AsynchronousLink.cxx

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#include <dbaccess/AsynchronousLink.hxx>
#include <vcl/svapp.hxx>
 
// OAsynchronousLink
using namespace dbaui;
OAsynchronousLink::OAsynchronousLink(const Link<void*, void>& _rHandler)
    : m_aHandler(_rHandler)
    , m_nEventId(nullptr)
{
}
 
OAsynchronousLink::~OAsynchronousLink()
{
    {
        std::unique_lock aEventGuard(m_aEventSafety);
        if (m_nEventId)
            Application::RemoveUserEvent(m_nEventId);
        m_nEventId = nullptr;
    }
 
    {
        std::unique_lock aDestructionGuard(m_aDestructionSafety);
        // this is just for the case we're deleted while another thread just handled the event :
        // if this other thread called our link while we were deleting the event here, the
        // link handler blocked. With leaving the above block it continued, but now we are prevented
        // to leave this destructor 'til the link handler recognizes that nEvent == 0 and leaves.
    }
}
 
void OAsynchronousLink::Call(void* _pArgument)
{
    std::unique_lock aEventGuard(m_aEventSafety);
    if (m_nEventId)
        Application::RemoveUserEvent(m_nEventId);
    m_nEventId = Application::PostUserEvent(LINK(this, OAsynchronousLink, OnAsyncCall), _pArgument);
}
 
void OAsynchronousLink::CancelCall()
{
    std::unique_lock aEventGuard(m_aEventSafety);
    if (m_nEventId)
        Application::RemoveUserEvent(m_nEventId);
    m_nEventId = nullptr;
}
 
IMPL_LINK(OAsynchronousLink, OnAsyncCall, void*, _pArg, void)
{
    {
        std::unique_lock aDestructionGuard(m_aDestructionSafety);
        {
            std::unique_lock aEventGuard(m_aEventSafety);
            if (!m_nEventId)
                // our destructor deleted the event just while we are waiting for m_aEventSafety
                // -> get outta here
                return;
            m_nEventId = nullptr;
        }
    }
    m_aHandler.Call(_pArg);
}
 
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