Add HikariCP connection pool for MySQL (#86)

* Add HikariCP connection pool for MySQL

* Make code more compatible with connection pooling

- Remove connection caching in Process/Consumer
- Use try-with-resources to make sure Connections always get closed, even in
  when an Exception occurs.

* Disable SSL for MySQL

build.gradle

@@ -37,6 +37,7 @@ dependencies {
     }
     compileOnly 'org.spigotmc:spigot-api:1.17-R0.1-SNAPSHOT'
     implementation 'org.bstats:bstats-bukkit-lite:1.7'
+    implementation 'com.zaxxer:HikariCP:4.0.3'
 }
 
 jar {
@@ -51,6 +52,7 @@ shadowJar {
     dependencies {
         // #toString because #getGroup technically returns an Object
         relocate('org.bstats', project.group.toString())
+        relocate('com.zaxxer', project.group.toString())
     }
     archiveClassifier.set(null)
 }

pom.xml

@@ -56,6 +56,10 @@
                   <pattern>org.bstats</pattern>
                   <shadedPattern>net.coreprotect</shadedPattern>
                 </relocation>
+                <relocation>
+                  <pattern>com.zaxxer</pattern>
+                  <shadedPattern>net.coreprotect</shadedPattern>
+                </relocation>
               </relocations>
             </configuration>
           </execution>
@@ -111,5 +115,10 @@
         </exclusion>
       </exclusions>
     </dependency>
+    <dependency>
+      <groupId>com.zaxxer</groupId>
+      <artifactId>HikariCP</artifactId>
+      <version>4.0.3</version>
+    </dependency>
   </dependencies>
 </project>

src/main/java/net/coreprotect/CoreProtectAPI.java

@@ -445,8 +445,7 @@ public class CoreProtectAPI extends Queue {
             return null;
         }
 
-        try {
+        try (Connection connection = Database.getConnection(false, 1000)) {
-            Connection connection = Database.getConnection(false, 1000);
             if (connection != null) {
                 Statement statement = connection.createStatement();
                 boolean restrictWorld = false;
@@ -488,7 +487,6 @@ public class CoreProtectAPI extends Queue {
                 }
 
                 statement.close();
-                connection.close();
             }
         }
         catch (Exception e) {

src/main/java/net/coreprotect/command/LookupCommand.java

@@ -324,9 +324,8 @@ public class LookupCommand {
             class BasicThread implements Runnable {
                 @Override
                 public void run() {
-                    try {
+                    try (Connection connection = Database.getConnection(true)) {
                         ConfigHandler.lookupThrottle.put(player2.getName(), new Object[] { true, System.currentTimeMillis() });
-                        Connection connection = Database.getConnection(true);
                         if (connection != null) {
                             Statement statement = connection.createStatement();
                             String blockdata = ChestTransactionLookup.performLookup(command.getName(), statement, location, player2, p2, finalLimit, false);
@@ -339,7 +338,6 @@ public class LookupCommand {
                                 Chat.sendComponent(player2, blockdata);
                             }
                             statement.close();
-                            connection.close();
                         }
                         else {
                             Chat.sendMessage(player2, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));
@@ -422,9 +420,8 @@ public class LookupCommand {
             class BasicThread implements Runnable {
                 @Override
                 public void run() {
-                    try {
+                    try (Connection connection = Database.getConnection(true)) {
                         ConfigHandler.lookupThrottle.put(player2.getName(), new Object[] { true, System.currentTimeMillis() });
-                        Connection connection = Database.getConnection(true);
                         if (connection != null) {
                             Statement statement = connection.createStatement();
                             if (t == 8) {
@@ -461,7 +458,6 @@ public class LookupCommand {
                                 }
                             }
                             statement.close();
-                            connection.close();
                         }
                         else {
                             Chat.sendMessage(player2, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));
@@ -681,7 +677,7 @@ public class LookupCommand {
                     class BasicThread2 implements Runnable {
                         @Override
                         public void run() {
-                            try {
+                            try (Connection connection = Database.getConnection(true)) {
                                 ConfigHandler.lookupThrottle.put(player2.getName(), new Object[] { true, System.currentTimeMillis() });
 
                                 List<String> uuidList = new ArrayList<>();
@@ -699,7 +695,6 @@ public class LookupCommand {
                                 ConfigHandler.lookupAlist.put(player2.getName(), finalArgAction);
                                 ConfigHandler.lookupRadius.put(player2.getName(), radius);
 
-                                Connection connection = Database.getConnection(true);
                                 if (connection != null) {
                                     Statement statement = connection.createStatement();
                                     String baduser = "";
@@ -950,7 +945,6 @@ public class LookupCommand {
                                         Chat.sendMessage(player2, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.USER_NOT_FOUND, baduser));
                                     }
                                     statement.close();
-                                    connection.close();
                                 }
                                 else {
                                     Chat.sendMessage(player2, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));

src/main/java/net/coreprotect/command/PurgeCommand.java

@@ -1,10 +1,7 @@
 package net.coreprotect.command;
 
 import java.io.File;
-import java.sql.Connection;
+import java.sql.*;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.ResultSetMetaData;
 import java.text.NumberFormat;
 import java.util.Arrays;
 import java.util.List;
@@ -94,14 +91,12 @@ public class PurgeCommand extends Consumer {
 
             @Override
             public void run() {
-                try {
+                try (Connection connection = Database.getConnection(false, 500)) {
                     int timestamp = (int) (System.currentTimeMillis() / 1000L);
                     int ptime = timestamp - seconds;
                     long removed = 0;
 
-                    Connection connection = null;
                     for (int i = 0; i <= 5; i++) {
-                        connection = Database.getConnection(false, 500);
                         if (connection != null) {
                             break;
                         }
@@ -344,8 +339,6 @@ public class PurgeCommand extends Consumer {
                         }
                     }
 
-                    connection.close();
-
                     if (abort) {
                         if (!Config.getGlobal().MYSQL) {
                             (new File(ConfigHandler.path + ConfigHandler.sqlite + ".tmp")).delete();

src/main/java/net/coreprotect/command/RollbackRestoreCommand.java

@@ -310,11 +310,10 @@ public class RollbackRestoreCommand {
                         class BasicThread2 implements Runnable {
                             @Override
                             public void run() {
-                                try {
+                                try (Connection connection = Database.getConnection(false, 1000)) {
                                     ConfigHandler.lookupThrottle.put(player.getName(), new Object[] { true, System.currentTimeMillis() });
                                     int action = finalAction;
                                     Location location = locationFinal;
-                                    Connection connection = Database.getConnection(false, 1000);
                                     if (connection != null) {
                                         Statement statement = connection.createStatement();
                                         String baduser = "";
@@ -407,7 +406,6 @@ public class RollbackRestoreCommand {
                                             Chat.sendMessage(player2, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.USER_NOT_FOUND, baduser));
                                         }
                                         statement.close();
-                                        connection.close();
                                     }
                                     else {
                                         Chat.sendMessage(player2, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));

src/main/java/net/coreprotect/config/ConfigHandler.java

@@ -14,6 +14,8 @@ import java.util.Map;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 
+import com.zaxxer.hikari.HikariConfig;
+import com.zaxxer.hikari.HikariDataSource;
 import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.entity.Player;
@@ -50,6 +52,7 @@ public class ConfigHandler extends Queue {
     public static String username = "root";
     public static String password = "";
     public static String prefix = "co_";
+    public static HikariDataSource hikariDataSource = null;
     public static final boolean isSpigot = Util.isSpigot();
     public static final boolean isPaper = Util.isPaper();
     public static volatile boolean serverRunning = false;
@@ -171,6 +174,12 @@ public class ConfigHandler extends Queue {
     }
 
     public static void loadDatabase() {
+        // close old pool when we reload the database, e.g. in purge command
+        if (ConfigHandler.hikariDataSource != null) {
+            ConfigHandler.hikariDataSource.close();
+            ConfigHandler.hikariDataSource = null;
+        }
+
         if (!Config.getGlobal().MYSQL) {
             try {
                 File tempFile = File.createTempFile("CoreProtect_" + System.currentTimeMillis(), ".tmp");
@@ -198,11 +207,29 @@ public class ConfigHandler extends Queue {
             catch (Exception e) {
                 e.printStackTrace();
             }
+        } else {
+            HikariConfig config = new HikariConfig();
+            config.setJdbcUrl("jdbc:mysql://" + ConfigHandler.host + ":" + ConfigHandler.port + "/" + ConfigHandler.database);
+            config.setUsername(ConfigHandler.username);
+            config.setPassword(ConfigHandler.password);
+            config.addDataSourceProperty("characterEncoding", "UTF-8");
+            config.addDataSourceProperty("connectionTimeout", "10000");
+            /* https://github.com/brettwooldridge/HikariCP/wiki/MySQL-Configuration */
+            /* https://cdn.oreillystatic.com/en/assets/1/event/21/Connector_J%20Performance%20Gems%20Presentation.pdf */
+            config.addDataSourceProperty("cachePrepStmts", "true");
+            config.addDataSourceProperty("prepStmtCacheSize", "250");
+            config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
+            config.addDataSourceProperty("useServerPrepStmts", "true");
+            config.addDataSourceProperty("useLocalSessionState", "true");
+            config.addDataSourceProperty("rewriteBatchedStatements", "true");
+            config.addDataSourceProperty("cacheServerConfiguration", "true");
+            config.addDataSourceProperty("maintainTimeStats", "false");
+            /* Disable SSL to suppress the unverified server identity warning */
+            config.addDataSourceProperty("useSSL", "false");
+
+            ConfigHandler.hikariDataSource = new HikariDataSource(config);
         }
 
-        if (ConfigHandler.serverRunning) {
-            Consumer.resetConnection = true;
-        }
         Database.createDatabaseTables(ConfigHandler.prefix, false);
     }
 
@@ -368,7 +395,11 @@ public class ConfigHandler extends Queue {
             ConfigHandler.loadConfig(); // Load (or create) the configuration file.
             ConfigHandler.loadDatabase(); // Initialize MySQL and create tables if necessary.
 
-            Connection connection = Database.getConnection(true, 0);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+
+        try (Connection connection = Database.getConnection(true, 0)) {
             Statement statement = connection.createStatement();
 
             ConfigHandler.checkPlayers(connection);
@@ -396,7 +427,6 @@ public class ConfigHandler extends Queue {
             }
 
             statement.close();
-            connection.close();
 
             return validVersion && databaseLock;
         }

src/main/java/net/coreprotect/consumer/Consumer.java

@@ -18,7 +18,6 @@ import net.coreprotect.consumer.process.Process;
 public class Consumer extends Process implements Runnable, Thread.UncaughtExceptionHandler {
 
     private static Thread consumerThread = null;
-    public static volatile boolean resetConnection = false;
     public static volatile int currentConsumer = 0;
     public static volatile boolean isPaused = false;
     public static volatile boolean transacting = false;
@@ -103,12 +102,6 @@ public class Consumer extends Process implements Runnable, Thread.UncaughtExcept
         try {
             while ((ConfigHandler.serverRunning || ConfigHandler.converterRunning) && (Consumer.isPaused || ConfigHandler.purgeRunning || Consumer.consumer_id.get(process_id)[1] == 1)) {
                 pausedSuccess = true;
-                if (Consumer.isPaused || ConfigHandler.purgeRunning) {
-                    if (connection != null) {
-                        connection.close();
-                        connection = null;
-                    }
-                }
                 Thread.sleep(100);
             }
         }

src/main/java/net/coreprotect/consumer/process/Process.java

@@ -2,6 +2,7 @@ package net.coreprotect.consumer.process;
 
 import java.sql.Connection;
 import java.sql.PreparedStatement;
+import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.Locale;
@@ -45,36 +46,13 @@ public class Process {
     public static final int BLOCKDATA_INSERT = 25;
     public static final int ITEM_TRANSACTION = 26;
 
-    protected static Connection connection = null;
     public static int lastLockUpdate = 0;
-    private static int lastConnection = 0;
     private static volatile int currentConsumerSize = 0;
 
     public static int getCurrentConsumerSize() {
         return currentConsumerSize;
     }
 
-    private static void validateConnection(boolean lastRun) {
-        try {
-            if (connection != null) {
-                int timeSinceLastConnection = ((int) (System.currentTimeMillis() / 1000L)) - lastConnection;
-                if ((!lastRun && timeSinceLastConnection > 900) || !connection.isValid(5) || Consumer.resetConnection) {
-                    connection.close();
-                    connection = null;
-                    Consumer.resetConnection = false;
-                }
-            }
-
-            if (connection == null && ConfigHandler.serverRunning) {
-                connection = Database.getConnection(false, 500);
-                lastConnection = (int) (System.currentTimeMillis() / 1000L);
-            }
-        }
-        catch (Exception e) {
-            e.printStackTrace();
-        }
-    }
-
     protected static void updateLockTable(Statement statement, int locked) {
         try {
             int unixTimestamp = (int) (System.currentTimeMillis() / 1000L);
@@ -90,9 +68,7 @@ public class Process {
     }
 
     protected static void processConsumer(int processId, boolean lastRun) {
-        try {
+        try (Connection connection = Database.getConnection(false, 500)) {
-            // Connection
-            validateConnection(lastRun);
             if (connection == null) {
                 return;
             }
@@ -243,7 +219,6 @@ public class Process {
                                 for (int index = (i - 1); index >= 0; index--) {
                                     consumerData.remove(index);
                                 }
-                                connection = null;
                                 currentConsumerSize = 0;
                                 Consumer.isPaused = false;
                                 return;
@@ -288,11 +263,6 @@ public class Process {
             users.clear();
             consumerObject.clear();
             consumerData.clear();
-
-            if (lastRun) {
-                connection.close();
-                connection = null;
-            }
         }
         catch (Exception e) {
             e.printStackTrace();

src/main/java/net/coreprotect/database/Database.java

@@ -138,15 +138,7 @@ public class Database extends Queue {
             }
             if (Config.getGlobal().MYSQL) {
                 try {
-                    /* Using useServerPrepStmts, cachePrepStmts, and rewriteBatchedStatements per https://github.com/brettwooldridge/HikariCP/wiki/MySQL-Configuration */
+                    connection = ConfigHandler.hikariDataSource.getConnection();
-                    String database = "jdbc:mysql://" + ConfigHandler.host + ":" + ConfigHandler.port + "/" + ConfigHandler.database + "?useUnicode=true&characterEncoding=utf-8&connectTimeout=10000&useSSL=false&allowPublicKeyRetrieval=true&useCursorFetch=true&useLocalSessionState=true&rewriteBatchedStatements=true&maintainTimeStats=false";
-                    connection = DriverManager.getConnection(database, ConfigHandler.username, ConfigHandler.password);
-
-                    /* Recommended implementation per https://dev.mysql.com/doc/refman/5.0/en/charset-applications.html & https://dev.mysql.com/doc/refman/5.0/en/charset-syntax.html */
-                    Statement statement = connection.createStatement();
-                    statement.executeUpdate("SET NAMES 'utf8mb4'"); // COLLATE 'utf8mb4mb4_general_ci'
-                    statement.close();
-
                     ConfigHandler.databaseReachable = true;
                 }
                 catch (Exception e) {
@@ -316,8 +308,7 @@ public class Database extends Queue {
 
         if (Config.getGlobal().MYSQL) {
             boolean success = false;
-            try {
+            try (Connection connection = Database.getConnection(true, true, true, 0)) {
-                Connection connection = Database.getConnection(true, true, true, 0);
                 if (connection != null) {
                     String index = "";
                     Statement statement = connection.createStatement();
@@ -357,7 +348,6 @@ public class Database extends Queue {
                         initializeTables(prefix, statement);
                     }
                     statement.close();
-                    connection.close();
                     success = true;
                 }
             }
@@ -369,8 +359,7 @@ public class Database extends Queue {
             }
         }
         if (!Config.getGlobal().MYSQL) {
-            try {
+            try (Connection connection = Database.getConnection(true, 0)) {
-                Connection connection = Database.getConnection(true, 0);
                 Statement statement = connection.createStatement();
                 List<String> tableData = new ArrayList<>();
                 List<String> indexData = new ArrayList<>();
@@ -553,7 +542,6 @@ public class Database extends Queue {
                     initializeTables(prefix, statement);
                 }
                 statement.close();
-                connection.close();
             }
             catch (Exception e) {
                 e.printStackTrace();

src/main/java/net/coreprotect/database/lookup/BlockLookupAPI.java

@@ -18,7 +18,7 @@ public class BlockLookupAPI {
     public static List<String[]> performLookup(Block block, int offset) {
         List<String[]> result = new ArrayList<>();
 
-        try {
+        try (Connection connection = Database.getConnection(false, 1000)) {
             if (block == null) {
                 return result;
             }
@@ -33,7 +33,6 @@ public class BlockLookupAPI {
                 checkTime = time - offset;
             }
 
-            Connection connection = Database.getConnection(false, 1000);
             if (connection == null) {
                 return result;
             }
@@ -62,7 +61,6 @@ public class BlockLookupAPI {
             }
             results.close();
             statement.close();
-            connection.close();
         }
         catch (Exception e) {
             e.printStackTrace();

src/main/java/net/coreprotect/listener/entity/HangingBreakByEntityListener.java

@@ -33,8 +33,7 @@ public final class HangingBreakByEntityListener extends Queue implements Listene
         class BasicThread implements Runnable {
             @Override
             public void run() {
-                try {
+                try (Connection connection = Database.getConnection(true)) {
-                    Connection connection = Database.getConnection(true);
                     if (connection != null) {
                         Statement statement = connection.createStatement();
                         String blockData = BlockLookup.performLookup(null, statement, block, player, 0, 1, 7);
@@ -49,7 +48,6 @@ public final class HangingBreakByEntityListener extends Queue implements Listene
                         }
 
                         statement.close();
-                        connection.close();
                     }
                     else {
                         Chat.sendMessage(player, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));

src/main/java/net/coreprotect/listener/player/ArmorStandManipulateListener.java

@@ -53,7 +53,6 @@ public final class ArmorStandManipulateListener extends Queue implements Listene
                     class BasicThread implements Runnable {
                         @Override
                         public void run() {
-                            try {
                             if (ConfigHandler.converterRunning) {
                                 Chat.sendMessage(finalPlayer, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.UPGRADE_IN_PROGRESS));
                                 return;
@@ -71,7 +70,7 @@ public final class ArmorStandManipulateListener extends Queue implements Listene
                             }
                             ConfigHandler.lookupThrottle.put(finalPlayer.getName(), new Object[] { true, System.currentTimeMillis() });
 
-                                Connection connection = Database.getConnection(true);
+                            try (Connection connection = Database.getConnection(true)) {
                                 if (connection != null) {
                                     Statement statement = connection.createStatement();
                                     Location standLocation = armorStand.getLocation();
@@ -86,7 +85,6 @@ public final class ArmorStandManipulateListener extends Queue implements Listene
                                         Chat.sendComponent(finalPlayer, blockData);
                                     }
                                     statement.close();
-                                    connection.close();
                                 }
                                 else {
                                     Chat.sendMessage(finalPlayer, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));

src/main/java/net/coreprotect/listener/player/PlayerInteractListener.java

@@ -87,7 +87,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
             class BasicThread implements Runnable {
                 @Override
                 public void run() {
-                    try {
                     if (ConfigHandler.converterRunning) {
                         player.sendMessage(Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.UPGRADE_IN_PROGRESS));
                         return;
@@ -104,7 +103,7 @@ public final class PlayerInteractListener extends Queue implements Listener {
                         }
                     }
 
-                        Connection connection = Database.getConnection(true);
+                    try (Connection connection = Database.getConnection(true)) {
                         if (connection != null) {
                             ConfigHandler.lookupThrottle.put(player.getName(), new Object[] { true, System.currentTimeMillis() });
                             Statement statement = connection.createStatement();
@@ -120,7 +119,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                             }
 
                             statement.close();
-                            connection.close();
                             ConfigHandler.lookupThrottle.put(player.getName(), new Object[] { false, System.currentTimeMillis() });
 
                             if (blockFinal instanceof Sign && player.getGameMode() != GameMode.CREATIVE) {
@@ -185,7 +183,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                         class BasicThread implements Runnable {
                             @Override
                             public void run() {
-                                try {
                                 if (ConfigHandler.converterRunning) {
                                     Chat.sendMessage(player, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.UPGRADE_IN_PROGRESS));
                                     return;
@@ -206,7 +203,7 @@ public final class PlayerInteractListener extends Queue implements Listener {
 
                                 ConfigHandler.lookupThrottle.put(player.getName(), new Object[] { true, System.currentTimeMillis() });
 
-                                    Connection connection = Database.getConnection(true);
+                                try (Connection connection = Database.getConnection(true)) {
                                     if (connection != null) {
                                         Statement statement = connection.createStatement();
                                         List<String> signData = SignMessageLookup.performLookup(null, statement, location, player, 1, 7);
@@ -225,7 +222,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                                         }
 
                                         statement.close();
-                                        connection.close();
                                     }
                                     else {
                                         Chat.sendMessage(player, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));
@@ -269,7 +265,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                         class BasicThread implements Runnable {
                             @Override
                             public void run() {
-                                try {
                                 if (ConfigHandler.converterRunning) {
                                     Chat.sendMessage(player, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.UPGRADE_IN_PROGRESS));
                                     return;
@@ -290,7 +285,7 @@ public final class PlayerInteractListener extends Queue implements Listener {
 
                                 ConfigHandler.lookupThrottle.put(player.getName(), new Object[] { true, System.currentTimeMillis() });
 
-                                    Connection connection = Database.getConnection(true);
+                                try (Connection connection = Database.getConnection(true)) {
                                     if (connection != null) {
                                         Statement statement = connection.createStatement();
                                         String blockData = ChestTransactionLookup.performLookup(null, statement, finalLocation, player, 1, 7, false);
@@ -305,7 +300,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                                         }
 
                                         statement.close();
-                                        connection.close();
                                     }
                                     else {
                                         Chat.sendMessage(player, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));
@@ -340,7 +334,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                         class BasicThread implements Runnable {
                             @Override
                             public void run() {
-                                try {
                                 if (ConfigHandler.converterRunning) {
                                     Chat.sendMessage(player, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.UPGRADE_IN_PROGRESS));
                                     return;
@@ -359,7 +352,7 @@ public final class PlayerInteractListener extends Queue implements Listener {
 
                                 ConfigHandler.lookupThrottle.put(player.getName(), new Object[] { true, System.currentTimeMillis() });
 
-                                    Connection connection = Database.getConnection(true);
+                                try (Connection connection = Database.getConnection(true)) {
                                     if (connection != null) {
                                         Statement statement = connection.createStatement();
                                         String blockData = InteractionLookup.performLookup(null, statement, finalInteractBlock, player, 0, 1, 7);
@@ -374,7 +367,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                                         }
 
                                         statement.close();
-                                        connection.close();
                                     }
                                     else {
                                         Chat.sendMessage(player, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));
@@ -421,7 +413,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                         class BasicThread implements Runnable {
                             @Override
                             public void run() {
-                                try {
                                 if (ConfigHandler.converterRunning) {
                                     Chat.sendMessage(finalPlayer, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.UPGRADE_IN_PROGRESS));
                                     return;
@@ -442,7 +433,7 @@ public final class PlayerInteractListener extends Queue implements Listener {
 
                                 ConfigHandler.lookupThrottle.put(finalPlayer.getName(), new Object[] { true, System.currentTimeMillis() });
 
-                                    Connection connection = Database.getConnection(true);
+                                try (Connection connection = Database.getConnection(true)) {
                                     if (connection != null) {
                                         Statement statement = connection.createStatement();
                                         if (finalBlock.getType().equals(Material.AIR) || finalBlock.getType().equals(Material.CAVE_AIR)) {
@@ -470,7 +461,6 @@ public final class PlayerInteractListener extends Queue implements Listener {
                                         }
 
                                         statement.close();
-                                        connection.close();
                                     }
                                     else {
                                         Chat.sendMessage(finalPlayer, Color.DARK_AQUA + "CoreProtect " + Color.WHITE + "- " + Phrase.build(Phrase.DATABASE_BUSY));

src/main/java/net/coreprotect/patch/Patch.java

@@ -151,10 +151,9 @@ public class Patch {
         int result = -1;
         patching = true;
 
-        try {
+        try (Connection connection = Database.getConnection(true, 0)) {
             boolean patched = false;
             boolean allPatches = true;
-            Connection connection = Database.getConnection(true, 0);
             Statement statement = connection.createStatement();
             Integer[] newVersion = lastVersion;
 
@@ -221,7 +220,6 @@ public class Patch {
             }
 
             statement.close();
-            connection.close();
         }
         catch (Exception e) {
             e.printStackTrace();