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/logging.h"
  26
  27 #include "common/assert.h"
  28 #include "lib/assert-pre.h"
  29 #include "lib/assert-post.h"
  30 #include <babeltrace2/graph/connection.h>
  31 #include "lib/object.h"
  32 #include "compat/compiler.h"
  33 #include <stdbool.h>
  34 #include <stdlib.h>
  35 #include <glib.h>
  36
  37 #include "component.h"
  38 #include "connection.h"
  39 #include "graph.h"
  40 #include "message/iterator.h"
  41 #include "port.h"
  42
  43 static
  44 void destroy_connection(struct bt_object *obj)
  45 {
  46         struct bt_connection *connection = container_of(obj,
  47                         struct bt_connection, base);
  48
  49         BT_LIB_LOGI("Destroying connection: %!+x", connection);
  50
  51         /*
  52          * Make sure that each message iterator which was created for
  53          * this connection is finalized before we destroy it. Once a
  54          * message iterator is finalized, you cannot use it.
  55          *
  56          * Because connections are destroyed before components within a
  57          * graph, this ensures that message iterators are always
  58          * finalized before their upstream component.
  59          *
  60          * Ending the connection does exactly this. We pass `false` to
  61          * bt_connection_end() here to avoid removing this connection
  62          * from the graph: if we're here, we're already in the graph's
  63          * destructor.
  64          */
  65         bt_connection_end(connection, false);
  66         g_ptr_array_free(connection->iterators, TRUE);
  67         connection->iterators = NULL;
  68
  69         /*
  70          * No bt_object_put_ref on ports as a connection only holds _weak_
  71          * references to them.
  72          */
  73         g_free(connection);
  74 }
  75
  76 static
  77 void try_remove_connection_from_graph(struct bt_connection *connection)
  78 {
  79         void *graph = (void *) bt_object_borrow_parent(&connection->base);
  80
  81         if (connection->base.ref_count > 0 ||
  82                         connection->downstream_port ||
  83                         connection->upstream_port ||
  84                         connection->iterators->len > 0) {
  85                 return;
  86         }
  87
  88         /*
  89          * At this point we know that:
  90          *
  91          * 1. The connection is ended (ports were disconnected).
  92          * 2. All the message iterators that this connection
  93          *    created, if any, are finalized.
  94          * 3. The connection's reference count is 0, so only the
  95          *    parent (graph) owns this connection after this call.
  96          *
  97          * In other words, no other object than the graph knows this
  98          * connection.
  99          *
 100          * It is safe to remove the connection from the graph, therefore
 101          * destroying it.
 102          */
 103         BT_LIB_LOGD("Removing self from graph's connections: "
 104                 "%![graph-]+g, %![conn-]+x", graph, connection);
 105         bt_graph_remove_connection(graph, connection);
 106 }
 107
 108 static
 109 void parent_is_owner(struct bt_object *obj)
 110 {
 111         struct bt_connection *connection = container_of(obj,
 112                         struct bt_connection, base);
 113
 114         try_remove_connection_from_graph(connection);
 115 }
 116
 117 BT_HIDDEN
 118 struct bt_connection *bt_connection_create(struct bt_graph *graph,
 119                 struct bt_port *upstream_port,
 120                 struct bt_port *downstream_port)
 121 {
 122         struct bt_connection *connection = NULL;
 123
 124         BT_LIB_LOGI("Creating connection: "
 125                 "%![graph-]+g, %![up-port-]+p, %![down-port-]+p",
 126                 graph, upstream_port, downstream_port);
 127         connection = g_new0(struct bt_connection, 1);
 128         if (!connection) {
 129                 BT_LIB_LOGE_APPEND_CAUSE("Failed to allocate one connection.");
 130                 goto end;
 131         }
 132
 133         bt_object_init_shared_with_parent(&connection->base,
 134                 destroy_connection);
 135         bt_object_set_parent_is_owner_listener_func(&connection->base,
 136                 parent_is_owner);
 137         connection->iterators = g_ptr_array_new();
 138         if (!connection->iterators) {
 139                 BT_LIB_LOGE_APPEND_CAUSE("Failed to allocate a GPtrArray.");
 140                 BT_OBJECT_PUT_REF_AND_RESET(connection);
 141                 goto end;
 142         }
 143
 144         /* Weak references are taken, see comment in header. */
 145         connection->upstream_port = upstream_port;
 146         connection->downstream_port = downstream_port;
 147         BT_LIB_LOGD("Setting upstream port's connection: %!+p", upstream_port);
 148         bt_port_set_connection(upstream_port, connection);
 149         BT_LIB_LOGD("Setting downstream port's connection: %!+p",
 150                 downstream_port);
 151         bt_port_set_connection(downstream_port, connection);
 152         bt_object_set_parent(&connection->base, &graph->base);
 153         BT_LIB_LOGI("Created connection: %!+x", connection);
 154
 155 end:
 156         return connection;
 157 }
 158
 159 BT_HIDDEN
 160 void bt_connection_end(struct bt_connection *conn, bool try_remove_from_graph)
 161 {
 162         struct bt_port *downstream_port = conn->downstream_port;
 163         struct bt_port *upstream_port = conn->upstream_port;
 164         size_t i;
 165
 166         BT_LIB_LOGI("Ending connection: %!+x, try-remove-from-graph=%d",
 167                 conn, try_remove_from_graph);
 168
 169         /*
 170          * Any of the following message callback functions could
 171          * remove one of the connection's ports from its component. To
 172          * make sure that at least logging in called functions works
 173          * with existing objects, get a local reference on both ports.
 174          */
 175         bt_object_get_ref(downstream_port);
 176         bt_object_get_ref(upstream_port);
 177
 178         if (downstream_port) {
 179                 BT_LIB_LOGD("Disconnecting connection's downstream port: %!+p",
 180                         downstream_port);
 181                 bt_port_set_connection(downstream_port, NULL);
 182                 conn->downstream_port = NULL;
 183         }
 184
 185         if (upstream_port) {
 186                 BT_LIB_LOGD("Disconnecting connection's upstream port: %!+p",
 187                         upstream_port);
 188                 bt_port_set_connection(upstream_port, NULL);
 189                 conn->upstream_port = NULL;
 190         }
 191
 192         /*
 193          * It is safe to put the local port references now that we don't
 194          * need them anymore. This could indeed destroy them.
 195          */
 196         bt_object_put_ref(downstream_port);
 197         bt_object_put_ref(upstream_port);
 198
 199         /*
 200          * Because this connection is ended, finalize each message
 201          * iterator created from it.
 202          *
 203          * In practice, this only happens when the connection is
 204          * destroyed and not all its message iterators were finalized,
 205          * which is on graph destruction.
 206          */
 207         for (i = 0; i < conn->iterators->len; i++) {
 208                 struct bt_message_iterator *iterator =
 209                         g_ptr_array_index(conn->iterators, i);
 210
 211                 BT_LIB_LOGD("Finalizing message iterator created by "
 212                         "this ended connection: %![iter-]+i", iterator);
 213                 bt_message_iterator_try_finalize(
 214                         iterator);
 215
 216                 /*
 217                  * Make sure this iterator does not try to remove itself
 218                  * from this connection's iterators on destruction
 219                  * because this connection won't exist anymore.
 220                  */
 221                 bt_message_iterator_set_connection(
 222                         iterator, NULL);
 223         }
 224
 225         g_ptr_array_set_size(conn->iterators, 0);
 226
 227         if (try_remove_from_graph) {
 228                 try_remove_connection_from_graph(conn);
 229         }
 230 }
 231
 232 const struct bt_port_output *bt_connection_borrow_upstream_port_const(
 233                 const struct bt_connection *connection)
 234 {
 235         BT_ASSERT_PRE_DEV_NON_NULL(connection, "Connection");
 236         return (void *) connection->upstream_port;
 237 }
 238
 239 const struct bt_port_input *bt_connection_borrow_downstream_port_const(
 240                 const struct bt_connection *connection)
 241 {
 242         BT_ASSERT_PRE_DEV_NON_NULL(connection, "Connection");
 243         return (void *) connection->downstream_port;
 244 }
 245
 246 BT_HIDDEN
 247 void bt_connection_remove_iterator(struct bt_connection *conn,
 248                 struct bt_message_iterator *iterator)
 249 {
 250         g_ptr_array_remove(conn->iterators, iterator);
 251         BT_LIB_LOGD("Removed message iterator from connection: "
 252                 "%![conn-]+x, %![iter-]+i", conn, iterator);
 253         try_remove_connection_from_graph(conn);
 254 }
 255
 256 void bt_connection_get_ref(const struct bt_connection *connection)
 257 {
 258         bt_object_get_ref(connection);
 259 }
 260
 261 void bt_connection_put_ref(const struct bt_connection *connection)
 262 {
 263         bt_object_put_ref(connection);
 264 }