add pub sub test programs

Lesson learned: subscription working for empty messages can be done, but
needs nng_socket_set() instead of nng_socket_set_string().

src/CMakeLists.txt

@@ -50,5 +50,15 @@ target_compile_features(mesy_nng_push_pull_main PRIVATE cxx_std_17)
 target_link_libraries(mesy_nng_push_pull_main PRIVATE mesytec-mvlc PRIVATE nng)
 target_compile_options(mesy_nng_push_pull_main PRIVATE ${MVLC_NNG_NODE_WARN_FLAGS})
 
+add_executable(mesy_nng_pub_producer pub_producer.cc)
+target_compile_features(mesy_nng_pub_producer PRIVATE cxx_std_17)
+target_link_libraries(mesy_nng_pub_producer PRIVATE mesytec-mvlc PRIVATE nng)
+target_compile_options(mesy_nng_pub_producer PRIVATE ${MVLC_NNG_NODE_WARN_FLAGS})
+
+add_executable(mesy_nng_sub_consumer sub_consumer.cc)
+target_compile_features(mesy_nng_sub_consumer PRIVATE cxx_std_17)
+target_link_libraries(mesy_nng_sub_consumer PRIVATE mesytec-mvlc PRIVATE nng)
+target_compile_options(mesy_nng_sub_consumer PRIVATE ${MVLC_NNG_NODE_WARN_FLAGS})
+
 #unset(CMAKE_C_CLANG_TIDY)
 #unset(CMAKE_CXX_CLANG_TIDY)

src/pub_producer.cc

@@ -0,0 +1,36 @@
+#include "common.h"
+#include <nng/protocol/pubsub0/pub.h>
+#include <thread>
+#include <iostream>
+
+int main(int argc, char *argv[])
+{
+    spdlog::set_level(spdlog::level::info);
+
+    nng_socket pubSocket = NNG_SOCKET_INITIALIZER;
+
+    if (int res = nng_pub0_open(&pubSocket))
+        mesy_nng_fatal("nng_pub0_open", res);
+
+    if (int res = nng_listen(pubSocket, "tcp://*:42777", nullptr, 0))
+        mesy_nng_fatal("nng_listen tcp", res);
+
+    while (true)
+    {
+        std::cout << "Enter size of pub message:";
+        size_t size = 0;
+        std::cin >> size;
+
+        fmt::print("Publishing message of size {}\n", size);
+
+        nng_msg *msg = nullptr;
+
+        if (int res = nng_msg_alloc(&msg, size))
+            mesy_nng_fatal("nng_msg_alloc", res);
+
+        if (auto res = nng_sendmsg(pubSocket, msg, 0))
+            mesy_nng_fatal("nng_sendmsg", res);
+    }
+
+    return 0;
+}

src/sub_consumer.cc

@@ -0,0 +1,43 @@
+#include "common.h"
+#include <nng/protocol/pubsub0/sub.h>
+#include <thread>
+#include <iostream>
+
+int main(int argc, char *argv[])
+{
+    spdlog::set_level(spdlog::level::info);
+
+    nng_socket subSocket = NNG_SOCKET_INITIALIZER;
+
+    if (int res = nng_sub0_open(&subSocket))
+        mesy_nng_fatal("nng_sub0_open", res);
+
+    //if (int res = nng_socket_set_string(subSocket, NNG_OPT_SUB_SUBSCRIBE, ""))
+    //    mesy_nng_fatal("consumer socket subscribe", res);
+
+    if (int res = nng_socket_set(subSocket, NNG_OPT_SUB_SUBSCRIBE, nullptr, 0))
+        mesy_nng_fatal("consumer socket subscribe", res);
+
+    if (int res = nng_dial(subSocket, "tcp://127.0.0.1:42777", nullptr, 0))
+        mesy_nng_fatal("nng_dial tcp", res);
+
+    while (true)
+    {
+        std::cout << "Waiting for incoming message...\n";
+        nng_msg *msg = nullptr;
+
+        if (auto res = receive_message(subSocket, &msg))
+        {
+            if (res != NNG_ETIMEDOUT)
+                mesy_nng_fatal("receive_message", res);
+            spdlog::warn("consumer timed out in recv");
+            continue;
+        }
+
+        fmt::print("Received message of size {}\n", nng_msg_len(msg));
+
+        nng_msg_free(msg);
+    }
+
+    return 0;
+}