dbaccess/source/sdbtools/connection/connectiondependent.hxx

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  30
  31 #ifndef DBACCESS_CONNECTION_DEPENDENT_HXX
  32 #define DBACCESS_CONNECTION_DEPENDENT_HXX
  33
  34 /** === begin UNO includes === **/
  35 #include <com/sun/star/sdbc/XConnection.hpp>
  36 #include <com/sun/star/lang/DisposedException.hpp>
  37 /** === end UNO includes === **/
  38
  39 #include <comphelper/componentcontext.hxx>
  40 #include <cppuhelper/weakref.hxx>
  41 #include <osl/mutex.hxx>
  42
  43 //........................................................................
  44 namespace sdbtools
  45 {
  46 //........................................................................
  47
  48     //====================================================================
  49     //= ConnectionDependentComponent
  50     //====================================================================
  51     class ConnectionDependentComponent
  52     {
  53     private:
  54         mutable ::osl::Mutex    m_aMutex;
  55         ::com::sun::star::uno::WeakReference< ::com::sun::star::sdbc::XConnection >
  56                                 m_aConnection;
  57         ::comphelper::ComponentContext
  58                                 m_aContext;
  59
  60         /** a hard reference to the connection we're working for
  61
  62             This member is only valid as long as a EntryGuard is on the stack.
  63             The guard will, in its constructor, set the member, and reset it in its destructor.
  64             This ensures that the connection is only held hard when it's needed, and weak otherwise.
  65         */
  66         ::com::sun::star::uno::Reference< ::com::sun::star::sdbc::XConnection >
  67                                 m_xConnection;
  68
  69     protected:
  70         ::osl::Mutex&   getMutex() const { return m_aMutex; }
  71
  72         const ::comphelper::ComponentContext&
  73                         getContext() const { return m_aContext; }
  74
  75     protected:
  76         class EntryGuard;
  77
  78     protected:
  79         ConnectionDependentComponent( const ::comphelper::ComponentContext& _rContext )
  80             :m_aContext( _rContext )
  81         {
  82         }
  83
  84         /** sets the connection we depend on.
  85
  86             To be called exactly once.
  87
  88             @param  _rxConnection
  89                 the connection to set
  90         */
  91         void    setWeakConnection( const ::com::sun::star::uno::Reference< ::com::sun::star::sdbc::XConnection >& _rxConnection )
  92         {
  93             m_aConnection = _rxConnection;
  94         }
  95
  96         const ::com::sun::star::uno::Reference< ::com::sun::star::sdbc::XConnection >&
  97                 getConnection() const { return m_xConnection; }
  98
  99     public:
 100     struct GuardAccess;
 101     friend struct GuardAccess;
 102         /** helper for granting exclusive access to various other methods
 103         */
 104         struct GuardAccess { friend class EntryGuard; private: GuardAccess() { } };
 105
 106         ::osl::Mutex&   getMutex( GuardAccess ) const { return m_aMutex; }
 107
 108         inline bool acquireConnection( GuardAccess )
 109         {
 110             m_xConnection = (::com::sun::star::uno::Reference< ::com::sun::star::sdbc::XConnection >)m_aConnection;
 111             return m_xConnection.is();
 112         }
 113         inline void releaseConnection( GuardAccess )
 114         {
 115             m_xConnection.clear();
 116         }
 117     };
 118
 119     //====================================================================
 120     //= ConnectionDependentComponent::EntryGuard
 121     //====================================================================
 122     /** a class for guarding methods of a connection-dependent component
 123
 124         This class serves multiple purposes:
 125         <ul><li>It ensures multi-threading safety by guarding the component's mutex
 126                 as long as it lives.</li>
 127             <li>It ensures that the component's connection is alive. The constructor
 128                 throws a DisposedException if no hard reference to the connection can
 129                 be obtained.</li>
 130         </ul>
 131     */
 132     class ConnectionDependentComponent::EntryGuard
 133     {
 134     private:
 135         ::osl::MutexGuard               m_aMutexGuard;
 136         ConnectionDependentComponent&   m_rComponent;
 137
 138     public:
 139         EntryGuard( ConnectionDependentComponent& _rComponent )
 140             :m_aMutexGuard( _rComponent.getMutex( ConnectionDependentComponent::GuardAccess() ) )
 141             ,m_rComponent( _rComponent )
 142         {
 143             if ( !m_rComponent.acquireConnection( ConnectionDependentComponent::GuardAccess() ) )
 144                 throw ::com::sun::star::lang::DisposedException();
 145         }
 146
 147         ~EntryGuard()
 148         {
 149             m_rComponent.releaseConnection( ConnectionDependentComponent::GuardAccess() );
 150         }
 151     };
 152
 153
 154 //........................................................................
 155 } // namespace sdbtools
 156 //........................................................................
 157
 158 #endif // DBACCESS_CONNECTION_DEPENDENT_HXX
 159