threadex.hxx

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#ifndef INCLUDED_VCL_THREADEX_HXX
#define INCLUDED_VCL_THREADEX_HXX

#include <osl/conditn.hxx>
#include <tools/link.hxx>
#include <vcl/dllapi.h>

#include <optional>
#include <memory>

namespace vcl
{
    class VCL_DLLPUBLIC SolarThreadExecutor
    {
        osl::Condition          m_aStart;
        osl::Condition          m_aFinish;
        bool                    m_bTimeout;

        DECL_DLLPRIVATE_LINK( worker, void*, void );

    public:
        SolarThreadExecutor();
        virtual ~SolarThreadExecutor();

        virtual void doIt() = 0;
        void execute();
    };

namespace solarthread {

namespace detail {

template <typename FuncT, typename ResultT>
class GenericSolarThreadExecutor final : public SolarThreadExecutor
{
public:
    static ResultT exec( FuncT const& func )
    {
        typedef GenericSolarThreadExecutor<FuncT, ResultT> ExecutorT;
        ::std::unique_ptr<ExecutorT> const pExecutor( new ExecutorT(func) );
        pExecutor->execute();
        if (pExecutor->m_exc)
            std::rethrow_exception(pExecutor->m_exc);
        return *pExecutor->m_result;
    }

private:
    explicit GenericSolarThreadExecutor( FuncT const& func )
        : m_func(func), m_result() {}

    virtual void doIt() override
    {
        try {
            m_result = m_func();
        }
        catch (...) {
            m_exc = std::current_exception();
        }
    }

    std::exception_ptr m_exc;
#ifdef _MSC_VER
    FuncT m_func; // "const" and std::bind() results in Error C3848 expression would lose const-volatile qualifiers
#else
    FuncT const m_func;
#endif
    // using std::optional here omits the need that ResultT is default
    // constructable:
    ::std::optional<ResultT> m_result;
};

template <typename FuncT>
class GenericSolarThreadExecutor<FuncT, void> final : public SolarThreadExecutor
{
public:
    static void exec( FuncT const& func )
    {
        typedef GenericSolarThreadExecutor<FuncT, void> ExecutorT;
        ::std::unique_ptr<ExecutorT> const pExecutor( new ExecutorT(func) );
        pExecutor->execute();
        if (pExecutor->m_exc)
            std::rethrow_exception(pExecutor->m_exc);
    }

private:
    explicit GenericSolarThreadExecutor( FuncT const& func )
        : m_func(func) {}

    virtual void doIt() override
    {
        try {
            m_func();
        }
        catch (...) {
            m_exc = std::current_exception();
        }
    }

    std::exception_ptr m_exc;
    FuncT const m_func;
};

} // namespace detail


template <typename FuncT>
inline auto syncExecute(FuncT const& func) -> decltype(func())
{
    return detail::GenericSolarThreadExecutor<
        FuncT, decltype(func())>::exec(func);
}

} // namespace solarthread
} // namespace vcl

#endif // INCLUDED_VCL_THREADEX_HXX

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