HDFS-12350. Support meta tags in configs. Contributed by Ajay Kumar.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java

@@ -259,7 +259,18 @@ public String toString() {
    */
   private static final WeakHashMap<Configuration,Object> REGISTRY = 
     new WeakHashMap<Configuration,Object>();
-  
+
+  /**
+   * Map to register all classes holding property tag enums.
+   */
+  private static final Map<String, Class>
+      REGISTERED_TAG_CLASS = new HashMap<>();
+  /**
+   * Map to hold properties by there tag groupings.
+   */
+  private final Map<PropertyTag, Properties> propertyTagsMap =
+      new ConcurrentHashMap<>();
+
   /**
    * List of default Resources. Resources are loaded in the order of the list 
    * entries
@@ -738,6 +749,12 @@ public Configuration() {
   public Configuration(boolean loadDefaults) {
     this.loadDefaults = loadDefaults;
     updatingResource = new ConcurrentHashMap<String, String[]>();
+
+    // Register all classes holding property tags with
+    REGISTERED_TAG_CLASS.put("core", CorePropertyTag.class);
+    REGISTERED_TAG_CLASS.put("hdfs", HDFSPropertyTag.class);
+    REGISTERED_TAG_CLASS.put("yarn", YarnPropertyTag.class);
+
     synchronized(Configuration.class) {
       REGISTRY.put(this, null);
     }
@@ -765,6 +782,8 @@ public Configuration(Configuration other) {
      this.finalParameters = Collections.newSetFromMap(
          new ConcurrentHashMap<String, Boolean>());
      this.finalParameters.addAll(other.finalParameters);
+     this.REGISTERED_TAG_CLASS.putAll(other.REGISTERED_TAG_CLASS);
+     this.propertyTagsMap.putAll(other.propertyTagsMap);
    }
    
     synchronized(Configuration.class) {
@@ -2823,6 +2842,10 @@ private Resource loadResource(Properties properties,
               } else if ("source".equals(propertyAttr)) {
                 confSource.add(StringInterner.weakIntern(
                     reader.getAttributeValue(i)));
+              } else if ("tag".equals(propertyAttr)) {
+                //Read tags and put them in propertyTagsMap
+                readTagFromConfig(reader.getAttributeValue(i), confName,
+                    confValue, confSource);
               }
             }
             break;
@@ -2830,6 +2853,7 @@ private Resource loadResource(Properties properties,
           case "value":
           case "final":
           case "source":
+          case "tag":
             parseToken = true;
             token.setLength(0);
             break;
@@ -2911,6 +2935,13 @@ private Resource loadResource(Properties properties,
           case "source":
             confSource.add(StringInterner.weakIntern(token.toString()));
             break;
+          case "tag":
+            if (token.length() > 0) {
+              //Read tags and put them in propertyTagsMap
+              readTagFromConfig(token.toString(), confName,
+                  confValue, confSource);
+            }
+            break;
           case "include":
             if (fallbackAllowed && !fallbackEntered) {
               throw new IOException("Fetch fail on include for '"
@@ -2962,6 +2993,48 @@ private Resource loadResource(Properties properties,
     }
   }
 
+  private void readTagFromConfig(String attributeValue, String confName, String
+      confValue, List<String> confSource) {
+    for (String tagStr : attributeValue.split(",")) {
+      tagStr = tagStr.trim();
+      try {
+        if (confSource.size() > 0) {
+          for (String source : confSource) {
+            PropertyTag tag1 = this.getPropertyTag(tagStr,
+                source.split("-")[0]);
+            if (propertyTagsMap.containsKey(tag1)) {
+              propertyTagsMap.get(tag1)
+                  .setProperty(confName, confValue);
+            } else {
+              Properties props = new Properties();
+              props.setProperty(confName, confValue);
+              propertyTagsMap.put(tag1, props);
+            }
+          }
+        } else {
+          //If no source is set try to find tag in CorePropertyTag
+          if (propertyTagsMap
+              .containsKey(CorePropertyTag.valueOf(tagStr)
+              )) {
+            propertyTagsMap.get(CorePropertyTag.valueOf(tagStr))
+                .setProperty(confName, confValue);
+          } else {
+            Properties props = new Properties();
+            props.setProperty(confName, confValue);
+            propertyTagsMap.put(CorePropertyTag.valueOf(tagStr),
+                props);
+          }
+        }
+      } catch (IllegalArgumentException iae) {
+        //Log the invalid tag and continue to parse rest of the
+        // properties.
+        LOG.info("Invalid tag '" + tagStr + "' found for "
+            + "property:" + confName, iae);
+      }
+
+    }
+  }
+
   private void overlay(Properties to, Properties from) {
     for (Entry<Object, Object> entry: from.entrySet()) {
       to.put(entry.getKey(), entry.getValue());
@@ -3438,4 +3511,45 @@ public static boolean hasWarnedDeprecation(String name) {
     }
     return false;
   }
+
+  /**
+   * Get all properties belonging to tag.
+   * @return Properties with matching properties
+   */
+  public Properties getAllPropertiesByTag(final PropertyTag tag) {
+    Properties props = new Properties();
+    if (propertyTagsMap.containsKey(tag)) {
+      props.putAll(propertyTagsMap.get(tag));
+    }
+    return props;
+  }
+
+  /**
+   * Get all properties belonging to list of input tags. Calls
+   * getAllPropertiesByTag internally.
+   *
+   * @return Properties with all matching properties
+   */
+  public Properties getAllPropertiesByTags(final List<PropertyTag> tagList) {
+    Properties prop = new Properties();
+    for (PropertyTag tag : tagList) {
+      prop.putAll(this.getAllPropertiesByTag(tag));
+    }
+    return prop;
+  }
+
+  /**
+   * Get Property tag Enum corresponding to given source.
+   *
+   * @param tagStr String representation of Enum
+   * @param group Group to which enum belongs.Ex hdfs,yarn
+   * @return Properties with all matching properties
+   */
+  private PropertyTag getPropertyTag(String tagStr, String group) {
+    PropertyTag tag = null;
+    if (REGISTERED_TAG_CLASS.containsKey(group)) {
+      tag = (PropertyTag) Enum.valueOf(REGISTERED_TAG_CLASS.get(group), tagStr);
+    }
+    return tag;
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/CorePropertyTag.java

@@ -0,0 +1,37 @@
+/**
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.conf;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/***************************************************************************
+ * Enum for tagging hadoop core properties according to there usage.
+ * CorePropertyTag implements the
+ * {@link org.apache.hadoop.conf.PropertyTag} interface,
+ ***************************************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public enum CorePropertyTag implements PropertyTag {
+  CORE,
+  REQUIRED,
+  PERFORMANCE,
+  CLIENT,
+  SERVER,
+  SECURITY,
+  DEBUG
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/HDFSPropertyTag.java

@@ -0,0 +1,41 @@
+/**
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.conf;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/***************************************************************************
+ * Enum for tagging hdfs properties according to there usage or application.
+ * HDFSPropertyTag implements the
+ * {@link org.apache.hadoop.conf.PropertyTag} interface,
+ ***************************************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public enum HDFSPropertyTag implements PropertyTag {
+  HDFS,
+  NAMENODE,
+  DATANODE,
+  REQUIRED,
+  SECURITY,
+  KERBEROS,
+  PERFORMANCE,
+  CLIENT,
+  SERVER,
+  DEBUG,
+  DEPRICATED
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/PropertyTag.java

@@ -0,0 +1,30 @@
+/**
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.conf;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/***********************************************************
+ * PropertyTag is used for creating extendable property tag Enums.
+ * Property tags will group related properties together.
+ ***********************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public interface PropertyTag {
+
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/YarnPropertyTag.java

@@ -0,0 +1,39 @@
+/**
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.conf;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/***************************************************************************
+ * Enum for tagging yarn properties according to there usage or application.
+ * YarnPropertyTag implements the
+ * {@link org.apache.hadoop.conf.PropertyTag} interface,
+ ***************************************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public enum YarnPropertyTag implements PropertyTag {
+  YARN,
+  RESOURCEMANAGER,
+  SECURITY,
+  KERBEROS,
+  PERFORMANCE,
+  CLIENT,
+  REQUIRED,
+  SERVER,
+  DEBUG
+}

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java

@@ -38,6 +38,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Properties;
 import java.util.Random;
 import java.util.Set;
 import java.util.regex.Pattern;
@@ -53,7 +54,6 @@
 
 import org.apache.commons.lang.StringUtils;
 import org.apache.hadoop.conf.Configuration.IntegerRanges;
-import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.io.IOUtils;
@@ -135,6 +135,7 @@ private void writeConfiguration() throws IOException{
 
   private void endConfig() throws IOException{
     out.write("</configuration>\n");
+    out.flush();
     out.close();
   }
 
@@ -577,6 +578,34 @@ void appendProperty(String name, String val, boolean isFinal,
     out.write("</property>\n");
   }
 
+  private void appendPropertyByTag(String name, String val, String tags,
+      String... sources) throws IOException {
+    appendPropertyByTag(name, val, false, tags, sources);
+  }
+
+  private void appendPropertyByTag(String name, String val, boolean isFinal,
+      String tag, String... sources) throws IOException {
+    out.write("<property>");
+    out.write("<name>");
+    out.write(name);
+    out.write("</name>");
+    out.write("<value>");
+    out.write(val);
+    out.write("</value>");
+    if (isFinal) {
+      out.write("<final>true</final>");
+    }
+    for (String s : sources) {
+      out.write("<source>");
+      out.write(s);
+      out.write("</source>");
+    }
+    out.write("<tag>");
+    out.write(tag);
+    out.write("</tag>");
+    out.write("</property>\n");
+  }
+
   void appendCompactFormatProperty(String name, String val) throws IOException {
     appendCompactFormatProperty(name, val, false);
   }
@@ -2215,4 +2244,85 @@ public static void main(String[] argv) throws Exception {
       TestConfiguration.class.getName()
     });
   }
+
+  @Test
+  public void testGetAllPropertiesByTags() throws Exception {
+
+    out = new BufferedWriter(new FileWriter(CONFIG));
+    startConfig();
+    appendPropertyByTag("dfs.cblock.trace.io", "false", "DEBUG");
+    appendPropertyByTag("dfs.replication", "1", "PERFORMANCE,REQUIRED");
+    appendPropertyByTag("dfs.namenode.logging.level", "INFO", "CLIENT,DEBUG");
+    endConfig();
+
+    Path fileResource = new Path(CONFIG);
+    conf.addResource(fileResource);
+    conf.getProps();
+
+    List<PropertyTag> tagList = new ArrayList<>();
+    tagList.add(CorePropertyTag.REQUIRED);
+    tagList.add(CorePropertyTag.PERFORMANCE);
+    tagList.add(CorePropertyTag.DEBUG);
+    tagList.add(CorePropertyTag.CLIENT);
+
+    Properties properties = conf.getAllPropertiesByTags(tagList);
+    assertEq(3, properties.size());
+    assertEq(true, properties.containsKey("dfs.namenode.logging.level"));
+    assertEq(true, properties.containsKey("dfs.replication"));
+    assertEq(true, properties.containsKey("dfs.cblock.trace.io"));
+    assertEq(false, properties.containsKey("namenode.host"));
+  }
+
+  @Test
+  public void testGetAllPropertiesWithSourceByTags() throws Exception {
+
+    out = new BufferedWriter(new FileWriter(CONFIG));
+    startConfig();
+    appendPropertyByTag("dfs.cblock.trace.io", "false", "DEBUG",
+        "hdfs-default.xml", "core-site.xml");
+    appendPropertyByTag("dfs.replication", "1", "PERFORMANCE,HDFS",
+        "hdfs-default.xml");
+    appendPropertyByTag("yarn.resourcemanager.work-preserving-recovery"
+        + ".enabled", "INFO", "CLIENT,DEBUG", "yarn-default.xml", "yarn-site"
+        + ".xml");
+    endConfig();
+
+    Path fileResource = new Path(CONFIG);
+    conf.addResource(fileResource);
+    conf.getProps();
+
+    List<PropertyTag> tagList = new ArrayList<>();
+    tagList.add(CorePropertyTag.REQUIRED);
+
+    Properties properties;
+    properties = conf.getAllPropertiesByTags(tagList);
+    assertNotEquals(3, properties.size());
+
+    tagList.add(HDFSPropertyTag.DEBUG);
+    tagList.add(YarnPropertyTag.CLIENT);
+    tagList.add(HDFSPropertyTag.PERFORMANCE);
+    tagList.add(HDFSPropertyTag.HDFS);
+    properties = conf.getAllPropertiesByTags(tagList);
+    assertEq(3, properties.size());
+
+    assertEq(true, properties.containsKey("dfs.cblock.trace.io"));
+    assertEq(true, properties.containsKey("dfs.replication"));
+    assertEq(true, properties
+        .containsKey("yarn.resourcemanager.work-preserving-recovery.enabled"));
+    assertEq(false, properties.containsKey("namenode.host"));
+
+    tagList.clear();
+    tagList.add(HDFSPropertyTag.DEBUG);
+    properties = conf.getAllPropertiesByTags(tagList);
+    assertEq(true, properties.containsKey("dfs.cblock.trace.io"));
+    assertEq(false, properties.containsKey("yarn.resourcemanager"
+        + ".work-preserving-recovery"));
+
+    tagList.clear();
+    tagList.add(YarnPropertyTag.DEBUG);
+    properties = conf.getAllPropertiesByTags(tagList);
+    assertEq(false, properties.containsKey("dfs.cblock.trace.io"));
+    assertEq(true, properties.containsKey("yarn.resourcemanager"
+        + ".work-preserving-recovery.enabled"));
+  }
 }