Rewrite session code and add support for persistent sessions.

src/bukkit/java/com/sk89q/worldedit/bukkit/BukkitCommandSender.java

@@ -19,19 +19,27 @@
 
 package com.sk89q.worldedit.bukkit;
 
-import com.sk89q.worldedit.WorldEditPermissionException;
+import com.sk89q.worldedit.session.SessionKey;
+import com.sk89q.worldedit.util.auth.AuthorizationException;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.internal.cui.CUIEvent;
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
+import javax.annotation.Nullable;
 import java.io.File;
+import java.util.UUID;
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 public class BukkitCommandSender implements Actor {
 
+    /**
+     * One time generated ID.
+     */
+    private static final UUID DEFAULT_ID = UUID.fromString("a233eb4b-4cab-42cd-9fd9-7e7b9a3f74be");
+
     private CommandSender sender;
     private WorldEditPlugin plugin;
 
@@ -44,6 +52,11 @@ public class BukkitCommandSender implements Actor {
         this.sender = sender;
     }
 
+    @Override
+    public UUID getUniqueId() {
+        return DEFAULT_ID;
+    }
+
     @Override
     public String getName() {
         return sender.getName();
@@ -93,7 +106,7 @@ public class BukkitCommandSender implements Actor {
     }
 
     @Override
-    public void checkPermission(String permission) throws WorldEditPermissionException {
+    public void checkPermission(String permission) throws AuthorizationException {
     }
 
     @Override
@@ -115,4 +128,29 @@ public class BukkitCommandSender implements Actor {
     public void dispatchCUIEvent(CUIEvent event) {
     }
 
+    @Override
+    public SessionKey getSessionKey() {
+        return new SessionKey() {
+            @Nullable
+            @Override
+            public String getName() {
+                return null;
+            }
+
+            @Override
+            public boolean isActive() {
+                return false;
+            }
+
+            @Override
+            public boolean isPersistent() {
+                return false;
+            }
+
+            @Override
+            public UUID getUniqueId() {
+                return DEFAULT_ID;
+            }
+        };
+    }
 }

src/bukkit/java/com/sk89q/worldedit/bukkit/BukkitPlayer.java

@@ -30,14 +30,18 @@ import com.sk89q.worldedit.blocks.BaseBlock;
 import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.extent.inventory.BlockBag;
 import com.sk89q.worldedit.internal.cui.CUIEvent;
+import com.sk89q.worldedit.session.SessionKey;
+import org.bukkit.Bukkit;
 import org.bukkit.GameMode;
 import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 
 import javax.annotation.Nullable;
+import java.util.UUID;
 
 public class BukkitPlayer extends LocalPlayer {
+
     private Player player;
     private WorldEditPlugin plugin;
 
@@ -46,6 +50,11 @@ public class BukkitPlayer extends LocalPlayer {
         this.player = player;
     }
 
+    @Override
+    public UUID getUniqueId() {
+        return player.getUniqueId();
+    }
+
     @Override
     public int getItemInHand() {
         ItemStack itemStack = player.getItemInHand();
@@ -192,4 +201,48 @@ public class BukkitPlayer extends LocalPlayer {
     public <T> T getFacet(Class<? extends T> cls) {
         return null;
     }
+
+    @Override
+    public SessionKey getSessionKey() {
+        return new SessionKeyImpl(this.player.getUniqueId(), player.getName());
+    }
+
+    private static class SessionKeyImpl implements SessionKey {
+        // If not static, this will leak a reference
+
+        private final UUID uuid;
+        private final String name;
+
+        private SessionKeyImpl(UUID uuid, String name) {
+            this.uuid = uuid;
+            this.name = name;
+        }
+
+        @Override
+        public UUID getUniqueId() {
+            return uuid;
+        }
+
+        @Nullable
+        @Override
+        public String getName() {
+            return name;
+        }
+
+        @Override
+        public boolean isActive() {
+            // This is a thread safe call on CraftBukkit because it uses a
+            // CopyOnWrite list for the list of players, but the Bukkit
+            // specification doesn't require thread safety (though the
+            // spec is extremely incomplete)
+            return Bukkit.getServer().getPlayerExact(name) != null;
+        }
+
+        @Override
+        public boolean isPersistent() {
+            return true;
+        }
+
+    }
+
 }

src/bukkit/java/com/sk89q/worldedit/bukkit/WorldEditListener.java

@@ -37,7 +37,6 @@ import org.bukkit.event.block.Action;
 import org.bukkit.event.player.PlayerCommandPreprocessEvent;
 import org.bukkit.event.player.PlayerGameModeChangeEvent;
 import org.bukkit.event.player.PlayerInteractEvent;
-import org.bukkit.event.player.PlayerQuitEvent;
 
 /**
  * Handles all events thrown in relation to a Player
@@ -62,20 +61,6 @@ public class WorldEditListener implements Listener {
         this.plugin = plugin;
     }
 
-    /**
-     * Called when a player leaves a server
-     *
-     * @param event Relevant event details
-     */
-    @EventHandler
-    public void onPlayerQuit(PlayerQuitEvent event) {
-        if (!plugin.getInternalPlatform().isHookingEvents()) {
-            return;
-        }
-
-        plugin.getWorldEdit().markExpire(plugin.wrapPlayer(event.getPlayer()));
-    }
-
     @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
     public void onGamemode(PlayerGameModeChangeEvent event) {
         if (!plugin.getInternalPlatform().isHookingEvents()) {

src/bukkit/java/com/sk89q/worldedit/bukkit/WorldEditPlugin.java

@@ -110,9 +110,6 @@ public class WorldEditPlugin extends JavaPlugin implements TabCompleter {
         // Now we can register events
         getServer().getPluginManager().registerEvents(new WorldEditListener(this), this);
 
-        // Register session timer
-        getServer().getScheduler().runTaskTimerAsynchronously(this, new SessionTimer(worldEdit, getServer()), 120, 120);
-
         // If we are on MCPC+/Cauldron, then Forge will have already loaded
         // Forge WorldEdit and there's (probably) not going to be any other
         // platforms to be worried about... at the current time of writing

src/forge/java/com/sk89q/worldedit/forge/ForgePlayer.java

@@ -27,6 +27,7 @@ import com.sk89q.worldedit.extension.platform.AbstractPlayerActor;
 import com.sk89q.worldedit.extent.inventory.BlockBag;
 import com.sk89q.worldedit.internal.LocalWorldAdapter;
 import com.sk89q.worldedit.internal.cui.CUIEvent;
+import com.sk89q.worldedit.session.SessionKey;
 import com.sk89q.worldedit.util.Location;
 import net.minecraft.entity.player.EntityPlayerMP;
 import net.minecraft.item.ItemStack;
@@ -34,6 +35,7 @@ import net.minecraft.network.packet.Packet250CustomPayload;
 import net.minecraft.util.ChatMessageComponent;
 
 import javax.annotation.Nullable;
+import java.util.UUID;
 
 public class ForgePlayer extends AbstractPlayerActor {
 
@@ -41,13 +43,21 @@ public class ForgePlayer extends AbstractPlayerActor {
 
     protected ForgePlayer(EntityPlayerMP player) {
         this.player = player;
+        ThreadSafeCache.getInstance().getOnlineIds().add(getUniqueId());
     }
 
+    @Override
+    public UUID getUniqueId() {
+        return player.getUniqueID();
+    }
+
+    @Override
     public int getItemInHand() {
         ItemStack is = this.player.getCurrentEquippedItem();
         return is == null ? 0 : is.itemID;
     }
 
+    @Override
     public String getName() {
         return this.player.username;
     }
@@ -67,26 +77,32 @@ public class ForgePlayer extends AbstractPlayerActor {
                 this.player.cameraPitch);
     }
 
+    @Override
     public WorldVector getPosition() {
         return new WorldVector(LocalWorldAdapter.adapt(ForgeWorldEdit.inst.getWorld(this.player.worldObj)), this.player.posX, this.player.posY, this.player.posZ);
     }
 
+    @Override
     public com.sk89q.worldedit.world.World getWorld() {
         return ForgeWorldEdit.inst.getWorld(this.player.worldObj);
     }
 
+    @Override
     public double getPitch() {
         return this.player.rotationPitch;
     }
 
+    @Override
     public double getYaw() {
         return this.player.rotationYaw;
     }
 
+    @Override
     public void giveItem(int type, int amt) {
         this.player.inventory.addItemStackToInventory(new ItemStack(type, amt, 0));
     }
 
+    @Override
     public void dispatchCUIEvent(CUIEvent event) {
         String[] params = event.getParameters();
         String send = event.getTypeId();
@@ -97,42 +113,50 @@ public class ForgePlayer extends AbstractPlayerActor {
         this.player.playerNetServerHandler.sendPacketToPlayer(packet);
     }
 
+    @Override
     public void printRaw(String msg) {
         for (String part : msg.split("\n")) {
             this.player.sendChatToPlayer(ChatMessageComponent.createFromText(part));
         }
     }
 
+    @Override
     public void printDebug(String msg) {
         for (String part : msg.split("\n")) {
             this.player.sendChatToPlayer(ChatMessageComponent.createFromText("\u00a77" + part));
         }
     }
 
+    @Override
     public void print(String msg) {
         for (String part : msg.split("\n")) {
             this.player.sendChatToPlayer(ChatMessageComponent.createFromText("\u00a7d" + part));
         }
     }
 
+    @Override
     public void printError(String msg) {
         for (String part : msg.split("\n")) {
             this.player.sendChatToPlayer(ChatMessageComponent.createFromText("\u00a7c" + part));
         }
     }
 
+    @Override
     public void setPosition(Vector pos, float pitch, float yaw) {
         this.player.playerNetServerHandler.setPlayerLocation(pos.getX(), pos.getY(), pos.getZ(), pitch, yaw);
     }
 
+    @Override
     public String[] getGroups() {
         return new String[]{}; // WorldEditMod.inst.getPermissionsResolver().getGroups(this.player.username);
     }
 
+    @Override
     public BlockBag getInventoryBlockBag() {
         return null;
     }
 
+    @Override
     public boolean hasPermission(String perm) {
         return ForgeUtil.hasPermission(this.player, perm);
     }
@@ -143,4 +167,45 @@ public class ForgePlayer extends AbstractPlayerActor {
         return null;
     }
 
+    @Override
+    public SessionKey getSessionKey() {
+        return new SessionKeyImpl(player.getUniqueID(), player.username);
+    }
+
+    private static class SessionKeyImpl implements SessionKey {
+        // If not static, this will leak a reference
+
+        private final UUID uuid;
+        private final String name;
+
+        private SessionKeyImpl(UUID uuid, String name) {
+            this.uuid = uuid;
+            this.name = name;
+        }
+
+        @Override
+        public UUID getUniqueId() {
+            return uuid;
+        }
+
+        @Nullable
+        @Override
+        public String getName() {
+            return name;
+        }
+
+        @Override
+        public boolean isActive() {
+            // We can't directly check if the player is online because
+            // the list of players is not thread safe
+            return ThreadSafeCache.getInstance().getOnlineIds().contains(uuid);
+        }
+
+        @Override
+        public boolean isPersistent() {
+            return true;
+        }
+
+    }
+
 }

src/forge/java/com/sk89q/worldedit/forge/ForgeWorldEdit.java

@@ -32,8 +32,15 @@ import cpw.mods.fml.common.FMLLog;
 import cpw.mods.fml.common.Mod;
 import cpw.mods.fml.common.Mod.EventHandler;
 import cpw.mods.fml.common.Mod.Instance;
-import cpw.mods.fml.common.event.*;
+import cpw.mods.fml.common.event.FMLInitializationEvent;
+import cpw.mods.fml.common.event.FMLPostInitializationEvent;
+import cpw.mods.fml.common.event.FMLPreInitializationEvent;
+import cpw.mods.fml.common.event.FMLServerAboutToStartEvent;
+import cpw.mods.fml.common.event.FMLServerStartedEvent;
+import cpw.mods.fml.common.event.FMLServerStoppingEvent;
 import cpw.mods.fml.common.network.NetworkMod;
+import cpw.mods.fml.common.registry.TickRegistry;
+import cpw.mods.fml.relauncher.Side;
 import net.minecraft.entity.player.EntityPlayerMP;
 import net.minecraft.world.World;
 import net.minecraftforge.common.MinecraftForge;
@@ -84,6 +91,8 @@ public class ForgeWorldEdit {
 
         config = new ForgeConfiguration(this);
         config.load();
+
+        TickRegistry.registerTickHandler(ThreadSafeCache.getInstance(), Side.SERVER);
     }
 
     @EventHandler

src/forge/java/com/sk89q/worldedit/forge/ThreadSafeCache.java

@@ -0,0 +1,91 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.forge;
+
+import cpw.mods.fml.common.FMLCommonHandler;
+import cpw.mods.fml.common.ITickHandler;
+import cpw.mods.fml.common.TickType;
+import net.minecraft.entity.player.EntityPlayerMP;
+
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.CopyOnWriteArraySet;
+
+/**
+ * Caches data that cannot be accessed from another thread safely.
+ */
+class ThreadSafeCache implements ITickHandler {
+
+    private static final long REFRESH_DELAY = 1000 * 30;
+    private static final ThreadSafeCache INSTANCE = new ThreadSafeCache();
+    private Set<UUID> onlineIds = Collections.emptySet();
+    private long lastRefresh = 0;
+
+    /**
+     * Get an concurrent-safe set of UUIDs of online players.
+     *
+     * @return a set of UUIDs
+     */
+    public Set<UUID> getOnlineIds() {
+        return onlineIds;
+    }
+
+    @Override
+    public void tickStart(EnumSet<TickType> type, Object... tickData) {
+        long now = System.currentTimeMillis();
+
+        if (now - lastRefresh > REFRESH_DELAY) {
+            Set<UUID> onlineIds = new HashSet<UUID>();
+
+            for (Object object : FMLCommonHandler.instance().getMinecraftServerInstance().getConfigurationManager().playerEntityList) {
+                if (object != null) {
+                    EntityPlayerMP player = (EntityPlayerMP) object;
+                    onlineIds.add(player.getUniqueID());
+                }
+            }
+
+            this.onlineIds = new CopyOnWriteArraySet<UUID>(onlineIds);
+
+            lastRefresh = now;
+        }
+    }
+
+    @Override
+    public void tickEnd(EnumSet<TickType> type, Object... tickData) {
+    }
+
+    @Override
+    public EnumSet<TickType> ticks() {
+        return EnumSet.of(TickType.SERVER);
+    }
+
+    @Override
+    public String getLabel() {
+        return "WorldEdit Cache";
+    }
+
+    public static ThreadSafeCache getInstance() {
+        return INSTANCE;
+    }
+
+}

src/main/java/com/sk89q/worldedit/LocalSession.java

@@ -40,9 +40,6 @@ import com.sk89q.worldedit.regions.RegionSelector;
 import com.sk89q.worldedit.regions.selector.CuboidRegionSelector;
 import com.sk89q.worldedit.session.ClipboardHolder;
 import com.sk89q.worldedit.session.request.Request;
-import com.sk89q.worldedit.util.formatting.ColorCodeBuilder;
-import com.sk89q.worldedit.util.formatting.Style;
-import com.sk89q.worldedit.util.formatting.StyledFragment;
 import com.sk89q.worldedit.world.World;
 import com.sk89q.worldedit.world.snapshot.Snapshot;
 
@@ -52,57 +49,102 @@ import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.Map;
 import java.util.TimeZone;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
- * An instance of this represents the WorldEdit session of a user. A session
+ * Stores session information.
- * stores history and settings. Sessions are not tied particularly to any
- * player and can be shuffled between players, saved, and loaded.
- *
- * @author sk89q
  */
 public class LocalSession {
 
-    private static final boolean SHOW_HELP_MESSAGE = false;
+    public transient static int MAX_HISTORY_SIZE = 15;
 
-    public static int MAX_HISTORY_SIZE = 15;
+    // Non-session related fields
-    public static int EXPIRATION_GRACE = 600000;
+    private transient LocalConfiguration config;
+    private transient final AtomicBoolean dirty = new AtomicBoolean();
 
-    private LocalConfiguration config;
+    // Session related
+    private transient RegionSelector selector = new CuboidRegionSelector();
+    private transient boolean placeAtPos1 = false;
+    private transient LinkedList<EditSession> history = new LinkedList<EditSession>();
+    private transient int historyPointer = 0;
+    private transient ClipboardHolder clipboard;
+    private transient boolean toolControl = true;
+    private transient boolean superPickaxe = false;
+    private transient BlockTool pickaxeMode = new SinglePickaxe();
+    private transient Map<Integer, Tool> tools = new HashMap<Integer, Tool>();
+    private transient int maxBlocksChanged = -1;
+    private transient boolean useInventory;
+    private transient Snapshot snapshot;
+    private transient boolean hasCUISupport = false;
+    private transient int cuiVersion = -1;
+    private transient boolean fastMode = false;
+    private transient Mask mask;
+    private transient TimeZone timezone = TimeZone.getDefault();
 
-    private long expirationTime = System.currentTimeMillis() + EXPIRATION_GRACE;
+    // Saved properties
-    private RegionSelector selector = new CuboidRegionSelector();
-    private boolean placeAtPos1 = false;
-    private LinkedList<EditSession> history = new LinkedList<EditSession>();
-    private int historyPointer = 0;
-    private ClipboardHolder clipboard;
-    private boolean toolControl = true;
-    private boolean superPickaxe = false;
-    private BlockTool pickaxeMode = new SinglePickaxe();
-    private Map<Integer, Tool> tools = new HashMap<Integer, Tool>();
-    private int maxBlocksChanged = -1;
-    private boolean useInventory;
-    private Snapshot snapshot;
     private String lastScript;
-    private boolean beenToldVersion = false;
-    private boolean hasCUISupport = false;
-    private int cuiVersion = -1;
-    private boolean fastMode = false;
-    private Mask mask;
-    private TimeZone timezone = TimeZone.getDefault();
 
     /**
      * Construct the object.
      *
-     * @param config
+     * <p>{@link #setConfiguration(LocalConfiguration)} should be called
+     * later with configuration.</p>
      */
-    public LocalSession(LocalConfiguration config) {
+    public LocalSession() {
+    }
+
+    /**
+     * Construct the object.
+     *
+     * @param config the configuration
+     */
+    public LocalSession(@Nullable LocalConfiguration config) {
         this.config = config;
     }
 
+    /**
+     * Set the configuration.
+     *
+     * @param config the configuration
+     */
+    public void setConfiguration(LocalConfiguration config) {
+        checkNotNull(config);
+        this.config = config;
+    }
+
+    /**
+     * Get whether this session is "dirty" and has changes that needs to
+     * be committed.
+     *
+     * @return true if dirty
+     */
+    public boolean isDirty() {
+        return dirty.get();
+    }
+
+    /**
+     * Set this session as dirty.
+     */
+    private void setDirty() {
+        dirty.set(true);
+    }
+
+    /**
+     * Get whether this session is "dirty" and has changes that needs to
+     * be committed, and reset it to {@code false}.
+     *
+     * @return true if the dirty value was {@code true}
+     */
+    public boolean compareAndResetDirty() {
+        return dirty.compareAndSet(true, false);
+    }
+
     /**
      * Get the session's timezone.
      *
-     * @return
+     * @return the timezone
      */
     public TimeZone getTimeZone() {
         return timezone;
@@ -111,9 +153,10 @@ public class LocalSession {
     /**
      * Set the session's timezone.
      *
-     * @param timezone
+     * @param timezone the user's timezone
      */
     public void setTimezone(TimeZone timezone) {
+        checkNotNull(timezone);
         this.timezone = timezone;
     }
 
@@ -129,9 +172,11 @@ public class LocalSession {
      * Remember an edit session for the undo history. If the history maximum
      * size is reached, old edit sessions will be discarded.
      *
-     * @param editSession
+     * @param editSession the edit session
      */
     public void remember(EditSession editSession) {
+        checkNotNull(editSession);
+
         // Don't store anything if no changes were made
         if (editSession.size() == 0) return;
 
@@ -149,8 +194,8 @@ public class LocalSession {
     /**
      * Performs an undo.
      *
-     * @param newBlockBag
+     * @param newBlockBag a new block bag
-     * @param player
+     * @param player the player
      * @return whether anything was undone
      */
     public EditSession undo(BlockBag newBlockBag, LocalPlayer player) {
@@ -160,11 +205,13 @@ public class LocalSession {
     /**
      * Performs an undo.
      *
-     * @param newBlockBag
+     * @param newBlockBag a new block bag
-     * @param player
+     * @param player the player
      * @return whether anything was undone
      */
     public EditSession undo(BlockBag newBlockBag, Player player) {
+        checkNotNull(newBlockBag);
+        checkNotNull(player);
         --historyPointer;
         if (historyPointer >= 0) {
             EditSession editSession = history.get(historyPointer);
@@ -183,8 +230,8 @@ public class LocalSession {
     /**
      * Performs a redo
      *
-     * @param newBlockBag
+     * @param newBlockBag a new block bag
-     * @param player
+     * @param player the player
      * @return whether anything was redone
      */
     public EditSession redo(BlockBag newBlockBag, LocalPlayer player) {
@@ -194,11 +241,13 @@ public class LocalSession {
     /**
      * Performs a redo
      *
-     * @param newBlockBag
+     * @param newBlockBag a new block bag
-     * @param player
+     * @param player the player
      * @return whether anything was redone
      */
     public EditSession redo(BlockBag newBlockBag, Player player) {
+        checkNotNull(newBlockBag);
+        checkNotNull(player);
         if (historyPointer < history.size()) {
             EditSession editSession = history.get(historyPointer);
             EditSession newEditSession = WorldEdit.getInstance().getEditSessionFactory()
@@ -213,6 +262,9 @@ public class LocalSession {
         return null;
     }
 
+    /**
+     * @deprecated Use {@link #getRegionSelector(World)}
+     */
     @Deprecated
     public RegionSelector getRegionSelector(LocalWorld world) {
         return getRegionSelector((World) world);
@@ -222,10 +274,11 @@ public class LocalSession {
      * Get the region selector for defining the selection. If the selection
      * was defined for a different world, the old selection will be discarded.
      *
-     * @param world
+     * @param world the world
-     * @return position
+     * @return position the position
      */
     public RegionSelector getRegionSelector(World world) {
+        checkNotNull(world);
         if (selector.getIncompleteRegion().getWorld() == null) {
             selector = new CuboidRegionSelector(world);
         } else if (!selector.getIncompleteRegion().getWorld().equals(world)) {
@@ -236,16 +289,16 @@ public class LocalSession {
     }
 
     /**
-     * Get the region selector. This won't check worlds so make sure that
+     * @deprecated use {@link #getRegionSelector(World)}
-     * this region selector isn't used blindly.
-     *
-     * @return position
      */
     @Deprecated
     public RegionSelector getRegionSelector() {
         return selector;
     }
 
+    /**
+     * @deprecated use {@link #setRegionSelector(World, RegionSelector)}
+     */
     @Deprecated
     public void setRegionSelector(LocalWorld world, RegionSelector selector) {
         setRegionSelector((World) world, selector);
@@ -254,10 +307,12 @@ public class LocalSession {
     /**
      * Set the region selector.
      *
-     * @param world
+     * @param world the world
-     * @param selector
+     * @param selector the selector
      */
     public void setRegionSelector(World world, RegionSelector selector) {
+        checkNotNull(world);
+        checkNotNull(selector);
         selector.getIncompleteRegion().setWorld(world);
         this.selector = selector;
     }
@@ -265,13 +320,16 @@ public class LocalSession {
     /**
      * Returns true if the region is fully defined.
      *
-     * @return
+     * @return true if a region selection is defined
      */
     @Deprecated
     public boolean isRegionDefined() {
         return selector.isDefined();
     }
 
+    /**
+     * @deprecated use {@link #isSelectionDefined(World)}
+     */
     @Deprecated
     public boolean isSelectionDefined(LocalWorld world) {
         return isSelectionDefined((World) world);
@@ -280,10 +338,11 @@ public class LocalSession {
     /**
      * Returns true if the region is fully defined for the specified world.
      *
-     * @param world
+     * @param world the world
-     * @return
+     * @return true if a region selection is defined
      */
     public boolean isSelectionDefined(World world) {
+        checkNotNull(world);
         if (selector.getIncompleteRegion().getWorld() == null || !selector.getIncompleteRegion().getWorld().equals(world)) {
             return false;
         }
@@ -291,16 +350,16 @@ public class LocalSession {
     }
 
     /**
-     * Use <code>getSelection()</code>.
+     * @deprecated use {@link #getSelection(World)}
-     *
-     * @return region
-     * @throws IncompleteRegionException
      */
     @Deprecated
     public Region getRegion() throws IncompleteRegionException {
         return selector.getRegion();
     }
 
+    /**
+     * @deprecated use {@link #getSelection(World)}
+     */
     @Deprecated
     public Region getSelection(LocalWorld world) throws IncompleteRegionException {
         return getSelection((World) world);
@@ -309,14 +368,15 @@ public class LocalSession {
     /**
      * Get the selection region. If you change the region, you should
      * call learnRegionChanges().  If the selection is defined in
-     * a different world, the <code>IncompleteRegionException</code>
+     * a different world, the {@code IncompleteRegionException}
      * exception will be thrown.
      *
-     * @param world
+     * @param world the world
-     * @return region
+     * @return a region
-     * @throws IncompleteRegionException
+     * @throws IncompleteRegionException if no region is selected
      */
     public Region getSelection(World world) throws IncompleteRegionException {
+        checkNotNull(world);
         if (selector.getIncompleteRegion().getWorld() == null || !selector.getIncompleteRegion().getWorld().equals(world)) {
             throw new IncompleteRegionException();
         }
@@ -326,7 +386,7 @@ public class LocalSession {
     /**
      * Get the selection world.
      *
-     * @return
+     * @return the the world of the selection
      */
     public World getSelectionWorld() {
         return selector.getIncompleteRegion().getWorld();
@@ -335,7 +395,7 @@ public class LocalSession {
     /**
      * Gets the clipboard.
      *
-     * @return clipboard, may be null
+     * @return clipboard
      * @throws EmptyClipboardException thrown if no clipboard is set
      */
     public ClipboardHolder getClipboard() throws EmptyClipboardException {
@@ -368,7 +428,7 @@ public class LocalSession {
     /**
      * Change tool control setting.
      *
-     * @param toolControl
+     * @param toolControl true to enable tool control
      */
     public void setToolControl(boolean toolControl) {
         this.toolControl = toolControl;
@@ -386,7 +446,7 @@ public class LocalSession {
     /**
      * Set the maximum number of blocks that can be changed.
      *
-     * @param maxBlocksChanged
+     * @param maxBlocksChanged the maximum number of blocks changed
      */
     public void setBlockChangeLimit(int maxBlocksChanged) {
         this.maxBlocksChanged = maxBlocksChanged;
@@ -418,7 +478,7 @@ public class LocalSession {
     /**
      * Toggle the super pick axe.
      *
-     * @return status
+     * @return whether the super pick axe is now enabled
      */
     public boolean toggleSuperPickAxe() {
         superPickaxe = !superPickaxe;
@@ -426,13 +486,15 @@ public class LocalSession {
     }
 
     /**
-     * Get the placement position.
+     * Get the position use for commands that take a center point
+     * (i.e. //forestgen, etc.).
      *
-     * @param player
+     * @param player the player
-     * @return position
+     * @return the position to use
-     * @throws IncompleteRegionException
+     * @throws IncompleteRegionException thrown if a region is not fully selected
      */
     public Vector getPlacementPosition(Player player) throws IncompleteRegionException {
+        checkNotNull(player);
         if (!placeAtPos1) {
             return player.getBlockIn();
         }
@@ -443,7 +505,7 @@ public class LocalSession {
     /**
      * Toggle placement position.
      *
-     * @return
+     * @return whether "place at position 1" is now enabled
      */
     public boolean togglePlacementPosition() {
         placeAtPos1 = !placeAtPos1;
@@ -453,10 +515,12 @@ public class LocalSession {
     /**
      * Get a block bag for a player.
      *
-     * @param player
+     * @param player the player to get the block bag for
-     * @return
+     * @return a block bag
      */
+    @Nullable
     public BlockBag getBlockBag(Player player) {
+        checkNotNull(player);
         if (!useInventory) {
             return null;
         }
@@ -468,6 +532,7 @@ public class LocalSession {
      *
      * @return the snapshot
      */
+    @Nullable
     public Snapshot getSnapshot() {
         return snapshot;
     }
@@ -475,34 +540,38 @@ public class LocalSession {
     /**
      * Select a snapshot.
      *
-     * @param snapshot
+     * @param snapshot a snapshot
      */
-    public void setSnapshot(Snapshot snapshot) {
+    public void setSnapshot(@Nullable Snapshot snapshot) {
         this.snapshot = snapshot;
     }
 
     /**
-     * @return the superPickaxeMode
+     * Get the assigned block tool.
+     *
+     * @return the super pickaxe tool mode
      */
     public BlockTool getSuperPickaxe() {
         return pickaxeMode;
     }
 
     /**
-     * Set the super pickaxe tool.
+     * Set the super pick axe tool.
      *
-     * @param tool
+     * @param tool the tool to set
      */
     public void setSuperPickaxe(BlockTool tool) {
+        checkNotNull(tool);
         this.pickaxeMode = tool;
     }
 
     /**
      * Get the tool assigned to the item.
      *
-     * @param item
+     * @param item the item type ID
-     * @return the tool
+     * @return the tool, which may be {@link null}
      */
+    @Nullable
     public Tool getTool(int item) {
         return tools.get(item);
     }
@@ -512,10 +581,11 @@ public class LocalSession {
      * or the tool is not assigned, the slot will be replaced with the
      * brush tool.
      *
-     * @param item
+     * @param item the item type ID
-     * @return the tool
+     * @return the tool, or {@code null}
-     * @throws InvalidToolBindException
+     * @throws InvalidToolBindException if the item can't be bound to that item
      */
+    @Nullable
     public BrushTool getBrushTool(int item) throws InvalidToolBindException {
         Tool tool = getTool(item);
 
@@ -530,11 +600,11 @@ public class LocalSession {
     /**
      * Set the tool.
      *
-     * @param item
+     * @param item the item type ID
-     * @param tool the tool to set
+     * @param tool the tool to set, which can be {@code null}
-     * @throws InvalidToolBindException
+     * @throws InvalidToolBindException if the item can't be bound to that item
      */
-    public void setTool(int item, Tool tool) throws InvalidToolBindException {
+    public void setTool(int item, @Nullable Tool tool) throws InvalidToolBindException {
         if (item > 0 && item < 255) {
             throw new InvalidToolBindException(item, "Blocks can't be used");
         } else if (item == config.wandItem) {
@@ -549,7 +619,7 @@ public class LocalSession {
     /**
      * Returns whether inventory usage is enabled for this session.
      *
-     * @return the useInventory
+     * @return if inventory is being used
      */
     public boolean isUsingInventory() {
         return useInventory;
@@ -558,7 +628,7 @@ public class LocalSession {
     /**
      * Set the state of inventory usage.
      *
-     * @param useInventory the useInventory to set
+     * @param useInventory if inventory is to be used
      */
     public void setUseInventory(boolean useInventory) {
         this.useInventory = useInventory;
@@ -567,8 +637,9 @@ public class LocalSession {
     /**
      * Get the last script used.
      *
-     * @return the lastScript
+     * @return the last script's name
      */
+    @Nullable
     public String getLastScript() {
         return lastScript;
     }
@@ -576,58 +647,55 @@ public class LocalSession {
     /**
      * Set the last script used.
      *
-     * @param lastScript the lastScript to set
+     * @param lastScript the last script's name
      */
-    public void setLastScript(String lastScript) {
+    public void setLastScript(@Nullable String lastScript) {
         this.lastScript = lastScript;
+        setDirty();
     }
 
     /**
      * Tell the player the WorldEdit version.
      *
-     * @param player
+     * @param player the player
      */
-    @SuppressWarnings({"PointlessBooleanExpression", "ConstantConditions"})
     public void tellVersion(Actor player) {
-        if (config.showHelpInfo && SHOW_HELP_MESSAGE) {
-            if (!beenToldVersion) {
-                StyledFragment fragment = new StyledFragment(Style.GRAY_DARK);
-                fragment.append("Need help with WorldEdit? Ask us on IRC (irc.esper.net #sk89q) or on our forums @ http://forum.enginehub.org");
-                player.printRaw(ColorCodeBuilder.asColorCodes(fragment));
-                beenToldVersion = true;
-            }
-        }
     }
 
     /**
-     * Dispatch a CUI event but only if the player has CUI support.
+     * Dispatch a CUI event but only if the actor has CUI support.
      *
-     * @param player
+     * @param actor the actor
-     * @param event
+     * @param event the event
      */
-    public void dispatchCUIEvent(Actor player, CUIEvent event) {
+    public void dispatchCUIEvent(Actor actor, CUIEvent event) {
+        checkNotNull(actor);
+        checkNotNull(event);
+
         if (hasCUISupport) {
-            player.dispatchCUIEvent(event);
+            actor.dispatchCUIEvent(event);
         }
     }
 
     /**
      * Dispatch the initial setup CUI messages.
      *
-     * @param player
+     * @param actor the actor
      */
-    public void dispatchCUISetup(Player player) {
+    public void dispatchCUISetup(Actor actor) {
         if (selector != null) {
-            dispatchCUISelection(player);
+            dispatchCUISelection(actor);
         }
     }
 
     /**
      * Send the selection information.
      *
-     * @param player
+     * @param actor the actor
      */
-    public void dispatchCUISelection(Player player) {
+    public void dispatchCUISelection(Actor actor) {
+        checkNotNull(actor);
+
         if (!hasCUISupport) {
             return;
         }
@@ -636,17 +704,24 @@ public class LocalSession {
             CUIRegion tempSel = (CUIRegion) selector;
 
             if (tempSel.getProtocolVersion() > cuiVersion) {
-                player.dispatchCUIEvent(new SelectionShapeEvent(tempSel.getLegacyTypeID()));
+                actor.dispatchCUIEvent(new SelectionShapeEvent(tempSel.getLegacyTypeID()));
-                tempSel.describeLegacyCUI(this, player);
+                tempSel.describeLegacyCUI(this, actor);
             } else {
-                player.dispatchCUIEvent(new SelectionShapeEvent(tempSel.getTypeID()));
+                actor.dispatchCUIEvent(new SelectionShapeEvent(tempSel.getTypeID()));
-                tempSel.describeCUI(this, player);
+                tempSel.describeCUI(this, actor);
             }
 
         }
     }
 
-    public void describeCUI(Actor player) {
+    /**
+     * Describe the selection to the CUI actor.
+     *
+     * @param actor the actor
+     */
+    public void describeCUI(Actor actor) {
+        checkNotNull(actor);
+
         if (!hasCUISupport) {
             return;
         }
@@ -655,15 +730,22 @@ public class LocalSession {
             CUIRegion tempSel = (CUIRegion) selector;
 
             if (tempSel.getProtocolVersion() > cuiVersion) {
-                tempSel.describeLegacyCUI(this, player);
+                tempSel.describeLegacyCUI(this, actor);
             } else {
-                tempSel.describeCUI(this, player);
+                tempSel.describeCUI(this, actor);
             }
 
         }
     }
 
+    /**
+     * Handle a CUI initialization message.
+     *
+     * @param text the message
+     */
     public void handleCUIInitializationMessage(String text) {
+        checkNotNull(text);
+
         String[] split = text.split("\\|");
         if (split.length > 1 && split[0].equalsIgnoreCase("v")) { // enough fields and right message
             setCUISupport(true);
@@ -678,7 +760,7 @@ public class LocalSession {
     /**
      * Gets the status of CUI support.
      *
-     * @return
+     * @return true if CUI is enabled
      */
     public boolean hasCUISupport() {
         return hasCUISupport;
@@ -687,7 +769,7 @@ public class LocalSession {
     /**
      * Sets the status of CUI support.
      *
-     * @param support
+     * @param support true if CUI is enabled
      */
     public void setCUISupport(boolean support) {
         hasCUISupport = support;
@@ -696,7 +778,7 @@ public class LocalSession {
     /**
      * Gets the client's CUI protocol version
      *
-     * @return
+     * @return the CUI version
      */
     public int getCUIVersion() {
         return cuiVersion;
@@ -705,7 +787,7 @@ public class LocalSession {
     /**
      * Sets the client's CUI protocol version
      *
-     * @param cuiVersion
+     * @param cuiVersion the CUI version
      */
     public void setCUIVersion(int cuiVersion) {
         this.cuiVersion = cuiVersion;
@@ -714,10 +796,13 @@ public class LocalSession {
     /**
      * Detect date from a user's input.
      *
-     * @param input
+     * @param input the input to parse
-     * @return
+     * @return a date
      */
+    @Nullable
     public Calendar detectDate(String input) {
+        checkNotNull(input);
+
         Time.setTimeZone(getTimeZone());
         Options opt = new com.sk89q.jchronic.Options();
         opt.setNow(Calendar.getInstance(getTimeZone()));
@@ -730,27 +815,9 @@ public class LocalSession {
     }
 
     /**
-     * Update the last update time for calculating expiration.
+     * @deprecated use {@link #createEditSession(Player)}
-     */
-    public void update() {
-        expirationTime = System.currentTimeMillis();
-    }
-
-    /**
-     * Returns whether this session has expired.
-     *
-     * @return
-     */
-    public boolean hasExpired() {
-        return System.currentTimeMillis() - expirationTime > EXPIRATION_GRACE;
-    }
-
-    /**
-     * Construct a new edit session.
-     *
-     * @param player
-     * @return
      */
+    @Deprecated
     public EditSession createEditSession(LocalPlayer player) {
         return createEditSession((Player) player);
     }
@@ -758,11 +825,13 @@ public class LocalSession {
     /**
      * Construct a new edit session.
      *
-     * @param player
+     * @param player the player
-     * @return
+     * @return an edit session
      */
     @SuppressWarnings("deprecation")
     public EditSession createEditSession(Player player) {
+        checkNotNull(player);
+
         BlockBag blockBag = getBlockBag(player);
 
         // Create an edit session
@@ -779,7 +848,7 @@ public class LocalSession {
     /**
      * Checks if the session has fast mode enabled.
      *
-     * @return
+     * @return true if fast mode is enabled
      */
     public boolean hasFastMode() {
         return fastMode;
@@ -788,7 +857,7 @@ public class LocalSession {
     /**
      * Set fast mode.
      *
-     * @param fastMode
+     * @param fastMode true if fast mode is enabled
      */
     public void setFastMode(boolean fastMode) {
         this.fastMode = fastMode;

src/main/java/com/sk89q/worldedit/WorldEdit.java

@@ -660,41 +660,6 @@ public class WorldEdit {
         }
     }
 
-    /**
-     * Handle a disconnection.
-     *
-     * @param player the player
-     */
-    @Deprecated
-    public void handleDisconnect(Player player) {
-        forgetPlayer(player);
-    }
-
-    /**
-     * Mark for expiration of the session.
-     *
-     * @param player the player
-     */
-    public void markExpire(Player player) {
-        sessions.markforExpiration(player);
-    }
-
-    /**
-     * Forget a player.
-     *
-     * @param player the player
-     */
-    public void forgetPlayer(Player player) {
-        sessions.remove(player);
-    }
-
-    /*
-     * Flush expired sessions.
-     */
-    public void flushExpiredSessions(SessionCheck checker) {
-        sessions.removeExpired(checker);
-    }
-
     /**
      * Called on arm swing.
      *

src/main/java/com/sk89q/worldedit/command/WorldEditCommands.java

@@ -24,6 +24,7 @@ import com.sk89q.minecraft.util.commands.CommandContext;
 import com.sk89q.minecraft.util.commands.CommandPermissions;
 import com.sk89q.worldedit.*;
 import com.sk89q.worldedit.entity.Player;
+import com.sk89q.worldedit.event.platform.ConfigurationLoadEvent;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.extension.platform.Capability;
 import com.sk89q.worldedit.extension.platform.Platform;
@@ -78,6 +79,7 @@ public class WorldEditCommands {
     @CommandPermissions("worldedit.reload")
     public void reload(Actor actor) throws WorldEditException {
         we.getServer().reload();
+        we.getEventBus().post(new ConfigurationLoadEvent(we.getPlatformManager().queryCapability(Capability.CONFIGURATION).getConfiguration()));
         actor.print("Configuration reloaded!");
     }
 

src/main/java/com/sk89q/worldedit/event/platform/ConfigurationLoadEvent.java

@@ -0,0 +1,53 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.event.platform;
+
+import com.sk89q.worldedit.LocalConfiguration;
+import com.sk89q.worldedit.event.Event;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Raised when the configuration has been loaded or re-loaded.
+ */
+public class ConfigurationLoadEvent extends Event {
+
+    private final LocalConfiguration configuration;
+
+    /**
+     * Create a new instance.
+     *
+     * @param configuration the new configuration
+     */
+    public ConfigurationLoadEvent(LocalConfiguration configuration) {
+        checkNotNull(configuration);
+        this.configuration = configuration;
+    }
+
+    /**
+     * Get the configuration.
+     *
+     * @return the configuration
+     */
+    public LocalConfiguration getConfiguration() {
+        return configuration;
+    }
+
+}

src/main/java/com/sk89q/worldedit/event/platform/PlatformInitializeEvent.java

@@ -17,15 +17,15 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-package com.sk89q.worldedit;
+package com.sk89q.worldedit.event.platform;
+
+import com.sk89q.worldedit.event.Event;
 
 /**
- * @author zml2008
+ * Fired when configuration has been loaded and the platform is in the
+ * intialization stage.
+ *
+ * <p>This event is fired once.</p>
  */
-public class WorldEditPermissionException extends WorldEditException {
+public class PlatformInitializeEvent extends Event {
-    private static final long serialVersionUID = 1L;
-
-    public WorldEditPermissionException() {
-        super("You don't have permission to do this.");
-    }
 }

src/main/java/com/sk89q/worldedit/extension/platform/AbstractPlayerActor.java

@@ -19,13 +19,13 @@
 
 package com.sk89q.worldedit.extension.platform;
 
+import com.sk89q.worldedit.util.auth.AuthorizationException;
 import com.sk89q.worldedit.BlockWorldVector;
 import com.sk89q.worldedit.LocalPlayer;
 import com.sk89q.worldedit.NotABlockException;
 import com.sk89q.worldedit.PlayerDirection;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.WorldEditException;
-import com.sk89q.worldedit.WorldEditPermissionException;
 import com.sk89q.worldedit.WorldVector;
 import com.sk89q.worldedit.WorldVectorFace;
 import com.sk89q.worldedit.blocks.BaseBlock;
@@ -464,9 +464,9 @@ public abstract class AbstractPlayerActor implements Actor, Player, Cloneable {
     }
 
     @Override
-    public void checkPermission(String permission) throws WorldEditPermissionException {
+    public void checkPermission(String permission) throws AuthorizationException {
         if (!hasPermission(permission)) {
-            throw new WorldEditPermissionException();
+            throw new AuthorizationException();
         }
     }
 

src/main/java/com/sk89q/worldedit/extension/platform/Actor.java

@@ -19,16 +19,17 @@
 
 package com.sk89q.worldedit.extension.platform;
 
-import com.sk89q.worldedit.WorldEditPermissionException;
 import com.sk89q.worldedit.internal.cui.CUIEvent;
-import com.sk89q.worldedit.world.World;
+import com.sk89q.worldedit.session.SessionOwner;
+import com.sk89q.worldedit.util.Identifiable;
+import com.sk89q.worldedit.util.auth.Subject;
 
 import java.io.File;
 
 /**
  * An object that can perform actions in WorldEdit.
  */
-public interface Actor {
+public interface Actor extends Identifiable, SessionOwner, Subject {
 
     /**
      * Get the name of the actor.
@@ -72,30 +73,6 @@ public interface Actor {
      */
     boolean canDestroyBedrock();
 
-    /**
-     * Get a actor's list of groups.
-     *
-     * @return an array containing a group name per entry
-     */
-    String[] getGroups();
-
-    /**
-     * Checks if a player has permission.
-     *
-     * @param perm The permission to check
-     * @return true if the player has that permission
-     */
-    boolean hasPermission(String perm);
-
-    /**
-     * Check whether this actor has the given permission, and throw an
-     * exception if not.
-     *
-     * @param permission the permission
-     * @throws WorldEditPermissionException thrown if permission is not availabe
-     */
-    void checkPermission(String permission) throws WorldEditPermissionException;
-
     /**
      * Return whether this actor is a player.
      *

src/main/java/com/sk89q/worldedit/extension/platform/PlatformManager.java

@@ -19,12 +19,22 @@
 
 package com.sk89q.worldedit.extension.platform;
 
-import com.sk89q.worldedit.*;
+import com.sk89q.worldedit.LocalConfiguration;
+import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.ServerInterface;
 import com.sk89q.worldedit.Vector;
-import com.sk89q.worldedit.command.tool.*;
+import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.WorldVector;
+import com.sk89q.worldedit.command.tool.BlockTool;
+import com.sk89q.worldedit.command.tool.DoubleActionBlockTool;
+import com.sk89q.worldedit.command.tool.DoubleActionTraceTool;
+import com.sk89q.worldedit.command.tool.Tool;
+import com.sk89q.worldedit.command.tool.TraceTool;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.event.platform.BlockInteractEvent;
+import com.sk89q.worldedit.event.platform.ConfigurationLoadEvent;
 import com.sk89q.worldedit.event.platform.Interaction;
+import com.sk89q.worldedit.event.platform.PlatformInitializeEvent;
 import com.sk89q.worldedit.event.platform.PlatformReadyEvent;
 import com.sk89q.worldedit.event.platform.PlayerInputEvent;
 import com.sk89q.worldedit.internal.ServerInterfaceAdapter;
@@ -34,8 +44,13 @@ import com.sk89q.worldedit.util.eventbus.Subscribe;
 import com.sk89q.worldedit.world.World;
 
 import javax.annotation.Nullable;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.EnumMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
 import java.util.Map.Entry;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -56,6 +71,8 @@ public class PlatformManager {
     private final List<Platform> platforms = new ArrayList<Platform>();
     private final Map<Capability, Platform> preferences = new EnumMap<Capability, Platform>(Capability.class);
     private @Nullable String firstSeenVersion;
+    private final AtomicBoolean initialized = new AtomicBoolean();
+    private final AtomicBoolean configured = new AtomicBoolean();
 
     /**
      * Create a new platform manager.
@@ -163,6 +180,11 @@ public class PlatformManager {
                 capability.initialize(this, preferred);
             }
         }
+
+        // Fire configuration event
+        if (preferences.containsKey(Capability.CONFIGURATION) && configured.compareAndSet(false, true)) {
+            worldEdit.getEventBus().post(new ConfigurationLoadEvent(queryCapability(Capability.CONFIGURATION).getConfiguration()));
+        }
     }
 
     /**
@@ -276,6 +298,9 @@ public class PlatformManager {
     @Subscribe
     public void handlePlatformReady(PlatformReadyEvent event) {
         choosePreferred();
+        if (initialized.compareAndSet(false, true)) {
+            worldEdit.getEventBus().post(new PlatformInitializeEvent());
+        }
     }
 
     @SuppressWarnings("deprecation")

src/main/java/com/sk89q/worldedit/extension/platform/PlayerProxy.java

@@ -25,11 +25,14 @@ import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extent.inventory.BlockBag;
 import com.sk89q.worldedit.internal.cui.CUIEvent;
+import com.sk89q.worldedit.session.SessionKey;
 import com.sk89q.worldedit.util.Location;
 import com.sk89q.worldedit.world.World;
 
 import javax.annotation.Nullable;
 
+import java.util.UUID;
+
 import static com.google.common.base.Preconditions.checkNotNull;
 
 class PlayerProxy extends AbstractPlayerActor {
@@ -50,6 +53,11 @@ class PlayerProxy extends AbstractPlayerActor {
         this.world = world;
     }
 
+    @Override
+    public UUID getUniqueId() {
+        return basePlayer.getUniqueId();
+    }
+
     @Override
     public int getItemInHand() {
         return basePlayer.getItemInHand();
@@ -145,4 +153,9 @@ class PlayerProxy extends AbstractPlayerActor {
     public <T> T getFacet(Class<? extends T> cls) {
         return basePlayer.getFacet(cls);
     }
+
+    @Override
+    public SessionKey getSessionKey() {
+        return basePlayer.getSessionKey();
+    }
 }

src/main/java/com/sk89q/worldedit/session/MissingSessionException.java

@@ -0,0 +1,42 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.session;
+
+/**
+ * Raised when the session is missing.
+ */
+public class MissingSessionException extends Exception {
+
+    public MissingSessionException() {
+    }
+
+    public MissingSessionException(String message) {
+        super(message);
+    }
+
+    public MissingSessionException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public MissingSessionException(Throwable cause) {
+        super(cause);
+    }
+
+}

src/main/java/com/sk89q/worldedit/session/SessionKey.java

@@ -0,0 +1,62 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.session;
+
+import com.sk89q.worldedit.util.Identifiable;
+
+import javax.annotation.Nullable;
+
+/**
+ * Provides information about a session.
+ *
+ * <p>A reference for this object may be kept around for a long time.</p>
+ */
+public interface SessionKey extends Identifiable {
+
+    /**
+     * Get the name for this session, if one is available, so that it can
+     * be referred to by others.
+     *
+     * @return a name or {@code null}
+     */
+    @Nullable
+    String getName();
+
+    /**
+     * Return whether the session is still active. Sessions that are inactive
+     * for a prolonged amount of time may be removed. If this method
+     * always returns {@code false}, the the related session may never
+     * be stored.
+     *
+     * <p>This method may be called from any thread, so this call
+     * must be thread safe.</p>
+     *
+     * @return true if active
+     */
+    boolean isActive();
+
+    /**
+     * Return whether this session should be persisted.
+     *
+     * @return true if persistent
+     */
+    boolean isPersistent();
+
+}

src/main/java/com/sk89q/worldedit/session/SessionManager.java

@@ -19,28 +19,53 @@
 
 package com.sk89q.worldedit.session;
 
-import com.sk89q.worldedit.*;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.ListeningExecutorService;
+import com.google.common.util.concurrent.MoreExecutors;
+import com.sk89q.worldedit.LocalConfiguration;
+import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.entity.Player;
-import com.sk89q.worldedit.extension.platform.Actor;
+import com.sk89q.worldedit.event.platform.ConfigurationLoadEvent;
+import com.sk89q.worldedit.session.storage.JsonFileSessionStore;
+import com.sk89q.worldedit.session.storage.SessionStore;
+import com.sk89q.worldedit.session.storage.VoidStore;
+import com.sk89q.worldedit.util.concurrency.EvenMoreExecutors;
+import com.sk89q.worldedit.util.eventbus.Subscribe;
 
 import javax.annotation.Nullable;
+import java.io.File;
+import java.io.IOException;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.UUID;
+import java.util.concurrent.Callable;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * Session manager for WorldEdit.
- * </p>
+ *
- * Get a reference to one from {@link WorldEdit}.
+ * <p>Get a reference to one from {@link WorldEdit}.</p>
- * </p>
+ *
- * While this class is thread-safe, the returned session may not be.
+ * <p>While this class is thread-safe, the returned session may not be.</p>
  */
 public class SessionManager {
 
+    public static int EXPIRATION_GRACE = 600000;
+    private static final int FLUSH_PERIOD = 1000 * 30;
+    private static final ListeningExecutorService executorService = MoreExecutors.listeningDecorator(EvenMoreExecutors.newBoundedCachedThreadPool(0, 1, 5));
+    private static final Logger log = Logger.getLogger(SessionManager.class.getCanonicalName());
+    private final Timer timer = new Timer();
     private final WorldEdit worldEdit;
-    private final HashMap<String, LocalSession> sessions = new HashMap<String, LocalSession>();
+    private final Map<UUID, SessionHolder> sessions = new HashMap<UUID, SessionHolder>();
+    private SessionStore store = new VoidStore();
 
     /**
      * Create a new session manager.
@@ -48,73 +73,98 @@ public class SessionManager {
      * @param worldEdit a WorldEdit instance
      */
     public SessionManager(WorldEdit worldEdit) {
+        checkNotNull(worldEdit);
         this.worldEdit = worldEdit;
+
+        worldEdit.getEventBus().register(this);
+        timer.schedule(new SessionTracker(), FLUSH_PERIOD, FLUSH_PERIOD);
     }
 
     /**
-     * Get whether a session exists for the given actor.
+     * Get whether a session exists for the given owner.
      *
-     * @param actor the actor
+     * @param owner the owner
      * @return true if a session exists
      */
-    public synchronized boolean contains(Actor actor) {
+    public synchronized boolean contains(SessionOwner owner) {
-        checkNotNull(actor);
+        checkNotNull(owner);
-        return sessions.containsKey(getKey(actor));
+        return sessions.containsKey(getKey(owner));
     }
 
     /**
-     * Gets the session for an actor and return it if it exists, otherwise
+     * Find a session by its name specified by {@link SessionKey#getName()}.
-     * return <code>null</code>.
      *
-     * @param actor the actor
+     * @param name the name
-     * @return the session for the actor, if it exists
+     * @return the session, if found, otherwise {@code null}
      */
-    public synchronized @Nullable LocalSession find(Actor actor) {
+    @Nullable
-        checkNotNull(actor);
+    public synchronized LocalSession findByName(String name) {
-        return sessions.get(getKey(actor));
-    }
-
-    /**
-     * Gets the session for someone named by the given name and return it if
-     * it exists, otherwise return <code>null</code>.
-     *
-     * @param name the actor's name
-     * @return the session for the actor, if it exists
-     */
-    public synchronized @Nullable LocalSession findByName(String name) {
         checkNotNull(name);
-        return sessions.get(name);
+        for (SessionHolder holder : sessions.values()) {
+            String test = holder.key.getName();
+            if (test != null && name.equals(test)) {
+                return holder.session;
+            }
+        }
+
+        return null;
     }
 
     /**
-     * Get the session for an actor and create one if one doesn't exist.
+     * Gets the session for an owner and return it if it exists, otherwise
+     * return {@code null}.
      *
-     * @param actor the actor
+     * @param owner the owner
+     * @return the session for the owner, if it exists
+     */
+    @Nullable
+    public synchronized LocalSession getIfPresent(SessionOwner owner) {
+        checkNotNull(owner);
+        SessionHolder stored = sessions.get(getKey(owner));
+        if (stored != null) {
+            return stored.session;
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Get the session for an owner and create one if one doesn't exist.
+     *
+     * @param owner the owner
      * @return a session
      */
-    public synchronized LocalSession get(Actor actor) {
+    public synchronized LocalSession get(SessionOwner owner) {
-        checkNotNull(actor);
+        checkNotNull(owner);
 
-        LocalSession session;
+        LocalSession session = getIfPresent(owner);
         LocalConfiguration config = worldEdit.getConfiguration();
+        SessionKey sessionKey = owner.getSessionKey();
 
-        if (sessions.containsKey(actor.getName())) {
+        // No session exists yet -- create one
-            session = sessions.get(actor.getName());
+        if (session == null) {
-        } else {
+            try {
-            session = new LocalSession(config);
+                session = store.load(getKey(sessionKey));
+            } catch (IOException e) {
+                log.log(Level.WARNING, "Failed to load saved session", e);
+                session = new LocalSession();
+            }
+
+            session.setConfiguration(config);
             session.setBlockChangeLimit(config.defaultChangeLimit);
-            // Remember the session
+
-            sessions.put(actor.getName(), session);
+            // Remember the session if the session is still active
+            if (sessionKey.isActive()) {
+                sessions.put(getKey(owner), new SessionHolder(sessionKey, session));
+            }
         }
 
         // Set the limit on the number of blocks that an operation can
-        // change at once, or don't if the actor has an override or there
+        // change at once, or don't if the owner has an override or there
         // is no limit. There is also a default limit
         int currentChangeLimit = session.getBlockChangeLimit();
 
-        if (!actor.hasPermission("worldedit.limit.unrestricted")
+        if (!owner.hasPermission("worldedit.limit.unrestricted") && config.maxChangeLimit > -1) {
-                && config.maxChangeLimit > -1) {
-
             // If the default limit is infinite but there is a maximum
             // limit, make sure to not have it be overridden
             if (config.defaultChangeLimit < 0) {
@@ -130,47 +180,90 @@ public class SessionManager {
             }
         }
 
-        // Have the session use inventory if it's enabled and the actor
+        // Have the session use inventory if it's enabled and the owner
         // doesn't have an override
         session.setUseInventory(config.useInventory
                 && !(config.useInventoryOverride
-                && (actor.hasPermission("worldedit.inventory.unrestricted")
+                && (owner.hasPermission("worldedit.inventory.unrestricted")
-                || (config.useInventoryCreativeOverride && (!(actor instanceof Player) || ((Player) actor).hasCreativeMode())))));
+                || (config.useInventoryCreativeOverride && (!(owner instanceof Player) || ((Player) owner).hasCreativeMode())))));
 
         return session;
     }
 
     /**
-     * Get the key to use in the map for an actor.
+     * Save a map of sessions to disk.
      *
-     * @param actor the actor
+     * @param sessions a map of sessions to save
+     * @return a future that completes on save or error
+     */
+    private ListenableFuture<?> commit(final Map<SessionKey, LocalSession> sessions) {
+        checkNotNull(sessions);
+
+        if (sessions.isEmpty()) {
+            return Futures.immediateFuture(sessions);
+        }
+
+        return executorService.submit(new Callable<Object>() {
+            @Override
+            public Object call() throws Exception {
+                Exception exception = null;
+
+                for (Map.Entry<SessionKey, LocalSession> entry : sessions.entrySet()) {
+                    SessionKey key = entry.getKey();
+
+                    if (key.isPersistent()) {
+                        try {
+                            store.save(getKey(key), entry.getValue());
+                        } catch (IOException e) {
+                            log.log(Level.WARNING, "Failed to write session for UUID " + getKey(key), e);
+                            exception = e;
+                        }
+                    }
+                }
+
+                if (exception != null) {
+                    throw exception;
+                }
+
+                return sessions;
+            }
+        });
+    }
+
+    /**
+     * Get the key to use in the map for an owner.
+     *
+     * @param owner the owner
      * @return the key object
      */
-    protected String getKey(Actor actor) {
+    protected UUID getKey(SessionOwner owner) {
-        return actor.getName();
+        return getKey(owner.getSessionKey());
     }
 
+
     /**
-     * Mark for expiration.
+     * Get the key to use in the map for a {@code SessionKey}.
      *
-     * @param actor the actor
+     * @param key the session key object
+     * @return the key object
      */
-    public synchronized void markforExpiration(Actor actor) {
+    protected UUID getKey(SessionKey key) {
-        checkNotNull(actor);
+        String forcedKey = System.getProperty("worldedit.session.uuidOverride");
-        LocalSession session = find(actor);
+        if (forcedKey != null) {
-        if (session != null) {
+            return UUID.fromString(forcedKey);
-            session.update();
+        } else {
+            return key.getUniqueId();
         }
     }
 
     /**
-     * Remove the session for the given actor if one exists.
+     * Remove the session for the given owner if one exists.
      *
-     * @param actor the actor
+     * @param owner the owner
      */
-    public synchronized void remove(Actor actor) {
+    public synchronized void remove(SessionOwner owner) {
-        checkNotNull(actor);
+        checkNotNull(owner);
-        sessions.remove(actor.getName());
+        sessions.remove(getKey(owner));
     }
 
     /**
@@ -180,20 +273,63 @@ public class SessionManager {
         sessions.clear();
     }
 
+    @Subscribe
+    public void onConfigurationLoad(ConfigurationLoadEvent event) {
+        LocalConfiguration config = event.getConfiguration();
+        File dir = new File(config.getWorkingDirectory(), "sessions");
+        store = new JsonFileSessionStore(dir);
+    }
+
     /**
-     * Remove expired sessions with the given session checker.
+     * Stores the owner of a session, the session, and the last active time.
-     *
-     * @param checker the session checker
      */
-    public synchronized void removeExpired(SessionCheck checker) {
+    private static class SessionHolder {
-        Iterator<Map.Entry<String, LocalSession>> it = sessions.entrySet().iterator();
+        private final SessionKey key;
+        private final LocalSession session;
+        private long lastActive = System.currentTimeMillis();
+
+        private SessionHolder(SessionKey key, LocalSession session) {
+            this.key = key;
+            this.session = session;
+        }
+    }
+
+    /**
+     * Removes inactive sessions after they have been inactive for a period
+     * of time. Commits them as well.
+     */
+    private class SessionTracker extends TimerTask {
+        @Override
+        public void run() {
+            synchronized (SessionManager.this) {
+                long now = System.currentTimeMillis();
+                Iterator<SessionHolder> it = sessions.values().iterator();
+                Map<SessionKey, LocalSession> saveQueue = new HashMap<SessionKey, LocalSession>();
 
                 while (it.hasNext()) {
-            Map.Entry<String, LocalSession> entry = it.next();
+                    SessionHolder stored = it.next();
-            if (entry.getValue().hasExpired() && !checker.isOnlinePlayer(entry.getKey())) {
+                    if (stored.key.isActive()) {
+                        stored.lastActive = now;
+
+                        if (stored.session.compareAndResetDirty()) {
+                            saveQueue.put(stored.key, stored.session);
+                        }
+                    } else {
+                        if (now - stored.lastActive > EXPIRATION_GRACE) {
+                            if (stored.session.compareAndResetDirty()) {
+                                saveQueue.put(stored.key, stored.session);
+                            }
+
                             it.remove();
                         }
                     }
                 }
 
+                if (!saveQueue.isEmpty()) {
+                    commit(saveQueue);
+                }
+            }
+        }
+    }
+
 }

src/main/java/com/sk89q/worldedit/session/SessionOwner.java

@@ -0,0 +1,37 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.session;
+
+import com.sk89q.worldedit.util.Identifiable;
+import com.sk89q.worldedit.util.auth.Subject;
+
+/**
+ * An object that owns a session.
+ */
+public interface SessionOwner extends Subject {
+
+    /**
+     * Get an object describing this session.
+     *
+     * @return the status object
+     */
+    SessionKey getSessionKey();
+
+}

src/main/java/com/sk89q/worldedit/session/TransientSessionException.java

@@ -0,0 +1,42 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.session;
+
+/**
+ * Thrown if the session cannot be persisted
+ * (because {@link SessionKey#isPersistent()} returns false).
+ */
+public class TransientSessionException extends Exception {
+
+    public TransientSessionException() {
+    }
+
+    public TransientSessionException(String message) {
+        super(message);
+    }
+
+    public TransientSessionException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public TransientSessionException(Throwable cause) {
+        super(cause);
+    }
+}

src/main/java/com/sk89q/worldedit/session/storage/JsonFileSessionStore.java

@@ -0,0 +1,135 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.session.storage;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonIOException;
+import com.google.gson.JsonParseException;
+import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.util.gson.GsonUtil;
+import com.sk89q.worldedit.util.io.Closer;
+
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.UUID;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Stores sessions as JSON files in a directory.
+ *
+ * <p>Currently, this implementation doesn't handle thread safety very well.</p>
+ */
+public class JsonFileSessionStore implements SessionStore {
+
+    private static final Logger log = Logger.getLogger(JsonFileSessionStore.class.getCanonicalName());
+    private final Gson gson;
+    private final File dir;
+
+    /**
+     * Create a new session store.
+     *
+     * @param dir the directory
+     */
+    public JsonFileSessionStore(File dir) {
+        checkNotNull(dir);
+
+        if (!dir.isDirectory()) {
+            if (!dir.mkdirs()) {
+                log.log(Level.WARNING, "Failed to create directory '" + dir.getPath() + "' for sessions");
+            }
+        }
+
+        this.dir = dir;
+
+        GsonBuilder builder = GsonUtil.createBuilder();
+        gson = builder.create();
+    }
+
+    /**
+     * Get the path for the given UUID.
+     *
+     * @param id the ID
+     * @return the file
+     */
+    private File getPath(UUID id) {
+        checkNotNull(id);
+        return new File(dir, id + ".json");
+    }
+
+    @Override
+    public LocalSession load(UUID id) throws IOException {
+        File file = getPath(id);
+        Closer closer = Closer.create();
+        try {
+            FileReader fr = closer.register(new FileReader(file));
+            BufferedReader br = closer.register(new BufferedReader(fr));
+            return gson.fromJson(br, LocalSession.class);
+        } catch (JsonParseException e) {
+            throw new IOException(e);
+        } catch (FileNotFoundException e) {
+            return new LocalSession();
+        } finally {
+            try {
+                closer.close();
+            } catch (IOException ignored) {
+            }
+        }
+    }
+
+    @Override
+    public void save(UUID id, LocalSession session) throws IOException {
+        File finalFile = getPath(id);
+        File tempFile = new File(finalFile.getParentFile(), finalFile.getName() + ".tmp");
+        Closer closer = Closer.create();
+
+        try {
+            FileWriter fr = closer.register(new FileWriter(tempFile));
+            BufferedWriter bw = closer.register(new BufferedWriter(fr));
+            gson.toJson(session, bw);
+        } catch (JsonIOException e) {
+            throw new IOException(e);
+        } finally {
+            try {
+                closer.close();
+            } catch (IOException ignored) {
+            }
+        }
+
+        if (finalFile.exists()) {
+            if (!finalFile.delete()) {
+                log.log(Level.WARNING, "Failed to delete " + finalFile.getPath() + " so the .tmp file can replace it");
+            }
+        }
+
+        if (!tempFile.renameTo(finalFile)) {
+            log.log(Level.WARNING, "Failed to rename temporary session file to " + finalFile.getPath());
+        }
+    }
+
+}

src/main/java/com/sk89q/worldedit/session/storage/SessionStore.java

@@ -0,0 +1,57 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.session.storage;
+
+import com.sk89q.worldedit.LocalSession;
+
+import java.io.IOException;
+import java.util.UUID;
+
+/**
+ * Commits sessions to disk.
+ *
+ * <p>Both {@link #load(UUID)} and {@link #save(UUID, LocalSession)} may be
+ * called at the same in different threads, so implementations should
+ * be aware of this issue.</p>
+ */
+public interface SessionStore {
+
+    /**
+     * Load a session identified by the given UUID.
+     *
+     * <p>If the session does not exist (has never been saved), then
+     * a new {@link LocalSession} must be returned.</p>
+     *
+     * @param id the UUID
+     * @return a session
+     * @throws IOException thrown on read error
+     */
+    LocalSession load(UUID id) throws IOException;
+
+    /**
+     * Save the given session identified by the given UUID.
+     *
+     * @param id the UUID
+     * @param session a session
+     * @throws IOException thrown on read error
+     */
+    void save(UUID id, LocalSession session) throws IOException;
+
+}

src/main/java/com/sk89q/worldedit/session/storage/VoidStore.java

@@ -17,34 +17,25 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-package com.sk89q.worldedit.bukkit;
+package com.sk89q.worldedit.session.storage;
 
-import org.bukkit.Server;
+import com.sk89q.worldedit.LocalSession;
-import org.bukkit.entity.Player;
+
-import com.sk89q.worldedit.SessionCheck;
+import java.io.IOException;
-import com.sk89q.worldedit.WorldEdit;
+import java.util.UUID;
 
 /**
- * Used to remove expired sessions in Bukkit.
+ * A session store that doesn't know how to store sessions.
  */
-class SessionTimer implements Runnable {
+public class VoidStore implements SessionStore {
 
-    private WorldEdit worldEdit;
+    @Override
-    private SessionCheck checker;
+    public LocalSession load(UUID id) throws IOException {
-
+        return new LocalSession();
-    SessionTimer(WorldEdit worldEdit, final Server server) {
-        this.worldEdit = worldEdit;
-        this.checker = new SessionCheck() {
-            public boolean isOnlinePlayer(String name) {
-                Player player = server.getPlayer(name);
-                return player != null && player.isOnline();
-            }
-        };
     }
 
     @Override
-    public void run() {
+    public void save(UUID id, LocalSession session) throws IOException {
-        worldEdit.flushExpiredSessions(checker);
     }
 
 }

src/main/java/com/sk89q/worldedit/util/Identifiable.java

@@ -17,21 +17,20 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-package com.sk89q.worldedit;
+package com.sk89q.worldedit.util;
+
+import java.util.UUID;
 
 /**
- * Used to discard old sessions.
+ * Represents an object that can be identified by a UUID.
- *
- * @author sk89q
  */
-public interface SessionCheck {
+public interface Identifiable {
 
     /**
-     * Checks if a player is online.
+     * Get the UUID for this object.
      *
-     * @param name
+     * @return the UUID
-     * @return
      */
-    public boolean isOnlinePlayer(String name);
+    UUID getUniqueId();
 
 }

src/main/java/com/sk89q/worldedit/util/YAMLConfiguration.java

@@ -22,6 +22,7 @@ package com.sk89q.worldedit.util;
 import com.sk89q.util.yaml.YAMLProcessor;
 import com.sk89q.worldedit.LocalConfiguration;
 import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.session.SessionManager;
 import com.sk89q.worldedit.world.snapshot.SnapshotRepository;
 
 import java.io.IOException;
@@ -106,7 +107,7 @@ public class YAMLConfiguration extends LocalConfiguration {
 
         allowSymlinks = config.getBoolean("files.allow-symbolic-links", false);
         LocalSession.MAX_HISTORY_SIZE = Math.max(0, config.getInt("history.size", 15));
-        LocalSession.EXPIRATION_GRACE = config.getInt("history.expiration", 10) * 60 * 1000;
+        SessionManager.EXPIRATION_GRACE = config.getInt("history.expiration", 10) * 60 * 1000;
 
         showHelpInfo = config.getBoolean("show-help-on-first-use", true);
 

src/main/java/com/sk89q/worldedit/util/auth/AuthorizationException.java

@@ -0,0 +1,43 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.util.auth;
+
+import com.sk89q.worldedit.WorldEditException;
+
+/**
+ * Raised when authorization is not granted.
+ */
+public class AuthorizationException extends WorldEditException {
+
+    public AuthorizationException() {
+    }
+
+    public AuthorizationException(String message) {
+        super(message);
+    }
+
+    public AuthorizationException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public AuthorizationException(Throwable cause) {
+        super(cause);
+    }
+}

src/main/java/com/sk89q/worldedit/util/auth/Subject.java

@@ -0,0 +1,51 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.util.auth;
+
+/**
+ * A subject has authorization attached to it.
+ */
+public interface Subject {
+
+    /**
+     * Get a list of groups that this subject is a part of.
+     *
+     * @return an array containing a group name per entry
+     */
+    String[] getGroups();
+
+    /**
+     * Check whether this subject has been granted the given permission
+     * and throw an exception on error.
+     *
+     * @param permission the permission
+     * @throws AuthorizationException thrown if not permitted
+     */
+    void checkPermission(String permission) throws AuthorizationException;
+
+    /**
+     * Return whether this subject has the given permission.
+     *
+     * @param permission the permission
+     * @return true if permission is granted
+     */
+    boolean hasPermission(String permission);
+
+}

src/main/java/com/sk89q/worldedit/util/concurrency/EvenMoreExecutors.java

@@ -0,0 +1,54 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.util.concurrency;
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Even more {@code ExecutorService} factory methods.
+ */
+public final class EvenMoreExecutors {
+
+    private EvenMoreExecutors() {
+    }
+
+    /**
+     * Creates a thread pool that creates new threads as needed up to
+     * a maximum number of threads, but will reuse previously constructed
+     * threads when they are available.
+     *
+     * @param minThreads the minimum number of threads to have at a given time
+     * @param maxThreads the maximum number of threads to have at a given time
+     * @param queueSize the size of the queue before new submissions are rejected
+     * @return the newly created thread pool
+     */
+    public static ExecutorService newBoundedCachedThreadPool(int minThreads, int maxThreads, int queueSize) {
+        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
+                minThreads, maxThreads,
+                60L, TimeUnit.SECONDS,
+                new ArrayBlockingQueue<Runnable>(queueSize));
+        threadPoolExecutor.allowCoreThreadTimeOut(true);
+        return threadPoolExecutor;
+    }
+
+}

src/main/java/com/sk89q/worldedit/util/gson/GsonUtil.java

@@ -0,0 +1,44 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.util.gson;
+
+import com.google.gson.GsonBuilder;
+import com.sk89q.worldedit.Vector;
+
+/**
+ * Utility methods for Google's GSON library.
+ */
+public final class GsonUtil {
+
+    private GsonUtil() {
+    }
+
+    /**
+     * Create a standard {@link GsonBuilder} for WorldEdit.
+     *
+     * @return a builder
+     */
+    public static GsonBuilder createBuilder() {
+        GsonBuilder gsonBuilder = new GsonBuilder();
+        gsonBuilder.registerTypeAdapter(Vector.class, new VectorAdapter());
+        return gsonBuilder;
+    }
+
+}