made disk_io_settings be synchronized through the job queue

docs/manual.rst

@@ -3193,6 +3193,7 @@ that will be sent to the tracker. The user-agent is a good way to identify your
 		bool use_parole_mode;
 		int cache_size;
 		int cache_expiry;
+		bool use_read_cache;
 		std::pair<int, int> outgoing_ports;
 		char peer_tos;
 
@@ -3420,6 +3421,9 @@ It defaults to 512 (= 8 MB).
 ``cache_expiry`` is the number of seconds from the last cached write to a piece
 in the write cache, to when it's forcefully flushed to disk. Default is 60 second.
 
+``use_read_cache``, is set to true (default), the disk cache is also used to
+cache pieces read from disk. Blocks for writing pieces takes presedence.
+
 ``outgoing_ports``, if set to something other than (0, 0) is a range of ports
 used to bind outgoing sockets to. This may be useful for users whose router
 allows them to assign QoS classes to traffic based on its local port. It is

include/libtorrent/disk_io_thread.hpp

@@ -89,6 +89,7 @@ namespace libtorrent
 			, abort_thread
 			, clear_read_cache
 			, abort_torrent
+			, update_settings
 		};
 
 		action_t action;
@@ -186,8 +187,6 @@ namespace libtorrent
 			, std::vector<cached_piece_info>& ret) const;
 
 		cache_status status() const;
-		void set_cache_size(int s);
-		void set_cache_expiry(int ex);
 
 		void operator()();
 

include/libtorrent/session_settings.hpp

@@ -124,6 +124,7 @@ namespace libtorrent
 			, use_parole_mode(true)
 			, cache_size(512)
 			, cache_expiry(60)
+			, use_read_cache(true)
 			, outgoing_ports(0,0)
 			, peer_tos(0)
 			, active_downloads(8)
@@ -372,6 +373,10 @@ namespace libtorrent
 		// to disk. Default is 60 seconds.
 		int cache_expiry;
 
+		// when true, the disk I/O thread uses the disk
+		// cache for caching blocks read from disk too
+		bool use_read_cache;
+
 		// if != (0, 0), this is the range of ports that
 		// outgoing connections will be bound to. This
 		// is useful for users that have routers that

src/disk_io_thread.cpp

@@ -145,20 +145,6 @@ namespace libtorrent
 		return m_cache_stats;
 	}
 
-	void disk_io_thread::set_cache_size(int s)
-	{
-		mutex_t::scoped_lock l(m_piece_mutex);
-		TORRENT_ASSERT(s >= 0);
-		m_cache_size = s;
-	}
-
-	void disk_io_thread::set_cache_expiry(int ex)
-	{
-		mutex_t::scoped_lock l(m_piece_mutex);
-		TORRENT_ASSERT(ex > 0);
-		m_cache_expiry = ex;
-	}
-
 	// aborts read operations
 	void disk_io_thread::stop(boost::intrusive_ptr<piece_manager> s)
 	{
@@ -870,6 +856,21 @@ namespace libtorrent
 
 			switch (j.action)
 			{
+				case disk_io_job::update_settings:
+				{
+#ifdef TORRENT_DISK_STATS
+					m_log << log_time() << " update_settings " << std::endl;
+#endif
+					TORRENT_ASSERT(j.buffer);
+					session_settings const& s = *((session_settings*)j.buffer);
+					TORRENT_ASSERT(s.cache_size >= 0);
+					TORRENT_ASSERT(s.cache_expiry > 0);
+
+					mutex_t::scoped_lock l(m_piece_mutex);
+					m_cache_size = s.cache_size;
+					m_cache_expiry = s.cache_expiry;
+					m_use_read_cache = s.use_read_cache;
+				}
 				case disk_io_job::abort_torrent:
 				{
 #ifdef TORRENT_DISK_STATS

src/session_impl.cpp

@@ -582,10 +582,16 @@ namespace aux {
 
 		// less than 5 seconds unchoke interval is insane
 		TORRENT_ASSERT(s.unchoke_interval >= 5);
-		if (m_settings.cache_size != s.cache_size)
-			m_disk_thread.set_cache_size(s.cache_size);
-		if (m_settings.cache_expiry != s.cache_expiry)
-			m_disk_thread.set_cache_expiry(s.cache_expiry);
+
+
+		// if disk io thread settings were changed
+		// post a notification to that thread
+		bool update_disk_io_thread = false;
+		if (m_settings.cache_size != s.cache_size
+			|| m_settings.cache_expiry != s.cache_expiry
+			|| m_settings.use_read_cache != s.use_read_cache)
+			update_disk_io_thread = true;
+
 		// if queuing settings were changed, recalculate
 		// queued torrents sooner
 		if ((m_settings.active_downloads != s.active_downloads
@@ -596,6 +602,14 @@ namespace aux {
 		m_settings = s;
  		if (m_settings.connection_speed <= 0) m_settings.connection_speed = 200;
  
+		if (update_disk_io_thread)
+		{
+			disk_io_job j;
+			j.buffer = (char*)&m_settings;
+			j.action = disk_io_job::update_settings;
+			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 ' '.