added shared database access and file based migrations to core

core/src/main/java/eu/mhsl/craftattack/spawn/core/Main.java

@@ -4,6 +4,7 @@ import eu.mhsl.craftattack.spawn.core.api.client.RepositoryLoader;
 import eu.mhsl.craftattack.spawn.core.api.server.HttpServer;
 import eu.mhsl.craftattack.spawn.core.appliance.Appliance;
 import eu.mhsl.craftattack.spawn.core.config.Configuration;
+import eu.mhsl.craftattack.spawn.core.database.Database;
 import org.bukkit.Bukkit;
 import org.bukkit.event.HandlerList;
 import org.bukkit.plugin.java.JavaPlugin;
@@ -23,6 +24,7 @@ public final class Main extends JavaPlugin {
 
     private List<Appliance> appliances;
     private RepositoryLoader repositoryLoader;
+    private Database database;
     private Reflections reflections;
 
     @Override
@@ -42,6 +44,8 @@ public final class Main extends JavaPlugin {
         Configuration.readConfig();
         List<String> disabledAppliances = Configuration.pluginConfig.getStringList("disabledAppliances");
 
+        this.database = new Database(Configuration.cfg.getConfigurationSection("database"));
+
         Main.logger().info("Initializing reflections...");
         this.reflections = new Reflections(projectPackage);
 
@@ -94,6 +98,8 @@ public final class Main extends JavaPlugin {
         HandlerList.unregisterAll(this);
         Bukkit.getScheduler().cancelTasks(this);
         Main.logger().info("Disabled " + this.appliances.size() + " appliances!");
+
+        if(this.database != null) this.database.close();
     }
 
     public Appliance restartAppliance(Class<? extends Appliance> applianceClass) {
@@ -138,6 +144,10 @@ public final class Main extends JavaPlugin {
         return this.appliances;
     }
 
+    public Database getDatabase() {
+        return this.database;
+    }
+
     public RepositoryLoader getRepositoryLoader() {
         return this.repositoryLoader;
     }

core/src/main/java/eu/mhsl/craftattack/spawn/core/appliance/Appliance.java

@@ -4,6 +4,7 @@ import eu.mhsl.craftattack.spawn.core.Main;
 import eu.mhsl.craftattack.spawn.core.api.client.Repository;
 import eu.mhsl.craftattack.spawn.core.api.server.HttpServer;
 import eu.mhsl.craftattack.spawn.core.config.Configuration;
+import eu.mhsl.craftattack.spawn.core.database.Migrations;
 import org.bukkit.Bukkit;
 import org.bukkit.command.PluginCommand;
 import org.bukkit.configuration.ConfigurationSection;
@@ -107,6 +108,7 @@ public abstract class Appliance {
     }
 
     public void enableSequence(JavaPlugin plugin) {
+        Migrations.apply(Main.instance().getDatabase(), this.migrationsName());
         this.onEnable();
         this.initialize(plugin);
     }
@@ -116,6 +118,14 @@ public abstract class Appliance {
         this.destruct(plugin);
     }
 
+    /**
+     * Name of the folder containing this appliance's SQL migrations: {@code migrations/<name>/} in the resources.
+     */
+    private String migrationsName() {
+        String name = this.getClass().getSimpleName();
+        return Character.toLowerCase(name.charAt(0)) + name.substring(1);
+    }
+
     protected <T extends Appliance> T queryAppliance(Class<T> clazz) {
         return Main.instance().getAppliance(clazz);
     }

core/src/main/java/eu/mhsl/craftattack/spawn/core/database/Database.java

@@ -0,0 +1,131 @@
+package eu.mhsl.craftattack.spawn.core.database;
+
+import eu.mhsl.craftattack.spawn.core.Main;
+import org.bukkit.configuration.ConfigurationSection;
+import org.jetbrains.annotations.Nullable;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+
+/**
+ * Shared MariaDB access for all appliances. Configured in the "database" section of the config.
+ * All statements run on a single background thread in submission order, so callers (e.g. login events)
+ * are never blocked. Without configuration the database is unavailable and all calls are ignored.
+ */
+public class Database {
+    @FunctionalInterface
+    public interface SqlAction {
+        void run(Connection connection) throws SQLException;
+    }
+
+    @FunctionalInterface
+    public interface SqlQuery<T> {
+        T run(Connection connection) throws SQLException;
+    }
+
+    private final @Nullable String jdbcUrl;
+    private final String user;
+    private final String password;
+    private final ThreadPoolExecutor executor = new ThreadPoolExecutor(
+        1, 1, 0, TimeUnit.MILLISECONDS,
+        new ArrayBlockingQueue<>(1000),
+        runnable -> new Thread(runnable, "Spawn-Database"),
+        (runnable, executor) -> Main.logger().warning("Database queue full, dropping statement")
+    );
+    private @Nullable Connection connection;
+
+    public Database(@Nullable ConfigurationSection config) {
+        String host = config == null ? "" : config.getString("host", "");
+        if(host.isBlank()) {
+            this.jdbcUrl = null;
+            this.user = "";
+            this.password = "";
+            Main.logger().info("No database configured, database features are disabled");
+            return;
+        }
+
+        this.jdbcUrl = String.format(
+            "jdbc:mysql://%s:%d/%s?connectTimeout=3000&socketTimeout=10000&allowMultiQueries=true",
+            host,
+            config.getInt("port", 3306),
+            config.getString("name", "craftattack")
+        );
+        this.user = config.getString("user", "");
+        this.password = config.getString("password", "");
+    }
+
+    public boolean isAvailable() {
+        return this.jdbcUrl != null;
+    }
+
+    /**
+     * Runs the action in the background without waiting for it. Errors are logged.
+     */
+    public void execute(String description, SqlAction action) {
+        if(!this.isAvailable()) return;
+        this.executor.execute(() -> {
+            try {
+                action.run(this.getConnection());
+            } catch(SQLException e) {
+                this.handleError(description, e);
+            }
+        });
+    }
+
+    /**
+     * Runs the query in the background. The future fails if the database is unavailable or the query fails.
+     */
+    public <T> CompletableFuture<T> query(SqlQuery<T> query) {
+        CompletableFuture<T> future = new CompletableFuture<>();
+        if(!this.isAvailable()) {
+            future.completeExceptionally(new IllegalStateException("No database configured"));
+            return future;
+        }
+        this.executor.execute(() -> {
+            try {
+                future.complete(query.run(this.getConnection()));
+            } catch(SQLException e) {
+                this.closeConnection();
+                future.completeExceptionally(e);
+            }
+        });
+        return future;
+    }
+
+    public void close() {
+        this.executor.shutdown();
+        try {
+            if(!this.executor.awaitTermination(5, TimeUnit.SECONDS))
+                Main.logger().warning("Database: pending statements were not finished before shutdown");
+        } catch(InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+        this.closeConnection();
+    }
+
+    private Connection getConnection() throws SQLException {
+        if(this.connection == null || !this.connection.isValid(2))
+            this.connection = DriverManager.getConnection(this.jdbcUrl, this.user, this.password);
+        return this.connection;
+    }
+
+    private void closeConnection() {
+        if(this.connection == null) return;
+        try {
+            this.connection.close();
+        } catch(SQLException ignored) {
+        }
+        this.connection = null;
+    }
+
+    private void handleError(String description, SQLException e) {
+        Main.logger().log(Level.WARNING, String.format("Database: %s failed: %s", description, e.getMessage()));
+        this.closeConnection();
+    }
+}

core/src/main/java/eu/mhsl/craftattack/spawn/core/database/Migrations.java

@@ -0,0 +1,138 @@
+package eu.mhsl.craftattack.spawn.core.database;
+
+import eu.mhsl.craftattack.spawn.core.Main;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Applies SQL migration files shipped in the plugin jar.
+ * Files live in {@code migrations/<appliance>/NNN_description.sql} and run in ascending order of NNN.
+ * Applied versions are tracked per appliance in the table {@code schema_migrations}.
+ */
+public class Migrations {
+    private static final String DIRECTORY = "migrations/";
+    private static final Pattern FILE_PATTERN = Pattern.compile("^([^/]+)/(\\d+)_[^/]+\\.sql$");
+    private static Map<String, List<Migration>> migrationsByAppliance;
+
+    private record Migration(int version, String fileName, String path) {
+    }
+
+    /**
+     * Queues all pending migrations of the appliance on the database thread,
+     * so they run before any statement the appliance submits afterwards.
+     */
+    public static void apply(Database database, String appliance) {
+        List<Migration> migrations = findMigrations().getOrDefault(appliance, List.of());
+        if(migrations.isEmpty()) return;
+
+        if(!database.isAvailable()) {
+            Main.logger().warning(String.format("Appliance '%s' has migrations, but no database is configured", appliance));
+            return;
+        }
+
+        database.execute("migrations of " + appliance, connection -> {
+            createMigrationTable(connection);
+            Set<Integer> applied = appliedVersions(connection, appliance);
+            for(Migration migration : migrations) {
+                if(applied.contains(migration.version())) continue;
+                Main.logger().info(String.format("Applying migration %s/%s", appliance, migration.fileName()));
+                try(Statement statement = connection.createStatement()) {
+                    statement.execute(readResource(migration.path()));
+                }
+                markApplied(connection, appliance, migration);
+            }
+        });
+    }
+
+    private static synchronized Map<String, List<Migration>> findMigrations() {
+        if(migrationsByAppliance != null) return migrationsByAppliance;
+        Map<String, List<Migration>> migrations = new HashMap<>();
+        try(JarFile jar = new JarFile(pluginJar())) {
+            jar.stream()
+                .map(JarEntry::getName)
+                .filter(name -> name.startsWith(DIRECTORY))
+                .forEach(path -> {
+                    Matcher matcher = FILE_PATTERN.matcher(path.substring(DIRECTORY.length()));
+                    if(!matcher.matches()) return;
+                    String fileName = path.substring(path.lastIndexOf('/') + 1);
+                    migrations.computeIfAbsent(matcher.group(1), appliance -> new ArrayList<>())
+                        .add(new Migration(Integer.parseInt(matcher.group(2)), fileName, path));
+                });
+        } catch(IOException e) {
+            throw new IllegalStateException("Could not read migrations from plugin jar", e);
+        }
+        migrations.values().forEach(list -> list.sort(Comparator.comparingInt(Migration::version)));
+        migrationsByAppliance = migrations;
+        return migrations;
+    }
+
+    private static void createMigrationTable(Connection connection) throws SQLException {
+        try(Statement statement = connection.createStatement()) {
+            statement.execute("""
+                CREATE TABLE IF NOT EXISTS schema_migrations (
+                    appliance VARCHAR(64) NOT NULL,
+                    version INT NOT NULL,
+                    file_name VARCHAR(255) NOT NULL,
+                    applied_at DATETIME NOT NULL DEFAULT UTC_TIMESTAMP(),
+                    PRIMARY KEY (appliance, version)
+                ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
+                """);
+        }
+    }
+
+    private static Set<Integer> appliedVersions(Connection connection, String appliance) throws SQLException {
+        Set<Integer> versions = new HashSet<>();
+        try(PreparedStatement statement = connection.prepareStatement("SELECT version FROM schema_migrations WHERE appliance = ?")) {
+            statement.setString(1, appliance);
+            try(ResultSet result = statement.executeQuery()) {
+                while(result.next()) versions.add(result.getInt(1));
+            }
+        }
+        return versions;
+    }
+
+    private static void markApplied(Connection connection, String appliance, Migration migration) throws SQLException {
+        try(PreparedStatement statement = connection.prepareStatement("INSERT INTO schema_migrations (appliance, version, file_name) VALUES (?, ?, ?)")) {
+            statement.setString(1, appliance);
+            statement.setInt(2, migration.version());
+            statement.setString(3, migration.fileName());
+            statement.executeUpdate();
+        }
+    }
+
+    private static String readResource(String path) throws SQLException {
+        try(InputStream stream = Main.class.getClassLoader().getResourceAsStream(path)) {
+            if(stream == null) throw new SQLException("Migration file not found: " + path);
+            return new String(stream.readAllBytes(), StandardCharsets.UTF_8);
+        } catch(IOException e) {
+            throw new SQLException("Could not read migration file " + path, e);
+        }
+    }
+
+    private static File pluginJar() {
+        try {
+            return new File(Main.class.getProtectionDomain().getCodeSource().getLocation().toURI());
+        } catch(Exception e) {
+            throw new IllegalStateException("Could not locate plugin jar", e);
+        }
+    }
+}