From b74412f56d4a5126062fa38b35c95325be3b2a45 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jes=C3=BAs=20P=C3=A9rez?=
 <78275223+jepemi@users.noreply.github.com>
Date: Tue, 6 Feb 2024 08:54:01 +0100
Subject: [PATCH] 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>
---
 code/DDSCodeTester.cpp                        | 11 +++++
 code/XMLTester.xml                            | 15 +++++++
 .../non_consolidated_qos.rst                  | 44 +++++++++++++++++++
 docs/fastdds/rtps_layer/rtps_layer.rst        |  1 +
 docs/fastdds/transport/tcp/tcp.rst            |  3 --
 5 files changed, 71 insertions(+), 3 deletions(-)

diff --git a/code/DDSCodeTester.cpp b/code/DDSCodeTester.cpp
index 2071f19a6..deee1204c 100644
--- a/code/DDSCodeTester.cpp
+++ b/code/DDSCodeTester.cpp
@@ -865,6 +865,17 @@ 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
diff --git a/code/XMLTester.xml b/code/XMLTester.xml
index 7222c1b3c..177f965a5 100644
--- a/code/XMLTester.xml
+++ b/code/XMLTester.xml
@@ -3592,6 +3592,21 @@
 </participant>
 <!--><-->
 
+<!-->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>
+<!--><-->
+
 <!-->XML_TYPELOOKUP_SERVICE_ENABLING<-->
 <participant profile_name="participant_typelookup_service_enabled">
     <rtps>
diff --git a/docs/fastdds/property_policies/non_consolidated_qos.rst b/docs/fastdds/property_policies/non_consolidated_qos.rst
index 7b0e14656..9858014d1 100644
--- a/docs/fastdds/property_policies/non_consolidated_qos.rst
+++ b/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: <!--><-->
diff --git a/docs/fastdds/rtps_layer/rtps_layer.rst b/docs/fastdds/rtps_layer/rtps_layer.rst
index 99b6744d4..6b19aec4c 100644
--- a/docs/fastdds/rtps_layer/rtps_layer.rst
+++ b/docs/fastdds/rtps_layer/rtps_layer.rst
@@ -184,6 +184,7 @@ function of the :ref:`dds_layer_domainParticipantQos`, XML profiles (see :ref:`R
      * |TCPTransportDescriptor::calculate_crc-api|, |TCPTransportDescriptor::check_crc-api| and
        |TCPTransportDescriptor::apply_security-api| are set to false.
      * |TCPTransportDescriptor::enable_tcp_nodelay-api| is set to true.
+     * :ref:`property_policies_tcp_non_blocking_send` is set to true.
      * |TCPTransportDescriptor::keep_alive_thread-api| and
        |TCPTransportDescriptor::accept_thread-api| use the default configuration.
 
diff --git a/docs/fastdds/transport/tcp/tcp.rst b/docs/fastdds/transport/tcp/tcp.rst
index 5baa4fbbd..e4545e60d 100644
--- a/docs/fastdds/transport/tcp/tcp.rst
+++ b/docs/fastdds/transport/tcp/tcp.rst
@@ -357,6 +357,3 @@ A TCP version of helloworld example can be found in the
 `HelloWorldExampleTCP folder <https://github.com/eProsima/Fast-DDS/tree/master/examples/cpp/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*.
-
-
-