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+/* -*- 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 .
+ */
+
+#pragma once
+
+#include <com/sun/star/sdbc/XConnection.hpp>
+#include <com/sun/star/lang/DisposedException.hpp>
+#include <com/sun/star/uno/XComponentContext.hpp>
+
+#include <cppuhelper/weakref.hxx>
+#include <osl/mutex.hxx>
+#include <utility>
+
+namespace sdbtools
+{
+
+ // ConnectionDependentComponent
+ class ConnectionDependentComponent
+ {
+ private:
+ mutable ::osl::Mutex m_aMutex;
+ css::uno::WeakReference< css::sdbc::XConnection >
+ m_aConnection;
+ css::uno::Reference< css::uno::XComponentContext >
+ m_aContext;
+
+ /** a hard reference to the connection we're working for
+
+ This member is only valid as long as a EntryGuard is on the stack.
+ The guard will, in its constructor, set the member, and reset it in its destructor.
+ This ensures that the connection is only held hard when it's needed, and weak otherwise.
+ */
+ css::uno::Reference< css::sdbc::XConnection >
+ m_xConnection;
+
+ protected:
+ ::osl::Mutex& getMutex() const { return m_aMutex; }
+
+ const css::uno::Reference< css::uno::XComponentContext >&
+ getContext() const { return m_aContext; }
+
+ protected:
+ class EntryGuard;
+
+ protected:
+ explicit ConnectionDependentComponent( css::uno::Reference< css::uno::XComponentContext > _xContext )
+ :m_aContext(std::move( _xContext ))
+ {
+ }
+
+ /** sets the connection we depend on.
+
+ To be called exactly once.
+
+ @param _rxConnection
+ the connection to set
+ */
+ void setWeakConnection( const css::uno::Reference< css::sdbc::XConnection >& _rxConnection )
+ {
+ m_aConnection = _rxConnection;
+ }
+
+ const css::uno::Reference< css::sdbc::XConnection >&
+ getConnection() const { return m_xConnection; }
+
+ public:
+ struct GuardAccess;
+ friend struct GuardAccess;
+ /** helper for granting exclusive access to various other methods
+ */
+ struct GuardAccess { friend class EntryGuard; private: GuardAccess() { } };
+
+ ::osl::Mutex& getMutex( GuardAccess ) const { return m_aMutex; }
+
+ bool acquireConnection( GuardAccess )
+ {
+ m_xConnection.set(m_aConnection);
+ return m_xConnection.is();
+ }
+ void releaseConnection( GuardAccess )
+ {
+ m_xConnection.clear();
+ }
+ };
+
+ // ConnectionDependentComponent::EntryGuard
+ /** a class for guarding methods of a connection-dependent component
+
+ This class serves multiple purposes:
+ <ul><li>It ensures multi-threading safety by guarding the component's mutex
+ as long as it lives.</li>
+ <li>It ensures that the component's connection is alive. The constructor
+ throws a DisposedException if no hard reference to the connection can
+ be obtained.</li>
+ </ul>
+ */
+ class ConnectionDependentComponent::EntryGuard
+ {
+ private:
+ ::osl::MutexGuard m_aMutexGuard;
+ ConnectionDependentComponent& m_rComponent;
+
+ public:
+ explicit EntryGuard( ConnectionDependentComponent& _rComponent )
+ :m_aMutexGuard( _rComponent.getMutex( ConnectionDependentComponent::GuardAccess() ) )
+ ,m_rComponent( _rComponent )
+ {
+ if ( !m_rComponent.acquireConnection( ConnectionDependentComponent::GuardAccess() ) )
+ throw css::lang::DisposedException();
+ }
+
+ ~EntryGuard()
+ {
+ m_rComponent.releaseConnection( ConnectionDependentComponent::GuardAccess() );
+ }
+ };
+
+} // namespace sdbtools
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */