Allow disabling of OS cache. This will prevent RAM increases on Windows when seeding many files. Closes #1699.

src/preferences/advancedsettings.h

@@ -13,7 +13,7 @@
 #include "preferences.h"
 
 enum AdvSettingsCols {PROPERTY, VALUE};
-enum AdvSettingsRows {DISK_CACHE, DISK_CACHE_TTL, OUTGOING_PORT_MIN, OUTGOING_PORT_MAX, IGNORE_LIMIT_LAN, RECHECK_COMPLETED, LIST_REFRESH, RESOLVE_COUNTRIES, RESOLVE_HOSTS, MAX_HALF_OPEN, SUPER_SEEDING, NETWORK_IFACE, NETWORK_ADDRESS, PROGRAM_NOTIFICATIONS, TRACKER_STATUS, TRACKER_PORT,
+enum AdvSettingsRows {DISK_CACHE, DISK_CACHE_TTL, OS_CACHE, OUTGOING_PORT_MIN, OUTGOING_PORT_MAX, IGNORE_LIMIT_LAN, RECHECK_COMPLETED, LIST_REFRESH, RESOLVE_COUNTRIES, RESOLVE_HOSTS, MAX_HALF_OPEN, SUPER_SEEDING, NETWORK_IFACE, NETWORK_ADDRESS, PROGRAM_NOTIFICATIONS, TRACKER_STATUS, TRACKER_PORT,
                     #if defined(Q_OS_WIN) || defined(Q_OS_MAC)
                       UPDATE_CHECK,
                     #endif
@@ -29,7 +29,7 @@ class AdvancedSettings: public QTableWidget {
 
 private:
   QSpinBox spin_cache, outgoing_ports_min, outgoing_ports_max, spin_list_refresh, spin_maxhalfopen, spin_tracker_port;
-  QCheckBox cb_ignore_limits_lan, cb_recheck_completed, cb_resolve_countries, cb_resolve_hosts,
+  QCheckBox cb_os_cache, cb_ignore_limits_lan, cb_recheck_completed, cb_resolve_countries, cb_resolve_hosts,
   cb_super_seeding, cb_program_notifications, cb_tracker_status, cb_confirm_torrent_deletion,
   cb_enable_tracker_ext;
   QComboBox combo_iface;
@@ -71,6 +71,8 @@ public slots:
     // Disk write cache
     pref->setDiskCacheSize(spin_cache.value());
     pref->setDiskCacheTTL(spin_cache_ttl.value());
+    // Enable OS cache
+    pref->setOsCache(cb_os_cache.isChecked());
     // Outgoing ports
     pref->setOutgoingPortsMin(outgoing_ports_min.value());
     pref->setOutgoingPortsMax(outgoing_ports_max.value());
@@ -188,6 +190,9 @@ private slots:
     spin_cache_ttl.setValue(pref->diskCacheTTL());
     spin_cache_ttl.setSuffix(tr(" s", " seconds"));
     setRow(DISK_CACHE_TTL, tr("Disk cache expiry interval"), &spin_cache_ttl);
+    // Enable OS cache
+    cb_os_cache.setChecked(pref->osCache());
+    setRow(OS_CACHE, tr("Enable OS cache"), &cb_os_cache);
     // Outgoing port Min
     outgoing_ports_min.setMinimum(0);
     outgoing_ports_min.setMaximum(65535);

src/preferences/preferences.cpp

@@ -1139,6 +1139,14 @@ void Preferences::setDiskCacheTTL(uint ttl) {
   setValue("Preferences/Downloads/DiskWriteCacheTTL", ttl);
 }
 
+bool Preferences::osCache() const {
+  return value("Preferences/Advanced/osCache", true).toBool();
+}
+
+void Preferences::setOsCache(bool enable) {
+  setValue("Preferences/Advanced/osCache", enable);
+}
+
 uint Preferences::outgoingPortsMin() const {
   return value("Preferences/Advanced/OutgoingPortsMin", 0).toUInt();
 }

src/preferences/preferences.h

@@ -308,6 +308,8 @@ public:
   void setDiskCacheSize(uint size);
   uint diskCacheTTL() const;
   void setDiskCacheTTL(uint ttl);
+  bool osCache() const;
+  void setOsCache(bool enable);
   uint outgoingPortsMin() const;
   void setOutgoingPortsMin(uint val);
   uint outgoingPortsMax() const;

src/qtlibtorrent/qbtsession.cpp

@@ -411,6 +411,9 @@ void QBtSession::configureSession() {
   sessionSettings.cache_size = cache_size ? cache_size * 64 : -1;
   sessionSettings.cache_expiry = pref->diskCacheTTL();
   qDebug() << "Using a disk cache size of" << cache_size << "MiB";
+  session_settings::io_buffer_mode_t mode = pref->osCache() ? session_settings::enable_os_cache : session_settings::disable_os_cache;
+  sessionSettings.disk_io_read_mode = mode;
+  sessionSettings.disk_io_write_mode = mode;
   sessionSettings.anonymous_mode = pref->isAnonymousModeEnabled();
   if (sessionSettings.anonymous_mode) {
     addConsoleMessage(tr("Anonymous mode [ON]"), "blue");