Chris@102: 
Chris@102: //          Copyright Oliver Kowalke 2014.
Chris@102: // Distributed under the Boost Software License, Version 1.0.
Chris@102: //    (See accompanying file LICENSE_1_0.txt or copy at
Chris@102: //          http://www.boost.org/LICENSE_1_0.txt)
Chris@102: 
Chris@102: #ifndef BOOST_CONTEXT_EXECUTION_CONTEXT_H
Chris@102: #define BOOST_CONTEXT_EXECUTION_CONTEXT_H
Chris@102: 
Chris@102: #include <boost/context/detail/config.hpp>
Chris@102: 
Chris@102: #if ! defined(BOOST_CONTEXT_NO_EXECUTION_CONTEXT)
Chris@102: 
Chris@102: # include <cstddef>
Chris@102: # include <cstdint>
Chris@102: # include <cstdlib>
Chris@102: # include <exception>
Chris@102: # include <memory>
Chris@102: # include <tuple>
Chris@102: # include <utility>
Chris@102: 
Chris@102: # include <boost/assert.hpp>
Chris@102: # include <boost/config.hpp>
Chris@102: # include <boost/context/fcontext.hpp>
Chris@102: # include <boost/intrusive_ptr.hpp>
Chris@102: 
Chris@102: # include <boost/context/stack_context.hpp>
Chris@102: # include <boost/context/segmented_stack.hpp>
Chris@102: 
Chris@102: # ifdef BOOST_HAS_ABI_HEADERS
Chris@102: #  include BOOST_ABI_PREFIX
Chris@102: # endif
Chris@102: 
Chris@102: # if defined(BOOST_USE_SEGMENTED_STACKS)
Chris@102: extern "C" {
Chris@102: 
Chris@102: void __splitstack_getcontext( void * [BOOST_CONTEXT_SEGMENTS]);
Chris@102: 
Chris@102: void __splitstack_setcontext( void * [BOOST_CONTEXT_SEGMENTS]);
Chris@102: 
Chris@102: }
Chris@102: # endif
Chris@102: 
Chris@102: namespace boost {
Chris@102: namespace context {
Chris@102: 
Chris@102: struct preallocated {
Chris@102:     void        *   sp;
Chris@102:     std::size_t     size;
Chris@102:     stack_context   sctx;
Chris@102: 
Chris@102:     preallocated( void * sp_, std::size_t size_, stack_context sctx_) noexcept :
Chris@102:         sp( sp_), size( size_), sctx( sctx_) {
Chris@102:     }
Chris@102: };
Chris@102: 
Chris@102: class BOOST_CONTEXT_DECL execution_context {
Chris@102: private:
Chris@102:     struct fcontext {
Chris@102:         std::size_t     use_count;
Chris@102:         fcontext_t      fctx;
Chris@102:         stack_context   sctx;
Chris@102: 
Chris@102:         // main-context
Chris@102:         fcontext() noexcept :
Chris@102:             use_count( 1),
Chris@102:             fctx( nullptr),
Chris@102:             sctx() {
Chris@102:         } 
Chris@102: 
Chris@102:         // worker-context
Chris@102:         fcontext( fcontext_t fctx_, stack_context const& sctx_) noexcept :
Chris@102:             use_count( 0),
Chris@102:             fctx( fctx_),
Chris@102:             sctx( sctx_) {
Chris@102:         } 
Chris@102: 
Chris@102:         virtual ~fcontext() noexcept {
Chris@102:         }
Chris@102: 
Chris@102:         virtual void deallocate() {
Chris@102:         }
Chris@102: 
Chris@102:         virtual void run() noexcept {
Chris@102:         }
Chris@102: 
Chris@102:         friend void intrusive_ptr_add_ref( fcontext * ctx) {
Chris@102:             ++ctx->use_count;
Chris@102:         }
Chris@102: 
Chris@102:         friend void intrusive_ptr_release( fcontext * ctx) {
Chris@102:             BOOST_ASSERT( nullptr != ctx);
Chris@102: 
Chris@102:             if ( 0 == --ctx->use_count) {
Chris@102:                 ctx->~fcontext();
Chris@102:             }
Chris@102:         }
Chris@102:     };
Chris@102: 
Chris@102:     template< typename Fn, typename StackAlloc >
Chris@102:     class worker_fcontext : public fcontext {
Chris@102:     private:
Chris@102:         StackAlloc      salloc_;
Chris@102:         Fn              fn_;
Chris@102: 
Chris@102:         static void destroy( worker_fcontext * p) {
Chris@102:             StackAlloc salloc( p->salloc_);
Chris@102:             stack_context sctx( p->sctx);
Chris@102:             p->~worker_fcontext();
Chris@102:             salloc.deallocate( sctx);
Chris@102:         }
Chris@102: 
Chris@102:     public:
Chris@102:         explicit worker_fcontext( stack_context sctx, StackAlloc const& salloc, fcontext_t fctx, Fn && fn) noexcept :
Chris@102:             fcontext( fctx, sctx),
Chris@102:             salloc_( salloc),
Chris@102:             fn_( std::forward< Fn >( fn) ) {
Chris@102:         }
Chris@102: 
Chris@102:         void deallocate() override final {
Chris@102:             destroy( this);
Chris@102:         }
Chris@102: 
Chris@102:         void run() noexcept override final {
Chris@102:             fn_();
Chris@102:         }
Chris@102:     };
Chris@102: 
Chris@102:     static void entry_func( intptr_t p) noexcept {
Chris@102:         BOOST_ASSERT( 0 != p);
Chris@102: 
Chris@102:         fcontext * bp( reinterpret_cast< fcontext * >( p) );
Chris@102:         BOOST_ASSERT( nullptr != bp);
Chris@102: 
Chris@102:         bp->run();
Chris@102:     }
Chris@102: 
Chris@102:     typedef boost::intrusive_ptr< fcontext >    ptr_t;
Chris@102: 
Chris@102:     thread_local static fcontext                main_ctx_;
Chris@102:     thread_local static ptr_t                   current_ctx_;
Chris@102: 
Chris@102:     boost::intrusive_ptr< fcontext >            ptr_;
Chris@102: # if defined(BOOST_USE_SEGMENTED_STACKS)
Chris@102:     bool                                        use_segmented_stack_ = false;
Chris@102: # endif
Chris@102: 
Chris@102:     template< typename StackAlloc, typename Fn >
Chris@102:     static fcontext * create_context( StackAlloc salloc, Fn && fn) {
Chris@102:         typedef worker_fcontext< Fn, StackAlloc >  func_t;
Chris@102: 
Chris@102:         stack_context sctx( salloc.allocate() );
Chris@102:         // reserve space for control structure
Chris@102:         std::size_t size = sctx.size - sizeof( func_t);
Chris@102:         void * sp = static_cast< char * >( sctx.sp) - sizeof( func_t);
Chris@102: #if 0
Chris@102:         constexpr std::size_t func_alignment = 64; // alignof( func_t);
Chris@102:         constexpr std::size_t func_size = sizeof( func_t);
Chris@102:         // reserve space on stack
Chris@102:         void * sp = static_cast< char * >( sctx.sp) - func_size - func_alignment;
Chris@102:         // align sp pointer
Chris@102:         sp = std::align( func_alignment, func_size, sp, func_size + func_alignment);
Chris@102:         BOOST_ASSERT( nullptr != sp);
Chris@102:         // calculate remaining size
Chris@102:         std::size_t size = sctx.size - ( static_cast< char * >( sctx.sp) - static_cast< char * >( sp) );
Chris@102: #endif
Chris@102:         // create fast-context
Chris@102:         fcontext_t fctx = make_fcontext( sp, size, & execution_context::entry_func);
Chris@102:         BOOST_ASSERT( nullptr != fctx);
Chris@102:         // placment new for control structure on fast-context stack
Chris@102:         return new ( sp) func_t( sctx, salloc, fctx, std::forward< Fn >( fn) );
Chris@102:     }
Chris@102: 
Chris@102:     template< typename StackAlloc, typename Fn >
Chris@102:     static fcontext * create_context( preallocated palloc, StackAlloc salloc, Fn && fn) {
Chris@102:         typedef worker_fcontext< Fn, StackAlloc >  func_t;
Chris@102: 
Chris@102:         // reserve space for control structure
Chris@102:         std::size_t size = palloc.size - sizeof( func_t);
Chris@102:         void * sp = static_cast< char * >( palloc.sp) - sizeof( func_t);
Chris@102: #if 0
Chris@102:         constexpr std::size_t func_alignment = 64; // alignof( func_t);
Chris@102:         constexpr std::size_t func_size = sizeof( func_t);
Chris@102:         // reserve space on stack
Chris@102:         void * sp = static_cast< char * >( palloc.sp) - func_size - func_alignment;
Chris@102:         // align sp pointer
Chris@102:         sp = std::align( func_alignment, func_size, sp, func_size + func_alignment);
Chris@102:         BOOST_ASSERT( nullptr != sp);
Chris@102:         // calculate remaining size
Chris@102:         std::size_t size = palloc.size - ( static_cast< char * >( palloc.sp) - static_cast< char * >( sp) );
Chris@102: #endif
Chris@102:         // create fast-context
Chris@102:         fcontext_t fctx = make_fcontext( sp, size, & execution_context::entry_func);
Chris@102:         BOOST_ASSERT( nullptr != fctx);
Chris@102:         // placment new for control structure on fast-context stack
Chris@102:         return new ( sp) func_t( palloc.sctx, salloc, fctx, std::forward< Fn >( fn) );
Chris@102:     }
Chris@102: 
Chris@102:     template< typename StackAlloc, typename Fn, typename Tpl, std::size_t ... I >
Chris@102:     static fcontext * create_worker_fcontext( StackAlloc salloc,
Chris@102:                                               Fn && fn_, Tpl && tpl_,
Chris@102:                                               std::index_sequence< I ... >) {
Chris@102:         return create_context( salloc,
Chris@102:                                [fn=std::forward< Fn >( fn_),tpl=std::forward< Tpl >( tpl_)] () mutable {
Chris@102:                                    try {
Chris@102:                                        fn(
Chris@102:                                            // std::tuple_element<> does not perfect forwarding
Chris@102:                                            std::forward< decltype( std::get< I >( std::declval< Tpl >() ) ) >(
Chris@102:                                                 std::get< I >( std::forward< Tpl >( tpl) ) ) ... );
Chris@102:                                    } catch (...) {
Chris@102:                                        std::terminate();
Chris@102:                                    }
Chris@102:                                });
Chris@102:     }
Chris@102: 
Chris@102:     template< typename StackAlloc, typename Fn, typename Tpl, std::size_t ... I >
Chris@102:     static fcontext * create_worker_fcontext( preallocated palloc, StackAlloc salloc,
Chris@102:                                               Fn && fn_, Tpl && tpl_,
Chris@102:                                               std::index_sequence< I ... >) {
Chris@102:         return create_context( palloc, salloc,
Chris@102:                                [fn=std::forward< Fn >( fn_),tpl=std::forward< Tpl >( tpl_)] () mutable {
Chris@102:                                    try {
Chris@102:                                        fn(
Chris@102:                                            // std::tuple_element<> does not perfect forwarding
Chris@102:                                            std::forward< decltype( std::get< I >( std::declval< Tpl >() ) ) >(
Chris@102:                                                 std::get< I >( std::forward< Tpl >( tpl) ) ) ... );
Chris@102:                                    } catch (...) {
Chris@102:                                        std::terminate();
Chris@102:                                    }
Chris@102:                                });
Chris@102:     }
Chris@102: 
Chris@102:     execution_context() :
Chris@102:         ptr_( current_ctx_) {
Chris@102:     }
Chris@102: 
Chris@102: public:
Chris@102:     static execution_context current() noexcept {
Chris@102:         return execution_context();
Chris@102:     }
Chris@102: 
Chris@102: # if defined(BOOST_USE_SEGMENTED_STACKS)
Chris@102:     template< typename Fn, typename ... Args >
Chris@102:     explicit execution_context( segmented_stack salloc, Fn && fn, Args && ... args) :
Chris@102:         ptr_( create_worker_fcontext( salloc,
Chris@102:                                       std::forward< Fn >( fn),
Chris@102:                                       std::make_tuple( std::forward< Args >( args) ... ),
Chris@102:                                       std::index_sequence_for< Args ... >() ) ),
Chris@102:         use_segmented_stack_( true) {
Chris@102:     }
Chris@102: 
Chris@102:     template< typename Fn, typename ... Args >
Chris@102:     explicit execution_context( preallocated palloc, segmented_stack salloc, Fn && fn, Args && ... args) :
Chris@102:         ptr_( create_worker_fcontext( palloc, salloc,
Chris@102:                                       std::forward< Fn >( fn),
Chris@102:                                       std::make_tuple( std::forward< Args >( args) ... ),
Chris@102:                                       std::index_sequence_for< Args ... >() ) ),
Chris@102:         use_segmented_stack_( true) {
Chris@102:     }
Chris@102: # endif
Chris@102: 
Chris@102:     template< typename StackAlloc, typename Fn, typename ... Args >
Chris@102:     explicit execution_context( StackAlloc salloc, Fn && fn, Args && ... args) :
Chris@102:         ptr_( create_worker_fcontext( salloc,
Chris@102:                                       std::forward< Fn >( fn),
Chris@102:                                       std::make_tuple( std::forward< Args >( args) ... ),
Chris@102:                                       std::index_sequence_for< Args ... >() ) ) {
Chris@102:     }
Chris@102: 
Chris@102:     template< typename StackAlloc, typename Fn, typename ... Args >
Chris@102:     explicit execution_context( preallocated palloc, StackAlloc salloc, Fn && fn, Args && ... args) :
Chris@102:         ptr_( create_worker_fcontext( palloc, salloc,
Chris@102:                                       std::forward< Fn >( fn),
Chris@102:                                       std::make_tuple( std::forward< Args >( args) ... ),
Chris@102:                                       std::index_sequence_for< Args ... >() ) ) {
Chris@102:     }
Chris@102: 
Chris@102:     void resume( bool preserve_fpu = false) noexcept {
Chris@102:         fcontext * old_ctx( current_ctx_.get() );
Chris@102:         fcontext * new_ctx( ptr_.get() );
Chris@102:         current_ctx_ = ptr_;
Chris@102: # if defined(BOOST_USE_SEGMENTED_STACKS)
Chris@102:         if ( use_segmented_stack_) {
Chris@102:             __splitstack_getcontext( old_ctx->sctx.segments_ctx);
Chris@102:             __splitstack_setcontext( new_ctx->sctx.segments_ctx);
Chris@102: 
Chris@102:             jump_fcontext( & old_ctx->fctx, new_ctx->fctx, reinterpret_cast< intptr_t >( new_ctx), preserve_fpu);
Chris@102: 
Chris@102:             __splitstack_setcontext( old_ctx->sctx.segments_ctx);
Chris@102:         } else {
Chris@102:             jump_fcontext( & old_ctx->fctx, new_ctx->fctx, reinterpret_cast< intptr_t >( new_ctx), preserve_fpu);
Chris@102:         }
Chris@102: # else
Chris@102:         jump_fcontext( & old_ctx->fctx, new_ctx->fctx, reinterpret_cast< intptr_t >( new_ctx), preserve_fpu);
Chris@102: # endif
Chris@102:     }
Chris@102: };
Chris@102: 
Chris@102: }}
Chris@102: 
Chris@102: # ifdef BOOST_HAS_ABI_HEADERS
Chris@102: # include BOOST_ABI_SUFFIX
Chris@102: # endif
Chris@102: 
Chris@102: #endif
Chris@102: 
Chris@102: #endif // BOOST_CONTEXT_EXECUTION_CONTEXT_H