premiere-libtorrent/include/libtorrent/disk_io_thread.hpp

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/*
Copyright (c) 2007, 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.
*/
#ifndef TORRENT_DISK_IO_THREAD
#define TORRENT_DISK_IO_THREAD
#ifdef TORRENT_DISK_STATS
#include <fstream>
#endif
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#include "libtorrent/storage.hpp"
#include <boost/thread/thread.hpp>
#include <boost/thread/mutex.hpp>
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#include <boost/thread/condition.hpp>
#include <boost/function.hpp>
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#include <boost/bind.hpp>
#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"
#ifndef TORRENT_DISABLE_POOL_ALLOCATOR
#include <boost/pool/pool.hpp>
#endif
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namespace libtorrent
{
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struct cached_piece_info
{
int piece;
std::vector<bool> blocks;
ptime last_use;
enum kind_t { read_cache = 0, write_cache = 1 };
kind_t kind;
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};
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struct disk_io_job
{
disk_io_job()
: action(read)
, buffer(0)
, buffer_size(0)
, piece(0)
, offset(0)
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, priority(0)
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{}
enum action_t
{
read
, write
, hash
, move_storage
, release_files
, delete_files
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, check_fastresume
, check_files
, save_resume_data
, rename_file
, abort_thread
, clear_read_cache
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};
action_t action;
char* buffer;
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int buffer_size;
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boost::intrusive_ptr<piece_manager> storage;
// arguments used for read and write
int piece, offset;
// used for move_storage and rename_file. On errors, this is set
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// to the error message
std::string str;
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// on error, this is set to the path of the
// file the disk operation failed on
std::string error_file;
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// priority decides whether or not this
// job will skip entries in the queue or
// not. It always skips in front of entries
// with lower priority
int priority;
boost::shared_ptr<entry> resume_data;
// the error code from the file operation
error_code error;
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// this is called when operation completes
boost::function<void(int, disk_io_job const&)> callback;
};
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struct cache_status
{
cache_status()
: blocks_written(0)
, writes(0)
, blocks_read(0)
, blocks_read_hit(0)
, reads(0)
, cache_size(0)
, read_cache_size(0)
{}
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// the number of 16kB blocks written
size_type blocks_written;
// the number of write operations used
size_type writes;
// (blocks_written - writes) / blocks_written represents the
// "cache hit" ratio in the write cache
// the number of blocks read
// the number of blocks passed back to the bittorrent engine
size_type blocks_read;
// the number of blocks that was just copied from the read cache
size_type blocks_read_hit;
// the number of read operations used
size_type reads;
// the number of blocks in the cache (both read and write)
int cache_size;
// the number of blocks in the cache used for read cache
int read_cache_size;
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};
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// this is a singleton consisting of the thread and a queue
// of disk io jobs
struct disk_io_thread : boost::noncopyable
{
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disk_io_thread(io_service& ios, int block_size = 16 * 1024);
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~disk_io_thread();
#ifdef TORRENT_STATS
int disk_allocations() const
{ return m_allocations; }
#endif
void join();
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// aborts read operations
void stop(boost::intrusive_ptr<piece_manager> s);
void add_job(disk_io_job const& j
, boost::function<void(int, disk_io_job const&)> const& f
= boost::function<void(int, disk_io_job const&)>());
// keep track of the number of bytes in the job queue
// at any given time. i.e. the sum of all buffer_size.
// this is used to slow down the download global download
// speed when the queue buffer size is too big.
size_type queue_buffer_size() const
{ return m_queue_buffer_size; }
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void get_cache_info(sha1_hash const& ih
, std::vector<cached_piece_info>& ret) const;
cache_status status() const;
void set_cache_size(int s);
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void set_cache_expiry(int ex);
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void operator()();
#ifndef NDEBUG
bool is_disk_buffer(char* buffer) const;
#endif
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char* allocate_buffer();
void free_buffer(char* buf);
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#ifndef NDEBUG
void check_invariant() const;
#endif
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private:
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struct cached_piece_entry
{
int piece;
// storage this piece belongs to
boost::intrusive_ptr<piece_manager> storage;
// the last time a block was writting to this piece
ptime last_use;
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// the number of blocks in the cache for this piece
int num_blocks;
// the pointers to the block data
boost::shared_array<char*> blocks;
};
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typedef boost::recursive_mutex mutex_t;
typedef std::list<cached_piece_entry> cache_t;
bool test_error(disk_io_job& j);
// cache operations
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cache_t::iterator find_cached_piece(
cache_t& cache, disk_io_job const& j
, mutex_t::scoped_lock& l);
// write cache operations
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void flush_oldest_piece(mutex_t::scoped_lock& l);
void flush_expired_pieces();
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void flush_and_remove(cache_t::iterator i, mutex_t::scoped_lock& l);
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);
// read cache operations
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bool clear_oldest_read_piece(cache_t::iterator ignore
, mutex_t::scoped_lock& l);
int read_into_piece(cached_piece_entry& p, int start_block, mutex_t::scoped_lock& l);
int cache_read_block(disk_io_job const& j, mutex_t::scoped_lock& l);
void free_piece(cached_piece_entry& p, mutex_t::scoped_lock& l);
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bool make_room(int num_blocks
, cache_t::iterator ignore
, mutex_t::scoped_lock& l);
int try_read_from_cache(disk_io_job const& j);
// this mutex only protects m_jobs, m_queue_buffer_size
// and m_abort
mutable mutex_t m_queue_mutex;
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boost::condition m_signal;
bool m_abort;
std::list<disk_io_job> m_jobs;
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size_type m_queue_buffer_size;
// this protects the piece cache and related members
mutable mutex_t m_piece_mutex;
// write cache
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cache_t m_pieces;
// read cache
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cache_t m_read_pieces;
// total number of blocks in use by both the read
// and the write cache. This is not supposed to
// exceed m_cache_size
cache_status m_cache_stats;
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int m_num_cached_blocks;
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// in (16kB) blocks
int m_cache_size;
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// expiration time of cache entries in seconds
int m_cache_expiry;
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// if set to true, each piece flush will allocate
// one piece worth of temporary memory on the heap
// and copy the block data into it, and then perform
// a single write operation from that buffer.
// if memory is constrained, that temporary buffer
// might is avoided by setting this to false.
// in case the allocation fails, the piece flush
// falls back to writing each block separately.
bool m_coalesce_writes;
bool m_coalesce_reads;
bool m_use_read_cache;
// this only protects the pool allocator
mutable mutex_t m_pool_mutex;
#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;
#endif
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// number of bytes per block. The BitTorrent
// protocol defines the block size to 16 KiB.
int m_block_size;
#ifdef TORRENT_DISK_STATS
std::ofstream m_log;
#endif
#ifdef TORRENT_STATS
int m_allocations;
#endif
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size_type m_writes;
size_type m_blocks_written;
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io_service& m_ios;
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// thread for performing blocking disk io operations
boost::thread m_disk_io_thread;
};
}
#endif