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Diffstat (limited to 'qpid/cpp/src/qpid/Plugin.h')
-rw-r--r-- | qpid/cpp/src/qpid/Plugin.h | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/qpid/cpp/src/qpid/Plugin.h b/qpid/cpp/src/qpid/Plugin.h new file mode 100644 index 0000000000..4e057872b9 --- /dev/null +++ b/qpid/cpp/src/qpid/Plugin.h @@ -0,0 +1,129 @@ +#ifndef QPID_PLUGIN_H +#define QPID_PLUGIN_H + +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + * + */ + +#include <boost/noncopyable.hpp> +#include <boost/function.hpp> +#include <vector> +#include "qpid/CommonImportExport.h" + +/**@file Generic plug-in framework. */ + +namespace qpid { +struct Options; + +/** + * Plug-in base class. + */ +class Plugin : private boost::noncopyable { + public: + typedef std::vector<Plugin*> Plugins; + /** Default value returned by initOrder() */ + static const int DEFAULT_INIT_ORDER=1000; + + /** + * Base interface for targets that can receive plug-ins. + * Also allows plug-ins to attach a a function to be called + * when the target is 'finalized'. + */ + class Target : private boost::noncopyable + { + public: + /** Calls finalize() if not already called. */ + QPID_COMMON_EXTERN virtual ~Target(); + + /** Run all the finalizers */ + QPID_COMMON_EXTERN void finalize(); + + /** Add a function to run when finalize() is called */ + QPID_COMMON_EXTERN void addFinalizer(const boost::function<void()>&); + + private: + std::vector<boost::function<void()> > finalizers; + }; + + /** + * Constructor registers the plug-in to appear in getPlugins(). + * + * A concrete Plugin is instantiated as a global or static + * member variable in a library so it is registered during + * initialization when the library is loaded. + */ + QPID_COMMON_EXTERN Plugin(); + + QPID_COMMON_EXTERN virtual ~Plugin(); + + /** + * Configuration options for the plugin. + * Then will be updated during option parsing by the host program. + * + * @return An options group or 0 for no options. Default returns 0. + * Plugin retains ownership of return value. + */ + QPID_COMMON_EXTERN virtual Options* getOptions(); + + /** + * Initialize Plugin functionality on a Target, called before + * initializing the target. + * + * Plugins should ignore targets they don't recognize. + * + * Called before the target itself is initialized. + */ + virtual void earlyInitialize(Target&) = 0; + + /** + * Initialize Plugin functionality on a Target. Called after + * initializing the target. + * + * Plugins should ignore targets they don't recognize. + * + * Called after the target is fully initialized. + */ + virtual void initialize(Target&) = 0; + + /** + * Initialization order. If a plugin does not override this, it + * returns DEFAULT_INIT_ORDER. Plugins that need to be initialized + * earlier/later than normal can override initOrder to return + * a lower/higher value than DEFAULT_INIT_ORDER. + */ + QPID_COMMON_EXTERN virtual int initOrder() const; + + /** List of registered Plugin objects. + * Caller must not delete plugin pointers. + */ + QPID_COMMON_EXTERN static const Plugins& getPlugins(); + + /** Call earlyInitialize() on all registered plugins */ + QPID_COMMON_EXTERN static void earlyInitAll(Target&); + + /** Call initialize() on all registered plugins */ + QPID_COMMON_EXTERN static void initializeAll(Target&); + + /** For each registered plugin, add plugin.getOptions() to opts. */ + QPID_COMMON_EXTERN static void addOptions(Options& opts); +}; + +} // namespace qpid + +#endif /*!QPID_PLUGIN_H*/ |