mirror of https://github.com/Icinga/icinga2.git
154 lines
4.3 KiB
C++
154 lines
4.3 KiB
C++
/******************************************************************************
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* Icinga 2 *
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* Copyright (C) 2012 Icinga Development Team (http://www.icinga.org/) *
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* *
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* This program is free software; you can redistribute it and/or *
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* modify it under the terms of the GNU General Public License *
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* as published by the Free Software Foundation; either version 2 *
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* of the License, or (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the Free Software Foundation *
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. *
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******************************************************************************/
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#ifndef ASYNCTASK_H
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#define ASYNCTASK_H
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namespace icinga
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{
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/**
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* An asynchronous task.
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*
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* @ingroup base
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*/
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template<typename TClass, typename TResult>
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class AsyncTask : public Object
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{
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public:
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typedef shared_ptr<AsyncTask<TClass, TResult> > Ptr;
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typedef weak_ptr<AsyncTask<TClass, TResult> > WeakPtr;
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typedef function<void (const shared_ptr<TClass>&)> CompletionCallback;
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/**
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* Constructor for the AsyncTask class.
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*/
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AsyncTask(void)
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: m_Finished(false), m_ResultRetrieved(false)
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{ }
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/**
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* Destructor for the AsyncTask class.
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*/
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~AsyncTask(void)
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{
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if (!m_Finished) {
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Logger::Write(LogCritical, "base", "Contract violation: "
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"AsyncTask was destroyed before its completion callback was invoked.");
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} else if (!m_ResultRetrieved) {
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Logger::Write(LogCritical, "base", "Contract violation: "
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"AsyncTask was destroyed before its result was retrieved.");
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}
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}
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/**
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* Starts the async task. The caller must hold a reference to the AsyncTask
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* object until the completion callback is invoked.
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*/
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void Start(const CompletionCallback& completionCallback)
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{
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m_CompletionCallback = completionCallback;
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try {
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Run();
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} catch (const exception& ex) {
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FinishException(boost::current_exception());
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}
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}
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/**
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* Retrieves the result of the task. Throws an exception if one is stored in
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* the AsyncTask object.
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*
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* @returns The task's result.
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*/
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TResult GetResult(void)
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{
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if (!m_Finished)
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throw runtime_error("GetResult called on an unfinished AsyncTask");
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if (m_ResultRetrieved)
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throw runtime_error("GetResult called on an AsyncTask whose result was already retrieved.");
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if (m_Exception)
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boost::rethrow_exception(m_Exception);
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m_ResultRetrieved = true;
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TResult result;
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std::swap(m_Result, result);
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return result;
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}
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/**
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* Finishes the task using an exception.
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*
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* @param ex The exception.
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*/
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void FinishException(const boost::exception_ptr& ex)
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{
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m_Exception = ex;
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FinishInternal();
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}
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/**
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* Finishes the task using an ordinary result.
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*
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* @param result The result.
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*/
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void FinishResult(const TResult& result)
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{
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m_Result = result;
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FinishInternal();
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}
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protected:
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virtual void Run(void) = 0;
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private:
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/**
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* Finishes the task and causes the completion callback to be invoked. This
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* function must be called before the object is destroyed.
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*/
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void FinishInternal(void)
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{
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assert(!m_Finished);
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m_Finished = true;
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m_CompletionCallback(GetSelf());
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/* Clear callback because the bound function might hold a
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* reference to this task. */
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m_CompletionCallback = CompletionCallback();
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}
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CompletionCallback m_CompletionCallback; /**< The completion callback. */
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TResult m_Result; /**< The task's result. */
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boost::exception_ptr m_Exception; /**< The task's exception. */
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bool m_Finished; /**< Whether the task is finished. */
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bool m_ResultRetrieved; /**< Whether the result was retrieved. */
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};
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}
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#endif /* ASYNCTASK_H */
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