include/comphelper/asyncnotification.hxx

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