YARN-9873. Version Number for each Scheduler Config Change. Contributed by Prabhu Joseph.

(cherry picked from commit be901f49628a553cfe6a3942478cb528cce2b266)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/MutableConfigurationProvider.java

@@ -65,6 +65,12 @@ public interface MutableConfigurationProvider {
    */
   Configuration getConfiguration();
 
+  /**
+   * Get the last updated scheduler config version.
+   * @return Last updated scheduler config version.
+   */
+  long getConfigVersion() throws Exception;
+
   void formatConfigurationInStore(Configuration conf) throws Exception;
 
   void revertToOldConfig(Configuration config) throws Exception;

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/InMemoryConfigurationStore.java

@@ -33,11 +33,13 @@ public class InMemoryConfigurationStore extends YarnConfigurationStore {
 
   private Configuration schedConf;
   private LogMutation pendingMutation;
+  private long configVersion;
 
   @Override
   public void initialize(Configuration conf, Configuration schedConf,
       RMContext rmContext) {
     this.schedConf = schedConf;
+    this.configVersion = 1L;
   }
 
   @Override
@@ -56,6 +58,7 @@ public class InMemoryConfigurationStore extends YarnConfigurationStore {
           schedConf.set(kv.getKey(), kv.getValue());
         }
       }
+      this.configVersion = this.configVersion + 1L;
     }
     pendingMutation = null;
   }
@@ -70,6 +73,11 @@ public class InMemoryConfigurationStore extends YarnConfigurationStore {
     return schedConf;
   }
 
+  @Override
+  public long getConfigVersion() {
+    return configVersion;
+  }
+
   @Override
   public List<LogMutation> getConfirmedConfHistory(long fromId) {
     // Unimplemented.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/LeveldbConfigurationStore.java

@@ -68,8 +68,11 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
   private static final String DB_NAME = "yarn-conf-store";
   private static final String LOG_KEY = "log";
   private static final String VERSION_KEY = "version";
+  private static final String CONF_VERSION_NAME = "conf-version-store";
+  private static final String CONF_VERSION_KEY = "conf-version";
 
   private DB db;
+  private DB versiondb;
   private long maxLogs;
   private Configuration conf;
   private LogMutation pendingMutation;
@@ -102,11 +105,11 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
   public void format() throws Exception {
     close();
     FileSystem fs = FileSystem.getLocal(conf);
-    fs.delete(getStorageDir(), true);
+    fs.delete(getStorageDir(DB_NAME), true);
   }
 
   private void initDatabase(Configuration config) throws Exception {
-    Path storeRoot = createStorageDir();
+    Path storeRoot = createStorageDir(DB_NAME);
     Options options = new Options();
     options.createIfMissing(false);
     options.comparator(new DBComparator() {
@@ -142,6 +145,29 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
       }
     });
 
+    Path confVersion = createStorageDir(CONF_VERSION_NAME);
+    Options confOptions = new Options();
+    confOptions.createIfMissing(false);
+    LOG.info("Using conf version at " + confVersion);
+    File confVersionFile = new File(confVersion.toString());
+    try {
+      versiondb = JniDBFactory.factory.open(confVersionFile, confOptions);
+    } catch (NativeDB.DBException e) {
+      if (e.isNotFound() || e.getMessage().contains(" does not exist ")) {
+        LOG.info("Creating conf version at " + confVersionFile);
+        confOptions.createIfMissing(true);
+        try {
+          versiondb = JniDBFactory.factory.open(confVersionFile, confOptions);
+          versiondb.put(bytes(CONF_VERSION_KEY), bytes(String.valueOf(0)));
+        } catch (DBException dbErr) {
+          throw new IOException(dbErr.getMessage(), dbErr);
+        }
+      } else {
+        throw e;
+      }
+    }
+
+
     LOG.info("Using conf database at " + storeRoot);
     File dbfile = new File(storeRoot.toString());
     try {
@@ -158,6 +184,9 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
             initBatch.put(bytes(kv.getKey()), bytes(kv.getValue()));
           }
           db.write(initBatch);
+          long configVersion = getConfigVersion() + 1L;
+          versiondb.put(bytes(CONF_VERSION_KEY),
+              bytes(String.valueOf(configVersion)));
         } catch (DBException dbErr) {
           throw new IOException(dbErr.getMessage(), dbErr);
         }
@@ -167,20 +196,20 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
     }
   }
 
-  private Path createStorageDir() throws IOException {
-    Path root = getStorageDir();
+  private Path createStorageDir(String storageName) throws IOException {
+    Path root = getStorageDir(storageName);
     FileSystem fs = FileSystem.getLocal(conf);
     fs.mkdirs(root, new FsPermission((short) 0700));
     return root;
   }
 
-  private Path getStorageDir() throws IOException {
+  private Path getStorageDir(String storageName) throws IOException {
     String storePath = conf.get(YarnConfiguration.RM_SCHEDCONF_STORE_PATH);
     if (storePath == null) {
       throw new IOException("No store location directory configured in " +
           YarnConfiguration.RM_SCHEDCONF_STORE_PATH);
     }
-    return new Path(storePath, DB_NAME);
+    return new Path(storePath, storageName);
   }
 
   @Override
@@ -188,6 +217,9 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
     if (db != null) {
       db.close();
     }
+    if (versiondb != null) {
+      versiondb.close();
+    }
   }
 
   @Override
@@ -213,6 +245,9 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
           updateBatch.put(bytes(changes.getKey()), bytes(changes.getValue()));
         }
       }
+      long configVersion = getConfigVersion() + 1L;
+      versiondb.put(bytes(CONF_VERSION_KEY),
+          bytes(String.valueOf(configVersion)));
     }
     db.write(updateBatch);
     pendingMutation = null;
@@ -258,6 +293,13 @@ public class LeveldbConfigurationStore extends YarnConfigurationStore {
     return config;
   }
 
+  @Override
+  public long getConfigVersion() {
+    String version = new String(versiondb.get(bytes(CONF_VERSION_KEY)),
+        StandardCharsets.UTF_8);
+    return Long.parseLong(version);
+  }
+
   @Override
   public List<LogMutation> getConfirmedConfHistory(long fromId) {
     return null; // unimplemented

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/MutableCSConfigurationProvider.java

@@ -117,6 +117,11 @@ public class MutableCSConfigurationProvider implements CSConfigurationProvider,
     return new Configuration(schedConf);
   }
 
+  @Override
+  public long getConfigVersion() throws Exception {
+    return confStore.getConfigVersion();
+  }
+
   @Override
   public ConfigurationMutationACLPolicy getAclMutationPolicy() {
     return aclMutationPolicy;

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/YarnConfigurationStore.java

@@ -131,6 +131,12 @@ public abstract class YarnConfigurationStore {
    */
    public abstract void format() throws Exception;
 
+  /**
+   * Get the last updated config version.
+   * @return Last updated config version.
+   */
+  public abstract long getConfigVersion() throws Exception;
+
   /**
    * Get a list of confirmed configuration mutations starting from a given id.
    * @param fromId id from which to start getting mutations, inclusive

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/ZKConfigurationStore.java

@@ -62,11 +62,13 @@ public class ZKConfigurationStore extends YarnConfigurationStore {
   private static final String LOGS_PATH = "LOGS";
   private static final String CONF_STORE_PATH = "CONF_STORE";
   private static final String FENCING_PATH = "FENCING";
+  private static final String CONF_VERSION_PATH = "CONF_VERSION";
 
   private String zkVersionPath;
   private String logsPath;
   private String confStorePath;
   private String fencingNodePath;
+  private String confVersionPath;
 
   @VisibleForTesting
   protected ZKCuratorManager zkManager;
@@ -89,6 +91,7 @@ public class ZKConfigurationStore extends YarnConfigurationStore {
     this.logsPath = getNodePath(znodeParentPath, LOGS_PATH);
     this.confStorePath = getNodePath(znodeParentPath, CONF_STORE_PATH);
     this.fencingNodePath = getNodePath(znodeParentPath, FENCING_PATH);
+    this.confVersionPath = getNodePath(znodeParentPath, CONF_VERSION_PATH);
 
     zkManager.createRootDirRecursively(znodeParentPath, zkAcl);
     zkManager.delete(fencingNodePath);
@@ -99,6 +102,11 @@ public class ZKConfigurationStore extends YarnConfigurationStore {
           serializeObject(new LinkedList<LogMutation>()), -1);
     }
 
+    if (!zkManager.exists(confVersionPath)) {
+      zkManager.create(confVersionPath);
+      zkManager.setData(confVersionPath, String.valueOf(0), -1);
+    }
+
     if (!zkManager.exists(confStorePath)) {
       zkManager.create(confStorePath);
       HashMap<String, String> mapSchedConf = new HashMap<>();
@@ -106,6 +114,8 @@ public class ZKConfigurationStore extends YarnConfigurationStore {
         mapSchedConf.put(entry.getKey(), entry.getValue());
       }
       zkManager.setData(confStorePath, serializeObject(mapSchedConf), -1);
+      long configVersion = getConfigVersion() + 1L;
+      zkManager.setData(confVersionPath, String.valueOf(configVersion), -1);
     }
   }
 
@@ -185,6 +195,9 @@ public class ZKConfigurationStore extends YarnConfigurationStore {
       }
       zkManager.safeSetData(confStorePath, serializeObject(mapConf), -1,
           zkAcl, fencingNodePath);
+      long configVersion = getConfigVersion() + 1L;
+      zkManager.setData(confVersionPath, String.valueOf(configVersion), -1);
+
     }
     pendingMutation = null;
   }
@@ -213,6 +226,11 @@ public class ZKConfigurationStore extends YarnConfigurationStore {
     return null;
   }
 
+  @Override
+  public long getConfigVersion() throws Exception {
+    return Long.parseLong(zkManager.getStringData(confVersionPath));
+  }
+
   @Override
   public List<LogMutation> getConfirmedConfHistory(long fromId) {
     return null; // unimplemented

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMWSConsts.java

@@ -51,6 +51,9 @@ public final class RMWSConsts {
   /** Path for {@code RMWebServices#formatSchedulerConfiguration}. */
   public static final String FORMAT_SCHEDULER_CONF = "/scheduler-conf/format";
 
+  /** Path for {@code RMWebServices#getSchedulerConfigurationVersion}. */
+  public static final String SCHEDULER_CONF_VERSION = "/scheduler-conf/version";
+
   /** Path for {@code RMWebServiceProtocol#dumpSchedulerLogs}. */
   public static final String SCHEDULER_LOGS = "/scheduler/logs";
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMWebServices.java

@@ -188,6 +188,7 @@ import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.ResourceInfo;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.SchedulerInfo;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.SchedulerTypeInfo;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.StatisticsItemInfo;
+import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.ConfigVersionInfo;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.ConfInfo;
 import org.apache.hadoop.yarn.server.security.ApplicationACLsManager;
 import org.apache.hadoop.yarn.server.utils.BuilderUtils;
@@ -2404,7 +2405,7 @@ public class RMWebServices extends WebServices implements RMWebServiceProtocol {
       }
     } else {
       return Response.status(Status.BAD_REQUEST)
-          .entity("Configuration change only supported by " +
+          .entity("Scheduler Configuration format only supported by " +
           "MutableConfScheduler.").build();
     }
   }
@@ -2443,6 +2444,39 @@ public class RMWebServices extends WebServices implements RMWebServiceProtocol {
     }
   }
 
+  @GET
+  @Path(RMWSConsts.SCHEDULER_CONF_VERSION)
+  @Produces({ MediaType.APPLICATION_JSON + "; " + JettyUtils.UTF_8,
+       MediaType.APPLICATION_XML + "; " + JettyUtils.UTF_8 })
+  public Response getSchedulerConfigurationVersion(@Context
+      HttpServletRequest hsr) throws AuthorizationException {
+    // Only admin user is allowed to get scheduler conf version
+    UserGroupInformation callerUGI = getCallerUserGroupInformation(hsr, true);
+    initForWritableEndpoints(callerUGI, true);
+
+    ResourceScheduler scheduler = rm.getResourceScheduler();
+    if (scheduler instanceof MutableConfScheduler
+        && ((MutableConfScheduler) scheduler).isConfigurationMutable()) {
+      MutableConfigurationProvider mutableConfigurationProvider =
+          ((MutableConfScheduler) scheduler).getMutableConfProvider();
+
+      try {
+        long configVersion = mutableConfigurationProvider
+            .getConfigVersion();
+        return Response.status(Status.OK)
+            .entity(new ConfigVersionInfo(configVersion)).build();
+      } catch (Exception e) {
+        LOG.error("Exception thrown when fetching configuration version.", e);
+        return Response.status(Status.BAD_REQUEST).entity(e.getMessage())
+            .build();
+      }
+    } else {
+      return Response.status(Status.BAD_REQUEST)
+          .entity("Configuration Version only supported by "
+          + "MutableConfScheduler.").build();
+    }
+  }
+
   @GET
   @Path(RMWSConsts.CHECK_USER_ACCESS_TO_QUEUE)
   @Produces({ MediaType.APPLICATION_JSON + "; " + JettyUtils.UTF_8,

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/dao/ConfigVersionInfo.java

@@ -0,0 +1,44 @@
+/**
+ * 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.yarn.server.resourcemanager.webapp.dao;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlRootElement;
+
+/**
+ * Version of Scheduler Config.
+ */
+@XmlRootElement(name = "configversion")
+@XmlAccessorType(XmlAccessType.FIELD)
+public class ConfigVersionInfo {
+
+  private long versionID;
+
+  public ConfigVersionInfo() {
+  } // JAXB needs this
+
+  public ConfigVersionInfo(long version) {
+    this.versionID = version;
+  }
+
+  public long getVersionID() {
+    return this.versionID;
+  }
+
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/TestZKConfigurationStore.java

@@ -137,6 +137,21 @@ public class TestZKConfigurationStore extends ConfigurationStoreBaseTest {
     assertNull(confStore.retrieve());
   }
 
+  @Test
+  public void testGetConfigurationVersion() throws Exception {
+    confStore.initialize(conf, schedConf, rmContext);
+    long v1 = confStore.getConfigVersion();
+    assertEquals(1, v1);
+    Map<String, String> update = new HashMap<>();
+    update.put("keyver", "valver");
+    YarnConfigurationStore.LogMutation mutation =
+        new YarnConfigurationStore.LogMutation(update, TEST_USER);
+    confStore.logMutation(mutation);
+    confStore.confirmMutation(true);
+    long v2 = confStore.getConfigVersion();
+    assertEquals(2, v2);
+  }
+
   @Test
   public void testPersistUpdatedConfiguration() throws Exception {
     confStore.initialize(conf, schedConf, rmContext);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/TestRMWebServicesConfigurationMutation.java

@@ -228,6 +228,25 @@ public class TestRMWebServicesConfigurationMutation extends JerseyTestBase {
     assertEquals(3, newConf.getQueues("root").length);
   }
 
+  private long getConfigVersion() throws Exception {
+    WebResource r = resource();
+    ClientResponse response = r.path("ws").path("v1").path("cluster")
+        .queryParam("user.name", userName)
+        .path(RMWSConsts.SCHEDULER_CONF_VERSION)
+        .accept(MediaType.APPLICATION_JSON).get(ClientResponse.class);
+    assertEquals(Status.OK.getStatusCode(), response.getStatus());
+
+    JSONObject json = response.getEntity(JSONObject.class);
+    return Long.parseLong(json.get("versionID").toString());
+  }
+
+  @Test
+  public void testSchedulerConfigVersion() throws Exception {
+    assertEquals(1, getConfigVersion());
+    testAddNestedQueue();
+    assertEquals(2, getConfigVersion());
+  }
+
   @Test
   public void testAddNestedQueue() throws Exception {
     CapacitySchedulerConfiguration orgConf = getSchedulerConf();