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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) #ifndef BOOST_CONTEXT_EXECUTION_CONTEXT_V2_H #define BOOST_CONTEXT_EXECUTION_CONTEXT_V2_H #include <boost/context/detail/config.hpp> #include <algorithm> #include <cstddef> #include <cstdint> #include <cstdlib> #include <exception> #include <functional> #include <memory> #include <ostream> #include <tuple> #include <utility> #include <boost/assert.hpp> #include <boost/config.hpp> #include <boost/intrusive_ptr.hpp> #if defined(BOOST_NO_CXX17_STD_APPLY) #include <boost/context/detail/apply.hpp> #endif #include <boost/context/detail/disable_overload.hpp> #include <boost/context/detail/exception.hpp> #include <boost/context/detail/exchange.hpp> #include <boost/context/detail/fcontext.hpp> #include <boost/context/detail/tuple.hpp> #include <boost/context/fixedsize_stack.hpp> #include <boost/context/flags.hpp> #include <boost/context/preallocated.hpp> #include <boost/context/segmented_stack.hpp> #include <boost/context/stack_context.hpp> #ifdef BOOST_HAS_ABI_HEADERS # include BOOST_ABI_PREFIX #endif #if defined(BOOST_MSVC) # pragma warning(push) # pragma warning(disable: 4702) #endif namespace boost { namespace context { namespace detail { transfer_t ecv2_context_unwind( transfer_t); template< typename Rec > transfer_t ecv2_context_exit( transfer_t) noexcept; template< typename Rec > void ecv2_context_etry( transfer_t) noexcept; template< typename Ctx, typename Fn, typename ... Args > transfer_t ecv2_context_ontop( transfer_t); template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > fcontext_t ecv2_context_create( StackAlloc &&, Fn &&, Params && ...); template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > fcontext_t ecv2_context_create( preallocated, StackAlloc &&, Fn &&, Params && ...); template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > class ecv2_record { 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 * p) noexcept { typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_); stack_context sctx = p->sctx_; // deallocate ecv2_record p->~ecv2_record(); // destroy stack with stack allocator salloc.deallocate( sctx); } public: ecv2_record( 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( ecv2_record const&) = delete; ecv2_record & operator=( ecv2_record const&) = delete; void deallocate() noexcept { destroy( this); } transfer_t run( transfer_t t) { Ctx from{ t.fctx }; typename Ctx::args_tpl_t args = std::move( std::get<1>( * static_cast< std::tuple< std::exception_ptr, typename Ctx::args_tpl_t > * >( t.data) ) ); auto tpl = std::tuple_cat( params_, std::forward_as_tuple( std::move( from) ), std::move( args) ); // invoke context-function #if defined(BOOST_NO_CXX17_STD_APPLY) Ctx cc = boost::context::detail::apply( std::move( fn_), std::move( tpl) ); #else Ctx cc = std::apply( std::move( fn_), std::move( tpl) ); #endif return { exchange( cc.fctx_, nullptr), nullptr }; } }; } inline namespace v2 { template< typename ... Args > class execution_context { private: friend class ontop_error; typedef std::tuple< Args ... > args_tpl_t; typedef std::tuple< execution_context, typename std::decay< Args >::type ... > ret_tpl_t; template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > friend class detail::ecv2_record; template< typename Ctx, typename Fn, typename ... ArgsT > friend detail::transfer_t detail::ecv2_context_ontop( 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< 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< 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< 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; ret_tpl_t operator()( Args ... args); template< typename Fn > ret_tpl_t operator()( exec_ontop_arg_t, Fn && fn, Args ... args); 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_); } }; class ontop_error : public std::exception { private: detail::fcontext_t fctx_; public: ontop_error( detail::fcontext_t fctx) noexcept : fctx_{ fctx } { } template< typename ... Args > execution_context< Args ... > get_context() const noexcept { return execution_context< Args ... >{ fctx_ }; } }; template< typename ... Args > typename execution_context< Args ... >::ret_tpl_t execution_context< Args ... >::operator()( Args ... args) { BOOST_ASSERT( nullptr != fctx_); args_tpl_t data( std::forward< Args >( args) ... ); auto p = std::make_tuple( std::exception_ptr{}, std::move( data) ); detail::transfer_t t = detail::jump_fcontext( detail::exchange( fctx_, nullptr), & p); if ( nullptr != t.data) { auto p = static_cast< std::tuple< std::exception_ptr, args_tpl_t > * >( t.data); std::exception_ptr eptr = std::get< 0 >( * p); if ( eptr) { try { std::rethrow_exception( eptr); } catch (...) { std::throw_with_nested( ontop_error{ t.fctx } ); } } data = std::move( std::get< 1 >( * p) ); } return std::tuple_cat( std::forward_as_tuple( execution_context( t.fctx) ), std::move( data) ); } template< typename ... Args > template< typename Fn > typename execution_context< Args ... >::ret_tpl_t execution_context< Args ... >::operator()( exec_ontop_arg_t, Fn && fn, Args ... args) { BOOST_ASSERT( nullptr != fctx_); args_tpl_t data{ std::forward< Args >( args) ... }; auto p = std::make_tuple( fn, std::make_tuple( std::exception_ptr{}, std::move( data) ) ); detail::transfer_t t = detail::ontop_fcontext( detail::exchange( fctx_, nullptr), & p, detail::ecv2_context_ontop< execution_context, Fn, Args ... >); if ( nullptr != t.data) { auto p = static_cast< std::tuple< std::exception_ptr, args_tpl_t > * >( t.data); std::exception_ptr eptr = std::get< 0 >( * p); if ( eptr) { try { std::rethrow_exception( eptr); } catch (...) { std::throw_with_nested( ontop_error{ t.fctx } ); } } data = std::move( std::get< 1 >( * p) ); } return std::tuple_cat( std::forward_as_tuple( execution_context( t.fctx) ), std::move( data) ); } } namespace detail { template< int N > struct helper { template< typename T > static T convert( T && t) noexcept { return std::forward< T >( t); } }; template<> struct helper< 1 > { template< typename T > static std::tuple< T > convert( T && t) noexcept { return std::make_tuple( std::forward< T >( t) ); } }; inline transfer_t ecv2_context_unwind( transfer_t t) { throw forced_unwind( t.fctx); return { nullptr, nullptr }; } template< typename Rec > transfer_t ecv2_context_exit( transfer_t t) noexcept { Rec * rec = static_cast< Rec * >( t.data); // destroy context stack rec->deallocate(); return { nullptr, nullptr }; } template< typename Rec > void ecv2_context_etry( transfer_t t_) noexcept { // transfer control structure to the context-stack Rec * rec = static_cast< Rec * >( t_.data); BOOST_ASSERT( nullptr != rec); transfer_t t = { nullptr, nullptr }; try { // jump back to `ecv2_context_create()` t = jump_fcontext( t_.fctx, nullptr); // start executing t = rec->run( t); } catch ( forced_unwind const& ex) { t = { ex.fctx, nullptr }; #ifndef BOOST_ASSERT_IS_VOID const_cast< forced_unwind & >( ex).caught = true; #endif } BOOST_ASSERT( nullptr != t.fctx); // destroy context-stack of `this`context on next context ontop_fcontext( t.fctx, rec, ecv2_context_exit< Rec >); BOOST_ASSERT_MSG( false, "context already terminated"); } template< typename Ctx, typename Fn, typename ... Args > transfer_t ecv2_context_ontop( transfer_t t) { auto p = static_cast< std::tuple< Fn, std::tuple< std::exception_ptr, std::tuple< Args ... > > > * >( t.data); BOOST_ASSERT( nullptr != p); typename std::decay< Fn >::type fn = std::forward< Fn >( std::get< 0 >( * p) ); auto args = std::move( std::get< 1 >( std::get< 1 >( * p) ) ); try { // execute function #if defined(BOOST_NO_CXX17_STD_APPLY) std::get< 1 >( std::get< 1 >( * p) ) = helper< sizeof ... (Args) >::convert( boost::context::detail::apply( fn, std::move( args) ) ); #else std::get< 1 >( std::get< 1 >( * p) ) = helper< sizeof ... (Args) >::convert( std::apply( fn, std::move( args) ) ); #endif #if defined( BOOST_CONTEXT_HAS_CXXABI_H ) } catch ( abi::__forced_unwind const&) { throw; #endif } catch (...) { std::get< 0 >( std::get< 1 >( * p) ) = std::current_exception(); } // apply returned data return { t.fctx, & std::get< 1 >( * p) }; } template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params > fcontext_t ecv2_context_create( StackAlloc && salloc, Fn && fn, Params && ... params) { typedef ecv2_record< Ctx, StackAlloc, Fn, Params ... > ecv2_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( ecv2_record_t); void * sp = static_cast< char * >( sctx.sp) - sizeof( ecv2_record_t); #else constexpr std::size_t func_alignment = 64; // alignof( ecv2_record_t); constexpr std::size_t func_size = sizeof( ecv2_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< ecv2_record_t >); BOOST_ASSERT( nullptr != fctx); // placment new for control structure on context-stack auto rec = ::new ( sp) ecv2_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( preallocated palloc, StackAlloc && salloc, Fn && fn, Params && ... params) { typedef ecv2_record< Ctx, StackAlloc, Fn, Params ... > ecv2_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( ecv2_record_t); void * sp = static_cast< char * >( palloc.sp) - sizeof( ecv2_record_t); #else constexpr std::size_t func_alignment = 64; // alignof( ecv2_record_t); constexpr std::size_t func_size = sizeof( ecv2_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< ecv2_record_t >); BOOST_ASSERT( nullptr != fctx); // placment new for control structure on context-stack auto rec = ::new ( sp) ecv2_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; } } #include <boost/context/execution_context_v2_void.ipp> inline namespace v2 { template< typename ... Args > void swap( execution_context< Args ... > & l, execution_context< Args ... > & r) noexcept { l.swap( r); } }}} #if defined(BOOST_MSVC) # pragma warning(pop) #endif #ifdef BOOST_HAS_ABI_HEADERS # include BOOST_ABI_SUFFIX #endif #endif // BOOST_CONTEXT_EXECUTION_CONTEXT_V2_H