115 lines
3.9 KiB
C++
115 lines
3.9 KiB
C++
// Copyright Oliver Kowalke 2013.
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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_FIBERS_ALGO_ALGORITHM_H
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#define BOOST_FIBERS_ALGO_ALGORITHM_H
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#include <cstddef>
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#include <chrono>
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#include <boost/config.hpp>
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#include <boost/assert.hpp>
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#include <boost/fiber/properties.hpp>
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#include <boost/fiber/detail/config.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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namespace boost {
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namespace fibers {
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class context;
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namespace algo {
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struct BOOST_FIBERS_DECL algorithm {
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virtual ~algorithm() {}
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virtual void awakened( context *) noexcept = 0;
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virtual context * pick_next() noexcept = 0;
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virtual bool has_ready_fibers() const noexcept = 0;
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virtual void suspend_until( std::chrono::steady_clock::time_point const&) noexcept = 0;
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virtual void notify() noexcept = 0;
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};
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class BOOST_FIBERS_DECL algorithm_with_properties_base : public algorithm {
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public:
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// called by fiber_properties::notify() -- don't directly call
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virtual void property_change_( context * f, fiber_properties * props) noexcept = 0;
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protected:
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static fiber_properties* get_properties( context * f) noexcept;
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static void set_properties( context * f, fiber_properties * p) noexcept;
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};
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template< typename PROPS >
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struct algorithm_with_properties : public algorithm_with_properties_base {
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typedef algorithm_with_properties_base super;
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// Mark this override 'final': algorithm_with_properties subclasses
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// must override awakened() with properties parameter instead. Otherwise
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// you'd have to remember to start every subclass awakened() override
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// with: algorithm_with_properties<PROPS>::awakened(fb);
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virtual void awakened( context * f) noexcept override final {
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fiber_properties * props = super::get_properties( f);
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if ( nullptr == props) {
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// TODO: would be great if PROPS could be allocated on the new
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// fiber's stack somehow
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props = new_properties( f);
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// It is not good for new_properties() to return 0.
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BOOST_ASSERT_MSG(props, "new_properties() must return non-NULL");
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// new_properties() must return instance of (a subclass of) PROPS
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BOOST_ASSERT_MSG( dynamic_cast< PROPS * >( props),
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"new_properties() must return properties class");
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super::set_properties( f, props);
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}
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// Set algo_ again every time this fiber becomes READY. That
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// handles the case of a fiber migrating to a new thread with a new
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// algorithm subclass instance.
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props->set_algorithm( this);
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// Okay, now forward the call to subclass override.
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awakened( f, properties(f) );
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}
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// subclasses override this method instead of the original awakened()
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virtual void awakened( context *, PROPS& ) noexcept = 0;
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// used for all internal calls
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PROPS & properties( context * f) noexcept {
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return static_cast< PROPS & >( * super::get_properties( f) );
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}
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// override this to be notified by PROPS::notify()
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virtual void property_change( context * f, PROPS & props) noexcept {
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}
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// implementation for algorithm_with_properties_base method
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void property_change_( context * f, fiber_properties * props ) noexcept override final {
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property_change( f, * static_cast< PROPS * >( props) );
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}
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// Override this to customize instantiation of PROPS, e.g. use a different
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// allocator. Each PROPS instance is associated with a particular
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// context.
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virtual fiber_properties * new_properties( context * f) {
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return new PROPS( f);
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}
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};
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}}}
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_SUFFIX
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#endif
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#endif // BOOST_FIBERS_ALGO_ALGORITHM_H
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