fix support for auto disk cache size and disk buffer pool allocator behavior

examples/client_test.cpp

@@ -1451,8 +1451,8 @@ int main(int argc, char* argv[])
 #endif // TORRENT_USE_I2P
 			case 'C':
 				settings.set_int(settings_pack::cache_size, atoi(arg));
-				settings.set_bool(settings_pack::use_read_cache, atoi(arg) > 0);
+				settings.set_bool(settings_pack::use_read_cache, atoi(arg) != 0);
-				settings.set_int(settings_pack::cache_buffer_chunk_size, atoi(arg) / 100);
+				settings.set_int(settings_pack::cache_buffer_chunk_size, 0);
 				break;
 			case 'A': settings.set_int(settings_pack::allowed_fast_set_size, atoi(arg)); break;
 			case 'R': settings.set_int(settings_pack::read_cache_line_size, atoi(arg)); break;

simulation/test_swarm.cpp

@@ -97,7 +97,7 @@ TORRENT_TEST(session_stats)
 		// on alert
 		, [=](lt::alert const* a, lt::session& ses)
 		{
-			lt::session_stats_alert const* ss = lt::alert_cast<session_stats_alert>(a);
+			auto const* ss = lt::alert_cast<session_stats_alert>(a);
 			if (!ss) return;
 
 			// there's one downloading torrent

simulation/test_transfer.cpp

@@ -35,6 +35,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "create_torrent.hpp"
 #include "settings.hpp"
 #include "libtorrent/session.hpp"
+#include "libtorrent/session_stats.hpp"
 #include "libtorrent/deadline_timer.hpp"
 #include "libtorrent/settings_pack.hpp"
 #include "libtorrent/ip_filter.hpp"
@@ -194,6 +195,39 @@ void filter_ips(lt::session& ses)
 	ses.set_ip_filter(filter);
 }
 
+void set_cache_size(lt::session& ses, int val)
+{
+	using namespace libtorrent;
+	settings_pack pack;
+	pack.set_int(settings_pack::cache_size, val);
+	ses.apply_settings(pack);
+}
+
+int get_cache_size(lt::session& ses)
+{
+	using namespace libtorrent;
+	std::vector<stats_metric> stats = session_stats_metrics();
+	int const read_cache_idx = find_metric_idx("disk.read_cache_blocks");
+	int const write_cache_idx = find_metric_idx("disk.write_cache_blocks");
+	TEST_CHECK(read_cache_idx >= 0);
+	TEST_CHECK(write_cache_idx >= 0);
+	ses.set_alert_notify([](){});
+	ses.post_session_stats();
+	std::vector<alert*> alerts;
+	ses.pop_alerts(&alerts);
+	int cache_size = -1;
+	for (auto const a : alerts)
+	{
+		if (auto const* st = alert_cast<session_stats_alert>(a))
+		{
+			cache_size = st->values[read_cache_idx];
+			cache_size += st->values[write_cache_idx];
+			break;
+		}
+	}
+	return cache_size;
+}
+
 void set_proxy(lt::session& ses, int proxy_type, int flags = 0, bool proxy_peer_connections = true)
 {
 	// apply the proxy settings to session 0
@@ -391,3 +425,19 @@ TORRENT_TEST(no_proxy_utp_banned)
 	);
 }
 
+TORRENT_TEST(auto_disk_cache_size)
+{
+	using namespace libtorrent;
+	run_test(
+		[](lt::session& ses0, lt::session& ses1) { set_cache_size(ses0, -1); },
+		[](lt::session& ses, lt::alert const* alert) {},
+		[](std::shared_ptr<lt::session> ses[2]) {
+			TEST_EQUAL(is_seed(*ses[0]), true);
+
+			int const cache_size = get_cache_size(*ses[0]);
+			printf("cache size: %d\n", cache_size);
+			// this assumes the test torrent is at least 4 blocks
+			TEST_CHECK(cache_size > 4);
+		}
+	);
+}

src/disk_buffer_pool.cpp

@@ -371,11 +371,14 @@ namespace libtorrent
 #else
 			if (m_using_pool_allocator)
 			{
-				ret = static_cast<char*>(m_pool.malloc());
+				int const effective_block_size
-				int effective_block_size = m_cache_buffer_chunk_size
+					= m_in_use >= m_max_use
+					? 20 // use small increments once we've exceeded the cache size
+					: m_cache_buffer_chunk_size
 					? m_cache_buffer_chunk_size
 					: (std::max)(m_max_use / 10, 1);
 				m_pool.set_next_size(effective_block_size);
+				ret = static_cast<char*>(m_pool.malloc());
 			}
 			else
 			{
@@ -453,7 +456,9 @@ namespace libtorrent
 		m_cache_buffer_chunk_size = sett.get_int(settings_pack::cache_buffer_chunk_size);
 		m_lock_disk_cache = sett.get_bool(settings_pack::lock_disk_cache);
 #ifndef TORRENT_DISABLE_POOL_ALLOCATOR
-		m_want_pool_allocator = sett.get_bool(settings_pack::use_disk_cache_pool);
+		// if the chunk size is set to 1, there's no point in creating a pool
+		m_want_pool_allocator = sett.get_bool(settings_pack::use_disk_cache_pool)
+			&& (m_cache_buffer_chunk_size != 1);
 		// if there are no allocated blocks, it's OK to switch allocator
 		if (m_in_use == 0)
 			m_using_pool_allocator = m_want_pool_allocator;
@@ -476,7 +481,7 @@ namespace libtorrent
 			int const cache_size = sett.get_int(settings_pack::cache_size);
 			if (cache_size < 0)
 			{
-				boost::uint64_t phys_ram = total_physical_ram();
+				boost::uint64_t const phys_ram = total_physical_ram();
 				if (phys_ram == 0) m_max_use = 1024;
 				else m_max_use = phys_ram / 8 / m_block_size;
 
@@ -500,6 +505,8 @@ namespace libtorrent
 				m_exceeded_max_size = true;
 				m_trigger_cache_trim();
 			}
+			if (m_cache_buffer_chunk_size > m_max_use)
+				m_cache_buffer_chunk_size = m_max_use;
 		}
 
 #if TORRENT_USE_ASSERTS

src/disk_io_thread.cpp

@@ -1188,7 +1188,7 @@ namespace libtorrent
 
 	int disk_io_thread::do_read(disk_io_job* j, jobqueue_t& completed_jobs)
 	{
-		if (!m_settings.get_bool(settings_pack::use_read_cache)
+		if (m_settings.get_bool(settings_pack::use_read_cache) == false
 			|| m_settings.get_int(settings_pack::cache_size) == 0)
 		{
 			// we're not using a cache. This is the simple path
@@ -1462,7 +1462,7 @@ namespace libtorrent
 		// should we put this write job in the cache?
 		// if we don't use the cache we shouldn't.
 		if (m_settings.get_bool(settings_pack::use_write_cache)
-				&& m_settings.get_int(settings_pack::cache_size) > 0)
+			&& m_settings.get_int(settings_pack::cache_size) != 0)
 		{
 			mutex::scoped_lock l(m_cache_mutex);
 
@@ -1578,7 +1578,7 @@ namespace libtorrent
 		TORRENT_ASSERT(j->action == disk_io_job::read);
 
 		if (m_settings.get_bool(settings_pack::use_read_cache)
-			&& m_settings.get_int(settings_pack::cache_size) > 0)
+			&& m_settings.get_int(settings_pack::cache_size) != 0)
 		{
 			int ret = m_disk_cache.try_read(j);
 			if (ret >= 0)
@@ -1691,7 +1691,7 @@ namespace libtorrent
 		TORRENT_ASSERT(m_disk_cache.is_disk_buffer(j->buffer.disk_block));
 		l_.unlock();
 #endif
-		if (m_settings.get_int(settings_pack::cache_size) > 0
+		if (m_settings.get_int(settings_pack::cache_size) != 0
 			&& m_settings.get_bool(settings_pack::use_write_cache))
 		{
 			TORRENT_ASSERT((r.start % m_disk_cache.block_size()) == 0);
@@ -2327,7 +2327,7 @@ namespace libtorrent
 			}
 		}
 
-		if (pe == NULL && !m_settings.get_bool(settings_pack::use_read_cache))
+		if (pe == NULL && m_settings.get_bool(settings_pack::use_read_cache) == false)
 		{
 			l.unlock();
 			// if there's no piece in the cache, and the read cache is disabled
@@ -3463,7 +3463,7 @@ namespace libtorrent
 
 				if (j->action == disk_io_job::read
 					&& m_settings.get_bool(settings_pack::use_read_cache)
-					&& m_settings.get_int(settings_pack::cache_size) > 0)
+					&& m_settings.get_int(settings_pack::cache_size) != 0)
 				{
 					int state = prep_read_job_impl(j, false);
 					switch (state)