Merge pull request #3391 from Abyss777/refactor_drivers_groups

Split Drivers and Groups management

14 files changed, 463 insertions, 414 deletions

diff --git a/src/org/traccar/database/AttributesManager.java b/src/org/traccar/database/AttributesManager.java
index 4dc70eeb7..28816645a 100644
--- a/src/org/traccar/database/AttributesManager.java
+++ b/src/org/traccar/database/AttributesManager.java
@@ -17,18 +17,16 @@
 package org.traccar.database;
 
 import org.traccar.model.Attribute;
-import org.traccar.model.BaseModel;
 
-public class AttributesManager extends ExtendedObjectManager {
+public class AttributesManager extends ExtendedObjectManager<Attribute> {
 
     public AttributesManager(DataManager dataManager) {
         super(dataManager, Attribute.class);
     }
 
     @Override
-    public void updateCachedItem(BaseModel item) {
-        Attribute attribute = (Attribute) item;
-        Attribute cachedAttribute = (Attribute) getById(item.getId());
+    public void updateCachedItem(Attribute attribute) {
+        Attribute cachedAttribute = getById(attribute.getId());
         cachedAttribute.setDescription(attribute.getDescription());
         cachedAttribute.setAttribute(attribute.getAttribute());
         cachedAttribute.setExpression(attribute.getExpression());
diff --git a/src/org/traccar/database/BaseObjectManager.java b/src/org/traccar/database/BaseObjectManager.java
new file mode 100644
index 000000000..cc1dbde5f
--- /dev/null
+++ b/src/org/traccar/database/BaseObjectManager.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2017 Anton Tananaev (anton@traccar.org)
+ * Copyright 2017 Andrey Kunitsyn (andrey@traccar.org)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.traccar.database;
+
+import java.sql.SQLException;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.traccar.helper.Log;
+import org.traccar.model.BaseModel;
+
+public class BaseObjectManager<T extends BaseModel> {
+
+    private final DataManager dataManager;
+
+    private Map<Long, T> items;
+    private Class<T> baseClass;
+
+    protected BaseObjectManager(DataManager dataManager, Class<T> baseClass) {
+        this.dataManager = dataManager;
+        this.baseClass = baseClass;
+        refreshItems();
+    }
+
+    protected final DataManager getDataManager() {
+        return dataManager;
+    }
+
+    protected final Class<T> getBaseClass() {
+        return baseClass;
+    }
+
+    public T getById(long itemId) {
+        return items.get(itemId);
+    }
+
+    public void refreshItems() {
+        if (dataManager != null) {
+            try {
+                Collection<T> databaseItems = dataManager.getObjects(baseClass);
+                if (items == null) {
+                    items = new ConcurrentHashMap<>(databaseItems.size());
+                }
+                Set<Long> databaseItemIds = new HashSet<>();
+                for (T item : databaseItems) {
+                    databaseItemIds.add(item.getId());
+                    if (items.containsKey(item.getId())) {
+                        updateCachedItem(item);
+                    } else {
+                        addNewItem(item);
+                    }
+                }
+                for (Long cachedItemId : items.keySet()) {
+                    if (!databaseItemIds.contains(cachedItemId)) {
+                        removeCachedItem(cachedItemId);
+                    }
+                }
+            } catch (SQLException error) {
+                Log.warning(error);
+            }
+        }
+    }
+
+    protected void addNewItem(T item) {
+        items.put(item.getId(), item);
+    }
+
+    public void addItem(T item) throws SQLException {
+        dataManager.addObject(item);
+        addNewItem(item);
+    }
+
+    protected void updateCachedItem(T item) {
+        items.put(item.getId(), item);
+    }
+
+    public void updateItem(T item) throws SQLException {
+        dataManager.updateObject(item);
+        updateCachedItem(item);
+    }
+
+    protected void removeCachedItem(long itemId) {
+        items.remove(itemId);
+    }
+
+    public void removeItem(long itemId) throws SQLException {
+        BaseModel item = getById(itemId);
+        if (item != null) {
+            dataManager.removeObject(baseClass, itemId);
+            removeCachedItem(itemId);
+        }
+    }
+
+    public final Collection<T> getItems(Set<Long> itemIds) {
+        Collection<T> result = new LinkedList<>();
+        for (long itemId : itemIds) {
+            result.add(getById(itemId));
+        }
+        return result;
+    }
+
+    public Set<Long> getAllItems() {
+        return items.keySet();
+    }
+
+}
diff --git a/src/org/traccar/database/CalendarManager.java b/src/org/traccar/database/CalendarManager.java
index 6874020ec..44ced1082 100644
--- a/src/org/traccar/database/CalendarManager.java
+++ b/src/org/traccar/database/CalendarManager.java
@@ -18,7 +18,7 @@ package org.traccar.database;
 
 import org.traccar.model.Calendar;
 
-public class CalendarManager extends SimpleObjectManager {
+public class CalendarManager extends SimpleObjectManager<Calendar> {
 
     public CalendarManager(DataManager dataManager) {
         super(dataManager, Calendar.class);
diff --git a/src/org/traccar/database/ConnectionManager.java b/src/org/traccar/database/ConnectionManager.java
index 0baafb578..1445fb785 100644
--- a/src/org/traccar/database/ConnectionManager.java
+++ b/src/org/traccar/database/ConnectionManager.java
@@ -70,7 +70,7 @@ public class ConnectionManager {
     }
 
     public void updateDevice(final long deviceId, String status, Date time) {
-        Device device = Context.getIdentityManager().getDeviceById(deviceId);
+        Device device = Context.getIdentityManager().getById(deviceId);
         if (device == null) {
             return;
         }
diff --git a/src/org/traccar/database/DeviceManager.java b/src/org/traccar/database/DeviceManager.java
index 995aa8ac3..4aafe6631 100644
--- a/src/org/traccar/database/DeviceManager.java
+++ b/src/org/traccar/database/DeviceManager.java
@@ -19,7 +19,6 @@ import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
-import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
@@ -39,125 +38,41 @@ import org.traccar.model.Group;
 import org.traccar.model.Position;
 import org.traccar.model.Server;
 
-public class DeviceManager implements IdentityManager {
+public class DeviceManager extends BaseObjectManager<Device> implements IdentityManager, ManagableObjects {
 
     public static final long DEFAULT_REFRESH_DELAY = 300;
 
     private final Config config;
-    private final DataManager dataManager;
     private final long dataRefreshDelay;
     private boolean lookupGroupsAttribute;
 
-    private Map<Long, Device> devicesById;
     private Map<String, Device> devicesByUniqueId;
     private Map<String, Device> devicesByPhone;
     private AtomicLong devicesLastUpdate = new AtomicLong();
 
-    private Map<Long, Group> groupsById;
-    private AtomicLong groupsLastUpdate = new AtomicLong();
-
     private final Map<Long, Position> positions = new ConcurrentHashMap<>();
 
     private boolean fallbackToText;
 
     public DeviceManager(DataManager dataManager) {
-        this.dataManager = dataManager;
+        super(dataManager, Device.class);
         this.config = Context.getConfig();
         dataRefreshDelay = config.getLong("database.refreshDelay", DEFAULT_REFRESH_DELAY) * 1000;
         lookupGroupsAttribute = config.getBoolean("deviceManager.lookupGroupsAttribute");
         fallbackToText = config.getBoolean("command.fallbackToSms");
-        if (dataManager != null) {
-            try {
-                updateGroupCache(true);
-                updateDeviceCache(true);
-                for (Position position : dataManager.getLatestPositions()) {
-                    positions.put(position.getDeviceId(), position);
-                }
-            } catch (SQLException error) {
-                Log.warning(error);
-            }
-        }
+        refreshLastPositions();
     }
 
     private void updateDeviceCache(boolean force) throws SQLException {
-
         long lastUpdate = devicesLastUpdate.get();
         if ((force || System.currentTimeMillis() - lastUpdate > dataRefreshDelay)
                 && devicesLastUpdate.compareAndSet(lastUpdate, System.currentTimeMillis())) {
-            GeofenceManager geofenceManager = Context.getGeofenceManager();
-            Collection<Device> databaseDevices = dataManager.getObjects(Device.class);
-            if (devicesById == null) {
-                devicesById = new ConcurrentHashMap<>(databaseDevices.size());
-            }
-            if (devicesByUniqueId == null) {
-                devicesByUniqueId = new ConcurrentHashMap<>(databaseDevices.size());
-            }
-            if (devicesByPhone == null) {
-                devicesByPhone = new ConcurrentHashMap<>(databaseDevices.size());
-            }
-            Set<Long> databaseDevicesIds = new HashSet<>();
-            Set<String> databaseDevicesUniqueIds = new HashSet<>();
-            Set<String> databaseDevicesPhones = new HashSet<>();
-            for (Device device : databaseDevices) {
-                databaseDevicesIds.add(device.getId());
-                databaseDevicesUniqueIds.add(device.getUniqueId());
-                databaseDevicesPhones.add(device.getPhone());
-                if (devicesById.containsKey(device.getId())) {
-                    Device cachedDevice = devicesById.get(device.getId());
-                    cachedDevice.setName(device.getName());
-                    cachedDevice.setGroupId(device.getGroupId());
-                    cachedDevice.setCategory(device.getCategory());
-                    cachedDevice.setContact(device.getContact());
-                    cachedDevice.setModel(device.getModel());
-                    cachedDevice.setAttributes(device.getAttributes());
-                    if (!device.getUniqueId().equals(cachedDevice.getUniqueId())) {
-                        devicesByUniqueId.put(device.getUniqueId(), cachedDevice);
-                    }
-                    cachedDevice.setUniqueId(device.getUniqueId());
-                    if (device.getPhone() != null && !device.getPhone().isEmpty()
-                            && !device.getPhone().equals(cachedDevice.getPhone())) {
-                        devicesByPhone.put(device.getPhone(), cachedDevice);
-                    }
-                    cachedDevice.setPhone(device.getPhone());
-                } else {
-                    devicesById.put(device.getId(), device);
-                    devicesByUniqueId.put(device.getUniqueId(), device);
-                    if (device.getPhone() != null && !device.getPhone().isEmpty()) {
-                        devicesByPhone.put(device.getPhone(), device);
-                    }
-                    if (geofenceManager != null) {
-                        Position lastPosition = getLastPosition(device.getId());
-                        if (lastPosition != null) {
-                            device.setGeofenceIds(geofenceManager.getCurrentDeviceGeofences(lastPosition));
-                        }
-                    }
-                }
-            }
-            for (Iterator<Long> iterator = devicesById.keySet().iterator(); iterator.hasNext();) {
-                if (!databaseDevicesIds.contains(iterator.next())) {
-                    iterator.remove();
-                }
-            }
-            for (Iterator<String> iterator = devicesByUniqueId.keySet().iterator(); iterator.hasNext();) {
-                if (!databaseDevicesUniqueIds.contains(iterator.next())) {
-                    iterator.remove();
-                }
-            }
-            for (Iterator<String> iterator = devicesByPhone.keySet().iterator(); iterator.hasNext();) {
-                if (!databaseDevicesPhones.contains(iterator.next())) {
-                    iterator.remove();
-                }
-            }
+            refreshItems();
         }
     }
 
     @Override
-    public Device getDeviceById(long id) {
-        return devicesById.get(id);
-    }
-
-    @Override
-    public Device getDeviceByUniqueId(String uniqueId) throws SQLException {
+    public Device getByUniqueId(String uniqueId) throws SQLException {
         boolean forceUpdate = !devicesByUniqueId.containsKey(uniqueId) && !config.getBoolean("database.ignoreUnknown");
 
         updateDeviceCache(forceUpdate);
@@ -169,76 +84,127 @@ public class DeviceManager implements IdentityManager {
         return devicesByPhone.get(phone);
     }
 
+    @Override
+    public Set<Long> getAllItems() {
+        Set<Long> result = super.getAllItems();
+        if (result.isEmpty()) {
+            try {
+                updateDeviceCache(true);
+            } catch (SQLException e) {
+                Log.warning(e);
+            }
+            result = super.getAllItems();
+        }
+        return result;
+    }
+
     public Collection<Device> getAllDevices() {
-        boolean forceUpdate = devicesById.isEmpty();
+        return getItems(getAllItems());
+    }
 
-        try {
-            updateDeviceCache(forceUpdate);
-        } catch (SQLException e) {
-            Log.warning(e);
+    @Override
+    public Set<Long> getUserItems(long userId) {
+        if (Context.getPermissionsManager() != null) {
+            return Context.getPermissionsManager().getDevicePermissions(userId);
+        } else {
+            return new HashSet<>();
         }
-
-        return devicesById.values();
     }
 
-    public Collection<Device> getDevices(long userId) throws SQLException {
-        Collection<Device> devices = new ArrayList<>();
-        for (long id : Context.getPermissionsManager().getDevicePermissions(userId)) {
-            devices.add(devicesById.get(id));
+    @Override
+    public Set<Long> getManagedItems(long userId) {
+        Set<Long> result = new HashSet<>();
+        result.addAll(getUserItems(userId));
+        for (long managedUserId : Context.getUsersManager().getUserItems(userId)) {
+            result.addAll(getUserItems(managedUserId));
         }
-        return devices;
+        return result;
     }
 
-    public Collection<Device> getManagedDevices(long userId) throws SQLException {
-        Collection<Device> devices = new HashSet<>();
-        devices.addAll(getDevices(userId));
-        for (long managedUserId : Context.getUsersManager().getManagedItems(userId)) {
-            devices.addAll(getDevices(managedUserId));
+    private void putUniqueDeviceId(Device device) {
+        if (devicesByUniqueId == null) {
+            devicesByUniqueId = new ConcurrentHashMap<>(getAllItems().size());
         }
-        return devices;
+        devicesByUniqueId.put(device.getUniqueId(), device);
     }
 
-    public void addDevice(Device device) throws SQLException {
-        dataManager.addObject(device);
+    private void putPhone(Device device) {
+        if (devicesByPhone == null) {
+            devicesByPhone = new ConcurrentHashMap<>(getAllItems().size());
+        }
+        devicesByPhone.put(device.getPhone(), device);
+    }
 
-        devicesById.put(device.getId(), device);
-        devicesByUniqueId.put(device.getUniqueId(), device);
+    @Override
+    protected void addNewItem(Device device) {
+        super.addNewItem(device);
+        putUniqueDeviceId(device);
         if (device.getPhone() != null  && !device.getPhone().isEmpty()) {
-            devicesByPhone.put(device.getPhone(), device);
+            putPhone(device);
+        }
+        if (Context.getGeofenceManager() != null) {
+            Position lastPosition = getLastPosition(device.getId());
+            if (lastPosition != null) {
+                device.setGeofenceIds(Context.getGeofenceManager().getCurrentDeviceGeofences(lastPosition));
+            }
         }
     }
 
-    public void updateDevice(Device device) throws SQLException {
-        dataManager.updateObject(device);
+    @Override
+    protected void updateCachedItem(Device device) {
+        Device cachedDevice = getById(device.getId());
+        cachedDevice.setName(device.getName());
+        cachedDevice.setGroupId(device.getGroupId());
+        cachedDevice.setCategory(device.getCategory());
+        cachedDevice.setContact(device.getContact());
+        cachedDevice.setModel(device.getModel());
+        cachedDevice.setAttributes(device.getAttributes());
+        if (!device.getUniqueId().equals(cachedDevice.getUniqueId())) {
+            devicesByUniqueId.remove(cachedDevice.getUniqueId());
+            cachedDevice.setUniqueId(device.getUniqueId());
+            putUniqueDeviceId(cachedDevice);
+        }
+        if (device.getPhone() != null && !device.getPhone().isEmpty()
+                && !device.getPhone().equals(cachedDevice.getPhone())) {
+            devicesByPhone.remove(cachedDevice.getPhone());
+            cachedDevice.setPhone(device.getPhone());
+            putPhone(cachedDevice);
+        }
+    }
 
-        devicesById.put(device.getId(), device);
-        devicesByUniqueId.put(device.getUniqueId(), device);
-        if (device.getPhone() != null && !device.getPhone().isEmpty()) {
-            devicesByPhone.put(device.getPhone(), device);
+    @Override
+    protected void removeCachedItem(long deviceId) {
+        Device cachedDevice = getById(deviceId);
+        if (cachedDevice != null) {
+            String deviceUniqueId = cachedDevice.getUniqueId();
+            String phone = cachedDevice.getPhone();
+            super.removeCachedItem(deviceId);
+            devicesByUniqueId.remove(deviceUniqueId);
+            if (phone != null && !phone.isEmpty()) {
+                devicesByPhone.remove(phone);
+            }
         }
+        positions.remove(deviceId);
     }
 
     public void updateDeviceStatus(Device device) throws SQLException {
-        dataManager.updateDeviceStatus(device);
-        if (devicesById.containsKey(device.getId())) {
-            Device cachedDevice = devicesById.get(device.getId());
+        getDataManager().updateDeviceStatus(device);
+        Device cachedDevice = getById(device.getId());
+        if (cachedDevice != null) {
             cachedDevice.setStatus(device.getStatus());
         }
     }
 
-    public void removeDevice(long deviceId) throws SQLException {
-        dataManager.removeObject(Device.class, deviceId);
-
-        if (devicesById.containsKey(deviceId)) {
-            String deviceUniqueId = devicesById.get(deviceId).getUniqueId();
-            String phone = devicesById.get(deviceId).getPhone();
-            devicesById.remove(deviceId);
-            devicesByUniqueId.remove(deviceUniqueId);
-            if (phone != null && !phone.isEmpty()) {
-                devicesByPhone.remove(phone);
+    private void refreshLastPositions() {
+        if (getDataManager() != null) {
+            try {
+                for (Position position : getDataManager().getLatestPositions()) {
+                    positions.put(position.getDeviceId(), position);
+                }
+            } catch (SQLException error) {
+                Log.warning(error);
             }
         }
-        positions.remove(deviceId);
     }
 
     public boolean isLatestPosition(Position position) {
@@ -250,10 +216,11 @@ public class DeviceManager implements IdentityManager {
 
         if (isLatestPosition(position)) {
 
-            dataManager.updateLatestPosition(position);
+            getDataManager().updateLatestPosition(position);
 
-            if (devicesById.containsKey(position.getDeviceId())) {
-                devicesById.get(position.getDeviceId()).setPositionId(position.getId());
+            Device device = getById(position.getDeviceId());
+            if (device != null) {
+                device.setPositionId(position.getId());
             }
 
             positions.put(position.getDeviceId(), position);
@@ -274,7 +241,7 @@ public class DeviceManager implements IdentityManager {
         List<Position> result = new LinkedList<>();
 
         if (Context.getPermissionsManager() != null) {
-            for (long deviceId : Context.getPermissionsManager().getDevicePermissions(userId)) {
+            for (long deviceId : getUserItems(userId)) {
                 if (positions.containsKey(deviceId)) {
                     result.add(positions.get(deviceId));
                 }
@@ -284,96 +251,6 @@ public class DeviceManager implements IdentityManager {
         return result;
     }
 
-    private void updateGroupCache(boolean force) throws SQLException {
-
-        long lastUpdate = groupsLastUpdate.get();
-        if ((force || System.currentTimeMillis() - lastUpdate > dataRefreshDelay)
-                && groupsLastUpdate.compareAndSet(lastUpdate, System.currentTimeMillis())) {
-            Collection<Group> databaseGroups = dataManager.getObjects(Group.class);
-            if (groupsById == null) {
-                groupsById = new ConcurrentHashMap<>(databaseGroups.size());
-            }
-            Set<Long> databaseGroupsIds = new HashSet<>();
-            for (Group group : databaseGroups) {
-                databaseGroupsIds.add(group.getId());
-                if (groupsById.containsKey(group.getId())) {
-                    Group cachedGroup = groupsById.get(group.getId());
-                    cachedGroup.setName(group.getName());
-                    cachedGroup.setGroupId(group.getGroupId());
-                } else {
-                    groupsById.put(group.getId(), group);
-                }
-            }
-            for (Long cachedGroupId : groupsById.keySet()) {
-                if (!databaseGroupsIds.contains(cachedGroupId)) {
-                    groupsById.remove(cachedGroupId);
-                }
-            }
-            databaseGroupsIds.clear();
-        }
-    }
-
-    public Group getGroupById(long id) {
-        return groupsById.get(id);
-    }
-
-    public Collection<Group> getAllGroups() {
-        boolean forceUpdate = groupsById.isEmpty();
-
-        try {
-            updateGroupCache(forceUpdate);
-        } catch (SQLException e) {
-            Log.warning(e);
-        }
-
-        return groupsById.values();
-    }
-
-    public Collection<Group> getGroups(long userId) throws SQLException {
-        Collection<Group> groups = new ArrayList<>();
-        for (long id : Context.getPermissionsManager().getGroupPermissions(userId)) {
-            groups.add(getGroupById(id));
-        }
-        return groups;
-    }
-
-    public Collection<Group> getManagedGroups(long userId) throws SQLException {
-        Collection<Group> groups = new ArrayList<>();
-        groups.addAll(getGroups(userId));
-        for (long managedUserId : Context.getUsersManager().getManagedItems(userId)) {
-            groups.addAll(getGroups(managedUserId));
-        }
-        return groups;
-    }
-
-    private void checkGroupCycles(Group group) {
-        Set<Long> groups = new HashSet<>();
-        while (group != null) {
-            if (groups.contains(group.getId())) {
-                throw new IllegalArgumentException("Cycle in group hierarchy");
-            }
-            groups.add(group.getId());
-            group = groupsById.get(group.getGroupId());
-        }
-    }
-
-    public void addGroup(Group group) throws SQLException {
-        checkGroupCycles(group);
-        dataManager.addObject(group);
-        groupsById.put(group.getId(), group);
-    }
-
-    public void updateGroup(Group group) throws SQLException {
-        checkGroupCycles(group);
-        dataManager.updateObject(group);
-        groupsById.put(group.getId(), group);
-    }
-
-    public void removeGroup(long groupId) throws SQLException {
-        dataManager.removeObject(Group.class, groupId);
-        groupsById.remove(groupId);
-    }
-
     public boolean lookupAttributeBoolean(
             long deviceId, String attributeName, boolean defaultValue, boolean lookupConfig) {
         String result = lookupAttribute(deviceId, attributeName, lookupConfig);
@@ -420,18 +297,19 @@ public class DeviceManager implements IdentityManager {
 
     private String lookupAttribute(long deviceId, String attributeName, boolean lookupConfig) {
         String result = null;
-        Device device = getDeviceById(deviceId);
+        Device device = getById(deviceId);
         if (device != null) {
             result = device.getString(attributeName);
             if (result == null && lookupGroupsAttribute) {
                 long groupId = device.getGroupId();
                 while (groupId != 0) {
-                    if (getGroupById(groupId) != null) {
-                        result = getGroupById(groupId).getString(attributeName);
+                    Group group = Context.getGroupsManager().getById(groupId);
+                    if (group != null) {
+                        result = group.getString(attributeName);
                         if (result != null) {
                             break;
                         }
-                        groupId = getGroupById(groupId).getGroupId();
+                        groupId = group.getGroupId();
                     } else {
                         groupId = 0;
                     }
@@ -453,7 +331,7 @@ public class DeviceManager implements IdentityManager {
         Position last = positions.get(deviceTotalDistance.getDeviceId());
         if (last != null) {
             last.getAttributes().put(Position.KEY_TOTAL_DISTANCE, deviceTotalDistance.getTotalDistance());
-            dataManager.addPosition(last);
+            getDataManager().addPosition(last);
             updateLatestPosition(last);
         } else {
             throw new IllegalArgumentException();
@@ -466,9 +344,9 @@ public class DeviceManager implements IdentityManager {
             Position lastPosition = getLastPosition(deviceId);
             if (lastPosition != null) {
                 BaseProtocol protocol = Context.getServerManager().getProtocol(lastPosition.getProtocol());
-                protocol.sendTextCommand(devicesById.get(deviceId).getPhone(), command);
+                protocol.sendTextCommand(getById(deviceId).getPhone(), command);
             } else if (command.getType().equals(Command.TYPE_CUSTOM)) {
-                Context.getSmppManager().sendMessageSync(devicesById.get(deviceId).getPhone(),
+                Context.getSmppManager().sendMessageSync(getById(deviceId).getPhone(),
                         command.getString(Command.KEY_DATA), true);
             } else {
                 throw new RuntimeException("Command " + command.getType() + " is not supported");
diff --git a/src/org/traccar/database/DriversManager.java b/src/org/traccar/database/DriversManager.java
index 14b74bab1..d3866a5f0 100644
--- a/src/org/traccar/database/DriversManager.java
+++ b/src/org/traccar/database/DriversManager.java
@@ -20,11 +20,10 @@ import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
 import org.traccar.model.Driver;
-import org.traccar.model.BaseModel;
 
-public class DriversManager extends ExtendedObjectManager {
+public class DriversManager extends ExtendedObjectManager<Driver> {
 
-    private Map<String, Driver> driversByUniqueId;
+    private Map<String, Long> driversByUniqueId;
 
     public DriversManager(DataManager dataManager) {
         super(dataManager, Driver.class);
@@ -32,21 +31,20 @@ public class DriversManager extends ExtendedObjectManager {
 
     private void putUniqueDriverId(Driver driver) {
         if (driversByUniqueId == null) {
-            driversByUniqueId = new ConcurrentHashMap<>();
+            driversByUniqueId = new ConcurrentHashMap<>(getAllItems().size());
         }
-        driversByUniqueId.put(driver.getUniqueId(), driver);
+        driversByUniqueId.put(driver.getUniqueId(), driver.getId());
     }
 
     @Override
-    protected void addNewItem(BaseModel item) {
-        super.addNewItem(item);
-        putUniqueDriverId((Driver) item);
+    protected void addNewItem(Driver driver) {
+        super.addNewItem(driver);
+        putUniqueDriverId(driver);
     }
 
     @Override
-    protected void updateCachedItem(BaseModel item) {
-        Driver driver = (Driver) item;
-        Driver cachedDriver = (Driver) getById(driver.getId());
+    protected void updateCachedItem(Driver driver) {
+        Driver cachedDriver = getById(driver.getId());
         cachedDriver.setName(driver.getName());
         if (!driver.getUniqueId().equals(cachedDriver.getUniqueId())) {
             driversByUniqueId.remove(cachedDriver.getUniqueId());
@@ -58,7 +56,7 @@ public class DriversManager extends ExtendedObjectManager {
 
     @Override
     protected void removeCachedItem(long driverId) {
-        Driver cachedDriver = (Driver) getById(driverId);
+        Driver cachedDriver = getById(driverId);
         if (cachedDriver != null) {
             String driverUniqueId = cachedDriver.getUniqueId();
             super.removeCachedItem(driverId);
@@ -67,6 +65,6 @@ public class DriversManager extends ExtendedObjectManager {
     }
 
     public Driver getDriverByUniqueId(String uniqueId) {
-        return driversByUniqueId.get(uniqueId);
+        return getById(driversByUniqueId.get(uniqueId));
     }
 }
diff --git a/src/org/traccar/database/ExtendedObjectManager.java b/src/org/traccar/database/ExtendedObjectManager.java
index 2833b3bae..16785cb37 100644
--- a/src/org/traccar/database/ExtendedObjectManager.java
+++ b/src/org/traccar/database/ExtendedObjectManager.java
@@ -30,13 +30,13 @@ import org.traccar.model.Group;
 import org.traccar.model.Permission;
 import org.traccar.model.BaseModel;
 
-public abstract class ExtendedObjectManager extends SimpleObjectManager {
+public abstract class ExtendedObjectManager<T extends BaseModel> extends SimpleObjectManager<T> {
 
     private final Map<Long, Set<Long>> deviceItems = new ConcurrentHashMap<>();
     private final Map<Long, Set<Long>> deviceItemsWithGroups = new ConcurrentHashMap<>();
     private final Map<Long, Set<Long>> groupItems = new ConcurrentHashMap<>();
 
-    protected ExtendedObjectManager(DataManager dataManager, Class<? extends BaseModel> baseClass) {
+    protected ExtendedObjectManager(DataManager dataManager, Class<T> baseClass) {
         super(dataManager, baseClass);
         refreshExtendedPermissions();
     }
@@ -48,10 +48,6 @@ public abstract class ExtendedObjectManager extends SimpleObjectManager {
         return groupItems.get(groupId);
     }
 
-    protected final void clearGroupItems() {
-        groupItems.clear();
-    }
-
     public final Set<Long> getDeviceItems(long deviceId) {
         if (!deviceItems.containsKey(deviceId)) {
             deviceItems.put(deviceId, new HashSet<Long>());
@@ -59,10 +55,6 @@ public abstract class ExtendedObjectManager extends SimpleObjectManager {
         return deviceItems.get(deviceId);
     }
 
-    protected final void clearDeviceItems() {
-        deviceItems.clear();
-    }
-
     public Set<Long> getAllDeviceItems(long deviceId) {
         if (!deviceItemsWithGroups.containsKey(deviceId)) {
             deviceItemsWithGroups.put(deviceId, new HashSet<Long>());
@@ -83,16 +75,15 @@ public abstract class ExtendedObjectManager extends SimpleObjectManager {
                 Collection<Permission> databaseGroupPermissions =
                         getDataManager().getPermissions(Group.class, getBaseClass());
 
-                clearGroupItems();
+                groupItems.clear();
                 for (Permission groupPermission : databaseGroupPermissions) {
                     getGroupItems(groupPermission.getOwnerId()).add(groupPermission.getPropertyId());
                 }
 
                 Collection<Permission> databaseDevicePermissions =
                         getDataManager().getPermissions(Device.class, getBaseClass());
-                Collection<Device> allDevices = Context.getDeviceManager().getAllDevices();
 
-                clearDeviceItems();
+                deviceItems.clear();
                 deviceItemsWithGroups.clear();
 
                 for (Permission devicePermission : databaseDevicePermissions) {
@@ -100,12 +91,13 @@ public abstract class ExtendedObjectManager extends SimpleObjectManager {
                     getAllDeviceItems(devicePermission.getOwnerId()).add(devicePermission.getPropertyId());
                 }
 
-                for (Device device : allDevices) {
+                for (Device device : Context.getDeviceManager().getAllDevices()) {
                     long groupId = device.getGroupId();
                     while (groupId != 0) {
                         getAllDeviceItems(device.getId()).addAll(getGroupItems(groupId));
-                        if (Context.getDeviceManager().getGroupById(groupId) != null) {
-                            groupId = Context.getDeviceManager().getGroupById(groupId).getGroupId();
+                        Group group = (Group) Context.getGroupsManager().getById(groupId);
+                        if (group != null) {
+                            groupId = group.getGroupId();
                         } else {
                             groupId = 0;
                         }
diff --git a/src/org/traccar/database/GeofenceManager.java b/src/org/traccar/database/GeofenceManager.java
index 2c3c32c56..a32847cf9 100644
--- a/src/org/traccar/database/GeofenceManager.java
+++ b/src/org/traccar/database/GeofenceManager.java
@@ -23,7 +23,7 @@ import org.traccar.model.Device;
 import org.traccar.model.Geofence;
 import org.traccar.model.Position;
 
-public class GeofenceManager extends ExtendedObjectManager {
+public class GeofenceManager extends ExtendedObjectManager<Geofence> {
 
     public GeofenceManager(DataManager dataManager) {
         super(dataManager, Geofence.class);
@@ -38,7 +38,7 @@ public class GeofenceManager extends ExtendedObjectManager {
     public List<Long> getCurrentDeviceGeofences(Position position) {
         List<Long> result = new ArrayList<>();
         for (long geofenceId : getAllDeviceItems(position.getDeviceId())) {
-            Geofence geofence = (Geofence) getById(geofenceId);
+            Geofence geofence = getById(geofenceId);
             if (geofence != null && geofence.getGeometry()
                     .containsPoint(position.getLatitude(), position.getLongitude())) {
                 result.add(geofenceId);
diff --git a/src/org/traccar/database/GroupsManager.java b/src/org/traccar/database/GroupsManager.java
new file mode 100644
index 000000000..c0456085b
--- /dev/null
+++ b/src/org/traccar/database/GroupsManager.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright 2017 Anton Tananaev (anton@traccar.org)
+ * Copyright 2017 Andrey Kunitsyn (andrey@traccar.org)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.traccar.database;
+
+import java.sql.SQLException;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.traccar.Context;
+import org.traccar.helper.Log;
+import org.traccar.model.Group;
+
+public class GroupsManager extends BaseObjectManager<Group> implements ManagableObjects {
+
+    private AtomicLong groupsLastUpdate = new AtomicLong();
+    private final long dataRefreshDelay;
+
+    public GroupsManager(DataManager dataManager) {
+        super(dataManager, Group.class);
+        dataRefreshDelay = Context.getConfig().getLong("database.refreshDelay",
+                DeviceManager.DEFAULT_REFRESH_DELAY) * 1000;
+    }
+
+    private void checkGroupCycles(Group group) {
+        Set<Long> groups = new HashSet<>();
+        while (group != null) {
+            if (groups.contains(group.getId())) {
+                throw new IllegalArgumentException("Cycle in group hierarchy");
+            }
+            groups.add(group.getId());
+            group = getById(group.getGroupId());
+        }
+    }
+
+    private void updateGroupCache(boolean force) throws SQLException {
+        long lastUpdate = groupsLastUpdate.get();
+        if ((force || System.currentTimeMillis() - lastUpdate > dataRefreshDelay)
+                && groupsLastUpdate.compareAndSet(lastUpdate, System.currentTimeMillis())) {
+            refreshItems();
+        }
+    }
+
+    @Override
+    public Set<Long> getAllItems() {
+        Set<Long> result = super.getAllItems();
+        if (result.isEmpty()) {
+            try {
+                updateGroupCache(true);
+            } catch (SQLException e) {
+                Log.warning(e);
+            }
+            result = super.getAllItems();
+        }
+        return result;
+    }
+
+    @Override
+    protected void addNewItem(Group group) {
+        checkGroupCycles(group);
+        super.addNewItem(group);
+    }
+
+    @Override
+    protected void updateCachedItem(Group group) {
+        checkGroupCycles(group);
+        super.updateCachedItem(group);
+    }
+
+    @Override
+    public Set<Long> getUserItems(long userId) {
+        if (Context.getPermissionsManager() != null) {
+            return Context.getPermissionsManager().getGroupPermissions(userId);
+        } else {
+            return new HashSet<>();
+        }
+    }
+
+    @Override
+    public Set<Long> getManagedItems(long userId) {
+        Set<Long> result = new HashSet<>();
+        result.addAll(getUserItems(userId));
+        for (long managedUserId : Context.getUsersManager().getUserItems(userId)) {
+            result.addAll(getUserItems(managedUserId));
+        }
+        return result;
+    }
+
+}
diff --git a/src/org/traccar/database/IdentityManager.java b/src/org/traccar/database/IdentityManager.java
index c8c593a54..82d905963 100644
--- a/src/org/traccar/database/IdentityManager.java
+++ b/src/org/traccar/database/IdentityManager.java
@@ -20,9 +20,9 @@ import org.traccar.model.Position;
 
 public interface IdentityManager {
 
-    Device getDeviceById(long id);
+    Device getById(long id);
 
-    Device getDeviceByUniqueId(String uniqueId) throws Exception;
+    Device getByUniqueId(String uniqueId) throws Exception;
 
     Position getLastPosition(long deviceId);
 
diff --git a/src/org/traccar/database/ManagableObjects.java b/src/org/traccar/database/ManagableObjects.java
new file mode 100644
index 000000000..ec9549493
--- /dev/null
+++ b/src/org/traccar/database/ManagableObjects.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2017 Anton Tananaev (anton@traccar.org)
+ * Copyright 2017 Andrey Kunitsyn (andrey@traccar.org)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.traccar.database;
+
+import java.util.Set;
+
+public interface ManagableObjects {
+
+    Set<Long> getUserItems(long userId);
+
+    Set<Long> getManagedItems(long userId);
+
+}
diff --git a/src/org/traccar/database/PermissionsManager.java b/src/org/traccar/database/PermissionsManager.java
index b38ecf9bf..3b03c1900 100644
--- a/src/org/traccar/database/PermissionsManager.java
+++ b/src/org/traccar/database/PermissionsManager.java
@@ -18,6 +18,7 @@ package org.traccar.database;
 import org.traccar.Context;
 import org.traccar.helper.Log;
 import org.traccar.model.Attribute;
+import org.traccar.model.BaseModel;
 import org.traccar.model.Calendar;
 import org.traccar.model.Device;
 import org.traccar.model.Driver;
@@ -51,7 +52,7 @@ public class PermissionsManager {
         this.dataManager = dataManager;
         this.usersManager = usersManager;
         refreshServer();
-        refreshPermissions();
+        refreshDeviceAndGroupPermissions();
     }
 
     public User getUser(long userId) {
@@ -94,11 +95,12 @@ public class PermissionsManager {
         }
     }
 
-    public final void refreshPermissions() {
+    public final void refreshDeviceAndGroupPermissions() {
         groupPermissions.clear();
         devicePermissions.clear();
         try {
-            GroupTree groupTree = new GroupTree(Context.getDeviceManager().getAllGroups(),
+            GroupTree groupTree = new GroupTree(Context.getGroupsManager().getItems(
+                    Context.getGroupsManager().getAllItems()),
                     Context.getDeviceManager().getAllDevices());
             for (Permission groupPermission : dataManager.getPermissions(User.class, Group.class)) {
                 Set<Long> userGroupPermissions = getGroupPermissions(groupPermission.getOwnerId());
@@ -117,9 +119,9 @@ public class PermissionsManager {
             }
 
             groupDevices.clear();
-            for (Group group : Context.getDeviceManager().getAllGroups()) {
-                for (Device device : groupTree.getDevices(group.getId())) {
-                    getGroupDevices(group.getId()).add(device.getId());
+            for (long groupId : Context.getGroupsManager().getAllItems()) {
+                for (Device device : groupTree.getDevices(groupId)) {
+                    getGroupDevices(groupId).add(device.getId());
                 }
             }
 
@@ -159,14 +161,14 @@ public class PermissionsManager {
 
     public void checkManager(long userId, long managedUserId) throws SecurityException {
         checkManager(userId);
-        if (!usersManager.getManagedItems(userId).contains(managedUserId)) {
+        if (!usersManager.getUserItems(userId).contains(managedUserId)) {
             throw new SecurityException("User access denied");
         }
     }
 
     public void checkUserLimit(long userId) throws SecurityException {
         int userLimit = getUser(userId).getUserLimit();
-        if (userLimit != -1 && usersManager.getManagedItems(userId).size() >= userLimit) {
+        if (userLimit != -1 && usersManager.getUserItems(userId).size() >= userLimit) {
             throw new SecurityException("Manager user limit reached");
         }
     }
@@ -176,9 +178,9 @@ public class PermissionsManager {
         if (deviceLimit != -1) {
             int deviceCount = 0;
             if (isManager(userId)) {
-                deviceCount = Context.getDeviceManager().getManagedDevices(userId).size();
+                deviceCount = Context.getDeviceManager().getManagedItems(userId).size();
             } else {
-                deviceCount = getDevicePermissions(userId).size();
+                deviceCount = Context.getDeviceManager().getUserItems(userId).size();
             }
             if (deviceCount >= deviceLimit) {
                 throw new SecurityException("User device limit reached");
@@ -254,7 +256,7 @@ public class PermissionsManager {
     public void checkGroup(long userId, long groupId) throws SecurityException {
         if (!getGroupPermissions(userId).contains(groupId) && !isAdmin(userId)) {
             checkManager(userId);
-            for (long managedUserId : usersManager.getManagedItems(userId)) {
+            for (long managedUserId : usersManager.getUserItems(userId)) {
                 if (getGroupPermissions(managedUserId).contains(groupId)) {
                     return;
                 }
@@ -264,10 +266,10 @@ public class PermissionsManager {
     }
 
     public void checkDevice(long userId, long deviceId) throws SecurityException {
-        if (!getDevicePermissions(userId).contains(deviceId) && !isAdmin(userId)) {
+        if (!Context.getDeviceManager().getUserItems(userId).contains(deviceId) && !isAdmin(userId)) {
             checkManager(userId);
-            for (long managedUserId : usersManager.getManagedItems(userId)) {
-                if (getDevicePermissions(managedUserId).contains(deviceId)) {
+            for (long managedUserId : usersManager.getUserItems(userId)) {
+                if (Context.getDeviceManager().getUserItems(managedUserId).contains(deviceId)) {
                     return;
                 }
             }
@@ -283,7 +285,7 @@ public class PermissionsManager {
 
     public void checkPermission(Class<?> object, long userId, long objectId)
             throws SecurityException {
-        SimpleObjectManager manager = null;
+        SimpleObjectManager<? extends BaseModel> manager = null;
 
         if (object.equals(Device.class)) {
             checkDevice(userId, objectId);
@@ -314,6 +316,18 @@ public class PermissionsManager {
         }
     }
 
+    public void refreshAllUsersPermissions() {
+        if (Context.getGeofenceManager() != null) {
+            Context.getGeofenceManager().refreshUserItems();
+        }
+        Context.getCalendarManager().refreshUserItems();
+        Context.getDriversManager().refreshUserItems();
+        Context.getAttributesManager().refreshUserItems();
+        if (Context.getNotificationManager() != null) {
+            Context.getNotificationManager().refresh();
+        }
+    }
+
     public void refreshAllExtendedPermissions() {
         if (Context.getGeofenceManager() != null) {
             Context.getGeofenceManager().refreshExtendedPermissions();
@@ -326,7 +340,7 @@ public class PermissionsManager {
         if (permission.getOwnerClass().equals(User.class)) {
             if (permission.getPropertyClass().equals(Device.class)
                     || permission.getPropertyClass().equals(Group.class)) {
-                refreshPermissions();
+                refreshDeviceAndGroupPermissions();
                 refreshAllExtendedPermissions();
             } else if (permission.getPropertyClass().equals(ManagedUser.class)) {
                 usersManager.refreshUserItems();
diff --git a/src/org/traccar/database/SimpleObjectManager.java b/src/org/traccar/database/SimpleObjectManager.java
index 124178a05..0b4d11378 100644
--- a/src/org/traccar/database/SimpleObjectManager.java
+++ b/src/org/traccar/database/SimpleObjectManager.java
@@ -17,9 +17,7 @@
 package org.traccar.database;
 
 import java.sql.SQLException;
-import java.util.Collection;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
@@ -30,43 +28,16 @@ import org.traccar.model.BaseModel;
 import org.traccar.model.Permission;
 import org.traccar.model.User;
 
-public abstract class SimpleObjectManager {
+public abstract class SimpleObjectManager<T extends BaseModel> extends BaseObjectManager<T>
+        implements ManagableObjects {
 
-    private final DataManager dataManager;
+    private Map<Long, Set<Long>> userItems;
 
-    private Map<Long, BaseModel> items;
-    private final Map<Long, Set<Long>> userItems = new ConcurrentHashMap<>();
-
-    private Class<? extends BaseModel> baseClass;
-    private String baseClassIdName;
-
-    protected SimpleObjectManager(DataManager dataManager, Class<? extends BaseModel> baseClass) {
-        this.dataManager = dataManager;
-        this.baseClass = baseClass;
-        baseClassIdName = DataManager.makeNameId(baseClass);
-        refreshItems();
-    }
-
-    protected final DataManager getDataManager() {
-        return dataManager;
-    }
-
-    protected final Class<? extends BaseModel> getBaseClass() {
-        return baseClass;
-    }
-
-    protected final String getBaseClassIdName() {
-        return baseClassIdName;
-    }
-
-    public final BaseModel getById(long itemId) {
-        return items.get(itemId);
-    }
-
-    protected final void clearItems() {
-        items.clear();
+    protected SimpleObjectManager(DataManager dataManager, Class<T> baseClass) {
+        super(dataManager, baseClass);
     }
 
+    @Override
     public final Set<Long> getUserItems(long userId) {
         if (!userItems.containsKey(userId)) {
             userItems.put(userId, new HashSet<Long>());
@@ -74,47 +45,35 @@ public abstract class SimpleObjectManager {
         return userItems.get(userId);
     }
 
-    protected final void clearUserItems() {
-        userItems.clear();
+    @Override
+    public Set<Long> getManagedItems(long userId) {
+        Set<Long> result = new HashSet<>();
+        result.addAll(getUserItems(userId));
+        for (long managedUserId : Context.getUsersManager().getUserItems(userId)) {
+            result.addAll(getUserItems(managedUserId));
+        }
+        return result;
     }
 
     public final boolean checkItemPermission(long userId, long itemId) {
         return getUserItems(userId).contains(itemId);
     }
 
+    @Override
     public void refreshItems() {
-        if (dataManager != null) {
-            try {
-                Collection<? extends BaseModel> databaseItems = dataManager.getObjects(baseClass);
-                if (items == null) {
-                    items = new ConcurrentHashMap<>(databaseItems.size());
-                }
-                Set<Long> databaseItemIds = new HashSet<>();
-                for (BaseModel item : databaseItems) {
-                    databaseItemIds.add(item.getId());
-                    if (items.containsKey(item.getId())) {
-                        updateCachedItem(item);
-                    } else {
-                        addNewItem(item);
-                    }
-                }
-                for (Long cachedItemId : items.keySet()) {
-                    if (!databaseItemIds.contains(cachedItemId)) {
-                        removeCachedItem(cachedItemId);
-                    }
-                }
-            } catch (SQLException error) {
-                Log.warning(error);
-            }
-        }
+        super.refreshItems();
         refreshUserItems();
     }
 
     public final void refreshUserItems() {
-        if (dataManager != null) {
+        if (getDataManager() != null) {
             try {
-                clearUserItems();
-                for (Permission permission : dataManager.getPermissions(User.class, baseClass)) {
+                if (userItems != null) {
+                    userItems.clear();
+                } else {
+                    userItems = new ConcurrentHashMap<>();
+                }
+                for (Permission permission : getDataManager().getPermissions(User.class, getBaseClass())) {
                     getUserItems(permission.getOwnerId()).add(permission.getPropertyId());
                 }
             } catch (SQLException | ClassNotFoundException error) {
@@ -123,56 +82,10 @@ public abstract class SimpleObjectManager {
         }
     }
 
-    protected void addNewItem(BaseModel item) {
-        items.put(item.getId(), item);
-    }
-
-    public void addItem(BaseModel item) throws SQLException {
-        dataManager.addObject(item);
-        addNewItem(item);
-    }
-
-    protected void updateCachedItem(BaseModel item) {
-        items.put(item.getId(), item);
-    }
-
-    public void updateItem(BaseModel item) throws SQLException {
-        dataManager.updateObject(item);
-        updateCachedItem(item);
-    }
-
-    protected void removeCachedItem(long itemId) {
-        items.remove(itemId);
-    }
-
+    @Override
     public void removeItem(long itemId) throws SQLException {
-        BaseModel item = getById(itemId);
-        if (item != null) {
-            dataManager.removeObject(baseClass, itemId);
-            removeCachedItem(itemId);
-        }
+        super.removeItem(itemId);
         refreshUserItems();
     }
 
-    public final <T> Collection<T> getItems(Class<T> clazz, Set<Long> itemIds) {
-        Collection<T> result = new LinkedList<>();
-        for (long itemId : itemIds) {
-            result.add((T) getById(itemId));
-        }
-        return result;
-    }
-
-    public final Set<Long> getAllItems() {
-        return items.keySet();
-    }
-
-    public Set<Long> getManagedItems(long userId) {
-        Set<Long> result = new HashSet<>();
-        result.addAll(getUserItems(userId));
-        for (long managedUserId : Context.getUsersManager().getManagedItems(userId)) {
-            result.addAll(getUserItems(managedUserId));
-        }
-        return result;
-    }
-
 }
diff --git a/src/org/traccar/database/UsersManager.java b/src/org/traccar/database/UsersManager.java
index 3c9c8b280..28e6a31b2 100644
--- a/src/org/traccar/database/UsersManager.java
+++ b/src/org/traccar/database/UsersManager.java
@@ -16,14 +16,14 @@
  */
 package org.traccar.database;
 
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
-import org.traccar.model.BaseModel;
 import org.traccar.model.User;
 
-public class UsersManager extends SimpleObjectManager {
+public class UsersManager extends SimpleObjectManager<User> {
 
     private Map<String, Long> usersTokens;
 
@@ -41,16 +41,15 @@ public class UsersManager extends SimpleObjectManager {
     }
 
     @Override
-    protected void addNewItem(BaseModel item) {
-        super.addNewItem(item);
-        putToken((User) item);
+    protected void addNewItem(User user) {
+        super.addNewItem(user);
+        putToken(user);
     }
 
     @Override
-    protected void updateCachedItem(BaseModel item) {
-        User user = (User) item;
-        User cachedUser = (User) getById(item.getId());
-        super.updateCachedItem(item);
+    protected void updateCachedItem(User user) {
+        User cachedUser = getById(user.getId());
+        super.updateCachedItem(user);
         if (user.getToken() != null) {
             usersTokens.put(user.getToken(), user.getId());
         }
@@ -61,7 +60,7 @@ public class UsersManager extends SimpleObjectManager {
 
     @Override
     protected void removeCachedItem(long userId) {
-        User cachedUser = (User) getById(userId);
+        User cachedUser = getById(userId);
         if (cachedUser != null) {
             String userToken = cachedUser.getToken();
             super.removeCachedItem(userId);
@@ -73,11 +72,14 @@ public class UsersManager extends SimpleObjectManager {
 
     @Override
     public Set<Long> getManagedItems(long userId) {
-        return getUserItems(userId);
+        Set<Long> result = new HashSet<>();
+        result.addAll(getUserItems(userId));
+        result.add(userId);
+        return result;
     }
 
     public User getUserByToken(String token) {
-        return (User) getById(usersTokens.get(token));
+        return getById(usersTokens.get(token));
     }
 
 }