support disk I/O priority setting

ChangeLog

@@ -95,6 +95,7 @@
 	* added support for storing per-peer rate limits across reconnects
 	* improved fallocate support
 	* fixed magnet link issue when using resume data
+	* support disk I/O priority settings
 
 release 0.14.9
 

bindings/python/src/session_settings.cpp

@@ -99,6 +99,13 @@ void bind_session_settings()
         .def_readwrite("disk_cache_algorithm", &session_settings::disk_cache_algorithm)
         .def_readwrite("read_cache_line_size", &session_settings::read_cache_line_size)
         .def_readwrite("write_cache_line_size", &session_settings::write_cache_line_size)
+        .def_readwrite("optimistic_disk_retry", &session_settings::optimistic_disk_retry)
+        .def_readwrite("disable_hash_checks", &session_settings::disable_hash_checks)
+        .def_readwrite("allow_reordered_disk_operations", &session_settings::allow_reordered_disk_operations)
+        .def_readwrite("allow_i2p_mixed", &session_settings::allow_i2p_mixed)
+        .def_readwrite("max_suggest_pieces", &session_settings::max_suggest_pieces)
+        .def_readwrite("drop_skipped_requests", &session_settings::drop_skipped_requests)
+        .def_readwrite("low_prio_disk", &session_settings::low_prio_disk)
     ;
 
     enum_<proxy_settings::proxy_type>("proxy_type")

docs/manual.rst

@@ -3718,6 +3718,8 @@ session_settings
 		int max_suggest_pieces;
 
 		bool drop_skipped_requests;
+
+		bool low_prio_disk;
 	};
 
 ``user_agent`` this is the client identification to the tracker.
@@ -4180,6 +4182,13 @@ BitComet peers silently ignoring some requests. It may cause problems
 at high rates, and high level of reordering in the uploading peer, that's
 why it's disabled by default.
 
+``low_prio_disk`` determines if the disk I/O should use a normal
+or low priority policy. This defaults to true, which means that
+it's low priority by default. Other processes doing disk I/O will
+normally take priority in this mode. This is meant to improve the
+overall responsiveness of the system while downloading in the
+background. For high-performance server setups, this might not
+be desirable.
 
 pe_settings
 ===========

include/libtorrent/disk_io_thread.hpp

@@ -253,6 +253,7 @@ namespace libtorrent
 	{
 		disk_io_thread(io_service& ios
 			, boost::function<void()> const& queue_callback
+			, file_pool& fp
 			, int block_size = 16 * 1024);
 		~disk_io_thread();
 
@@ -399,6 +400,10 @@ namespace libtorrent
 		// exist anymore, and crash. This prevents that.
 		boost::optional<io_service::work> m_work;
 
+		// reference to the file_pool which is a member of
+		// the session_impl object
+		file_pool& m_file_pool;
+
 		// thread for performing blocking disk io operations
 		thread m_disk_io_thread;
 	};

include/libtorrent/file.hpp

@@ -241,6 +241,12 @@ namespace libtorrent
 
 		size_type phys_offset(size_type offset);
 
+#ifdef TORRENT_WINDOWS
+		HANDLE native_handle() const { return m_file_handle; }
+#else
+		int native_handle() const { return m_fd; }
+#endif
+
 	private:
 
 #ifdef TORRENT_WINDOWS

include/libtorrent/file_pool.hpp

@@ -52,7 +52,7 @@ namespace libtorrent
 {
 	struct TORRENT_EXPORT file_pool : boost::noncopyable
 	{
-		file_pool(int size = 40): m_size(size) {}
+		file_pool(int size = 40): m_size(size), m_low_prio_io(true) {}
 
 		boost::shared_ptr<file> open_file(void* st, std::string const& p
 			, int m, error_code& ec);
@@ -60,12 +60,15 @@ namespace libtorrent
 		void release(std::string const& p);
 		void resize(int size);
 		int size_limit() const { return m_size; }
+		void set_low_prio_io(bool b) { m_low_prio_io = b; }
 
 	private:
+		file_pool(file_pool const&);
 
 		void remove_oldest();
 
 		int m_size;
+		bool m_low_prio_io;
 
 		struct lru_file_entry
 		{

include/libtorrent/session_settings.hpp

@@ -185,6 +185,7 @@ namespace libtorrent
 			, allow_i2p_mixed(false)
 			, max_suggest_pieces(10)
 			, drop_skipped_requests(false)
+			, low_prio_disk(true)
 		{}
 
 		// this is the user agent that will be sent to the tracker
@@ -675,6 +676,13 @@ namespace libtorrent
 		// satisfied after the equivalence of the entire
 		// request queue has been received, will be considered lost
 		bool drop_skipped_requests;
+
+		// if this is set to true, the disk I/O will be
+		// run at lower-than-normal priority. This is
+		// intended to make the machine more responsive
+		// to foreground tasks, while bittorrent runs
+		// in the background
+		bool low_prio_disk;
 	};
 
 #ifndef TORRENT_DISABLE_DHT

src/disk_io_thread.cpp

@@ -41,6 +41,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/invariant_check.hpp"
 #include "libtorrent/error_code.hpp"
 #include "libtorrent/error.hpp"
+#include "libtorrent/file_pool.hpp"
 #include <boost/scoped_array.hpp>
 #include <boost/bind.hpp>
 
@@ -280,6 +281,7 @@ namespace libtorrent
 
 	disk_io_thread::disk_io_thread(io_service& ios
 		, boost::function<void()> const& queue_callback
+		, file_pool& fp
 		, int block_size)
 		: disk_buffer_pool(block_size)
 		, m_abort(false)
@@ -289,6 +291,7 @@ namespace libtorrent
 		, m_ios(ios)
 		, m_queue_callback(queue_callback)
 		, m_work(io_service::work(m_ios))
+		, m_file_pool(fp)
 		, m_disk_io_thread(boost::bind(&disk_io_thread::thread_fun, this))
 	{
 #ifdef TORRENT_DISK_STATS
@@ -1570,7 +1573,21 @@ namespace libtorrent
 					TORRENT_ASSERT(s.cache_size >= 0);
 					TORRENT_ASSERT(s.cache_expiry > 0);
 
+#if defined TORRENT_WINDOWS
+					if (m_settings.low_prio_disk != s.low_prio_disk)
+					{
+						m_file_pool.set_low_prio_io(s.low_prio_disk);
+						// we need to close all files, since the prio
+						// only takes affect when files are opened
+						m_file_pool.release(0);
+					}
+#endif
 					m_settings = s;
+					m_file_pool.resize(m_settings.file_pool_size);
+#if defined __APPLE__ && defined __MACH__ && MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
+					setiopolicy_np(IOPOL_TYPE_DISK, IOPOL_SCOPE_THREAD
+						, m_settings.low_prio_disk ? IOPOL_THROTTLE : IOPOL_DEFAULT);
+#endif
 					break;
 				}
 				case disk_io_job::abort_torrent:

src/file_pool.cpp

@@ -80,6 +80,15 @@ namespace libtorrent
 					m_files.erase(i);
 					return boost::shared_ptr<file>();
 				}
+#ifdef TORRENT_WINDOWS
+				if (m_low_prio_io)
+				{
+					FILE_IO_PRIORITY_HINT_INFO priorityHint;
+					priorityHint.PriorityHint = IoPriorityHintLow;
+					result = SetFileInformationByHandle(e.file_ptr->native_handle(),
+						FileIoPriorityHintInfo, &priorityHint, sizeof(PriorityHint));
+				}
+#endif
 				TORRENT_ASSERT(e.file_ptr->is_open());
 				e.mode = m;
 			}
@@ -126,10 +135,16 @@ namespace libtorrent
 		if (i != m_files.end()) m_files.erase(i);
 	}
 
+	// closes files belonging to the specified
+	// storage. If 0 is passed, all files are closed
 	void file_pool::release(void* st)
 	{
 		mutex::scoped_lock l(m_mutex);
-		TORRENT_ASSERT(st != 0);
+		if (st == 0)
+		{
+			m_files.clear();
+			return;
+		}
 
 		for (file_set::iterator i = m_files.begin();
 			i != m_files.end();)

src/session.cpp

@@ -175,6 +175,7 @@ namespace libtorrent
 		set.cache_buffer_chunk_size = 128;
 		set.read_cache_line_size = 512;
 		set.write_cache_line_size = 512;
+		set.low_prio_disk = false;
 		// one hour expiration
 		set.cache_expiry = 60 * 60;
 

src/session_impl.cpp

@@ -403,7 +403,7 @@ namespace aux {
 		, m_files(40)
 		, m_io_service()
 		, m_alerts(m_io_service)
-		, m_disk_thread(m_io_service, boost::bind(&session_impl::on_disk_queue, this))
+		, m_disk_thread(m_io_service, boost::bind(&session_impl::on_disk_queue, this), m_files)
 		, m_half_open(m_io_service)
 		, m_download_rate(peer_connection::download_channel)
 #ifdef TORRENT_VERBOSE_BANDWIDTH_LIMIT
@@ -1016,7 +1016,10 @@ namespace aux {
 #ifndef TORRENT_DISABLE_MLOCK
 			|| m_settings.lock_disk_cache != s.lock_disk_cache
 #endif
-			|| m_settings.use_read_cache != s.use_read_cache)
+			|| m_settings.use_read_cache != s.use_read_cache
+			|| m_settings.allow_reordered_disk_operations != s.allow_reordered_disk_operations
+			|| m_settings.file_pool_size != s.file_pool_size
+			|| m_settings.low_prio_disk != s.low_prio_disk)
 			update_disk_io_thread = true;
 
 		// if queuing settings were changed, recalculate
@@ -1037,7 +1040,6 @@ namespace aux {
 			m_disk_thread.add_job(j);
 		}
 
-		m_files.resize(m_settings.file_pool_size);
 		if (!s.auto_upload_slots) m_allowed_upload_slots = m_max_uploads;
 		// replace all occurances of '\n' with ' '.
 		std::string::iterator i = m_settings.user_agent.begin();

test/test_storage.cpp

@@ -243,7 +243,7 @@ void run_elevator_test()
 
 	{
 		error_code ec;
-		disk_io_thread dio(ios, &nop);
+		disk_io_thread dio(ios, &nop, fp);
 		boost::intrusive_ptr<piece_manager> pm(new piece_manager(boost::shared_ptr<void>(), ti, ""
 			, fp, dio, &create_test_storage, storage_mode_sparse));
 
@@ -379,7 +379,7 @@ void run_storage_tests(boost::intrusive_ptr<torrent_info> info
 	{
 	file_pool fp;
 	libtorrent::asio::io_service ios;
-	disk_io_thread io(ios, boost::function<void()>());
+	disk_io_thread io(ios, boost::function<void()>(), fp);
 	boost::shared_ptr<int> dummy(new int);
 	boost::intrusive_ptr<piece_manager> pm = new piece_manager(dummy, info
 		, test_path, fp, io, default_storage_constructor, storage_mode);
@@ -601,7 +601,7 @@ void test_check_files(std::string const& test_path
 
 	file_pool fp;
 	libtorrent::asio::io_service ios;
-	disk_io_thread io(ios, boost::function<void()>());
+	disk_io_thread io(ios, boost::function<void()>(), fp);
 	boost::shared_ptr<int> dummy(new int);
 	boost::intrusive_ptr<piece_manager> pm = new piece_manager(dummy, info
 		, test_path, fp, io, default_storage_constructor, storage_mode);