319 lines
8.5 KiB
C++
319 lines
8.5 KiB
C++
/*
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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_DISK_IO_THREAD
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#define TORRENT_DISK_IO_THREAD
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#ifdef TORRENT_DISK_STATS
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#include <fstream>
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#endif
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#include "libtorrent/storage.hpp"
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#include <boost/thread/thread.hpp>
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#include <boost/thread/mutex.hpp>
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#include <boost/thread/condition.hpp>
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#include <boost/function.hpp>
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#include <boost/bind.hpp>
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#include <boost/noncopyable.hpp>
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#include <boost/shared_array.hpp>
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#include <list>
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#include "libtorrent/config.hpp"
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#ifndef TORRENT_DISABLE_POOL_ALLOCATOR
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#include <boost/pool/pool.hpp>
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#endif
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namespace libtorrent
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{
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struct cached_piece_info
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{
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int piece;
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std::vector<bool> blocks;
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ptime last_use;
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enum kind_t { read_cache = 0, write_cache = 1 };
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kind_t kind;
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};
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struct disk_io_job
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{
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disk_io_job()
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: action(read)
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, buffer(0)
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, buffer_size(0)
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, piece(0)
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, offset(0)
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, priority(0)
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{}
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enum action_t
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{
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read
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, write
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, hash
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, move_storage
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, release_files
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, delete_files
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, check_fastresume
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, check_files
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, save_resume_data
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, rename_file
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, abort_thread
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, clear_read_cache
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};
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action_t action;
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char* buffer;
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int buffer_size;
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boost::intrusive_ptr<piece_manager> storage;
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// arguments used for read and write
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int piece, offset;
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// used for move_storage and rename_file. On errors, this is set
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// to the error message
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std::string str;
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// on error, this is set to the path of the
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// file the disk operation failed on
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std::string error_file;
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// priority decides whether or not this
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// job will skip entries in the queue or
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// not. It always skips in front of entries
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// with lower priority
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int priority;
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boost::shared_ptr<entry> resume_data;
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// the error code from the file operation
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error_code error;
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// this is called when operation completes
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boost::function<void(int, disk_io_job const&)> callback;
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};
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struct cache_status
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{
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cache_status()
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: blocks_written(0)
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, writes(0)
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, blocks_read(0)
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, blocks_read_hit(0)
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, reads(0)
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, cache_size(0)
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, read_cache_size(0)
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{}
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// the number of 16kB blocks written
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size_type blocks_written;
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// the number of write operations used
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size_type writes;
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// (blocks_written - writes) / blocks_written represents the
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// "cache hit" ratio in the write cache
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// the number of blocks read
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// the number of blocks passed back to the bittorrent engine
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size_type blocks_read;
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// the number of blocks that was just copied from the read cache
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size_type blocks_read_hit;
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// the number of read operations used
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size_type reads;
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// the number of blocks in the cache (both read and write)
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int cache_size;
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// the number of blocks in the cache used for read cache
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int read_cache_size;
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};
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// this is a singleton consisting of the thread and a queue
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// of disk io jobs
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struct disk_io_thread : boost::noncopyable
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{
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disk_io_thread(io_service& ios, int block_size = 16 * 1024);
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~disk_io_thread();
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#ifdef TORRENT_STATS
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int disk_allocations() const
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{ return m_allocations; }
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#endif
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void join();
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// aborts read operations
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void stop(boost::intrusive_ptr<piece_manager> s);
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void add_job(disk_io_job const& j
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, boost::function<void(int, disk_io_job const&)> const& f
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= boost::function<void(int, disk_io_job const&)>());
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// keep track of the number of bytes in the job queue
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// at any given time. i.e. the sum of all buffer_size.
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// this is used to slow down the download global download
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// speed when the queue buffer size is too big.
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size_type queue_buffer_size() const
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{ return m_queue_buffer_size; }
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void get_cache_info(sha1_hash const& ih
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, std::vector<cached_piece_info>& ret) const;
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cache_status status() const;
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void set_cache_size(int s);
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void set_cache_expiry(int ex);
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void operator()();
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#ifndef NDEBUG
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bool is_disk_buffer(char* buffer) const;
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#endif
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char* allocate_buffer();
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void free_buffer(char* buf);
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#ifndef NDEBUG
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void check_invariant() const;
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#endif
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private:
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struct cached_piece_entry
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{
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int piece;
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// storage this piece belongs to
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boost::intrusive_ptr<piece_manager> storage;
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// the last time a block was writting to this piece
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ptime last_use;
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// the number of blocks in the cache for this piece
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int num_blocks;
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// the pointers to the block data
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boost::shared_array<char*> blocks;
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};
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typedef boost::recursive_mutex mutex_t;
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typedef std::list<cached_piece_entry> cache_t;
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bool test_error(disk_io_job& j);
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// cache operations
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cache_t::iterator find_cached_piece(
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cache_t& cache, disk_io_job const& j
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, mutex_t::scoped_lock& l);
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// write cache operations
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void flush_oldest_piece(mutex_t::scoped_lock& l);
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void flush_expired_pieces();
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void flush_and_remove(cache_t::iterator i, mutex_t::scoped_lock& l);
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void flush(cache_t::iterator i, mutex_t::scoped_lock& l);
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void cache_block(disk_io_job& j, mutex_t::scoped_lock& l);
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// read cache operations
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bool clear_oldest_read_piece(cache_t::iterator ignore
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, mutex_t::scoped_lock& l);
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int read_into_piece(cached_piece_entry& p, int start_block, mutex_t::scoped_lock& l);
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int cache_read_block(disk_io_job const& j, mutex_t::scoped_lock& l);
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void free_piece(cached_piece_entry& p, mutex_t::scoped_lock& l);
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bool make_room(int num_blocks
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, cache_t::iterator ignore
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, mutex_t::scoped_lock& l);
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int try_read_from_cache(disk_io_job const& j);
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// this mutex only protects m_jobs, m_queue_buffer_size
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// and m_abort
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mutable mutex_t m_queue_mutex;
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boost::condition m_signal;
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bool m_abort;
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std::list<disk_io_job> m_jobs;
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size_type m_queue_buffer_size;
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// this protects the piece cache and related members
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mutable mutex_t m_piece_mutex;
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// write cache
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cache_t m_pieces;
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// read cache
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cache_t m_read_pieces;
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// total number of blocks in use by both the read
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// and the write cache. This is not supposed to
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// exceed m_cache_size
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cache_status m_cache_stats;
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int m_num_cached_blocks;
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// in (16kB) blocks
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int m_cache_size;
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// expiration time of cache entries in seconds
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int m_cache_expiry;
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// if set to true, each piece flush will allocate
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// one piece worth of temporary memory on the heap
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// and copy the block data into it, and then perform
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// a single write operation from that buffer.
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// if memory is constrained, that temporary buffer
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// might is avoided by setting this to false.
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// in case the allocation fails, the piece flush
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// falls back to writing each block separately.
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bool m_coalesce_writes;
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bool m_coalesce_reads;
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bool m_use_read_cache;
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// this only protects the pool allocator
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mutable mutex_t m_pool_mutex;
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#ifndef TORRENT_DISABLE_POOL_ALLOCATOR
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// memory pool for read and write operations
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// and disk cache
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boost::pool<> m_pool;
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#endif
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// number of bytes per block. The BitTorrent
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// protocol defines the block size to 16 KiB.
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int m_block_size;
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#ifdef TORRENT_DISK_STATS
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std::ofstream m_log;
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#endif
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#ifdef TORRENT_STATS
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int m_allocations;
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#endif
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size_type m_writes;
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size_type m_blocks_written;
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io_service& m_ios;
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// thread for performing blocking disk io operations
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boost::thread m_disk_io_thread;
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};
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}
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#endif
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