Core: add an option to disable plugin unload on exit

Author: Lukas955

src/core/configurator/plugin_finder.cpp

@@ -62,15 +62,30 @@ extern "C" {
 /** Component identification (for log) */
 static const char *comp_str = "Configurator (plugin finder)";
 
+ipx_plugin_finder::ipx_plugin_finder()
+{
+    // Enable automatic unload of plugins
+    unload_on_exit = true;
+}
+
 ipx_plugin_finder::~ipx_plugin_finder()
 {
     // Unload all plugins
     for (struct ipx_plugin_data *plugin : loaded_plugins) {
-        dlclose(plugin->cbs.handle);
+        if (unload_on_exit) {
+            dlclose(plugin->cbs.handle);
+        }
+
         delete plugin;
     }
 }
 
+void
+ipx_plugin_finder::auto_unload(bool enable)
+{
+    unload_on_exit = enable;
+}
+
 void
 ipx_plugin_finder::path_add(const std::string &pathname)
 {

src/core/configurator/plugin_finder.hpp

@@ -71,6 +71,7 @@ class ipx_plugin_finder {
     /** Search paths (files and directories) */
     std::vector<std::string> paths;
     std::vector<struct ipx_plugin_data *> loaded_plugins;
+    bool unload_on_exit;
 
     void find_in_paths(const std::string &name, uint16_t, struct ipx_ctx_callbacks &cbs);
     void *find_in_file(const std::string &name, uint16_t type, const char *path);
@@ -80,7 +81,7 @@ class ipx_plugin_finder {
 
 public:
     // Use default constructor and destructor
-    ipx_plugin_finder() = default;
+    ipx_plugin_finder();
     ~ipx_plugin_finder();
 
     /**
@@ -105,6 +106,18 @@ class ipx_plugin_finder {
     const struct ipx_plugin_data *
     find(const std::string &name, uint16_t type);
 
+    /**
+     * \brief Automatically unload all plugins on destroy
+     *
+     * This options allows plugin developers to disable automatic unload of plugins. Disabled
+     * unload leaves plugin symbols available even after the collector shutdown. This is necessary
+     * for analysis of performance and memory leaks. For example, valgrind is unable to identify
+     * position of memory leaks of unloaded plugins.
+     * \note By default, unload is enabled.
+     * \param[in] enable Enable/disable
+     */
+    void
+    auto_unload(bool enable);
 };
 
 #endif //IPFIXCOL_PLUGIN_FINDER_H

src/core/main.cpp

@@ -84,7 +84,7 @@ print_help()
 {
     std::cout
         << "IPFIX Collector daemon\n"
-        << "Usage: ipfixcol [-c FILE] [-p PATH] [-e DIR] [-P FILE] [-vVhd]\n"
+        << "Usage: ipfixcol2 [-c FILE] [-p PATH] [-e DIR] [-P FILE] [-r SIZE] [-vVhdu]\n"
         << "  -c FILE   Path to the startup configuration file\n"
         << "            (default: " << IPX_DEFAULT_STARTUP_CONFIG << ")\n"
         << "  -p PATH   Add path to a directory with plugins or to a file\n"
@@ -97,7 +97,8 @@ print_help()
         << "  -h        Show this help message and exit\n"
         << "  -V        Show version information and exit\n"
         << "  -v        Increase verbosity level (by default, show only error messages)\n"
-        << "            (can be used up to 3 times to add warning/info/debug messages)\n";
+        << "            (can be used up to 3 times to add warning/info/debug messages)\n"
+        << "  -u        Disable plugins unload on exit (only for plugin developers)\n";
 }
 
 /**
@@ -206,7 +207,7 @@ int main(int argc, char *argv[])
     // Parse configuration
     int opt;
     opterr = 0; // Disable default error messages
-    while ((opt = getopt(argc, argv, "c:vVhdp:e:P:r:")) != -1) {
+    while ((opt = getopt(argc, argv, "c:vVhdp:e:P:r:u")) != -1) {
         switch (opt) {
         case 'c': // Configuration file
             cfg_startup = optarg;
@@ -220,21 +221,24 @@ int main(int argc, char *argv[])
         case 'h': // Help
             print_help();
             return EXIT_SUCCESS;
-        case 'd':
+        case 'd': // Run as a standalone process (daemon)
             daemon_en = true;
             break;
         case 'p': // Plugin search path
             conf.finder.path_add(std::string(optarg));
             break;
-        case 'e':
+        case 'e': // Redefine path to Information Elements definition
             cfg_iedir = optarg;
             break;
-        case 'P':
+        case 'P': // Create a PID file
             pid_file = optarg;
             break;
-        case 'r':
+        case 'r': // Change ring size
             ring_size = optarg;
             break;
+        case 'u': // Disable automatic plugin unload
+            conf.finder.auto_unload(false);
+            break;
         default: // ?
             std::cerr << "Unknown parameter '" << static_cast<char>(optopt) << "'!" << std::endl;
             return EXIT_FAILURE;