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-rw-r--r--boost/context/fiber_fcontext.hpp365
1 files changed, 365 insertions, 0 deletions
diff --git a/boost/context/fiber_fcontext.hpp b/boost/context/fiber_fcontext.hpp
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+
+// Copyright Oliver Kowalke 2017.
+// 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_FIBER_H
+#define BOOST_CONTEXT_FIBER_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_CXX14_STD_EXCHANGE)
+#include <boost/context/detail/exchange.hpp>
+#endif
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+#include <boost/context/detail/invoke.hpp>
+#endif
+#include <boost/context/detail/disable_overload.hpp>
+#include <boost/context/detail/exception.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 {
+
+inline
+transfer_t fiber_unwind( transfer_t t) {
+ throw forced_unwind( t.fctx);
+ return { nullptr, nullptr };
+}
+
+template< typename Rec >
+transfer_t fiber_exit( transfer_t t) noexcept {
+ Rec * rec = static_cast< Rec * >( t.data);
+ // destroy context stack
+ rec->deallocate();
+ return { nullptr, nullptr };
+}
+
+template< typename Rec >
+void fiber_entry( transfer_t t) noexcept {
+ // transfer control structure to the context-stack
+ Rec * rec = static_cast< Rec * >( t.data);
+ BOOST_ASSERT( nullptr != t.fctx);
+ BOOST_ASSERT( nullptr != rec);
+ try {
+ // jump back to `create_context()`
+ t = jump_fcontext( t.fctx, nullptr);
+ // start executing
+ t.fctx = rec->run( t.fctx);
+ } catch ( forced_unwind const& e) {
+ t = { e.fctx, nullptr };
+ }
+ BOOST_ASSERT( nullptr != t.fctx);
+ // destroy context-stack of `this`context on next context
+ ontop_fcontext( t.fctx, rec, fiber_exit< Rec >);
+ BOOST_ASSERT_MSG( false, "context already terminated");
+}
+
+template< typename Ctx, typename Fn >
+transfer_t fiber_ontop( transfer_t t) {
+ auto p = static_cast< std::tuple< Fn > * >( t.data);
+ BOOST_ASSERT( nullptr != p);
+ typename std::decay< Fn >::type fn = std::get< 0 >( * p);
+ t.data = nullptr;
+ // execute function, pass fiber via reference
+ Ctx c = fn( Ctx{ t.fctx } );
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ return { exchange( c.fctx_, nullptr), nullptr };
+#else
+ return { std::exchange( c.fctx_, nullptr), nullptr };
+#endif
+}
+
+template< typename Ctx, typename StackAlloc, typename Fn >
+class fiber_record {
+private:
+ stack_context sctx_;
+ typename std::decay< StackAlloc >::type salloc_;
+ typename std::decay< Fn >::type fn_;
+
+ static void destroy( fiber_record * p) noexcept {
+ typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_);
+ stack_context sctx = p->sctx_;
+ // deallocate fiber_record
+ p->~fiber_record();
+ // destroy stack with stack allocator
+ salloc.deallocate( sctx);
+ }
+
+public:
+ fiber_record( stack_context sctx, StackAlloc && salloc,
+ Fn && fn) noexcept :
+ sctx_( sctx),
+ salloc_( std::forward< StackAlloc >( salloc)),
+ fn_( std::forward< Fn >( fn) ) {
+ }
+
+ fiber_record( fiber_record const&) = delete;
+ fiber_record & operator=( fiber_record const&) = delete;
+
+ void deallocate() noexcept {
+ destroy( this);
+ }
+
+ fcontext_t run( fcontext_t fctx) {
+ // invoke context-function
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+ Ctx c = boost::context::detail::invoke( fn_, Ctx{ fctx } );
+#else
+ Ctx c = std::invoke( fn_, Ctx{ fctx } );
+#endif
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ return exchange( c.fctx_, nullptr);
+#else
+ return std::exchange( c.fctx_, nullptr);
+#endif
+ }
+};
+
+template< typename Record, typename StackAlloc, typename Fn >
+fcontext_t create_fiber1( StackAlloc && salloc, Fn && fn) {
+ auto sctx = salloc.allocate();
+ // reserve space for control structure
+ void * storage = reinterpret_cast< void * >(
+ ( reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sizeof( Record) ) )
+ & ~static_cast< uintptr_t >( 0xff) );
+ // placment new for control structure on context stack
+ Record * record = new ( storage) Record{
+ sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
+ // 64byte gab between control structure and stack top
+ // should be 16byte aligned
+ void * stack_top = reinterpret_cast< void * >(
+ reinterpret_cast< uintptr_t >( storage) - static_cast< uintptr_t >( 64) );
+ void * stack_bottom = reinterpret_cast< void * >(
+ reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sctx.size) );
+ // create fast-context
+ const std::size_t size = reinterpret_cast< uintptr_t >( stack_top) - reinterpret_cast< uintptr_t >( stack_bottom);
+ const fcontext_t fctx = make_fcontext( stack_top, size, & fiber_entry< Record >);
+ BOOST_ASSERT( nullptr != fctx);
+ // transfer control structure to context-stack
+ return jump_fcontext( fctx, record).fctx;
+}
+
+template< typename Record, typename StackAlloc, typename Fn >
+fcontext_t create_fiber2( preallocated palloc, StackAlloc && salloc, Fn && fn) {
+ // reserve space for control structure
+ void * storage = reinterpret_cast< void * >(
+ ( reinterpret_cast< uintptr_t >( palloc.sp) - static_cast< uintptr_t >( sizeof( Record) ) )
+ & ~ static_cast< uintptr_t >( 0xff) );
+ // placment new for control structure on context-stack
+ Record * record = new ( storage) Record{
+ palloc.sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
+ // 64byte gab between control structure and stack top
+ void * stack_top = reinterpret_cast< void * >(
+ reinterpret_cast< uintptr_t >( storage) - static_cast< uintptr_t >( 64) );
+ void * stack_bottom = reinterpret_cast< void * >(
+ reinterpret_cast< uintptr_t >( palloc.sctx.sp) - static_cast< uintptr_t >( palloc.sctx.size) );
+ // create fast-context
+ const std::size_t size = reinterpret_cast< uintptr_t >( stack_top) - reinterpret_cast< uintptr_t >( stack_bottom);
+ const fcontext_t fctx = make_fcontext( stack_top, size, & fiber_entry< Record >);
+ BOOST_ASSERT( nullptr != fctx);
+ // transfer control structure to context-stack
+ return jump_fcontext( fctx, record).fctx;
+}
+
+}
+
+class fiber {
+private:
+ template< typename Ctx, typename StackAlloc, typename Fn >
+ friend class detail::fiber_record;
+
+ template< typename Ctx, typename Fn >
+ friend detail::transfer_t
+ detail::fiber_ontop( detail::transfer_t);
+
+ template< typename StackAlloc, typename Fn >
+ friend fiber
+ callcc( std::allocator_arg_t, StackAlloc &&, Fn &&);
+
+ template< typename StackAlloc, typename Fn >
+ friend fiber
+ callcc( std::allocator_arg_t, preallocated, StackAlloc &&, Fn &&);
+
+ detail::fcontext_t fctx_{ nullptr };
+
+ fiber( detail::fcontext_t fctx) noexcept :
+ fctx_{ fctx } {
+ }
+
+public:
+ fiber() noexcept = default;
+
+ template< typename Fn, typename = detail::disable_overload< fiber, Fn > >
+ fiber( Fn && fn) :
+ fiber{ std::allocator_arg, fixedsize_stack(), std::forward< Fn >( fn) } {
+ }
+
+ template< typename StackAlloc, typename Fn >
+ fiber( std::allocator_arg_t, StackAlloc && salloc, Fn && fn) :
+ fctx_{ detail::create_fiber1< detail::fiber_record< fiber, StackAlloc, Fn > >(
+ std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {
+ }
+
+ template< typename StackAlloc, typename Fn >
+ fiber( std::allocator_arg_t, preallocated palloc, StackAlloc && salloc, Fn && fn) :
+ fctx_{ detail::create_fiber2< detail::fiber_record< fiber, StackAlloc, Fn > >(
+ palloc, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {
+ }
+
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+ template< typename Fn >
+ fiber( std::allocator_arg_t, segmented_stack, Fn &&);
+
+ template< typename StackAlloc, typename Fn >
+ fiber( std::allocator_arg_t, preallocated, segmented_stack, Fn &&);
+#endif
+
+ ~fiber() {
+ if ( BOOST_UNLIKELY( nullptr != fctx_) ) {
+ detail::ontop_fcontext(
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ detail::exchange( fctx_, nullptr),
+#else
+ std::exchange( fctx_, nullptr),
+#endif
+ nullptr,
+ detail::fiber_unwind);
+ }
+ }
+
+ fiber( fiber && other) noexcept {
+ swap( other);
+ }
+
+ fiber & operator=( fiber && other) noexcept {
+ if ( BOOST_LIKELY( this != & other) ) {
+ fiber tmp = std::move( other);
+ swap( tmp);
+ }
+ return * this;
+ }
+
+ fiber( fiber const& other) noexcept = delete;
+ fiber & operator=( fiber const& other) noexcept = delete;
+
+ fiber resume() && {
+ BOOST_ASSERT( nullptr != fctx_);
+ return { detail::jump_fcontext(
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ detail::exchange( fctx_, nullptr),
+#else
+ std::exchange( fctx_, nullptr),
+#endif
+ nullptr).fctx };
+ }
+
+ template< typename Fn >
+ fiber resume_with( Fn && fn) && {
+ BOOST_ASSERT( nullptr != fctx_);
+ auto p = std::make_tuple( std::forward< Fn >( fn) );
+ return { detail::ontop_fcontext(
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ detail::exchange( fctx_, nullptr),
+#else
+ std::exchange( fctx_, nullptr),
+#endif
+ & p,
+ detail::fiber_ontop< fiber, Fn >).fctx };
+ }
+
+ explicit operator bool() const noexcept {
+ return nullptr != fctx_;
+ }
+
+ bool operator!() const noexcept {
+ return nullptr == fctx_;
+ }
+
+ bool operator==( fiber const& other) const noexcept {
+ return fctx_ == other.fctx_;
+ }
+
+ bool operator!=( fiber const& other) const noexcept {
+ return fctx_ != other.fctx_;
+ }
+
+ bool operator<( fiber const& other) const noexcept {
+ return fctx_ < other.fctx_;
+ }
+
+ bool operator>( fiber const& other) const noexcept {
+ return other.fctx_ < fctx_;
+ }
+
+ bool operator<=( fiber const& other) const noexcept {
+ return ! ( * this > other);
+ }
+
+ bool operator>=( fiber const& other) const noexcept {
+ return ! ( * this < other);
+ }
+
+ template< typename charT, class traitsT >
+ friend std::basic_ostream< charT, traitsT > &
+ operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other) {
+ if ( nullptr != other.fctx_) {
+ return os << other.fctx_;
+ } else {
+ return os << "{not-a-context}";
+ }
+ }
+
+ void swap( fiber & other) noexcept {
+ std::swap( fctx_, other.fctx_);
+ }
+};
+
+inline
+void swap( fiber & l, fiber & 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_FIBER_H
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