include/comphelper/asyncnotification.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
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   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #ifndef INCLUDED_COMPHELPER_ASYNCNOTIFICATION_HXX
  21 #define INCLUDED_COMPHELPER_ASYNCNOTIFICATION_HXX
  22
  23 #include <sal/config.h>
  24 #include <config_options.h>
  25
  26 #include <com/sun/star/document/DocumentEvent.hpp>
  27 #include <comphelper/comphelperdllapi.h>
  28 #include <rtl/ref.hxx>
  29 #include <sal/types.h>
  30 #include <salhelper/thread.hxx>
  31 #include <salhelper/simplereferenceobject.hxx>
  32 #include <memory>
  33
  34 namespace comphelper
  35 {
  36     //= AnyEvent
  37
  38     /** the very basic instance to hold a description of an event
  39     */
  40     class COMPHELPER_DLLPUBLIC AnyEvent : public salhelper::SimpleReferenceObject
  41     {
  42     public:
  43         AnyEvent();
  44
  45     protected:
  46         virtual ~AnyEvent() override;
  47
  48     private:
  49         AnyEvent( AnyEvent const & ) = delete;
  50         AnyEvent& operator=( AnyEvent const & ) = delete;
  51     };
  52
  53
  54     //= typedefs
  55
  56     typedef ::rtl::Reference< AnyEvent >    AnyEventRef;
  57
  58
  59     //= IEventProcessor
  60
  61     /** an event processor
  62
  63         @see AsyncEventNotifier
  64     */
  65     class SAL_NO_VTABLE IEventProcessor
  66     {
  67     public:
  68         /** process a single event
  69         */
  70         virtual void processEvent( const AnyEvent& _rEvent ) = 0;
  71
  72         virtual void SAL_CALL acquire() noexcept = 0;
  73         virtual void SAL_CALL release() noexcept = 0;
  74
  75     protected:
  76         ~IEventProcessor() {}
  77     };
  78
  79
  80     //= AsyncEventNotifier
  81
  82     struct EventNotifierImpl;
  83
  84     /** a helper class for notifying events asynchronously
  85
  86         If you need to notify certain events to external components, you usually should
  87         not do this while you have mutexes locked, to prevent multi-threading issues.
  88
  89         However, you do not always have complete control over all mutex guards on the stack.
  90         If, in such a case, the listener notification is one-way, you can decide to do it
  91         asynchronously.
  92
  93         The ->AsyncEventNotifier helps you to process such events asynchronously. Every
  94         event is tied to an ->IEventProcessor which is responsible for processing it.
  95
  96         The AsyncEventNotifier is implemented as a thread itself, which sleeps as long as there are no
  97         events in the queue. As soon as you add an event, the thread is woken up, processes the event,
  98         and sleeps again.
  99     */
 100     class COMPHELPER_DLLPUBLIC AsyncEventNotifierBase
 101     {
 102         friend struct EventNotifierImpl;
 103
 104     protected:
 105         std::unique_ptr<EventNotifierImpl>        m_xImpl;
 106
 107         SAL_DLLPRIVATE virtual ~AsyncEventNotifierBase();
 108
 109         // Thread
 110         SAL_DLLPRIVATE virtual void execute();
 111
 112     public:
 113         AsyncEventNotifierBase();
 114
 115         /** terminates the thread
 116
 117             Note that this is a cooperative termination - if you call this from a thread different
 118             from the notification thread itself, then it will block until the notification thread
 119             finished processing the current event. If you call it from the notification thread
 120             itself, it will return immediately, and the thread will be terminated as soon as
 121             the current notification is finished.
 122         */
 123         virtual void SAL_CALL terminate();
 124
 125         /** adds an event to the queue, together with the instance which is responsible for
 126             processing it
 127
 128             @param _rEvent
 129                 the event to add to the queue
 130             @param _xProcessor
 131                 the processor for the event.<br/>
 132                 Beware of life time issues here. If your event processor dies or becomes otherwise
 133                 nonfunctional, you are responsible for removing all respective events from the queue.
 134                 You can do this by calling ->removeEventsForProcessor
 135         */
 136         void addEvent( const AnyEventRef& _rEvent, const ::rtl::Reference< IEventProcessor >& _xProcessor );
 137
 138         /** removes all events for the given event processor from the queue
 139         */
 140         void removeEventsForProcessor( const ::rtl::Reference< IEventProcessor >& _xProcessor );
 141     };
 142
 143     /** This class is usable with rtl::Reference.
 144         As always, the thread must be joined somewhere.
 145      */
 146     class COMPHELPER_DLLPUBLIC AsyncEventNotifier final
 147         : public AsyncEventNotifierBase
 148         , public salhelper::Thread
 149     {
 150
 151     private:
 152         SAL_DLLPRIVATE virtual ~AsyncEventNotifier() override;
 153
 154         SAL_DLLPRIVATE virtual void execute() override;
 155
 156     public:
 157         /** constructs a notifier thread
 158
 159             @param name the thread name, see ::osl_setThreadName; must not be
 160             null
 161         */
 162         AsyncEventNotifier(char const* name);
 163
 164         virtual void SAL_CALL terminate() override;
 165     };
 166
 167     /** This is a hack (when proper joining is not possible), use of which
 168         should be avoided by good design.
 169      */
 170     class UNLESS_MERGELIBS_MORE(COMPHELPER_DLLPUBLIC) AsyncEventNotifierAutoJoin final
 171         : public AsyncEventNotifierBase
 172         , private osl::Thread
 173     {
 174
 175     private:
 176         SAL_DLLPRIVATE AsyncEventNotifierAutoJoin(char const* name);
 177
 178         SAL_DLLPRIVATE virtual void SAL_CALL run() override;
 179         SAL_DLLPRIVATE virtual void SAL_CALL onTerminated() override;
 180
 181     public:
 182         // only public so shared_ptr finds it
 183         SAL_DLLPRIVATE virtual ~AsyncEventNotifierAutoJoin() override;
 184
 185         static std::shared_ptr<AsyncEventNotifierAutoJoin>
 186             newAsyncEventNotifierAutoJoin(char const* name);
 187
 188         virtual void SAL_CALL terminate() override;
 189
 190         using osl::Thread::join;
 191         using osl::Thread::operator new;
 192         using osl::Thread::operator delete; // clang really wants this?
 193
 194         static void launch(std::shared_ptr<AsyncEventNotifierAutoJoin> const&);
 195     };
 196
 197
 198     //= EventHolder
 199
 200     /** AnyEvent derivee holding a foreign event instance
 201     */
 202     template < typename EVENT_OBJECT >
 203     class SAL_DLLPUBLIC_TEMPLATE EventHolder final : public AnyEvent
 204     {
 205     public:
 206         typedef EVENT_OBJECT    EventObjectType;
 207
 208     private:
 209         EventObjectType const m_aEvent;
 210
 211     public:
 212         EventHolder( EventObjectType _aEvent )
 213             :m_aEvent(std::move( _aEvent ))
 214         {
 215         }
 216
 217         const EventObjectType& getEventObject() const { return m_aEvent; }
 218     };
 219
 220     extern template class EventHolder<css::document::DocumentEvent>;
 221     using DocumentEventHolder = EventHolder<css::document::DocumentEvent>;
 222
 223     COMPHELPER_DLLPUBLIC void JoinAsyncEventNotifiers();
 224
 225 } // namespace comphelper
 226
 227
 228 #endif // INCLUDED_COMPHELPER_ASYNCNOTIFICATION_HXX
 229
 230 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */