refactor(config): Dependency Inversion on ConfigManager and `C… (#491)

Signed-off-by: Tobias Nett <[email protected]>

src/main/java/org/terasology/launcher/config/ConfigManager.java

@@ -41,11 +41,12 @@ public class ConfigManager {
     private static final String CONFIG_FILE = "config.json";
     private static volatile ConfigManager instance;
 
-    private final Path launcherDir;
+    private final Path launcherPath;
     private final Path configPath;
+    private final ConfigValidator validator;
     private final Gson gson;
     private Config config;
-    private final Service<Void> reader;
+    private final Service<Config> reader;
     private final Service<Void> writer;
 
     private ConfigManager() {
@@ -54,20 +55,26 @@ private ConfigManager() {
             throw new RuntimeException("Cannot create second instance of a singleton class");
         }
 
-        launcherDir = resolveLauncherDir();
-        configPath = launcherDir.resolve(CONFIG_FILE);
-        config = createDefaultConfig();
+        launcherPath = resolveLauncherDir();
+        configPath = launcherPath.resolve(CONFIG_FILE);
+        config = getDefaultConfigFor(launcherPath);
         gson = new GsonBuilder()
                 .registerTypeAdapter(Path.class, new PathAdapter())
                 .registerTypeAdapter(Package.class, new PackageAdapter())
                 .disableHtmlEscaping()
                 .setPrettyPrinting()
                 .create();
+        validator = new ConfigValidator(config);
 
-        reader = new ConfigReader(this);
-        writer = new ConfigWriter(this);
+        reader = new ConfigReader(configPath, launcherPath, gson, validator);
+        writer = new ConfigWriter(configPath, gson, config);
     }
 
+    /**
+     * Resolve the path to the launcher directory for host operating system.
+     *
+     * @return the absolute path to the launcher application directory
+     */
     private Path resolveLauncherDir() {
         final OperatingSystem os = OperatingSystem.getOS();
         if (os == OperatingSystem.UNKNOWN) {
@@ -82,19 +89,27 @@ private Path resolveLauncherDir() {
         // TODO: Use local methods for all stuff above
     }
 
-    private Config createDefaultConfig() {
+    /**
+     * The default configuration of the launcher with installation and data directories inside `launcherDir`.
+     *
+     * @param launcherDir the absolute path to launcher application directory
+     * @return the default configuration
+     */
+    private Config getDefaultConfigFor(final Path launcherDir) {
+        final GameConfig gameConfig = GameConfig.builder()
+                .installDir(launcherDir.resolve("Terasology"))
+                .dataDir(launcherDir.resolve("TerasologyData"))
+                .maxMemory(JavaHeapSize.GB_1_5)
+                .initMemory(JavaHeapSize.GB_1)
+                .javaParam("-XX:+UseParNewGC"
+                        + " -XX:+UseConcMarkSweepGC"
+                        + " -XX:MaxGCPauseMillis=20"
+                        + " -XX:ParallelGCThreads=10")
+                .logLevel(LogLevel.DEFAULT)
+                .build();
+
         return Config.builder()
-                .gameConfig(GameConfig.builder()
-                        .installDir(launcherDir.resolve("Terasology"))
-                        .dataDir(launcherDir.resolve("TerasologyData"))
-                        .maxMemory(JavaHeapSize.GB_1_5)
-                        .initMemory(JavaHeapSize.GB_1)
-                        .javaParam("-XX:+UseParNewGC"
-                                + " -XX:+UseConcMarkSweepGC"
-                                + " -XX:MaxGCPauseMillis=20"
-                                + " -XX:ParallelGCThreads=10")
-                        .logLevel(LogLevel.DEFAULT)
-                        .build())
+                .gameConfig(gameConfig)
                 .locale(Locale.ENGLISH)
                 .launcherDir(launcherDir)
                 .checkUpdatesOnLaunch(false)
@@ -110,7 +125,7 @@ private Config createDefaultConfig() {
      *
      * @return the reader service
      */
-    public Service<Void> getReader() {
+    public Service<Config> getReader() {
         return reader;
     }
 
@@ -125,8 +140,8 @@ public Service<Void> getWriter() {
         return writer;
     }
 
-    Path getLauncherDir() {
-        return launcherDir;
+    Path getLauncherPath() {
+        return launcherPath;
     }
 
     Path getConfigPath() {
@@ -138,17 +153,20 @@ Gson getGson() {
     }
 
     /**
-     * Provides an immutable {@link Config} instance. It is
-     * initially filled with default configurations which
-     * are reset after reader service is run.
+     * Provides an immutable {@link Config} instance.
      *
-     * @return the default {@link Config} instance
+     * The initial default configuration may be changed by running the reader service.
+     *
+     * @return the current launcher configuration as {@link Config} instance
      */
     public Config getConfig() {
         return config;
     }
 
-    void setConfig(Config config) {
+    void setConfig(final Config config) {
+        if (config == null) {
+            throw new IllegalArgumentException("Configuration 'config'  must not be 'null'!");
+        }
         this.config = config;
     }
 
@@ -160,11 +178,7 @@ void setConfig(Config config) {
     public static ConfigManager get() {
         // Double check locking
         if (instance == null) {
-            synchronized (ConfigManager.class) {
-                if (instance == null) {
-                    instance = new ConfigManager();
-                }
-            }
+            instance = new ConfigManager();
         }
         return instance;
     }

src/main/java/org/terasology/launcher/config/ConfigReader.java

@@ -16,6 +16,7 @@
 
 package org.terasology.launcher.config;
 
+import com.google.gson.Gson;
 import javafx.concurrent.Service;
 import javafx.concurrent.Task;
 import org.slf4j.Logger;
@@ -32,32 +33,35 @@
  * On success the {@link Config} instance is validated
  * and provided back to the {@link ConfigManager}.
  */
-class ConfigReader extends Service<Void> {
+class ConfigReader extends Service<Config> {
     private static final Logger logger = LoggerFactory.getLogger(ConfigReader.class);
 
-    private final ConfigManager manager;
     private final Path configPath;
+    private final Path launcherPath;
+    private final Gson decoder;
     private final ConfigValidator validator;
 
-    ConfigReader(ConfigManager manager) {
-        this.manager = manager;
-        configPath = manager.getConfigPath();
-        validator = new ConfigValidator(manager.getConfig());
+    ConfigReader(final Path configPath, final Path launcherPath, final Gson decoder, final ConfigValidator validator) {
+        this.configPath = configPath;
+        this.launcherPath = launcherPath;
+        this.decoder = decoder;
+        this.validator = validator;
     }
 
     @Override
-    protected Task<Void> createTask() {
-        return new Task<Void>() {
+    protected Task<Config> createTask() {
+        return new Task<Config>() {
             @Override
-            protected Void call() throws IOException {
+            protected Config call() throws IOException {
                 if (Files.exists(configPath)) {
                     try (BufferedReader reader = new BufferedReader(
                             new InputStreamReader(Files.newInputStream(configPath))
                     )) {
-                        final Config config = manager.getGson().fromJson(reader, Config.Builder.class)
-                                .launcherDir(manager.getLauncherDir())
+                        final Config config = decoder.fromJson(reader, Config.Builder.class)
+                                .launcherDir(launcherPath)
                                 .build();
-                        manager.setConfig(validator.validate(config));
+
+                        return validator.validate(config);
                     }
                 } else {
                     logger.warn("Config file was not found: {}", configPath);

src/main/java/org/terasology/launcher/config/ConfigValidator.java

@@ -28,10 +28,10 @@
 class ConfigValidator {
     private static final Logger logger = LoggerFactory.getLogger(ConfigValidator.class);
 
-    private final Config defaultConfig;
+    private final Config fallbackConfiguration;
 
     ConfigValidator(final Config defaultConfig) {
-        this.defaultConfig = defaultConfig;
+        this.fallbackConfiguration = defaultConfig;
     }
 
     /**
@@ -67,7 +67,7 @@ private JavaHeapSize validateMaxMemory(final GameConfig gameConfig) {
         ) {
             valid = gameConfig.getMaxMemory();
         } else {
-            valid = defaultConfig.getGameConfig().getMaxMemory();
+            valid = fallbackConfiguration.getGameConfig().getMaxMemory();
             logger.warn("Max memory cannot be greater than 1.5 GB for a 32-bit JVM");
             logger.debug("Continuing with max memory: {}", valid);
         }

src/main/java/org/terasology/launcher/config/ConfigWriter.java

@@ -16,6 +16,7 @@
 
 package org.terasology.launcher.config;
 
+import com.google.gson.Gson;
 import javafx.concurrent.Service;
 import javafx.concurrent.Task;
 import org.slf4j.Logger;
@@ -34,12 +35,22 @@
 class ConfigWriter extends Service<Void> {
     private static final Logger logger = LoggerFactory.getLogger(ConfigWriter.class);
 
-    private final ConfigManager manager;
     private final Path configPath;
+    private final Gson encoder;
 
-    ConfigWriter(ConfigManager manager) {
-        this.manager = manager;
-        configPath = manager.getConfigPath();
+    private Config config;
+
+    ConfigWriter(final Path configPath, final Gson encoder, final Config config) {
+        this.configPath = configPath;
+        this.encoder = encoder;
+        this.config = config;
+    }
+
+    public void setConfig(final Config config) {
+        if (config == null) {
+            throw new IllegalArgumentException("Configuration instance 'config' must not be 'null'!");
+        }
+        this.config = config;
     }
 
     @Override
@@ -50,7 +61,7 @@ protected Void call() throws IOException {
                 try (BufferedWriter writer = new BufferedWriter(
                         new OutputStreamWriter(Files.newOutputStream(configPath))
                 )) {
-                    manager.getGson().toJson(manager.getConfig(), Config.class, writer);
+                    encoder.toJson(config, Config.class, writer);
                 }
                 return null;
             }