clears read cache when paused. Saves memory

include/libtorrent/disk_io_thread.hpp

@@ -86,6 +86,7 @@ namespace libtorrent
 			, save_resume_data
 			, rename_file
 			, abort_thread
+			, clear_read_cache
 		};
 
 		action_t action;

include/libtorrent/storage.hpp

@@ -236,6 +236,10 @@ namespace libtorrent
 			boost::function<void(int, disk_io_job const&)> const& handler
 			= boost::function<void(int, disk_io_job const&)>());
 
+		void async_clear_read_cache(
+			boost::function<void(int, disk_io_job const&)> const& handler
+			= boost::function<void(int, disk_io_job const&)>());
+
 		void async_delete_files(
 			boost::function<void(int, disk_io_job const&)> const& handler
 			= boost::function<void(int, disk_io_job const&)>());

src/disk_io_thread.cpp

@@ -1003,6 +1003,39 @@ namespace libtorrent
 					if (ret != 0) test_error(j);
 					break;
 				}
+				case disk_io_job::clear_read_cache:
+				{
+#ifdef TORRENT_DISK_STATS
+					m_log << log_time() << " clear-cache" << std::endl;
+#endif
+					TORRENT_ASSERT(j.buffer == 0);
+
+					mutex_t::scoped_lock l(m_piece_mutex);
+					INVARIANT_CHECK;
+
+					for (cache_t::iterator i = m_read_pieces.begin();
+						i != m_read_pieces.end();)
+					{
+						if (i->storage == j.storage)
+						{
+							free_piece(*i, l);
+							i = m_read_pieces.erase(i);
+						}
+						else
+						{
+							++i;
+						}
+					}
+					l.unlock();
+#ifndef TORRENT_DISABLE_POOL_ALLOCATOR
+					{
+						mutex_t::scoped_lock l(m_pool_mutex);
+						m_pool.release_memory();
+					}
+#endif
+					ret = 0;
+					break;
+				}
 				case disk_io_job::delete_files:
 				{
 #ifdef TORRENT_DISK_STATS

src/storage.cpp

@@ -1275,6 +1275,15 @@ namespace libtorrent
 		m_io_thread.add_job(j, handler);
 	}
 
+	void piece_manager::async_clear_read_cache(
+		boost::function<void(int, disk_io_job const&)> const& handler)
+	{
+		disk_io_job j;
+		j.storage = this;
+		j.action = disk_io_job::clear_read_cache;
+		m_io_thread.add_job(j, handler);
+	}
+
 	void piece_manager::async_release_files(
 		boost::function<void(int, disk_io_job const&)> const& handler)
 	{

src/torrent.cpp

@@ -3753,6 +3753,7 @@ namespace libtorrent
 			TORRENT_ASSERT(m_storage);
 			m_storage->async_release_files(
 				bind(&torrent::on_torrent_paused, shared_from_this(), _1, _2));
+			m_storage->async_clear_read_cache();
 		}
 		else
 		{