127 lines
4.4 KiB
C++
127 lines
4.4 KiB
C++
/*
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Copyright (c) 2008-2015, Arvid Norberg
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TORRENT_DISK_BUFFER_HOLDER_HPP_INCLUDED
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#define TORRENT_DISK_BUFFER_HOLDER_HPP_INCLUDED
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#include "libtorrent/config.hpp"
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#include "libtorrent/assert.hpp"
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#include "libtorrent/disk_io_job.hpp" // for block_cache_reference
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#include <algorithm>
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#include <boost/shared_ptr.hpp>
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#include <boost/function.hpp>
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namespace libtorrent
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{
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struct disk_io_thread;
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struct disk_observer;
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struct buffer_allocator_interface
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{
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virtual char* allocate_disk_buffer(char const* category) = 0;
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virtual void free_disk_buffer(char* b) = 0;
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virtual void reclaim_block(block_cache_reference ref) = 0;
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virtual char* allocate_disk_buffer(bool& exceeded
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, boost::shared_ptr<disk_observer> o
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, char const* category) = 0;
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virtual char* async_allocate_disk_buffer(char const* category
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, boost::function<void(char*)> const& handler) = 0;
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protected:
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~buffer_allocator_interface() {}
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};
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// The disk buffer holder acts like a ``scoped_ptr`` that frees a disk buffer
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// when it's destructed, unless it's released. ``release`` returns the disk
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// buffer and transferres ownership and responsibility to free it to the caller.
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//
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// A disk buffer is freed by passing it to ``session_impl::free_disk_buffer()``.
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//
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// ``buffer()`` returns the pointer without transferring responsibility. If
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// this buffer has been released, ``buffer()`` will return 0.
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struct TORRENT_EXPORT disk_buffer_holder
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{
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// internal
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disk_buffer_holder(buffer_allocator_interface& alloc, char* buf);
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// construct a buffer holder that will free the held buffer
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// using a disk buffer pool directly (there's only one
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// disk_buffer_pool per session)
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disk_buffer_holder(buffer_allocator_interface& alloc, disk_io_job const& j);
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// frees any unreleased disk buffer held by this object
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~disk_buffer_holder();
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// return the held disk buffer and clear it from the
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// holder. The responsibility to free it is passed on
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// to the caller
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char* release();
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// return a pointer to the held buffer
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char* get() const { return m_buf; }
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// set the holder object to hold the specified buffer
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// (or NULL by default). If it's already holding a
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// disk buffer, it will first be freed.
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void reset(char* buf = 0);
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void reset(disk_io_job const& j);
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// swap pointers of two disk buffer holders.
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void swap(disk_buffer_holder& h)
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{
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TORRENT_ASSERT(&h.m_allocator == &m_allocator);
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std::swap(h.m_buf, m_buf);
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std::swap(h.m_ref, m_ref);
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}
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block_cache_reference ref() const { return m_ref; }
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typedef char* (disk_buffer_holder::*unspecified_bool_type)();
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// internal
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operator unspecified_bool_type() const
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{ return m_buf == 0? 0: &disk_buffer_holder::release; }
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private:
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// non-copyable
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disk_buffer_holder& operator=(disk_buffer_holder const&);
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disk_buffer_holder(disk_buffer_holder const*);
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buffer_allocator_interface& m_allocator;
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char* m_buf;
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block_cache_reference m_ref;
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};
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}
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#endif
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