Document libbabeltrace2's C API

[babeltrace.git] / include / babeltrace2 / graph / connection.h

diff --git a/include/babeltrace2/graph/connection.h b/include/babeltrace2/graph/connection.h
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+#ifndef BABELTRACE2_GRAPH_CONNECTION_H
+#define BABELTRACE2_GRAPH_CONNECTION_H
+
+/*
+ * Copyright (c) 2010-2019 EfficiOS Inc. and Linux Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef __BT_IN_BABELTRACE_H
+# error "Please include <babeltrace2/babeltrace.h> instead."
+#endif
+
+#include <babeltrace2/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*!
+@defgroup api-conn Connection
+@ingroup api-graph
+
+@brief
+    \bt_c_comp \bt_port connection.
+
+A <strong><em>connection</em></strong> is a link between an \bt_oport
+and an \bt_iport.
+
+@image html component-zoom.png
+
+A connection is a \ref api-fund-shared-object "shared object": get a new
+reference with bt_connection_get_ref() and put an existing reference with
+bt_connection_put_ref().
+
+The type of a connection is #bt_connection.
+
+Borrow the upstream (output) port and downstream (input) port of a
+connection with bt_connection_borrow_upstream_port_const() and
+bt_connection_borrow_downstream_port_const().
+*/
+
+/*! @{ */
+
+/*!
+@name Type
+@{
+
+@typedef struct bt_connection bt_connection;
+
+@brief
+    Connection.
+
+@}
+*/
+
+/*!
+@name Port access
+@{
+*/
+
+/*!
+@brief
+    Borrows the upstream \bt_iport of the connection \bt_p{connection}.
+
+@param[in] connection
+    Connection of which to borrow the upstream port.
+
+@returns
+    \em Borrowed reference of the upstream port of \bt_p{connection}.
+
+@bt_pre_not_null{connection}
+*/
+extern const bt_port_input *bt_connection_borrow_downstream_port_const(
+               const bt_connection *connection);
+
+/*!
+@brief
+    Borrows the downstream \bt_oport of the connection
+    \bt_p{connection}.
+
+@param[in] connection
+    Connection of which to borrow the downstream port.
+
+@returns
+    \em Borrowed reference of the downstream port of \bt_p{connection}.
+
+@bt_pre_not_null{connection}
+*/
+extern const bt_port_output *bt_connection_borrow_upstream_port_const(
+               const bt_connection *connection);
+
+/*! @} */
+
+/*!
+@name Reference count
+@{
+*/
+
+/*!
+@brief
+    Increments the \ref api-fund-shared-object "reference count" of
+    the connection \bt_p{connection}.
+
+@param[in] connection
+    @parblock
+    Connection of which to increment the reference count.
+
+    Can be \c NULL.
+    @endparblock
+
+@sa bt_connection_put_ref() &mdash;
+    Decrements the reference count of a connection.
+*/
+extern void bt_connection_get_ref(const bt_connection *connection);
+
+/*!
+@brief
+    Decrements the \ref api-fund-shared-object "reference count" of
+    the connection \bt_p{connection}.
+
+@param[in] connection
+    @parblock
+    Connection of which to decrement the reference count.
+
+    Can be \c NULL.
+    @endparblock
+
+@sa bt_connection_get_ref() &mdash;
+    Increments the reference count of a connection.
+*/
+extern void bt_connection_put_ref(const bt_connection *connection);
+
+/*!
+@brief
+    Decrements the reference count of the connection
+    \bt_p{_connection}, and then sets \bt_p{_connection} to \c NULL.
+
+@param _connection
+    @parblock
+    Connection of which to decrement the reference count.
+
+    Can contain \c NULL.
+    @endparblock
+
+@bt_pre_assign_expr{_connection}
+*/
+#define BT_CONNECTION_PUT_REF_AND_RESET(_connection)   \
+       do {                                            \
+               bt_connection_put_ref(_connection);     \
+               (_connection) = NULL;                   \
+       } while (0)
+
+/*!
+@brief
+    Decrements the reference count of the connection \bt_p{_dst}, sets
+    \bt_p{_dst} to \bt_p{_src}, and then sets \bt_p{_src} to \c NULL.
+
+This macro effectively moves a connection reference from the expression
+\bt_p{_src} to the expression \bt_p{_dst}, putting the existing
+\bt_p{_dst} reference.
+
+@param _dst
+    @parblock
+    Destination expression.
+
+    Can contain \c NULL.
+    @endparblock
+@param _src
+    @parblock
+    Source expression.
+
+    Can contain \c NULL.
+    @endparblock
+
+@bt_pre_assign_expr{_dst}
+@bt_pre_assign_expr{_src}
+*/
+#define BT_CONNECTION_MOVE_REF(_dst, _src)     \
+       do {                                    \
+               bt_connection_put_ref(_dst);    \
+               (_dst) = (_src);                \
+               (_src) = NULL;                  \
+       } while (0)
+
+/*! @} */
+
+/*! @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* BABELTRACE2_GRAPH_CONNECTION_H */