Adding channel-based ping-pong example

Author: hkaiser

libs/full/collectives/examples/CMakeLists.txt

@@ -1,4 +1,4 @@
-# Copyright (c) 2021 The STE||AR-Group
+# Copyright (c) 2021-2025 The STE||AR-Group
 #
 # SPDX-License-Identifier: BSL-1.0
 # Distributed under the Boost Software License, Version 1.0. (See accompanying
@@ -17,14 +17,17 @@ else()
   return()
 endif()
 
-set(example_programs channel_communicator distributed_pi)
+set(example_programs channel_communicator channel_pingpong distributed_pi)
 
 set(channel_communicator_PARAMETERS LOCALITIES 2 THREADS_PER_LOCALITY 2)
 set(channel_communicator_FLAGS DEPENDENCIES iostreams_component)
 
 set(distributed_pi_PARAMETERS LOCALITIES 2 THREADS_PER_LOCALITY 2)
 set(distributed_pi_FLAGS COMPILE_FLAGS -DHPX_HAVE_RUN_MAIN_EVERYWHERE)
 
+set(channel_pingpong_PARAMETERS LOCALITIES 2 THREADS_PER_LOCALITY 2)
+set(channel_pingpong_FLAGS COMPILE_FLAGS -DHPX_HAVE_RUN_MAIN_EVERYWHERE)
+
 foreach(example_program ${example_programs})
 
   set(sources ${example_program}.cpp)

libs/full/collectives/examples/channel_pingpong.cpp

@@ -0,0 +1,44 @@
+//  Copyright (c) 2025 Hartmut Kaiser
+//
+//  SPDX-License-Identifier: BSL-1.0
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <hpx/hpx_main.hpp>
+
+#if !defined(HPX_COMPUTE_DEVICE_CODE)
+#include <hpx/hpx.hpp>
+
+#include <iostream>
+
+int main()
+{
+    using namespace hpx::collectives;
+
+    std::uint32_t const locality_id = hpx::get_locality_id();
+    auto const comm = get_world_channel_communicator();
+
+    if (locality_id == 0)
+    {
+        set(hpx::launch::sync, comm, that_site_arg(1), 42, tag_arg(123));
+        int const received =
+            get<int>(hpx::launch::sync, comm, that_site_arg(1), tag_arg(123));
+        std::cout << "Received: " << received << "\n";
+    }
+    if (locality_id == 1)
+    {
+        int const received =
+            get<int>(hpx::launch::sync, comm, that_site_arg(0), tag_arg(123));
+        set(hpx::launch::sync, comm, that_site_arg(0), received, tag_arg(123));
+    }
+    return 0;
+}
+
+#else
+
+int main()
+{
+    return 0;
+}
+
+#endif