstream_port);
 195         bt_object_put_ref(upstream_port);
 196
 197         /*
 198          * Because this connection is ended, finalize each message
 199          * iterator created from it.
 200          *
 201          * In practice, this only happens when the connection is
 202          * destroyed and not all its message iterators were finalized,
 203          * which is on graph destruction.
 204          */
 205         for (i = 0; i < conn->iterators->len; i++) {
 206                 struct bt_self_component_port_input_message_iterator *iterator =
 207                         g_ptr_array_index(conn->iterators, i);
 208
 209                 BT_LIB_LOGD("Finalizing message iterator created by "
 210                         "this ended connection: %![iter-]+i", iterator);
 211                 bt_self_component_port_input_message_iterator_try_finalize(
 212                         iterator);
 213
 214                 /*
 215                  * Make sure this iterator does not try to remove itself
 216                  * from this connection's iterators on destruction
 217                  * because this connection won't exist anymore.
 218                  */
 219                 bt_self_component_port_input_message_iterator_set_connection(
 220                         iterator, NULL);
 221         }
 222
 223         g_ptr_array_set_size(conn->iterators, 0);
 224
 225         if (try_remove_from_graph) {
 226                 try_remove_connection_from_graph(conn);
 227         }
 228 }
 229
 230 const struct bt_port_output *bt_connection_borrow_upstream_port_const(
 231                 const struct bt_connection *connection)
 232 {
 233         BT_ASSERT_PRE_NON_NULL(connection, "Connection");
 234         return (void *) connection->upstream_port;
 235 }
 236
 237 const struct bt_port_input *bt_connection_borrow_downstream_port_const(
 238                 const struct bt_connection *connection)
 239 {
 240         BT_ASSERT_PRE_NON_NULL(connection, "Connection");
 241         return (void *) connection->downstream_port;
 242 }
 243
 244 BT_HIDDEN
 245 void bt_connection_remove_iterator(struct bt_connection *conn,
 246                 struct bt_self_component_port_input_message_iterator *iterator)
 247 {
 248         g_ptr_array_remove(conn->iterators, iterator);
 249         BT_LIB_LOGV("Removed message iterator from connection: "
 250                 "%![conn-]+x, %![iter-]+i", conn, iterator);
 251         try_remove_connection_from_graph(conn);
 252 }
 253
 254 void bt_connection_get_ref(const struct bt_connection *connection)
 255 {
 256         bt_object_get_ref(connection);
 257 }
 258
 259 void bt_connection_put_ref(const struct bt_connection *connection)
 260 {
 261         bt_object_put_ref(connection);
 262 }