FairMQ: Add plugin mechanism (Plugin and PluginManager classes)

fairmq/PluginManager.h

@@ -0,0 +1,116 @@
+/********************************************************************************
+ *    Copyright (C) 2017 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH    *
+ *                                                                              *
+ *              This software is distributed under the terms of the             *
+ *              GNU Lesser General Public Licence (LGPL) version 3,             *
+ *                  copied verbatim in the file "LICENSE"                       *
+ ********************************************************************************/
+
+#ifndef FAIR_MQ_PLUGINMANAGER_H
+#define FAIR_MQ_PLUGINMANAGER_H
+
+#include <fairmq/Plugin.h>
+#include <fairmq/Tools.h>
+#define BOOST_FILESYSTEM_VERSION 3
+#define BOOST_FILESYSTEM_NO_DEPRECATED
+#include <boost/filesystem.hpp>
+#include <boost/optional.hpp>
+#include <boost/program_options.hpp>
+#include <boost/dll/import.hpp>
+#include <boost/dll/shared_library.hpp>
+#include <boost/dll/runtime_symbol_info.hpp>
+#include <functional>
+#include <map>
+#include <memory>
+#include <stdexcept>
+#include <string>
+#include <tuple>
+#include <tuple>
+#include <vector>
+
+namespace fair
+{
+namespace mq
+{
+
+/**
+ * @class PluginManager PluginManager.h <fairmq/PluginManager.h>
+ * @brief manages and owns plugin instances
+ *
+ * The plugin manager is responsible for the whole plugin lifecycle. It
+ * facilitates three plugin mechanisms:
+ * A static (built-in) plugins
+ * B dynamic plugins (shared libraries)
+ */
+class PluginManager
+{
+    public:
+
+    using PluginFactory = std::shared_ptr<fair::mq::Plugin>();
+    using PluginProgOptions = const boost::optional<boost::program_options::options_description>();
+
+    PluginManager();
+
+    auto SetSearchPaths(const std::vector<boost::filesystem::path>&) -> void;
+    auto AppendSearchPath(const boost::filesystem::path&) -> void;
+    auto PrependSearchPath(const boost::filesystem::path&) -> void;
+    auto SearchPaths() const -> const std::vector<boost::filesystem::path>& { return fSearchPaths; }
+    struct BadSearchPath : std::invalid_argument { using std::invalid_argument::invalid_argument; };
+
+    auto LoadPlugin(const std::string& pluginName) -> void;
+    auto LoadPlugins(const std::vector<std::string>& pluginNames) -> void { for(const auto& pluginName : pluginNames) { LoadPlugin(pluginName); } }
+    struct PluginLoadError : std::runtime_error { using std::runtime_error::runtime_error; };
+
+    static auto ProgramOptions() -> const boost::optional<boost::program_options::options_description>;
+    static auto MakeFromCommandLineOptions(const std::vector<std::string>) -> std::shared_ptr<PluginManager>;
+    struct ProgramOptionsParseError : std::runtime_error { using std::runtime_error::runtime_error; };
+
+    static auto LibPrefix() -> const std::string& { return fgkLibPrefix; }
+
+    auto ForEachPlugin(std::function<void (Plugin&)> func) -> void { for(const auto& p : fPluginOrder) { func(*fPlugins[p]); } }
+    auto ForEachPluginProgOptions(std::function<void (const boost::program_options::options_description&)> func) const -> void { for(const auto& pair : fPluginProgOptions) { func(pair.second); } }
+
+    private:
+
+    static auto ValidateSearchPath(const boost::filesystem::path&) -> void;
+
+    auto LoadPluginStatic(const std::string& pluginName) -> void;
+    auto LoadPluginDynamic(const std::string& pluginName) -> void;
+    template<typename... Args>
+    auto LoadSymbols(const std::string& pluginName, Args&&... args) -> void
+    {
+        using namespace boost::dll;
+        using fair::mq::tools::ToString;
+
+        auto lib = shared_library{std::forward<Args>(args)...};
+
+        fPluginFactories[pluginName] = import_alias<PluginFactory>(
+            shared_library{lib},
+            ToString("make_", pluginName, "_plugin")
+        );
+
+        try
+        {
+            fPluginProgOptions.insert({
+                pluginName,
+                lib.get_alias<PluginProgOptions>(ToString("get_", pluginName, "_plugin_progoptions"))().value()
+            });
+        }
+        catch (const boost::bad_optional_access& e) { /* just ignore, if no prog options are declared */ }
+    }
+
+    auto InstantiatePlugin(const std::string& pluginName) -> void;
+
+    static const std::string fgkLibPrefix;
+    std::vector<boost::filesystem::path> fSearchPaths;
+    std::map<std::string, std::function<PluginFactory>> fPluginFactories;
+    std::map<std::string, std::shared_ptr<Plugin>> fPlugins;
+    std::vector<std::string> fPluginOrder;
+    std::map<std::string, boost::program_options::options_description> fPluginProgOptions;
+    
+}; /* class PluginManager */
+
+} /* namespace mq */
+} /* namespace fair */
+
+#endif /* FAIR_MQ_PLUGINMANAGER_H */