added resolver_cache_timeout setting (#1878)

added resolver_cache_timeout setting

ChangeLog

@@ -1,3 +1,4 @@
+	* added resolver_cache_timeout setting for internal host name resolver
 	* make parse_magnet_uri take a string_view instead of std::string
 	* deprecate add_torrent_params::url field. use parse_magnet_uri instead
 	* optimize download queue management

include/libtorrent/aux_/session_impl.hpp

@@ -704,6 +704,7 @@ namespace libtorrent
 			void update_auto_sequential();
 			void update_max_failcount();
 			void update_close_file_interval();
+			void update_resolver_cache_timeout();
 
 			void update_upnp();
 			void update_natpmp();

include/libtorrent/resolver.hpp

@@ -45,7 +45,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/socket.hpp"
 #include "libtorrent/resolver_interface.hpp"
 #include "libtorrent/address.hpp"
-#include "libtorrent/time.hpp"
 
 namespace libtorrent
 {
@@ -59,6 +58,8 @@ struct TORRENT_EXTRA_EXPORT resolver final : resolver_interface
 
 	virtual void abort() override;
 
+	virtual void set_cache_timeout(seconds timeout) override;
+
 private:
 
 	void on_lookup(error_code const& ec, tcp::resolver::iterator i

include/libtorrent/resolver_interface.hpp

@@ -38,6 +38,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include "libtorrent/error_code.hpp"
 #include "libtorrent/address.hpp"
+#include "libtorrent/time.hpp"
 
 namespace libtorrent
 {
@@ -62,6 +63,9 @@ struct TORRENT_EXTRA_EXPORT resolver_interface
 		, callback_t const& h) = 0;
 
 	virtual void abort() = 0;
+
+	virtual void set_cache_timeout(seconds timeout) = 0;
+
 protected:
 	~resolver_interface() {}
 };

include/libtorrent/settings_pack.hpp

@@ -1632,6 +1632,11 @@ namespace libtorrent
 			// given time.
 			max_web_seed_connections,
 
+			// the number of seconds before the internal host name resolver
+			// considers a cache value timed out, negative values are interpreted
+			// as zero.
+			resolver_cache_timeout,
+
 			max_int_setting_internal
 		};
 

src/resolver.cpp

@@ -132,4 +132,12 @@ namespace libtorrent
 	{
 		m_resolver.cancel();
 	}
+
+	void resolver::set_cache_timeout(seconds timeout)
+	{
+		if (timeout >= seconds(0))
+			m_timeout = timeout;
+		else
+			m_timeout = seconds(0);
+	}
 }

src/session_impl.cpp

@@ -625,6 +625,7 @@ namespace aux {
 		update_connections_limit();
 		update_unchoke_limit();
 		update_disk_threads();
+		update_resolver_cache_timeout();
 		update_upnp();
 		update_natpmp();
 		update_lsd();
@@ -5087,6 +5088,12 @@ namespace aux {
 		m_close_file_timer.async_wait(make_tick_handler(std::bind(&session_impl::on_close_file, this, _1)));
 	}
 
+	void session_impl::update_resolver_cache_timeout()
+	{
+		int const timeout = m_settings.get_int(settings_pack::resolver_cache_timeout);
+		m_host_resolver.set_cache_timeout(seconds(timeout));
+	}
+
 	void session_impl::update_proxy()
 	{
 		for (auto& i : m_listen_sockets)

src/settings_pack.cpp

@@ -335,6 +335,7 @@ namespace libtorrent
 		SET(web_seed_name_lookup_retry, 1800, nullptr),
 		SET(close_file_interval, CLOSE_FILE_INTERVAL, &session_impl::update_close_file_interval),
 		SET(max_web_seed_connections, 3, nullptr),
+		SET(resolver_cache_timeout, 1200, &session_impl::update_resolver_cache_timeout),
 	}});
 
 #undef SET

test/test_session.cpp

@@ -58,6 +58,7 @@ TORRENT_TEST(session)
 	settings_pack sett = settings();
 	sett.set_int(settings_pack::num_optimistic_unchoke_slots, 10);
 	sett.set_int(settings_pack::unchoke_slots_limit, 10);
+	sett.set_int(settings_pack::resolver_cache_timeout, 1000);
 
 	ses.apply_settings(sett);
 
@@ -90,6 +91,11 @@ TORRENT_TEST(session)
 	ses.apply_settings(sett);
 	TEST_CHECK(ses.get_settings().get_int(settings_pack::unchoke_slots_limit) == 8);
 
+	TEST_EQUAL(ses.get_settings().get_int(settings_pack::resolver_cache_timeout), 1000);
+	sett.set_int(settings_pack::resolver_cache_timeout, 1001);
+	ses.apply_settings(sett);
+	TEST_EQUAL(ses.get_settings().get_int(settings_pack::resolver_cache_timeout), 1001);
+
 	// make sure the destructor waits properly
 	// for the asynchronous call to set the alert
 	// mask completes, before it goes on to destruct

test/test_settings_pack.cpp

@@ -253,5 +253,7 @@ TORRENT_TEST(settings_pack_abi)
 	TEST_EQUAL(settings_pack::aio_threads, settings_pack::int_type_base + 104);
 	TEST_EQUAL(settings_pack::max_http_recv_buffer_size, settings_pack::int_type_base + 115);
 	TEST_EQUAL(settings_pack::web_seed_name_lookup_retry, settings_pack::int_type_base + 128);
+	TEST_EQUAL(settings_pack::close_file_interval, settings_pack::int_type_base + 129);
+	TEST_EQUAL(settings_pack::max_web_seed_connections, settings_pack::int_type_base + 130);
+	TEST_EQUAL(settings_pack::resolver_cache_timeout, settings_pack::int_type_base + 131);
 }
-