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| -rw-r--r-- | include/comphelper/asyncnotification.hxx | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/include/comphelper/asyncnotification.hxx b/include/comphelper/asyncnotification.hxx new file mode 100644 index 0000000000..5c24164889 --- /dev/null +++ b/include/comphelper/asyncnotification.hxx @@ -0,0 +1,225 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + * + * This file incorporates work covered by the following license notice: + * + * 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 . + */ + +#ifndef INCLUDED_COMPHELPER_ASYNCNOTIFICATION_HXX +#define INCLUDED_COMPHELPER_ASYNCNOTIFICATION_HXX + +#include <sal/config.h> + +#include <comphelper/comphelperdllapi.h> +#include <rtl/ref.hxx> +#include <sal/types.h> +#include <salhelper/thread.hxx> +#include <salhelper/simplereferenceobject.hxx> +#include <memory> + +namespace comphelper +{ + //= AnyEvent + + /** the very basic instance to hold a description of an event + */ + class COMPHELPER_DLLPUBLIC AnyEvent : public salhelper::SimpleReferenceObject + { + public: + AnyEvent(); + + protected: + virtual ~AnyEvent() override; + + private: + AnyEvent( AnyEvent const & ) = delete; + AnyEvent& operator=( AnyEvent const & ) = delete; + }; + + + //= typedefs + + typedef ::rtl::Reference< AnyEvent > AnyEventRef; + + + //= IEventProcessor + + /** an event processor + + @see AsyncEventNotifier + */ + class SAL_NO_VTABLE IEventProcessor + { + public: + /** process a single event + */ + virtual void processEvent( const AnyEvent& _rEvent ) = 0; + + virtual void SAL_CALL acquire() noexcept = 0; + virtual void SAL_CALL release() noexcept = 0; + + protected: + ~IEventProcessor() {} + }; + + + //= AsyncEventNotifier + + struct EventNotifierImpl; + + /** a helper class for notifying events asynchronously + + If you need to notify certain events to external components, you usually should + not do this while you have mutexes locked, to prevent multi-threading issues. + + However, you do not always have complete control over all mutex guards on the stack. + If, in such a case, the listener notification is one-way, you can decide to do it + asynchronously. + + The ->AsyncEventNotifier helps you to process such events asynchronously. Every + event is tied to an ->IEventProcessor which is responsible for processing it. + + The AsyncEventNotifier is implemented as a thread itself, which sleeps as long as there are no + events in the queue. As soon as you add an event, the thread is woken up, processes the event, + and sleeps again. + */ + class COMPHELPER_DLLPUBLIC AsyncEventNotifierBase + { + friend struct EventNotifierImpl; + + protected: + std::unique_ptr<EventNotifierImpl> m_xImpl; + + SAL_DLLPRIVATE virtual ~AsyncEventNotifierBase(); + + // Thread + SAL_DLLPRIVATE virtual void execute(); + + public: + AsyncEventNotifierBase(); + + /** terminates the thread + + Note that this is a cooperative termination - if you call this from a thread different + from the notification thread itself, then it will block until the notification thread + finished processing the current event. If you call it from the notification thread + itself, it will return immediately, and the thread will be terminated as soon as + the current notification is finished. + */ + virtual void SAL_CALL terminate(); + + /** adds an event to the queue, together with the instance which is responsible for + processing it + + @param _rEvent + the event to add to the queue + @param _xProcessor + the processor for the event.<br/> + Beware of life time issues here. If your event processor dies or becomes otherwise + nonfunctional, you are responsible for removing all respective events from the queue. + You can do this by calling ->removeEventsForProcessor + */ + void addEvent( const AnyEventRef& _rEvent, const ::rtl::Reference< IEventProcessor >& _xProcessor ); + + /** removes all events for the given event processor from the queue + */ + void removeEventsForProcessor( const ::rtl::Reference< IEventProcessor >& _xProcessor ); + }; + + /** This class is usable with rtl::Reference. + As always, the thread must be joined somewhere. + */ + class COMPHELPER_DLLPUBLIC AsyncEventNotifier final + : public AsyncEventNotifierBase + , public salhelper::Thread + { + + private: + SAL_DLLPRIVATE virtual ~AsyncEventNotifier() override; + + SAL_DLLPRIVATE virtual void execute() override; + + public: + /** constructs a notifier thread + + @param name the thread name, see ::osl_setThreadName; must not be + null + */ + AsyncEventNotifier(char const* name); + + virtual void SAL_CALL terminate() override; + }; + + /** This is a hack (when proper joining is not possible), use of which + should be avoided by good design. + */ + class COMPHELPER_DLLPUBLIC AsyncEventNotifierAutoJoin final + : public AsyncEventNotifierBase + , private osl::Thread + { + + private: + SAL_DLLPRIVATE AsyncEventNotifierAutoJoin(char const* name); + + SAL_DLLPRIVATE virtual void SAL_CALL run() override; + SAL_DLLPRIVATE virtual void SAL_CALL onTerminated() override; + + public: + // only public so shared_ptr finds it + SAL_DLLPRIVATE virtual ~AsyncEventNotifierAutoJoin() override; + + static std::shared_ptr<AsyncEventNotifierAutoJoin> + newAsyncEventNotifierAutoJoin(char const* name); + + virtual void SAL_CALL terminate() override; + + using osl::Thread::join; + using osl::Thread::operator new; + using osl::Thread::operator delete; // clang really wants this? + + static void launch(std::shared_ptr<AsyncEventNotifierAutoJoin> const&); + }; + + + //= EventHolder + + /** AnyEvent derivee holding a foreign event instance + */ + template < typename EVENT_OBJECT > + class SAL_DLLPUBLIC_RTTI EventHolder final : public AnyEvent + { + public: + typedef EVENT_OBJECT EventObjectType; + + private: + EventObjectType const m_aEvent; + + public: + EventHolder( EventObjectType _aEvent ) + :m_aEvent(std::move( _aEvent )) + { + } + + const EventObjectType& getEventObject() const { return m_aEvent; } + }; + + COMPHELPER_DLLPUBLIC void JoinAsyncEventNotifiers(); + +} // namespace comphelper + + +#endif // INCLUDED_COMPHELPER_ASYNCNOTIFICATION_HXX + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |