src/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 "LIB/CONNECTION"
  25 #include "lib/lib-logging.h"
  26
  27 #include "common/assert.h"
  28 #include "lib/assert-pre.h"
  29 #include <babeltrace2/graph/connection-const.h>
  30 #include "lib/object.h"
  31 #include "compat/compiler.h"
  32 #include <stdlib.h>
  33 #include <glib.h>
  34
  35 #include "component.h"
  36 #include "connection.h"
  37 #include "graph.h"
  38 #include "message/iterator.h"
  39 #include "port.h"
  40
  41 static
  42 void destroy_connection(struct bt_object *obj)
  43 {
  44         struct bt_connection *connection = container_of(obj,
  45                         struct bt_connection, base);
  46
  47         BT_LIB_LOGI("Destroying connection: %!+x", connection);
  48
  49         /*
  50          * Make sure that each message iterator which was created for
  51          * this connection is finalized before we destroy it. Once a
  52          * message iterator is finalized, all its method return NULL or
  53          * the BT_MESSAGE_ITERATOR_STATUS_CANCELED status.
  54          *
  55          * Because connections are destroyed before components within a
  56          * graph, this ensures that message iterators are always
  57          * finalized before their upstream component.
  58          *
  59          * Ending the connection does exactly this. We pass `false` to
  60          * bt_connection_end() here to avoid removing this connection
  61          * from the graph: if we're here, we're already in the graph's
  62          * destructor.
  63          */
  64         bt_connection_end(connection, false);
  65         g_ptr_array_free(connection->iterators, TRUE);
  66         connection->iterators = NULL;
  67
  68         /*
  69          * No bt_object_put_ref on ports as a connection only holds _weak_
  70          * references to them.
  71          */
  72         g_free(connection);
  73 }
  74
  75 static
  76 void try_remove_connection_from_graph(struct bt_connection *connection)
  77 {
  78         void *graph = (void *) bt_object_borrow_parent(&connection->base);
  79
  80         if (connection->base.ref_count > 0 ||
  81                         connection->downstream_port ||
  82                         connection->upstream_port ||
  83                         connection->iterators->len > 0) {
  84                 return;
  85         }
  86
  87         /*
  88          * At this point we know that:
  89          *
  90          * 1. The connection is ended (ports were disconnected).
  91          * 2. All the message iterators that this connection
  92          *    created, if any, are finalized.
  93          * 3. The connection's reference count is 0, so only the
  94          *    parent (graph) owns this connection after this call.
  95          *
  96          * In other words, no other object than the graph knows this
  97          * connection.
  98          *
  99          * It is safe to remove the connection from the graph, therefore
 100          * destroying it.
 101          */
 102         BT_LIB_LOGD("Removing self from graph's connections: "
 103                 "%![graph-]+g, %![conn-]+x", graph, connection);
 104         bt_graph_remove_connection(graph, connection);
 105 }
 106
 107 static
 108 void parent_is_owner(struct bt_object *obj)
 109 {
 110         struct bt_connection *connection = container_of(obj,
 111                         struct bt_connection, base);
 112
 113         try_remove_connection_from_graph(connection);
 114 }
 115
 116 BT_HIDDEN
 117 struct bt_connection *bt_connection_create(struct bt_graph *graph,
 118                 struct bt_port *upstream_port,
 119                 struct bt_port *downstream_port)
 120 {
 121         struct bt_connection *connection = NULL;
 122
 123         BT_LIB_LOGI("Creating connection: "
 124                 "%![graph-]+g, %![up-port-]+p, %![down-port-]+p",
 125                 graph, upstream_port, downstream_port);
 126         connection = g_new0(struct bt_connection, 1);
 127         if (!connection) {
 128                 BT_LOGE_STR("Failed to allocate one connection.");
 129                 goto end;
 130         }
 131
 132         bt_object_init_shared_with_parent(&connection->base,
 133                 destroy_connection);
 134         bt_object_set_parent_is_owner_listener_func(&connection->base,
 135                 parent_is_owner);
 136         connection->iterators = g_ptr_array_new();
 137         if (!connection->iterators) {
 138                 BT_LOGE_STR("Failed to allocate a GPtrArray.");
 139                 BT_OBJECT_PUT_REF_AND_RESET(connection);
 140                 goto end;
 141         }
 142
 143         /* Weak references are taken, see comment in header. */
 144         connection->upstream_port = upstream_port;
 145         connection->downstream_port = downstream_port;
 146         BT_LIB_LOGD("Setting upstream port's connection: %!+p", upstream_port);
 147         bt_port_set_connection(upstream_port, connection);
 148         BT_LIB_LOGD("Setting downstream port's connection: %!+p",
 149                 downstream_port);
 150         bt_port_set_connection(downstream_port, connection);
 151         bt_object_set_parent(&connection->base, &graph->base);
 152         BT_LIB_LOGI("Created connection: %!+x", connection);
 153
 154 end:
 155         return connection;
 156 }
 157
 158 BT_HIDDEN
 159 void bt_connection_end(struct bt_connection *conn, bool try_remove_from_graph)
 160 {
 161         struct bt_port *downstream_port = conn->downstream_port;
 162         struct bt_port *upstream_port = conn->upstream_port;
 163         size_t i;
 164
 165         BT_LIB_LOGI("Ending connection: %!+x, try-remove-from-graph=%d",
 166                 conn, try_remove_from_graph);
 167
 168         /*
 169          * Any of the following message callback functions could
 170          * remove one of the connection's ports from its component. To
 171          * make sure that at least logging in called functions works
 172          * with existing objects, get a local reference on both ports.
 173          */
 174         bt_object_get_ref(downstream_port);
 175         bt_object_get_ref(upstream_port);
 176
 177         if (downstream_port) {
 178                 BT_LIB_LOGD("Disconnecting connection's downstream port: %!+p",
 179                         downstream_port);
 180                 bt_port_set_connection(downstream_port, NULL);
 181                 conn->downstream_port = NULL;
 182         }
 183
 184         if (upstream_port) {
 185                 BT_LIB_LOGD("Disconnecting connection's upstream port: %!+p",
 186                         upstream_port);
 187                 bt_port_set_connection(upstream_port, NULL);
 188                 conn->upstream_port = NULL;
 189         }
 190
 191         /*
 192          * It is safe to put the local port references now that we don't
 193          * need them anymore. This could indeed destroy them.
 194          */
 195         bt_object_put_ref(downstream_port);
 196         bt_object_put_ref(upstream_port);
 197
 198         /*
 199          * Because this connection is ended, finalize each message
 200          * iterator created from it.
 201          *
 202          * In practice, this only happens when the connection is
 203          * destroyed and not all its message iterators were finalized,
 204          * which is on graph destruction.
 205          */
 206         for (i = 0; i < conn->iterators->len; i++) {
 207                 struct bt_self_component_port_input_message_iterator *iterator =
 208                         g_ptr_array_index(conn->iterators, i);
 209
 210                 BT_LIB_LOGD("Finalizing message iterator created by "
 211                         "this ended connection: %![iter-]+i", iterator);
 212                 bt_self_component_port_input_message_iterator_try_finalize(
 213                         iterator);
 214
 215                 /*
 216                  * Make sure this iterator does not try to remove itself
 217                  * from this connection's iterators on destruction
 218                  * because this connection won't exist anymore.
 219                  */
 220                 bt_self_component_port_input_message_iterator_set_connection(
 221                         iterator, NULL);
 222         }
 223
 224         g_ptr_array_set_size(conn->iterators, 0);
 225
 226         if (try_remove_from_graph) {
 227                 try_remove_connection_from_graph(conn);
 228         }
 229 }
 230
 231 const struct bt_port_output *bt_connection_borrow_upstream_port_const(
 232                 const struct bt_connection *connection)
 233 {
 234         BT_ASSERT_PRE_NON_NULL(connection, "Connection");
 235         return (void *) connection->upstream_port;
 236 }
 237
 238 const struct bt_port_input *bt_connection_borrow_downstream_port_const(
 239                 const struct bt_connection *connection)
 240 {
 241         BT_ASSERT_PRE_NON_NULL(connection, "Connection");
 242         return (void *) connection->downstream_port;
 243 }
 244
 245 BT_HIDDEN
 246 void bt_connection_remove_iterator(struct bt_connection *conn,
 247                 struct bt_self_component_port_input_message_iterator *iterator)
 248 {
 249         g_ptr_array_remove(conn->iterators, iterator);
 250         BT_LIB_LOGD("Removed message iterator from connection: "
 251                 "%![conn-]+x, %![iter-]+i", conn, iterator);
 252         try_remove_connection_from_graph(conn);
 253 }
 254
 255 void bt_connection_get_ref(const struct bt_connection *connection)
 256 {
 257         bt_object_get_ref(connection);
 258 }
 259
 260 void bt_connection_put_ref(const struct bt_connection *connection)
 261 {
 262         bt_object_put_ref(connection);
 263 }