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// Copyright Oliver Kowalke 2014. // Distributed under the Boost Software License, Version 1.0. // (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) namespace detail { template< typename Ctx, typename Fn > transfer_t ecv2_context_ontop_void( transfer_t); template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > fcontext_t ecv2_context_create_void( StackAlloc &&, Fn &&, Params && ...); template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > fcontext_t ecv2_context_create_void( preallocated, StackAlloc &&, Fn &&, Params && ...); template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > class ecv2_record_void { private: typename std::decay< StackAlloc >::type salloc_; stack_context sctx_; typename std::decay< Fn >::type fn_; std::tuple< typename std::decay< Params >::type ... > params_; static void destroy( ecv2_record_void * p) noexcept { typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_); stack_context sctx = p->sctx_; // deallocate record p->~ecv2_record_void(); // destroy stack with stack allocator salloc.deallocate( sctx); } public: ecv2_record_void( stack_context sctx, StackAlloc && salloc, Fn && fn, Params && ... params) noexcept : salloc_( std::forward< StackAlloc >( salloc) ), sctx_( sctx), fn_( std::forward< Fn >( fn) ), params_( std::forward< Params >( params) ... ) { } ecv2_record_void( ecv2_record_void const&) = delete; ecv2_record_void & operator=( ecv2_record_void const&) = delete; void deallocate() noexcept { destroy( this); } transfer_t run( transfer_t t) { Ctx from{ t.fctx }; // invoke context-function #if defined(BOOST_NO_CXX17_STD_APPLY) Ctx cc = boost::context::detail::apply( fn_, std::tuple_cat( params_, std::forward_as_tuple( std::move( from) ) ) ); #else Ctx cc = std::apply( fn_, std::tuple_cat( params_, std::forward_as_tuple( std::move( from) ) ) ); #endif return { exchange( cc.fctx_, nullptr), nullptr }; } }; } inline namespace v2 { template<> class execution_context< void > { private: friend class ontop_error; template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > friend class detail::ecv2_record_void; template< typename Ctx, typename Fn > friend detail::transfer_t detail::ecv2_context_ontop_void( detail::transfer_t); detail::fcontext_t fctx_{ nullptr }; execution_context( detail::fcontext_t fctx) noexcept : fctx_( fctx) { } public: execution_context() noexcept = default; #if defined(BOOST_USE_SEGMENTED_STACKS) // segmented-stack requires to preserve the segments of the `current` context // which is not possible (no global pointer to current context) template< typename Fn, typename ... Params > execution_context( std::allocator_arg_t, segmented_stack, Fn &&, Params && ...) = delete; template< typename Fn, typename ... Params > execution_context( std::allocator_arg_t, preallocated, segmented_stack, Fn &&, Params && ...) = delete; #else template< typename Fn, typename ... Params, typename = detail::disable_overload< execution_context, Fn > > execution_context( Fn && fn, Params && ... params) : // deferred execution of fn and its arguments // arguments are stored in std::tuple<> // non-type template parameter pack via std::index_sequence_for<> // preserves the number of arguments // used to extract the function arguments from std::tuple<> fctx_( detail::ecv2_context_create_void< execution_context >( fixedsize_stack(), std::forward< Fn >( fn), std::forward< Params >( params) ... ) ) { } template< typename StackAlloc, typename Fn, typename ... Params > execution_context( std::allocator_arg_t, StackAlloc && salloc, Fn && fn, Params && ... params) : // deferred execution of fn and its arguments // arguments are stored in std::tuple<> // non-type template parameter pack via std::index_sequence_for<> // preserves the number of arguments // used to extract the function arguments from std::tuple<> fctx_( detail::ecv2_context_create_void< execution_context >( std::forward< StackAlloc >( salloc), std::forward< Fn >( fn), std::forward< Params >( params) ... ) ) { } template< typename StackAlloc, typename Fn, typename ... Params > execution_context( std::allocator_arg_t, preallocated palloc, StackAlloc && salloc, Fn && fn, Params && ... params) : // deferred execution of fn and its arguments // arguments are stored in std::tuple<> // non-type template parameter pack via std::index_sequence_for<> // preserves the number of arguments // used to extract the function arguments from std::tuple<> fctx_( detail::ecv2_context_create_void< execution_context >( palloc, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn), std::forward< Params >( params) ... ) ) { } #endif ~execution_context() { if ( nullptr != fctx_) { detail::ontop_fcontext( detail::exchange( fctx_, nullptr), nullptr, detail::ecv2_context_unwind); } } execution_context( execution_context && other) noexcept : fctx_( other.fctx_) { other.fctx_ = nullptr; } execution_context & operator=( execution_context && other) noexcept { if ( this != & other) { execution_context tmp = std::move( other); swap( tmp); } return * this; } execution_context( execution_context const& other) noexcept = delete; execution_context & operator=( execution_context const& other) noexcept = delete; execution_context operator()() { BOOST_ASSERT( nullptr != fctx_); detail::transfer_t t = detail::jump_fcontext( detail::exchange( fctx_, nullptr), nullptr); if ( nullptr != t.data) { std::exception_ptr * eptr = static_cast< std::exception_ptr * >( t.data); try { std::rethrow_exception( * eptr); } catch (...) { std::throw_with_nested( ontop_error{ t.fctx } ); } } return execution_context( t.fctx); } template< typename Fn > execution_context operator()( exec_ontop_arg_t, Fn && fn) { BOOST_ASSERT( nullptr != fctx_); auto p = std::make_tuple( fn, std::exception_ptr{} ); detail::transfer_t t = detail::ontop_fcontext( detail::exchange( fctx_, nullptr), & p, detail::ecv2_context_ontop_void< execution_context, Fn >); if ( nullptr != t.data) { std::exception_ptr * eptr = static_cast< std::exception_ptr * >( t.data); try { std::rethrow_exception( * eptr); } catch (...) { std::throw_with_nested( ontop_error{ t.fctx } ); } } return execution_context( t.fctx); } explicit operator bool() const noexcept { return nullptr != fctx_; } bool operator!() const noexcept { return nullptr == fctx_; } bool operator<( execution_context const& other) const noexcept { return fctx_ < other.fctx_; } template< typename charT, class traitsT > friend std::basic_ostream< charT, traitsT > & operator<<( std::basic_ostream< charT, traitsT > & os, execution_context const& other) { if ( nullptr != other.fctx_) { return os << other.fctx_; } else { return os << "{not-a-context}"; } } void swap( execution_context & other) noexcept { std::swap( fctx_, other.fctx_); } }; } namespace detail { template< typename Ctx, typename Fn > transfer_t ecv2_context_ontop_void( transfer_t t) { auto p = static_cast< std::tuple< Fn, std::exception_ptr > * >( t.data); BOOST_ASSERT( nullptr != p); typename std::decay< Fn >::type fn = std::forward< Fn >( std::get< 0 >( * p) ); try { // execute function fn(); #if defined( BOOST_CONTEXT_HAS_CXXABI_H ) } catch ( abi::__forced_unwind const&) { throw; #endif } catch (...) { std::get< 1 >( * p) = std::current_exception(); return { t.fctx, & std::get< 1 >( * p ) }; } return { exchange( t.fctx, nullptr), nullptr }; } template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > fcontext_t ecv2_context_create_void( StackAlloc && salloc, Fn && fn, Params && ... params) { typedef ecv2_record_void< Ctx, StackAlloc, Fn, Params ... > record_t; auto sctx = salloc.allocate(); // reserve space for control structure #if defined(BOOST_NO_CXX11_CONSTEXPR) || defined(BOOST_NO_CXX11_STD_ALIGN) const std::size_t size = sctx.size - sizeof( record_t); void * sp = static_cast< char * >( sctx.sp) - sizeof( record_t); #else constexpr std::size_t func_alignment = 64; // alignof( record_t); constexpr std::size_t func_size = sizeof( record_t); // reserve space on stack void * sp = static_cast< char * >( sctx.sp) - func_size - func_alignment; // align sp pointer std::size_t space = func_size + func_alignment; sp = std::align( func_alignment, func_size, sp, space); BOOST_ASSERT( nullptr != sp); // calculate remaining size const std::size_t size = sctx.size - ( static_cast< char * >( sctx.sp) - static_cast< char * >( sp) ); #endif // create fast-context const fcontext_t fctx = make_fcontext( sp, size, & ecv2_context_etry< record_t >); BOOST_ASSERT( nullptr != fctx); // placment new for control structure on context-stack auto rec = ::new ( sp) record_t{ sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn), std::forward< Params >( params) ... }; // transfer control structure to context-stack return jump_fcontext( fctx, rec).fctx; } template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > fcontext_t ecv2_context_create_void( preallocated palloc, StackAlloc && salloc, Fn && fn, Params && ... params) { typedef ecv2_record_void< Ctx, StackAlloc, Fn, Params ... > record_t; // reserve space for control structure #if defined(BOOST_NO_CXX11_CONSTEXPR) || defined(BOOST_NO_CXX11_STD_ALIGN) const std::size_t size = palloc.size - sizeof( record_t); void * sp = static_cast< char * >( palloc.sp) - sizeof( record_t); #else constexpr std::size_t func_alignment = 64; // alignof( record_t); constexpr std::size_t func_size = sizeof( record_t); // reserve space on stack void * sp = static_cast< char * >( palloc.sp) - func_size - func_alignment; // align sp pointer std::size_t space = func_size + func_alignment; sp = std::align( func_alignment, func_size, sp, space); BOOST_ASSERT( nullptr != sp); // calculate remaining size const std::size_t size = palloc.size - ( static_cast< char * >( palloc.sp) - static_cast< char * >( sp) ); #endif // create fast-context const fcontext_t fctx = make_fcontext( sp, size, & ecv2_context_etry< record_t >); BOOST_ASSERT( nullptr != fctx); // placment new for control structure on context-stack auto rec = ::new ( sp) record_t{ palloc.sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn), std::forward< Params >( params) ... }; // transfer control structure to context-stack return jump_fcontext( fctx, rec).fctx; } }