Improve backup functionality (#3258)

Waits for an ongoing backup task to complete in onDisable (and yells at users for `/reload`ing), and adds a `backup.always-run` option to enable always running backups even when no users have logged in since the last backup.

Fixes #3257 and closes #2646.

Essentials/src/com/earth2me/essentials/Backup.java

@@ -7,6 +7,8 @@ import org.bukkit.command.CommandSender;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -20,11 +22,13 @@ public class Backup implements Runnable {
     private transient boolean running = false;
     private transient int taskId = -1;
     private transient boolean active = false;
+    private final AtomicBoolean pendingShutdown = new AtomicBoolean(false);
+    private transient CompletableFuture<Object> taskLock = null;
 
     public Backup(final IEssentials ess) {
         this.ess = ess;
         server = ess.getServer();
-        if (!ess.getOnlinePlayers().isEmpty()) {
+        if (!ess.getOnlinePlayers().isEmpty() || ess.getSettings().isAlwaysRunBackup()) {
             ess.runTaskAsynchronously(this::startTask);
         }
     }
@@ -52,12 +56,21 @@ public class Backup implements Runnable {
         }
     }
 
+    public CompletableFuture<Object> getTaskLock() {
+        return taskLock;
+    }
+
+    public void setPendingShutdown(boolean shutdown) {
+        pendingShutdown.set(shutdown);
+    }
+
     @Override
     public void run() {
         if (active) {
             return;
         }
         active = true;
+        taskLock = new CompletableFuture<>();
         final String command = ess.getSettings().getBackupCommand();
         if (command == null || "".equals(command)) {
             return;
@@ -66,6 +79,7 @@ public class Backup implements Runnable {
             final CommandSender cs = server.getConsoleSender();
             server.dispatchCommand(cs, "save-all");
             active = false;
+            taskLock.complete(new Object());
             return;
         }
         LOGGER.log(Level.INFO, tl("backupStarted"));
@@ -102,14 +116,17 @@ public class Backup implements Runnable {
                     @Override
                     public void run() {
                         server.dispatchCommand(cs, "save-on");
-                        if (ess.getOnlinePlayers().isEmpty()) {
+                        if (!ess.getSettings().isAlwaysRunBackup() && ess.getOnlinePlayers().isEmpty()) {
                             stopTask();
                         }
                         active = false;
+                        taskLock.complete(new Object());
                         LOGGER.log(Level.INFO, tl("backupFinished"));
                     }
                 }
-                ess.scheduleSyncDelayedTask(new BackupEnableSaveTask());
+                if (!pendingShutdown.get()) {
+                    ess.scheduleSyncDelayedTask(new BackupEnableSaveTask());
+                }
             }
         });
     }

Essentials/src/com/earth2me/essentials/Essentials.java

@@ -314,6 +314,7 @@ public class Essentials extends JavaPlugin implements net.ess3.api.IEssentials {
             handleCrash(ex);
             throw ex;
         }
+        getBackup().setPendingShutdown(false);
     }
 
     @Override
@@ -363,12 +364,17 @@ public class Essentials extends JavaPlugin implements net.ess3.api.IEssentials {
 
     @Override
     public void onDisable() {
+        boolean stopping = ServerState.isStopping();
+        if (!stopping) {
+            LOGGER.log(Level.SEVERE, tl("serverReloading"));
+        }
+        getBackup().setPendingShutdown(true);
         for (User user : getOnlineUsers()) {
             if (user.isVanished()) {
                 user.setVanished(false);
                 user.sendMessage(tl("unvanishedReload"));
             }
-            if (ServerState.isStopping()) {
+            if (stopping) {
                 user.setLastLocation();
                 if (!user.isHidden()) {
                     user.setLastLogout(System.currentTimeMillis());
@@ -379,6 +385,10 @@ public class Essentials extends JavaPlugin implements net.ess3.api.IEssentials {
             }
         }
         cleanupOpenInventories();
+        if (getBackup().getTaskLock() != null && !getBackup().getTaskLock().isDone()) {
+            LOGGER.log(Level.SEVERE, tl("backupInProgress"));
+            getBackup().getTaskLock().join();
+        }
         if (i18n != null) {
             i18n.onDisable();
         }

Essentials/src/com/earth2me/essentials/ISettings.java

@@ -32,6 +32,8 @@ public interface ISettings extends IConf {
 
     long getBackupInterval();
 
+    boolean isAlwaysRunBackup();
+
     String getChatFormat(String group);
 
     int getChatRadius();

Essentials/src/com/earth2me/essentials/Settings.java

@@ -425,6 +425,11 @@ public class Settings implements net.ess3.api.ISettings {
         return config.getString("backup.command", null);
     }
 
+    @Override
+    public boolean isAlwaysRunBackup() {
+        return config.getBoolean("backup.always-run", false);
+    }
+
     private final Map<String, String> chatFormats = Collections.synchronizedMap(new HashMap<>());
 
     @Override

Essentials/src/config.yml

@@ -371,6 +371,8 @@ unprotected-sign-names:
 backup:
   # Interval in minutes.
   interval: 30
+  # If true, the backup task will run even if there are no players online.
+  always-run: false
   # Unless you add a valid backup command or script here, this feature will be useless.
   # Use 'save-all' to simply force regular world saving without backup.
   #command: 'rdiff-backup World1 backups/World1'

Essentials/src/messages.properties

@@ -27,6 +27,7 @@ backOther=\u00a76Returned\u00a7c {0}\u00a76 to previous location.
 backupDisabled=\u00a74An external backup script has not been configured.
 backupFinished=\u00a76Backup finished.
 backupStarted=\u00a76Backup started.
+backupInProgress=\u00a76An external backup script is currently in progress! Halting plugin disable until finished.
 backUsageMsg=\u00a76Returning to previous location.
 balance=\u00a7aBalance\:\u00a7c {0}
 balanceOther=\u00a7aBalance of {0}\u00a7a\:\u00a7c {1}
@@ -484,6 +485,7 @@ seenOnline=\u00a76Player\u00a7c {0} \u00a76has been \u00a7aonline\u00a76 since \
 sellBulkPermission=\u00a76You do not have permission to bulk sell.
 sellHandPermission=\u00a76You do not have permission to hand sell.
 serverFull=Server is full\!
+serverReloading=There's a good chance you're reloading your server right now. If that's the case, why do you hate yourself? Expect no support from the EssentialsX team when using /reload.
 serverTotal=\u00a76Server Total\:\u00a7c {0}
 serverUnsupported=You are running an unsupported server version!
 setBal=\u00a7aYour balance was set to {0}.