add option to send signal to other processes on values changed

Author: NikolasK-source

src/CMakeLists.txt

@@ -7,16 +7,7 @@ target_sources(${Target} PRIVATE Modbus_TCP_Client_poll.cpp)
 target_sources(${Target} PRIVATE license.cpp)
 target_sources(${Target} PRIVATE sa_to_str.cpp)
 target_sources(${Target} PRIVATE Print_Time.cpp)
-
-
-# ---------------------------------------- header files (*.jpp, *.h, ...) ----------------------------------------------
-# ======================================================================================================================
-target_sources(${Target} PRIVATE modbus_shm.hpp)
-target_sources(${Target} PRIVATE Modbus_TCP_Client_poll.hpp)
-target_sources(${Target} PRIVATE license.hpp)
-target_sources(${Target} PRIVATE sa_to_str.hpp)
-target_sources(${Target} PRIVATE Print_Time.hpp)
-
+target_sources(${Target} PRIVATE Mb_Proc_Signal.cpp)
 
 # ---------------------------------------- subdirectories --------------------------------------------------------------
 # ======================================================================================================================

src/Mb_Proc_Signal.cpp

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2024 Nikolas Koesling <nikolas@koesling.info>.
+ * This program is free software. You can redistribute it and/or modify it under the terms of the GPLv3 License.
+ */
+
+#include "Mb_Proc_Signal.hpp"
+
+#include <cerrno>
+#include <modbus/modbus.h>
+#include <system_error>
+
+Mb_Proc_Signal Mb_Proc_Signal::instance;  // NOLINT
+
+Mb_Proc_Signal &Mb_Proc_Signal::get_instance() {
+    return instance;
+}
+
+void Mb_Proc_Signal::add_process(pid_t process) {
+    processes.insert(process);
+}
+
+void Mb_Proc_Signal::send_signal() {
+    for (auto proc : processes) {
+        auto ret = kill(proc, SIGUSR1);
+        if (ret == -1) {
+            throw std::system_error(
+                    errno, std::generic_category(), "Failed to send signal to process " + std::to_string(proc));
+        }
+    }
+}
+
+void mb_callback(uint8_t mb_funtion_code) {
+    switch (mb_funtion_code) {
+        case MODBUS_FC_WRITE_SINGLE_COIL:
+        case MODBUS_FC_WRITE_SINGLE_REGISTER:
+        case MODBUS_FC_WRITE_MULTIPLE_COILS:
+        case MODBUS_FC_WRITE_MULTIPLE_REGISTERS:
+        case MODBUS_FC_WRITE_AND_READ_REGISTERS: Mb_Proc_Signal::get_instance().send_signal(); break;
+        default:
+            // do nothing
+            break;
+    }
+}

src/Mb_Proc_Signal.hpp

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2024 Nikolas Koesling <nikolas@koesling.info>.
+ * This program is free software. You can redistribute it and/or modify it under the terms of the GPLv3 License.
+ */
+
+#include <cstdint>
+#include <unistd.h>
+#include <unordered_set>
+
+class Mb_Proc_Signal final {
+private:
+    std::unordered_set<pid_t> processes;
+
+    Mb_Proc_Signal() = default;
+
+    static Mb_Proc_Signal instance;
+
+public:
+    Mb_Proc_Signal(const Mb_Proc_Signal &)            = delete;
+    Mb_Proc_Signal(Mb_Proc_Signal &&)                 = delete;
+    Mb_Proc_Signal &operator=(const Mb_Proc_Signal &) = delete;
+    Mb_Proc_Signal &operator=(Mb_Proc_Signal &&)      = delete;
+    ~Mb_Proc_Signal()                                 = default;
+
+    static Mb_Proc_Signal &get_instance();
+
+    void add_process(pid_t process);
+
+    void send_signal();
+};
+
+void mb_callback(uint8_t mb_funtion_code);

src/Modbus_TCP_Client_poll.cpp

@@ -263,7 +263,10 @@ void Client_Poll::set_response_timeout(double timeout) {
     return static_cast<double>(timeout.sec) + (static_cast<double>(timeout.usec) / (1000.0 * 1000.0));  // NOLINT
 }
 
-Client_Poll::run_t Client_Poll::run(int signal_fd, bool reconnect, int timeout) {
+Client_Poll::run_t Client_Poll::run(int  signal_fd,
+                                    bool reconnect,
+                                    int  timeout,
+                                    void (*mb_function_callback)(uint8_t mb_function_code)) {
     std::size_t i = 0;
 
     // poll signal fd
@@ -418,6 +421,13 @@ Client_Poll::run_t Client_Poll::run(int signal_fd, bool reconnect, int timeout)
                                   << std::endl;  // NOLINT
                         close_con(client_addrs);
                     }
+
+                    // function code callback
+                    if (mb_function_callback) {
+                        const auto FUNCTION_CODE = query[7];
+                        mb_function_callback(FUNCTION_CODE);
+                    }
+
                 } else if (rc == -1) {
                     if (errno != ECONNRESET) {
                         std::cerr << Print_Time::iso << " ERROR: modbus_receive failed: " << modbus_strerror(errno)

src/Modbus_TCP_Client_poll.hpp

@@ -144,10 +144,15 @@ class Client_Poll {
      *                  true: continue listening for new connections if there is no client (Mosbus Server) left
      * @param timeout timeout valoue for call of poll (see: man 2 poll)
      * @param signal_fd signal file descriptor for termination signals
+     * @param mb_function_callback callback function that is called with the modbus function code on each modbus
+     * telegram
      * @return true continue
      * @return false terminate
      */
-    run_t run(int signal_fd, bool reconnect = true, int timeout = -1);
+    run_t run(int  signal_fd,
+              bool reconnect                                         = true,
+              int  timeout                                           = -1,
+              void (*mb_function_callback)(uint8_t mb_function_code) = nullptr);
 
 private:
 #ifdef OS_LINUX

src/main.cpp

@@ -3,6 +3,7 @@
  * This program is free software. You can redistribute it and/or modify it under the terms of the GPLv3 License.
  */
 
+#include "Mb_Proc_Signal.hpp"
 #include "Modbus_TCP_Client_poll.hpp"
 #include "Print_Time.hpp"
 #include "generated/version_info.hpp"
@@ -188,6 +189,8 @@ int main(int argc, char **argv) {
     options.add_options("version information")("git-hash", "print git hash");
     options.add_options("other")("license", "show licences (short)");
     options.add_options("other")("license-full", "show licences (full license text)");
+    options.add_options("signal")(
+            "k,signal", "send SIGUSR to process on writing modbus commands", cxxopts::value<std::vector<pid_t>>());
 
     // parse arguments
     cxxopts::ParseResult args;
@@ -440,6 +443,14 @@ int main(int argc, char **argv) {
         }
     }
 
+    bool SIGNAL_PROCESS = args.count("signal") > 0;
+    if (SIGNAL_PROCESS) {
+        auto &processes = args["signal"].as<std::vector<pid_t>>();
+        for (auto proc : processes) {
+            Mb_Proc_Signal::get_instance().add_process(proc);
+        }
+    }
+
 
     // create modbus client
     std::unique_ptr<Modbus::TCP::Client_Poll> client;
@@ -487,7 +498,7 @@ int main(int argc, char **argv) {
     try {
         [&]() {
             while (true) {
-                auto ret = client->run(signal_fd, RECONNECT, -1);
+                auto ret = client->run(signal_fd, RECONNECT, -1, SIGNAL_PROCESS ? &mb_callback : nullptr);
 
                 switch (ret) {
                     case Modbus::TCP::Client_Poll::run_t::ok: continue;