premiere-libtorrent/src/file_storage.cpp

/*

Copyright (c) 2003-2008, Arvid Norberg
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the distribution.
    * Neither the name of the author nor the names of its
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

*/

#include "libtorrent/pch.hpp"

#include "libtorrent/file_storage.hpp"
#include "libtorrent/file.hpp"
#include "libtorrent/utf8.hpp"
#include <boost/bind.hpp>
#include <cstdio>
#include <algorithm>

namespace libtorrent
{
	file_storage::file_storage()
		: m_total_size(0)
		, m_num_pieces(0)
		, m_piece_length(0)
	{}

	void file_storage::reserve(int num_files)
	{
		m_files.reserve(num_files);
	}

	int file_storage::piece_size(int index) const
	{
		TORRENT_ASSERT(index >= 0 && index < num_pieces());
		if (index == num_pieces()-1)
		{
			int size = int(total_size()
				- size_type(num_pieces() - 1) * piece_length());
			TORRENT_ASSERT(size > 0);
			TORRENT_ASSERT(size <= piece_length());
			return int(size);
		}
		else
			return piece_length();
	}

#if TORRENT_USE_WSTRING
	void file_storage::set_name(std::wstring const& n)
	{
		std::string utf8;
		wchar_utf8(n, utf8);
		m_name = utf8;
	}

	void file_storage::rename_file(int index, std::wstring const& new_filename)
	{
		TORRENT_ASSERT(index >= 0 && index < int(m_files.size()));
		std::string utf8;
		wchar_utf8(new_filename, utf8);
		m_files[index].path = utf8;
	}

	void file_storage::add_file(std::wstring const& file, size_type size, int flags
		, std::time_t mtime, std::string const& symlink_path)
	{
		std::string utf8;
		wchar_utf8(file, utf8);
		add_file(utf8, size, flags, mtime, symlink_path);
	}
#endif // TORRENT_USE_WSTRING

	void file_storage::rename_file(int index, std::string const& new_filename)
	{
		TORRENT_ASSERT(index >= 0 && index < int(m_files.size()));
		m_files[index].path = new_filename;
	}

	namespace
	{
		bool compare_file_offset(file_entry const& lhs, file_entry const& rhs)
		{
			return lhs.offset < rhs.offset;
		}
	}

	file_storage::iterator file_storage::file_at_offset(size_type offset) const
	{
		// find the file iterator and file offset
		file_entry target;
		target.offset = offset;
		TORRENT_ASSERT(!compare_file_offset(target, m_files.front()));

		std::vector<file_entry>::const_iterator file_iter = std::upper_bound(
			begin(), end(), target, compare_file_offset);

		TORRENT_ASSERT(file_iter != begin());
		--file_iter;
		return file_iter;
	}

	std::vector<file_slice> file_storage::map_block(int piece, size_type offset
		, int size) const
	{
		TORRENT_ASSERT(num_files() > 0);
		std::vector<file_slice> ret;

		if (m_files.empty()) return ret;

		// find the file iterator and file offset
		file_entry target;
		target.offset = piece * (size_type)m_piece_length + offset;
		TORRENT_ASSERT(target.offset + size <= m_total_size);
		TORRENT_ASSERT(!compare_file_offset(target, m_files.front()));

		std::vector<file_entry>::const_iterator file_iter = std::upper_bound(
			begin(), end(), target, compare_file_offset);

		TORRENT_ASSERT(file_iter != begin());
		--file_iter;

		size_type file_offset = target.offset - file_iter->offset;
		for (; size > 0; file_offset -= file_iter->size, ++file_iter)
		{
			TORRENT_ASSERT(file_iter != end());
			if (file_offset < file_iter->size)
			{
				file_slice f;
				f.file_index = file_iter - begin();
				f.offset = file_offset + file_iter->file_base;
				f.size = (std::min)(file_iter->size - file_offset, (size_type)size);
				size -= f.size;
				file_offset += f.size;
				ret.push_back(f);
			}
			
			TORRENT_ASSERT(size >= 0);
		}
		return ret;
	}
	
	peer_request file_storage::map_file(int file_index, size_type file_offset
		, int size) const
	{
		TORRENT_ASSERT(file_index < num_files());
		TORRENT_ASSERT(file_index >= 0);
		size_type offset = file_offset + at(file_index).offset;

		peer_request ret;
		ret.piece = int(offset / piece_length());
		ret.start = int(offset - ret.piece * piece_length());
		ret.length = size;
		return ret;
	}

	void file_storage::add_file(std::string const& file, size_type size, int flags
		, std::time_t mtime, std::string const& symlink_path)
	{
		TORRENT_ASSERT(size >= 0);
		if (!has_parent_path(file))
		{
			// you have already added at least one file with a
			// path to the file (branch_path), which means that
			// all the other files need to be in the same top
			// directory as the first file.
			TORRENT_ASSERT(m_files.empty());
			m_name = file;
		}
		else
		{
			if (m_files.empty())
				m_name = split_path(file).c_str();
		}
		TORRENT_ASSERT(m_name == split_path(file).c_str());
		m_files.push_back(file_entry());
		file_entry& e = m_files.back();
		e.file_index = m_files.size() - 1;
		e.size = size;
		e.path = file;
		e.offset = m_total_size;
		e.pad_file = (flags & pad_file) != 0;
		e.hidden_attribute = (flags & attribute_hidden) != 0;
		e.executable_attribute = (flags & attribute_executable) != 0;
		e.symlink_attribute = (flags & attribute_symlink) != 0;
		if (e.symlink_attribute)
		{
			e.symlink_index = m_symlinks.size();
			m_symlinks.push_back(symlink_path);

		}
		e.mtime = mtime;
		m_total_size += size;
	}

	void file_storage::add_file(file_entry const& ent, sha1_hash const* filehash
		, std::string const* symlink)
	{
		if (!has_parent_path(ent.path))
		{
			// you have already added at least one file with a
			// path to the file (branch_path), which means that
			// all the other files need to be in the same top
			// directory as the first file.
			TORRENT_ASSERT(m_files.empty());
			m_name = ent.path;
		}
		else
		{
			if (m_files.empty())
				m_name = *ent.path.begin();
		}
		m_files.push_back(ent);
		file_entry& e = m_files.back();
		e.offset = m_total_size;
		e.file_index = m_files.size() - 1;
		m_total_size += ent.size;
		if (filehash)
		{
			e.filehash_index = m_file_hashes.size();
			m_file_hashes.push_back(*filehash);
		}

		if (symlink)
		{
			e.symlink_index = m_symlinks.size();
			m_symlinks.push_back(*symlink);
		}
	}

	void file_storage::optimize(int pad_file_limit)
	{
		// the main purpuse of padding is to optimize disk
		// I/O. This is a conservative memory page size assumption
		int alignment = 8*1024;

		// it doesn't make any sense to pad files that
		// are smaller than one piece
		if (pad_file_limit >= 0 && pad_file_limit < alignment)
			pad_file_limit = alignment;

		// put the largest file at the front, to make sure
		// it's aligned
		std::vector<file_entry>::iterator i = std::max_element(m_files.begin(), m_files.end()
			, boost::bind(&file_entry::size, _1) < boost::bind(&file_entry::size, _2));

		using std::iter_swap;
		iter_swap(i, m_files.begin());

		size_type off = 0;
		int padding_file = 0;
		for (std::vector<file_entry>::iterator i = m_files.begin();
			i != m_files.end(); ++i)
		{
			if (pad_file_limit >= 0
				&& (off & (alignment-1)) != 0
				&& i->size > pad_file_limit
				&& i->pad_file == false)
			{
				// if we have pad files enabled, and this file is
				// not piece-aligned and the file size exceeds the
				// limit, and it's not a padding file itself.
				// so add a padding file in front of it
				int pad_size = alignment - (off & (alignment-1));
				
				// find the largest file that fits in pad_size
				std::vector<file_entry>::iterator best_match = m_files.end();
				for (std::vector<file_entry>::iterator j = i+1; j < m_files.end(); ++j)
				{
					if (j->size > pad_size) continue;
					if (best_match == m_files.end() || j->size > best_match->size)
						best_match = j;
				}

				if (best_match != m_files.end())
				{
					// we found one
					file_entry e = *best_match;
					m_files.erase(best_match);
					i = m_files.insert(i, e);
					i->offset = off;
					off += i->size;
					continue;
				}

				// we could not find a file that fits in pad_size
				// add a padding file

				file_entry e;
				i = m_files.insert(i, e);
				i->size = pad_size;
				i->offset = off;
				i->file_base = 0;
				char name[10];
				std::sprintf(name, "%d", padding_file);
				i->path = combine_path("_____padding_file", name);
				i->pad_file = true;
				off += pad_size;
				++padding_file;
				++i;
			}
			i->offset = off;
			off += i->size;
		}
		m_total_size = off;
	}
}