forked from premiere/premiere-libtorrent
193 lines
5.2 KiB
C++
193 lines
5.2 KiB
C++
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/*
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Copyright (c) 2007, 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_CHAINED_BUFFER_HPP_INCLUDED
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#define TORRENT_CHAINED_BUFFER_HPP_INCLUDED
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#include <boost/function.hpp>
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#include <asio.hpp>
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#include <list>
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#include <cstring>
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namespace libtorrent
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{
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struct chained_buffer
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{
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chained_buffer(): m_bytes(0), m_capacity(0) {}
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struct buffer_t
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{
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boost::function<void(char*)> free; // destructs the buffer
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char* buf; // the first byte of the buffer
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int size; // the total size of the buffer
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char* start; // the first byte to send/receive in the buffer
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int used_size; // this is the number of bytes to send/receive
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};
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bool empty() const { return m_bytes == 0; }
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int size() const { return m_bytes; }
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int capacity() const { return m_capacity; }
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void pop_front(int bytes_to_pop)
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{
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assert(bytes_to_pop <= m_bytes);
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while (bytes_to_pop > 0 && !m_vec.empty())
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{
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buffer_t& b = m_vec.front();
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if (b.used_size > bytes_to_pop)
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{
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b.start += bytes_to_pop;
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b.used_size -= bytes_to_pop;
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m_bytes -= bytes_to_pop;
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assert(m_bytes <= m_capacity);
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assert(m_bytes >= 0);
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assert(m_capacity >= 0);
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break;
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}
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b.free(b.buf);
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m_bytes -= b.used_size;
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m_capacity -= b.size;
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bytes_to_pop -= b.used_size;
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assert(m_bytes >= 0);
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assert(m_capacity >= 0);
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assert(m_bytes <= m_capacity);
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m_vec.pop_front();
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}
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}
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template <class D>
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void append_buffer(char* buffer, int size, int used_size, D const& destructor)
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{
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assert(size >= used_size);
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buffer_t b;
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b.buf = buffer;
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b.size = size;
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b.start = buffer;
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b.used_size = used_size;
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b.free = destructor;
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m_vec.push_back(b);
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m_bytes += used_size;
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m_capacity += size;
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assert(m_bytes <= m_capacity);
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}
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// returns the number of bytes available at the
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// end of the last chained buffer.
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int space_in_last_buffer()
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{
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if (m_vec.empty()) return 0;
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buffer_t& b = m_vec.back();
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return b.size - b.used_size - (b.start - b.buf);
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}
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// tries to copy the given buffer to the end of the
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// last chained buffer. If there's not enough room
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// it returns false
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bool append(char const* buf, int size)
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{
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char* insert = allocate_appendix(size);
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if (insert == 0) return false;
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std::memcpy(insert, buf, size);
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return true;
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}
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// tries to allocate memory from the end
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// of the last buffer. If there isn't
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// enough room, returns 0
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char* allocate_appendix(int size)
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{
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if (m_vec.empty()) return 0;
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buffer_t& b = m_vec.back();
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char* insert = b.start + b.used_size;
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if (insert + size > b.buf + b.size) return 0;
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b.used_size += size;
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m_bytes += size;
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assert(m_bytes <= m_capacity);
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return insert;
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}
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std::list<asio::const_buffer> const& build_iovec(int to_send)
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{
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m_tmp_vec.clear();
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for (std::list<buffer_t>::iterator i = m_vec.begin()
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, end(m_vec.end()); to_send > 0 && i != end; ++i)
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{
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if (i->used_size > to_send)
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{
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assert(to_send > 0);
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m_tmp_vec.push_back(asio::const_buffer(i->start, to_send));
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break;
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}
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assert(i->used_size > 0);
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m_tmp_vec.push_back(asio::const_buffer(i->start, i->used_size));
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to_send -= i->used_size;
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}
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return m_tmp_vec;
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}
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~chained_buffer()
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{
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for (std::list<buffer_t>::iterator i = m_vec.begin()
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, end(m_vec.end()); i != end; ++i)
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{
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i->free(i->buf);
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}
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}
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private:
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// this is the list of all the buffers we want to
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// send
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std::list<buffer_t> m_vec;
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// this is the number of bytes in the send buf.
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// this will always be equal to the sum of the
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// size of all buffers in vec
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int m_bytes;
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// the total size of all buffers in the chain
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// including unused space
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int m_capacity;
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// this is the vector of buffers used when
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// invoking the async write call
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std::list<asio::const_buffer> m_tmp_vec;
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};
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}
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#endif
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