/usr/include/qpid/Plugin.h is in libqpidcommon2-dev 0.14-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 | #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*/
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