TCP socket send buffer limit (#646) (#658)

* TCP socket send buffer limit (#646)

* Refs #20119: Add non_blocking_send to TCPTransportDescriptor

Signed-off-by: Jesus Perez <jesusperez@eprosima.com>

* Refs #20119: non_blocking_send moved to properties

Signed-off-by: Jesus Perez <jesusperez@eprosima.com>

* Refs #20119: Apply suggestions

Signed-off-by: Jesus Perez <jesusperez@eprosima.com>

---------

Signed-off-by: Jesus Perez <jesusperez@eprosima.com>
(cherry picked from commit b74412f)

# Conflicts:
#	code/XMLTester.xml
#	docs/fastdds/rtps_layer/rtps_layer.rst

* Refs #20119: Solve conflicts

Signed-off-by: Jesus Perez <jesusperez@eprosima.com>

* Refs #20119: Remove non_blocking_send true from large data

Signed-off-by: Jesus Perez <jesusperez@eprosima.com>

---------

Signed-off-by: Jesus Perez <jesusperez@eprosima.com>
Co-authored-by: Jesús Pérez <78275223+jepemi@users.noreply.github.com>
Co-authored-by: Jesus Perez <jesusperez@eprosima.com>

Author: mergify[bot]

code/DDSCodeTester.cpp

@@ -796,6 +796,17 @@ void dds_domain_examples()
             "unicast");
         //!--
     }
+
+    {
+        //DDS-TCP-NON-BLOCKING-SEND
+        DomainParticipantQos participant_qos;
+
+        // TCP transport will use non-blocking send
+        participant_qos.properties().properties().emplace_back(
+            "fastdds.tcp_transport.non_blocking_send",
+            "true");
+        //!--
+    }
 }
 
 //DOMAINPARTICIPANTLISTENER-DISCOVERY-CALLBACKS

code/XMLTester.xml

@@ -3883,6 +3883,21 @@
 -->
 <!--><-->
 
+<!-->XML-TCP-NON-BLOCKING-SEND<-->
+<participant profile_name="participant_xml_conf_tcp_non_blocking_send">
+    <rtps>
+        <propertiesPolicy>
+            <properties>
+                <property>
+                    <name>fastdds.tcp_transport.non_blocking_send</name>
+                    <value>true</value>
+                </property>
+            </properties>
+        </propertiesPolicy>
+    </rtps>
+</participant>
+<!--><-->
+
 <!-->LARGE_DATA_BUILTIN_TRANSPORTS<-->
 <!--
 <?xml version="1.0" encoding="UTF-8" ?>

docs/fastdds/property_policies/non_consolidated_qos.rst

@@ -351,3 +351,47 @@ The behavior regarding this can be configured using the property ``fastdds.shm.e
            :language: xml
            :start-after: <!-->XML-SHM-ENFORCE-META-TRAFFIC
            :end-before: <!--><-->
+
+.. _property_policies_tcp_non_blocking_send:
+
+TCP Non-blocking send
+^^^^^^^^^^^^^^^^^^^^^
+
+TCP transport will by default configure a :ref:`transport_tcp_tcp` with blocking send calls.
+When ``fastdds.tcp_transport.non_blocking_send`` property is set to ``true``, send operations will
+return immediately if the send buffer is full, but no error will be returned to the upper layer.
+This means that the application will behave as if the packet is sent and lost.
+
+When set to ``false``, send operations will block until the network buffer has space for the
+packet.
+
+.. list-table::
+   :header-rows: 1
+   :align: left
+
+   * - PropertyPolicyQos value
+     - Description
+     - Default
+   * - ``"false"``
+     - Block on send operations when send buffer is full.
+     - ✅
+   * - ``"true"``
+     - Do not block on send operations when send buffer is full.
+     -
+
+.. tabs::
+
+    .. tab:: C++
+
+        .. literalinclude:: /../code/DDSCodeTester.cpp
+           :language: c++
+           :start-after: //DDS-TCP-NON-BLOCKING-SEND
+           :end-before: //!--
+           :dedent: 8
+
+    .. tab:: XML
+
+        .. literalinclude:: /../code/XMLTester.xml
+           :language: xml
+           :start-after: <!-->XML-TCP-NON-BLOCKING-SEND
+           :end-before: <!--><-->

docs/fastdds/transport/tcp/tcp.rst

@@ -347,6 +347,3 @@ A TCP version of helloworld example can be found in the
 `HelloWorldExampleTCP folder <https://github.com/eProsima/Fast-DDS/tree/master/examples/C%2B%2B/DDS/HelloWorldExampleTCP>`_.
 It shows a publisher and a subscriber that communicate through TCP.
 The publisher is configured as *TCP server* while the Subscriber is acting as *TCP client*.
-
-
-