HDDS-1468. Inject configuration values to Java objects

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/Config.java

@@ -0,0 +1,47 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdds.conf;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Mark field to be configurable from ozone-site.xml.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Config {
+
+  /**
+   * Configuration fragment relative to the prefix defined with @ConfigGroup.
+   */
+  String key();
+
+  /**
+   * Type of configuration. Use AUTO to decide it based on the java type.
+   */
+  ConfigType type() default ConfigType.AUTO;
+
+  /**
+   * If type == TIME the unit should be defined with this attribute.
+   */
+  TimeUnit timeUnit() default TimeUnit.MILLISECONDS;
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/ConfigGroup.java

@@ -0,0 +1,32 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdds.conf;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Mark pojo which holds configuration variables.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface ConfigGroup {
+  String prefix();
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/ConfigType.java

@@ -0,0 +1,34 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdds.conf;
+
+/**
+ * Possible type of injected configuration.
+ * <p>
+ * AUTO means that the exact type will be identified based on the java type of
+ * the configuration field.
+ */
+public enum ConfigType {
+  AUTO,
+  STRING,
+  BOOLEAN,
+  INT,
+  LONG,
+  TIME,
+  SIZE
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/ConfigurationException.java

@@ -0,0 +1,34 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdds.conf;
+
+/**
+ * Exeception to throw in case of a configuration problem.
+ */
+public class ConfigurationException extends RuntimeException {
+  public ConfigurationException() {
+  }
+
+  public ConfigurationException(String message) {
+    super(message);
+  }
+
+  public ConfigurationException(String message, Throwable cause) {
+    super(message, cause);
+  }
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/OzoneConfiguration.java

@@ -28,6 +28,8 @@
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.XmlRootElement;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Enumeration;
@@ -61,6 +63,108 @@ public List<Property> readPropertyFromXml(URL url) throws JAXBException {
     return config.getProperties();
   }
 
+  /**
+   * Create a Configuration object and inject the required configuration values.
+   *
+   * @param configurationClass The class where the fields are annotated with
+   *                           the configuration.
+   * @return Initiated java object where the config fields are injected.
+   */
+  public <T> T getObject(Class<T> configurationClass) {
+
+    T configuration;
+
+    try {
+      configuration = configurationClass.newInstance();
+    } catch (InstantiationException | IllegalAccessException e) {
+      throw new ConfigurationException(
+          "Configuration class can't be created: " + configurationClass, e);
+    }
+    ConfigGroup configGroup =
+        configurationClass.getAnnotation(ConfigGroup.class);
+    String prefix = configGroup.prefix();
+
+    for (Method setterMethod : configurationClass.getMethods()) {
+      if (setterMethod.isAnnotationPresent(Config.class)) {
+
+        String methodLocation =
+            configurationClass + "." + setterMethod.getName();
+
+        Config configAnnotation = setterMethod.getAnnotation(Config.class);
+
+        String key = prefix + "." + configAnnotation.key();
+
+        Class<?>[] parameterTypes = setterMethod.getParameterTypes();
+        if (parameterTypes.length != 1) {
+          throw new ConfigurationException(
+              "@Config annotation should be used on simple setter: "
+                  + methodLocation);
+        }
+
+        ConfigType type = configAnnotation.type();
+
+        if (type == ConfigType.AUTO) {
+          type = detectConfigType(parameterTypes[0], methodLocation);
+        }
+
+        //Note: default value is handled by ozone-default.xml. Here we can
+        //use any default.
+        try {
+          switch (type) {
+          case STRING:
+            setterMethod.invoke(configuration, get(key));
+            break;
+          case INT:
+            setterMethod.invoke(configuration,
+                getInt(key, 0));
+            break;
+          case BOOLEAN:
+            setterMethod.invoke(configuration,
+                getBoolean(key, false));
+            break;
+          case LONG:
+            setterMethod.invoke(configuration,
+                getLong(key, 0));
+            break;
+          case TIME:
+            setterMethod.invoke(configuration,
+                getTimeDuration(key, 0, configAnnotation.timeUnit()));
+            break;
+          default:
+            throw new ConfigurationException(
+                "Unsupported ConfigType " + type + " on " + methodLocation);
+          }
+        } catch (InvocationTargetException | IllegalAccessException e) {
+          throw new ConfigurationException(
+              "Can't inject configuration to " + methodLocation, e);
+        }
+
+      }
+    }
+    return configuration;
+
+  }
+
+  private ConfigType detectConfigType(Class<?> parameterType,
+      String methodLocation) {
+    ConfigType type;
+    if (parameterType == String.class) {
+      type = ConfigType.STRING;
+    } else if (parameterType == Integer.class || parameterType == int.class) {
+      type = ConfigType.INT;
+    } else if (parameterType == Long.class || parameterType == long.class) {
+      type = ConfigType.LONG;
+    } else if (parameterType == Boolean.class
+        || parameterType == boolean.class) {
+      type = ConfigType.BOOLEAN;
+    } else {
+      throw new ConfigurationException(
+          "Unsupported configuration type " + parameterType + " in "
+              + methodLocation);
+    }
+    return type;
+  }
+
   /**
    * Class to marshall/un-marshall configuration from xml files.
    */
@@ -145,7 +249,7 @@ public String toString() {
     }
 
     @Override
-    public int hashCode(){
+    public int hashCode() {
       return this.getName().hashCode();
     }
 
@@ -169,6 +273,7 @@ public static void activate() {
    * does not override values of properties
    * if there is no tag present in the configs of
    * newly added resources.
+   *
    * @param tag
    * @return Properties that belong to the tag
    */
@@ -181,7 +286,7 @@ public Properties getAllPropertiesByTag(String tag) {
     Properties props = new Properties();
     Enumeration properties = propertiesByTag.propertyNames();
     while (properties.hasMoreElements()) {
-      Object propertyName =  properties.nextElement();
+      Object propertyName = properties.nextElement();
       // get the current value of the property
       Object value = updatedProps.getProperty(propertyName.toString());
       if (value != null) {

hadoop-hdds/common/src/test/java/org/apache/hadoop/hdds/conf/SimpleConfiguration.java

@@ -0,0 +1,83 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdds.conf;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Example configuration to test the configuration injection.
+ */
+@ConfigGroup(prefix = "ozone.scm.client")
+public class SimpleConfiguration {
+
+  private String clientAddress;
+
+  private String bindHost;
+
+  private boolean enabled;
+
+  private int port = 1234;
+
+  private long waitTime = 1;
+
+  @Config(key = "address")
+  public void setClientAddress(String clientAddress) {
+    this.clientAddress = clientAddress;
+  }
+
+  @Config(key = "bind.host")
+  public void setBindHost(String bindHost) {
+    this.bindHost = bindHost;
+  }
+
+  @Config(key = "enabled")
+  public void setEnabled(boolean enabled) {
+    this.enabled = enabled;
+  }
+
+  @Config(key = "port")
+  public void setPort(int port) {
+    this.port = port;
+  }
+
+  @Config(key = "wait", type = ConfigType.TIME, timeUnit =
+      TimeUnit.SECONDS)
+  public void setWaitTime(long waitTime) {
+    this.waitTime = waitTime;
+  }
+
+  public String getClientAddress() {
+    return clientAddress;
+  }
+
+  public String getBindHost() {
+    return bindHost;
+  }
+
+  public boolean isEnabled() {
+    return enabled;
+  }
+
+  public int getPort() {
+    return port;
+  }
+
+  public long getWaitTime() {
+    return waitTime;
+  }
+}