Refactor SPI interfaces (#149)

* refactor SPI

* only static spi

* Revert log changes

* Move all the ServiceLoader use into ConfigServiceLoader

* Rename ConfigSPI to ConfigExtension

* Remove unused META-INF/services/io.avaje.config.ConfigurationPlugin

As this is replaced by the generated one for ConfigExtension

* Move the initalisation of Parsers into ConfigServiceLoader so that it happens once.

* Improve javadoc for ConfigServiceLoader

---------

Co-authored-by: Rob Bygrave <robin.bygrave@gmail.com>

avaje-aws-appconfig/pom.xml

@@ -28,9 +28,16 @@
     <dependency>
       <groupId>io.avaje</groupId>
       <artifactId>avaje-config</artifactId>
-      <version>3.15-RC1</version>
+      <version>4.0-RC1</version>
       <scope>provided</scope>
     </dependency>
+
+    <dependency>
+      <groupId>io.avaje</groupId>
+      <artifactId>avaje-spi-service</artifactId>
+      <version>1.4</version>
+      <optional>true</optional>
+    </dependency>
 
     <dependency>
       <groupId>io.avaje</groupId>

avaje-aws-appconfig/src/main/java/io/avaje/config/appconfig/AppConfigPlugin.java

@@ -1,23 +1,29 @@
 package io.avaje.config.appconfig;
 
-import io.avaje.applog.AppLog;
-import io.avaje.config.ConfigParser;
-import io.avaje.config.Configuration;
-import io.avaje.config.ConfigurationSource;
+import static java.lang.System.Logger.Level.DEBUG;
+import static java.lang.System.Logger.Level.ERROR;
+import static java.lang.System.Logger.Level.INFO;
+import static java.lang.System.Logger.Level.TRACE;
+import static java.lang.System.Logger.Level.WARNING;
 
 import java.io.StringReader;
 import java.time.Instant;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.ReentrantLock;
 
-import static java.lang.System.Logger.Level.*;
+import io.avaje.applog.AppLog;
+import io.avaje.config.ConfigParser;
+import io.avaje.config.Configuration;
+import io.avaje.config.ConfigurationSource;
+import io.avaje.spi.ServiceProvider;
 
 /**
  * Plugin that loads AWS AppConfig as Yaml or Properties.
  * <p>
  * By default, will periodically reload the configuration if it has changed.
  */
+@ServiceProvider
 public final class AppConfigPlugin implements ConfigurationSource {
 
   private static final System.Logger log = AppLog.getLogger("io.avaje.config.AwsAppConfig");

avaje-aws-appconfig/src/main/java/module-info.java

@@ -1,3 +1,4 @@
+import io.avaje.config.ConfigExtension;
 import io.avaje.config.appconfig.AppConfigPlugin;
 
 module io.avaje.config.appconfig {
@@ -7,5 +8,6 @@
   requires io.avaje.config;
   requires java.net.http;
   requires transitive io.avaje.applog;
-  provides io.avaje.config.ConfigurationSource with AppConfigPlugin;
+  requires static io.avaje.spi;
+  provides ConfigExtension with AppConfigPlugin;
 }

avaje-config/pom.xml

@@ -10,7 +10,7 @@
 
   <groupId>io.avaje</groupId>
   <artifactId>avaje-config</artifactId>
-  <version>3.15-RC1</version>
+  <version>4.0-RC1</version>
 
   <scm>
     <developerConnection>scm:git:git@github.com:avaje/avaje-config.git</developerConnection>
@@ -31,6 +31,13 @@
       <version>1.1</version>
     </dependency>
 
+    <dependency>
+      <groupId>io.avaje</groupId>
+      <artifactId>avaje-spi-service</artifactId>
+      <version>1.4</version>
+      <optional>true</optional>
+    </dependency>
+
     <dependency>
       <groupId>io.avaje</groupId>
       <artifactId>avaje-applog</artifactId>

avaje-config/src/main/java/io/avaje/config/ConfigExtension.java

@@ -0,0 +1,23 @@
+package io.avaje.config;
+
+import io.avaje.spi.Service;
+
+/**
+ * Super interface for all extensions to avaje-config which are loaded via ServiceLoader.
+ * <p>
+ * Extend avaje-config by implementing one of the following extension interfaces below and
+ * have it registered with {@link java.util.ServiceLoader} as a {@link ConfigExtension}.
+ *
+ * <h4>Extensions</h4>
+ * <ul>
+ *   <li>{@link ConfigParser}</li>
+ *   <li>{@link ConfigurationLog}</li>
+ *   <li>{@link ConfigurationPlugin}</li>
+ *   <li>{@link ConfigurationSource}</li>
+ *   <li>{@link ResourceLoader}</li>
+ *   <li>{@link ModificationEventRunner}</li>
+ * </ul>
+ */
+@Service
+public interface ConfigExtension {
+}

avaje-config/src/main/java/io/avaje/config/ConfigParser.java

@@ -10,7 +10,7 @@
  * Load a config file into a flattened map.
  */
 @NonNullApi
-public interface ConfigParser {
+public interface ConfigParser extends ConfigExtension {
 
   /**
    * File extensions Supported by this parser

avaje-config/src/main/java/io/avaje/config/ConfigServiceLoader.java

@@ -0,0 +1,77 @@
+package io.avaje.config;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.ServiceLoader;
+
+/**
+ * Load all the avaje-config extensions via ServiceLoader using the single
+ * common ConfigExtension interface.
+ */
+final class ConfigServiceLoader {
+
+  private static final ConfigServiceLoader INSTANCE = new ConfigServiceLoader();
+
+  static ConfigServiceLoader get() {
+    return INSTANCE;
+  }
+
+  private final ConfigurationLog log;
+  private final ResourceLoader resourceLoader;
+  private final ModificationEventRunner eventRunner;
+  private final List<ConfigurationSource> sources = new ArrayList<>();
+  private final List<ConfigurationPlugin> plugins = new ArrayList<>();
+  private final Parsers parsers;
+
+  ConfigServiceLoader() {
+    ModificationEventRunner _eventRunner = null;
+    ConfigurationLog _log = null;
+    ResourceLoader _resourceLoader = null;
+    List<ConfigParser> otherParsers = new ArrayList<>();
+
+    for (var spi : ServiceLoader.load(ConfigExtension.class)) {
+      if (spi instanceof ConfigurationSource) {
+        sources.add((ConfigurationSource) spi);
+      } else if (spi instanceof ConfigurationPlugin) {
+        plugins.add((ConfigurationPlugin) spi);
+      } else if (spi instanceof ConfigParser) {
+        otherParsers.add((ConfigParser) spi);
+      } else if (spi instanceof ConfigurationLog) {
+        _log = (ConfigurationLog) spi;
+      } else if (spi instanceof ResourceLoader) {
+        _resourceLoader = (ResourceLoader) spi;
+      } else if (spi instanceof ModificationEventRunner) {
+        _eventRunner = (ModificationEventRunner) spi;
+      }
+    }
+
+    this.log = _log == null ? new DefaultConfigurationLog() : _log;
+    this.resourceLoader = _resourceLoader == null ? new DefaultResourceLoader() : _resourceLoader;
+    this.eventRunner = _eventRunner == null ? new CoreConfiguration.ForegroundEventRunner() : _eventRunner;
+    this.parsers = new Parsers(otherParsers);
+  }
+
+  Parsers parsers() {
+    return parsers;
+  }
+
+  ConfigurationLog log() {
+    return log;
+  }
+
+  ResourceLoader resourceLoader() {
+    return resourceLoader;
+  }
+
+  ModificationEventRunner eventRunner() {
+    return eventRunner;
+  }
+
+  List<ConfigurationSource> sources() {
+    return sources;
+  }
+
+  List<ConfigurationPlugin> plugins() {
+    return plugins;
+  }
+}

avaje-config/src/main/java/io/avaje/config/ConfigurationLog.java

@@ -9,7 +9,7 @@
  * control how the events are logged. For example, it might delay logging messages
  * until logging implementation has finished configuration.
  */
-public interface ConfigurationLog {
+public interface ConfigurationLog extends ConfigExtension {
 
   /**
    * Invoked when the configuration is being initialised.

avaje-config/src/main/java/io/avaje/config/ConfigurationPlugin.java

@@ -5,7 +5,7 @@
 /**
  * Plugin that is initiated after the configuration has been loaded.
  */
-public interface ConfigurationPlugin {
+public interface ConfigurationPlugin extends ConfigExtension {
 
   /**
    * Apply the plugin. Typically, a plugin might read configuration and do something

avaje-config/src/main/java/io/avaje/config/ConfigurationSource.java

@@ -3,7 +3,7 @@
 /**
  * Additional source to load and update configuration.
  */
-public interface ConfigurationSource {
+public interface ConfigurationSource extends ConfigExtension {
 
   /**
    * Load additional configuration.

avaje-config/src/main/java/io/avaje/config/CoreComponents.java

@@ -19,10 +19,11 @@ final class CoreComponents {
     this.plugins = plugins;
   }
 
+  /** For testing only */
   CoreComponents() {
     this.runner = new CoreConfiguration.ForegroundEventRunner();
     this.log = new DefaultConfigurationLog();
-    this.parsers = new Parsers();
+    this.parsers = new Parsers(Collections.emptyList());
     this.sources = Collections.emptyList();
     this.plugins = Collections.emptyList();
   }

avaje-config/src/main/java/io/avaje/config/CoreConfigurationBuilder.java

@@ -8,8 +8,6 @@
 import java.io.UncheckedIOException;
 import java.util.Map;
 import java.util.Properties;
-import java.util.ServiceLoader;
-import java.util.stream.Collectors;
 
 import static java.lang.System.Logger.Level.DEBUG;
 import static java.lang.System.Logger.Level.INFO;
@@ -18,20 +16,15 @@
 @NonNullApi
 final class CoreConfigurationBuilder implements Configuration.Builder {
 
-  private ConfigurationLog log = initialiseLog();
-  private final Parsers parsers = new Parsers();
   private final CoreEntry.CoreMap sourceMap = CoreEntry.newMap();
-  private ResourceLoader resourceLoader = initialiseResourceLoader();
-  private ModificationEventRunner eventRunner;
+  private final ConfigServiceLoader serviceLoader = ConfigServiceLoader.get();
+  private final Parsers parsers = serviceLoader.parsers();
+  private ConfigurationLog log = serviceLoader.log();
+  private ResourceLoader resourceLoader = serviceLoader.resourceLoader();
+  private ModificationEventRunner eventRunner = serviceLoader.eventRunner();
   private boolean includeResourceLoading;
   private InitialLoader initialLoader;
 
-  private static ConfigurationLog initialiseLog() {
-    return ServiceLoader.load(ConfigurationLog.class)
-        .findFirst()
-        .orElseGet(DefaultConfigurationLog::new);
-  }
-
   @Override
   public Configuration.Builder eventRunner(ModificationEventRunner eventRunner) {
     this.eventRunner = requireNonNull(eventRunner);
@@ -137,15 +130,7 @@ public Configuration.Builder includeResourceLoading() {
 
   @Override
   public Configuration build() {
-    final var runner = initRunner();
-    final var sources = ServiceLoader.load(ConfigurationSource.class).stream()
-      .map(ServiceLoader.Provider::get)
-      .collect(Collectors.toList());
-    final var plugins = ServiceLoader.load(ConfigurationPlugin.class).stream()
-      .map(ServiceLoader.Provider::get)
-      .collect(Collectors.toList());
-
-    var components = new CoreComponents(runner, log, parsers, sources, plugins);
+    var components = new CoreComponents(eventRunner, log, parsers, serviceLoader.sources(), serviceLoader.plugins());
     if (includeResourceLoading) {
       log.preInitialisation();
       initialLoader = new InitialLoader(components, resourceLoader);
@@ -162,19 +147,4 @@ private CoreEntry.CoreMap initEntries() {
   private CoreEntry.CoreMap initEntryMap() {
     return initialLoader == null ? CoreEntry.newMap() : initialLoader.load();
   }
-
-  private static ResourceLoader initialiseResourceLoader() {
-    return ServiceLoader.load(ResourceLoader.class)
-      .findFirst()
-      .orElseGet(DefaultResourceLoader::new);
-  }
-
-  private ModificationEventRunner initRunner() {
-    if (eventRunner == null) {
-      eventRunner = ServiceLoader.load(ModificationEventRunner.class)
-        .findFirst()
-        .orElseGet(CoreConfiguration.ForegroundEventRunner::new);
-    }
-    return eventRunner;
-  }
 }

avaje-config/src/main/java/io/avaje/config/ModificationEventRunner.java

@@ -9,7 +9,7 @@
  * The default is for event listener notification to be executed using the same thread
  * that is making the modifications to the configuration.
  */
-public interface ModificationEventRunner {
+public interface ModificationEventRunner extends ConfigExtension {
 
   /**
    * Run the task of notifying all the event listeners of a modification event

avaje-config/src/main/java/io/avaje/config/Parsers.java

@@ -1,8 +1,8 @@
 package io.avaje.config;
 
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
-import java.util.ServiceLoader;
 import java.util.Set;
 
 /**
@@ -12,13 +12,13 @@ final class Parsers {
 
   private final Map<String, ConfigParser> parserMap = new HashMap<>();
 
-  Parsers() {
+  Parsers(List<ConfigParser> otherParsers) {
     parserMap.put("properties", new PropertiesParser());
     if (!"true".equals(System.getProperty("skipYaml"))) {
       initYamlParser();
     }
     if (!"true".equals(System.getProperty("skipCustomParsing"))) {
-      initParsers();
+      initParsers(otherParsers);
     }
   }
 
@@ -34,12 +34,12 @@ private void initYamlParser() {
     parserMap.put("yaml", yamlLoader);
   }
 
-  private void initParsers() {
-    ServiceLoader.load(ConfigParser.class).forEach(p -> {
-      for (var ext : p.supportedExtensions()) {
-        parserMap.put(ext, p);
+  private void initParsers(List<ConfigParser> otherParsers) {
+    for (ConfigParser parser : otherParsers) {
+      for (var ext : parser.supportedExtensions()) {
+        parserMap.put(ext, parser);
       }
-    });
+    }
   }
 
   /**

avaje-config/src/main/java/io/avaje/config/ResourceLoader.java

@@ -13,7 +13,7 @@
  * Note there is a fallback to use {@link ClassLoader#getSystemResourceAsStream(String)}
  * if the ResourceLoader returns null.
  */
-public interface ResourceLoader {
+public interface ResourceLoader extends ConfigExtension {
 
   /**
    * Return the InputStream for the given resource or null if it can not be found.

avaje-config/src/main/java/module-info.java

@@ -6,11 +6,8 @@
   requires transitive io.avaje.applog;
   requires static org.yaml.snakeyaml;
 
-  uses io.avaje.config.ConfigParser;
-  uses io.avaje.config.ConfigurationLog;
-  uses io.avaje.config.ConfigurationPlugin;
-  uses io.avaje.config.ModificationEventRunner;
-  uses io.avaje.config.ConfigurationSource;
-  uses io.avaje.config.ResourceLoader;
+  requires static io.avaje.spi;
+
+  uses io.avaje.config.ConfigExtension;
 
 }