149 lines
4.3 KiB
Plaintext
149 lines
4.3 KiB
Plaintext
[/
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(C) Copyright 2007-8 Anthony Williams.
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(C) Copyright 2013 Oliver Kowalke.
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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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]
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[section:fls Fiber local storage]
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[heading Synopsis]
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Fiber local storage allows a separate instance of a given data item for
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each fiber.
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[heading Cleanup at fiber exit]
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When a fiber exits, the objects associated with each __fsp__ instance are
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destroyed. By default, the object pointed to by a pointer `p` is destroyed by
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invoking `delete p`, but this can be overridden for a specific instance of
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__fsp__ by providing a cleanup routine `func` to the constructor. In this case, the
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object is destroyed by invoking `func(p)`. The cleanup functions are called in an unspecified
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order.
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[class_heading fiber_specific_ptr]
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#include <boost/fiber/fss.hpp>
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namespace boost {
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namespace fibers {
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template< typename T >
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class fiber_specific_ptr {
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public:
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typedef T element_type;
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fiber_specific_ptr();
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explicit fiber_specific_ptr( void(*fn)(T*) );
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~fiber_specific_ptr();
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fiber_specific_ptr( fiber_specific_ptr const&) = delete;
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fiber_specific_ptr & operator=( fiber_specific_ptr const&) = delete;
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T * get() const noexcept;
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T * operator->() const noexcept;
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T & operator*() const noexcept;
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T * release();
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void reset( T *);
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};
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}}
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[heading Constructor]
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fiber_specific_ptr();
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explicit fiber_specific_ptr( void(*fn)(T*) );
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[variablelist
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[[Requires:] [`delete this->get()` is well-formed; `fn(this->get())` does not
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throw]]
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[[Effects:] [Construct a __fsp__ object for storing a pointer to an object of
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type `T` specific to each fiber. When `reset()` is called, or the
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fiber exits, __fsp__ calls `fn(this->get())`. If the no-arguments constructor
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is used, the default `delete`-based cleanup function
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will be used to destroy the fiber-local objects.]]
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[[Throws:] [__fiber_error__ if an error occurs.]]
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]
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[heading Destructor]
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~fiber_specific_ptr();
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[variablelist
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[[Requires:] [All the fiber specific instances associated to this __fsp__
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(except maybe the one associated to this fiber) must be nullptr.]]
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[[Effects:] [Calls `this->reset()` to clean up the associated value for the
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current fiber, and destroys `*this`.]]
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[[Remarks:] [The requirement is an implementation restriction. If the
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destructor promised to delete instances for all fibers, the implementation
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would be forced to maintain a list of all the fibers having an associated
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specific ptr, which is against the goal of fiber specific data. In general, a
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__fsp__ should outlive the fibers that use it.]]
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]
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[note Care needs to be taken to ensure that any fibers still running after an
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instance of __fsp__ has been destroyed do not call any member functions on that
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instance.]
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[member_heading fiber_specific_ptr..get]
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T * get() const noexcept;
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[variablelist
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[[Returns:] [The pointer associated with the current fiber.]]
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[[Throws:] [Nothing.]]
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]
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[note The initial value associated with an instance of __fsp__ is `nullptr` for
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each fiber.]
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[operator_heading fiber_specific_ptr..operator_arrow..operator->]
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T * operator->() const noexcept;
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[variablelist
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[[Requires:] [`this->get()` is not `nullptr`.]]
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[[Returns:] [`this->get()`]]
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[[Throws:] [Nothing.]]
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]
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[operator_heading fiber_specific_ptr..operator_star..operator*]
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T & operator*() const noexcept;
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[variablelist
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[[Requires:] [`this->get()` is not `nullptr`.]]
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[[Returns:] [`*(this->get())`]]
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[[Throws:] [Nothing.]]
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]
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[member_heading fiber_specific_ptr..release]
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T * release();
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[variablelist
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[[Effects:] [Return `this->get()` and store `nullptr` as the pointer associated
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with the current fiber without invoking the cleanup function.]]
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[[Postcondition:] [`this->get()==nullptr`]]
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[[Throws:] [Nothing.]]
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]
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[member_heading fiber_specific_ptr..reset]
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void reset( T * new_value);
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[variablelist
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[[Effects:] [If `this->get()!=new_value` and `this->get()` is not `nullptr`,
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invoke `delete this->get()` or `fn(this->get())` as appropriate. Store
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`new_value` as the pointer associated with the current fiber.]]
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[[Postcondition:] [`this->get()==new_value`]]
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[[Throws:] [Exception raised during cleanup of previous value.]]
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]
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[endsect]
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