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494 lines
17 KiB
C++
494 lines
17 KiB
C++
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// Copyright Oliver Kowalke 2014.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_CONTEXT_EXECUTION_CONTEXT_H
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#define BOOST_CONTEXT_EXECUTION_CONTEXT_H
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#include <boost/context/detail/config.hpp>
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#include <algorithm>
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#include <cstddef>
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#include <cstdint>
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#include <cstdlib>
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#include <exception>
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#include <functional>
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#include <memory>
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#include <ostream>
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#include <tuple>
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#include <utility>
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#include <boost/assert.hpp>
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#include <boost/config.hpp>
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#include <boost/intrusive_ptr.hpp>
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#if defined(BOOST_NO_CXX17_STD_APPLY)
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#include <boost/context/detail/apply.hpp>
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#endif
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#include <boost/context/detail/disable_overload.hpp>
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#include <boost/context/detail/exception.hpp>
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#include <boost/context/detail/exchange.hpp>
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#include <boost/context/detail/fcontext.hpp>
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#include <boost/context/detail/tuple.hpp>
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#include <boost/context/fixedsize_stack.hpp>
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#include <boost/context/flags.hpp>
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#include <boost/context/preallocated.hpp>
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#include <boost/context/segmented_stack.hpp>
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#include <boost/context/stack_context.hpp>
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_PREFIX
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#endif
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#if defined(BOOST_MSVC)
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# pragma warning(push)
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# pragma warning(disable: 4702)
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#endif
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namespace boost {
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namespace context {
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namespace detail {
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transfer_t context_unwind( transfer_t);
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template< typename Rec >
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transfer_t context_exit( transfer_t) noexcept;
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template< typename Rec >
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void context_entry( transfer_t) noexcept;
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template< typename Ctx, typename Fn, typename ... Args >
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transfer_t context_ontop( transfer_t);
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template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params >
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fcontext_t context_create( StackAlloc, Fn &&, Params && ...);
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template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params >
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fcontext_t context_create( preallocated, StackAlloc, Fn &&, Params && ...);
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template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params >
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class record {
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private:
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StackAlloc salloc_;
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stack_context sctx_;
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typename std::decay< Fn >::type fn_;
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std::tuple< typename std::decay< Params >::type ... > params_;
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static void destroy( record * p) noexcept {
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StackAlloc salloc = p->salloc_;
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stack_context sctx = p->sctx_;
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// deallocate record
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p->~record();
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// destroy stack with stack allocator
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salloc.deallocate( sctx);
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}
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public:
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record( stack_context sctx, StackAlloc const& salloc,
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Fn && fn, Params && ... params) noexcept :
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salloc_( salloc),
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sctx_( sctx),
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fn_( std::forward< Fn >( fn) ),
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params_( std::forward< Params >( params) ... ) {
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}
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record( record const&) = delete;
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record & operator=( record const&) = delete;
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void deallocate() noexcept {
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destroy( this);
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}
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transfer_t run( transfer_t t) {
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Ctx from{ t.fctx };
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typename Ctx::args_tpl_t args = std::move( * static_cast< typename Ctx::args_tpl_t * >( t.data) );
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auto tpl = std::tuple_cat(
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params_,
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std::forward_as_tuple( std::move( from) ),
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std::move( args) );
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// invoke context-function
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#if defined(BOOST_NO_CXX17_STD_APPLY)
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Ctx cc = apply( std::move( fn_), std::move( tpl) );
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#else
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Ctx cc = std::apply( std::move( fn_), std::move( tpl) );
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#endif
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return { exchange( cc.fctx_, nullptr), nullptr };
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}
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};
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}
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template< typename ... Args >
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class execution_context {
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private:
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friend class ontop_error;
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typedef std::tuple< Args ... > args_tpl_t;
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typedef std::tuple< execution_context, typename std::decay< Args >::type ... > ret_tpl_t;
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template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params >
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friend class detail::record;
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template< typename Ctx, typename Fn, typename ... ArgsT >
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friend detail::transfer_t detail::context_ontop( detail::transfer_t);
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detail::fcontext_t fctx_{ nullptr };
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execution_context( detail::fcontext_t fctx) noexcept :
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fctx_( fctx) {
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}
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public:
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constexpr execution_context() noexcept = default;
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#if defined(BOOST_USE_SEGMENTED_STACKS)
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// segmented-stack requires to preserve the segments of the `current` context
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// which is not possible (no global pointer to current context)
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template< typename Fn, typename ... Params >
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execution_context( std::allocator_arg_t, segmented_stack, Fn &&, Params && ...) = delete;
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template< typename Fn, typename ... Params >
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execution_context( std::allocator_arg_t, preallocated, segmented_stack, Fn &&, Params && ...) = delete;
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#else
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template< typename Fn,
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typename ... Params,
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typename = detail::disable_overload< execution_context, Fn >
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>
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execution_context( Fn && fn, Params && ... params) :
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// deferred execution of fn and its arguments
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// arguments are stored in std::tuple<>
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// non-type template parameter pack via std::index_sequence_for<>
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// preserves the number of arguments
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// used to extract the function arguments from std::tuple<>
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fctx_( detail::context_create< execution_context >(
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fixedsize_stack(),
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std::forward< Fn >( fn),
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std::forward< Params >( params) ... ) ) {
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}
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template< typename StackAlloc,
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typename Fn,
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typename ... Params
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>
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execution_context( std::allocator_arg_t, StackAlloc salloc, Fn && fn, Params && ... params) :
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// deferred execution of fn and its arguments
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// arguments are stored in std::tuple<>
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// non-type template parameter pack via std::index_sequence_for<>
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// preserves the number of arguments
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// used to extract the function arguments from std::tuple<>
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fctx_( detail::context_create< execution_context >(
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salloc,
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std::forward< Fn >( fn),
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std::forward< Params >( params) ... ) ) {
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}
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template< typename StackAlloc,
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typename Fn,
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typename ... Params
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>
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execution_context( std::allocator_arg_t, preallocated palloc, StackAlloc salloc, Fn && fn, Params && ... params) :
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// deferred execution of fn and its arguments
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// arguments are stored in std::tuple<>
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// non-type template parameter pack via std::index_sequence_for<>
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// preserves the number of arguments
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// used to extract the function arguments from std::tuple<>
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fctx_( detail::context_create< execution_context >(
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palloc, salloc,
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std::forward< Fn >( fn),
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std::forward< Params >( params) ... ) ) {
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}
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#endif
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~execution_context() {
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if ( nullptr != fctx_) {
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detail::ontop_fcontext( detail::exchange( fctx_, nullptr), nullptr, detail::context_unwind);
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}
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}
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execution_context( execution_context && other) noexcept :
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fctx_( other.fctx_) {
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other.fctx_ = nullptr;
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}
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execution_context & operator=( execution_context && other) noexcept {
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if ( this != & other) {
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execution_context tmp = std::move( other);
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swap( tmp);
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}
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return * this;
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}
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execution_context( execution_context const& other) noexcept = delete;
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execution_context & operator=( execution_context const& other) noexcept = delete;
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ret_tpl_t operator()( Args ... args);
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template< typename Fn >
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ret_tpl_t operator()( exec_ontop_arg_t, Fn && fn, Args ... args);
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explicit operator bool() const noexcept {
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return nullptr != fctx_;
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}
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bool operator!() const noexcept {
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return nullptr == fctx_;
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}
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bool operator==( execution_context const& other) const noexcept {
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return fctx_ == other.fctx_;
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}
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bool operator!=( execution_context const& other) const noexcept {
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return fctx_ != other.fctx_;
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}
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bool operator<( execution_context const& other) const noexcept {
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return fctx_ < other.fctx_;
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}
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bool operator>( execution_context const& other) const noexcept {
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return other.fctx_ < fctx_;
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}
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bool operator<=( execution_context const& other) const noexcept {
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return ! ( * this > other);
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}
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bool operator>=( execution_context const& other) const noexcept {
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return ! ( * this < other);
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}
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template< typename charT, class traitsT >
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friend std::basic_ostream< charT, traitsT > &
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operator<<( std::basic_ostream< charT, traitsT > & os, execution_context const& other) {
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if ( nullptr != other.fctx_) {
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return os << other.fctx_;
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} else {
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return os << "{not-a-context}";
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}
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}
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void swap( execution_context & other) noexcept {
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std::swap( fctx_, other.fctx_);
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}
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};
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class ontop_error : public std::exception {
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private:
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detail::fcontext_t fctx_;
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public:
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ontop_error( detail::fcontext_t fctx) noexcept :
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fctx_{ fctx } {
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}
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template< typename ... Args >
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execution_context< Args ... > get_context() const noexcept {
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return execution_context< Args ... >{ fctx_ };
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}
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};
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template< typename ... Args >
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typename execution_context< Args ... >::ret_tpl_t
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execution_context< Args ... >::operator()( Args ... args) {
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BOOST_ASSERT( nullptr != fctx_);
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args_tpl_t data( std::forward< Args >( args) ... );
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auto p = std::make_tuple( std::exception_ptr{}, std::move( data) );
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detail::transfer_t t = detail::jump_fcontext( detail::exchange( fctx_, nullptr), & p);
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if ( nullptr != t.data) {
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auto p = static_cast< std::tuple< std::exception_ptr, args_tpl_t > * >( t.data);
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std::exception_ptr eptr = std::get< 0 >( * p);
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if ( eptr) {
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try {
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std::rethrow_exception( eptr);
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} catch (...) {
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std::throw_with_nested( ontop_error{ t.fctx } );
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}
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}
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data = std::move( std::get< 1 >( * p) );
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}
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return std::tuple_cat( std::forward_as_tuple( execution_context( t.fctx) ), std::move( data) );
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}
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template< typename ... Args >
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template< typename Fn >
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typename execution_context< Args ... >::ret_tpl_t
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execution_context< Args ... >::operator()( exec_ontop_arg_t, Fn && fn, Args ... args) {
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BOOST_ASSERT( nullptr != fctx_);
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args_tpl_t data{ std::forward< Args >( args) ... };
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auto p = std::make_tuple( fn, std::make_tuple( std::exception_ptr{}, std::move( data) ) );
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detail::transfer_t t = detail::ontop_fcontext(
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detail::exchange( fctx_, nullptr),
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& p,
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detail::context_ontop< execution_context, Fn, Args ... >);
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if ( nullptr != t.data) {
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auto p = static_cast< std::tuple< std::exception_ptr, args_tpl_t > * >( t.data);
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std::exception_ptr eptr = std::get< 0 >( * p);
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if ( eptr) {
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try {
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std::rethrow_exception( eptr);
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} catch (...) {
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std::throw_with_nested( ontop_error{ t.fctx } );
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}
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}
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data = std::move( std::get< 1 >( * p) );
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}
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return std::tuple_cat( std::forward_as_tuple( execution_context( t.fctx) ), std::move( data) );
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}
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namespace detail {
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template< int N >
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struct helper {
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template< typename T >
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static T convert( T && t) noexcept {
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return std::forward< T >( t);
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}
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};
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template<>
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struct helper< 1 > {
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template< typename T >
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static std::tuple< T > convert( T && t) noexcept {
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return std::make_tuple( std::forward< T >( t) );
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}
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};
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inline
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transfer_t context_unwind( transfer_t t) {
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throw forced_unwind( t.fctx);
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return { nullptr, nullptr };
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}
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template< typename Rec >
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transfer_t context_exit( transfer_t t) noexcept {
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Rec * rec = static_cast< Rec * >( t.data);
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// destroy context stack
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rec->deallocate();
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return { nullptr, nullptr };
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}
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template< typename Rec >
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void context_entry( transfer_t t_) noexcept {
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// transfer control structure to the context-stack
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Rec * rec = static_cast< Rec * >( t_.data);
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BOOST_ASSERT( nullptr != rec);
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transfer_t t = { nullptr, nullptr };
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try {
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// jump back to `context_create()`
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t = jump_fcontext( t_.fctx, nullptr);
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// start executing
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t = rec->run( t);
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} catch ( forced_unwind const& e) {
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t = { e.fctx, nullptr };
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}
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BOOST_ASSERT( nullptr != t.fctx);
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// destroy context-stack of `this`context on next context
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ontop_fcontext( t.fctx, rec, context_exit< Rec >);
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BOOST_ASSERT_MSG( false, "context already terminated");
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}
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template< typename Ctx, typename Fn, typename ... Args >
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transfer_t context_ontop( transfer_t t) {
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auto p = static_cast< std::tuple< Fn, std::tuple< std::exception_ptr, std::tuple< Args ... > > > * >( t.data);
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BOOST_ASSERT( nullptr != p);
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typename std::decay< Fn >::type fn = std::forward< Fn >( std::get< 0 >( * p) );
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auto args = std::move( std::get< 1 >( std::get< 1 >( * p) ) );
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try {
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// execute function
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#if defined(BOOST_NO_CXX17_STD_APPLY)
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std::get< 1 >( std::get< 1 >( * p) ) = helper< sizeof ... (Args) >::convert( apply( fn, std::move( args) ) );
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#else
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std::get< 1 >( std::get< 1 >( * p) ) = helper< sizeof ... (Args) >::convert( std::apply( fn, std::move( args) ) );
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#endif
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} catch (...) {
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std::get< 0 >( std::get< 1 >( * p) ) = std::current_exception();
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}
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// apply returned data
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return { t.fctx, & std::get< 1 >( * p) };
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}
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template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params >
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fcontext_t context_create( StackAlloc salloc, Fn && fn, Params && ... params) {
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typedef record< Ctx, StackAlloc, Fn, Params ... > record_t;
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auto sctx = salloc.allocate();
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// reserve space for control structure
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#if defined(BOOST_NO_CXX11_CONSTEXPR) || defined(BOOST_NO_CXX11_STD_ALIGN)
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const std::size_t size = sctx.size - sizeof( record_t);
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void * sp = static_cast< char * >( sctx.sp) - sizeof( record_t);
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#else
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constexpr std::size_t func_alignment = 64; // alignof( record_t);
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constexpr std::size_t func_size = sizeof( record_t);
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// reserve space on stack
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void * sp = static_cast< char * >( sctx.sp) - func_size - func_alignment;
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// align sp pointer
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std::size_t space = func_size + func_alignment;
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sp = std::align( func_alignment, func_size, sp, space);
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BOOST_ASSERT( nullptr != sp);
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// calculate remaining size
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const std::size_t size = sctx.size - ( static_cast< char * >( sctx.sp) - static_cast< char * >( sp) );
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#endif
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// create fast-context
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const fcontext_t fctx = make_fcontext( sp, size, & context_entry< record_t >);
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BOOST_ASSERT( nullptr != fctx);
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// placment new for control structure on context-stack
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auto rec = ::new ( sp) record_t{
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sctx, salloc, std::forward< Fn >( fn), std::forward< Params >( params) ... };
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// transfer control structure to context-stack
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return jump_fcontext( fctx, rec).fctx;
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}
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template< typename Ctx, typename StackAlloc, typename Fn, typename ... Params >
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fcontext_t context_create( preallocated palloc, StackAlloc salloc, Fn && fn, Params && ... params) {
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typedef record< Ctx, StackAlloc, Fn, Params ... > record_t;
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// reserve space for control structure
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#if defined(BOOST_NO_CXX11_CONSTEXPR) || defined(BOOST_NO_CXX11_STD_ALIGN)
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const std::size_t size = palloc.size - sizeof( record_t);
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void * sp = static_cast< char * >( palloc.sp) - sizeof( record_t);
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#else
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constexpr std::size_t func_alignment = 64; // alignof( record_t);
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constexpr std::size_t func_size = sizeof( record_t);
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// reserve space on stack
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void * sp = static_cast< char * >( palloc.sp) - func_size - func_alignment;
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// align sp pointer
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std::size_t space = func_size + func_alignment;
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sp = std::align( func_alignment, func_size, sp, space);
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BOOST_ASSERT( nullptr != sp);
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// calculate remaining size
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const std::size_t size = palloc.size - ( static_cast< char * >( palloc.sp) - static_cast< char * >( sp) );
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#endif
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// create fast-context
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const fcontext_t fctx = make_fcontext( sp, size, & context_entry< record_t >);
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BOOST_ASSERT( nullptr != fctx);
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// placment new for control structure on context-stack
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auto rec = ::new ( sp) record_t{
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palloc.sctx, salloc, std::forward< Fn >( fn), std::forward< Params >( params) ... };
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// transfer control structure to context-stack
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return jump_fcontext( fctx, rec).fctx;
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}
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}
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#include <boost/context/execution_context_v2_void.ipp>
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template< typename ... Args >
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void swap( execution_context< Args ... > & l, execution_context< Args ... > & r) noexcept {
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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_H
|