YARN-9873. Mutation API Config Change updates Version Number. Contributed by Prabhu Joseph

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 @@ void logAndApplyMutation(UserGroupInformation user, SchedConfUpdateInfo
    */
   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;
 
   /**

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

@@ -148,6 +148,13 @@ public void confirmMutation(boolean isValid) throws Exception {
     tempConfigPath = null;
   }
 
+  @Override
+  public long getConfigVersion() throws Exception {
+    String version = getLatestConfigPath().getName().
+        substring(YarnConfiguration.CS_CONFIGURATION_FILE.length() + 1);
+    return Long.parseLong(version);
+  }
+
   private void finalizeFileSystemFile() throws IOException {
     // call confirmMutation() make sure tempConfigPath is not null
     Path finalConfigPath = getFinalConfigPath(tempConfigPath);

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 = System.currentTimeMillis();
   }
 
   @Override
@@ -57,6 +59,7 @@ public void confirmMutation(boolean isValid) {
         }
       }
     }
+    this.configVersion = System.currentTimeMillis();
     pendingMutation = null;
   }
 
@@ -70,6 +73,11 @@ public synchronized Configuration retrieve() {
     return schedConf;
   }
 
+  @Override
+  public long getConfigVersion() throws Exception {
+    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

@@ -68,6 +68,7 @@ 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_KEY = "conf-version";
 
   private DB db;
   private long maxLogs;
@@ -124,6 +125,10 @@ public int compare(byte[] key1, byte[] key2) {
           return 1;
         } else if (key2Str.equals(LOG_KEY)) {
           return -1;
+        } else if (key1Str.equals(CONF_VERSION_KEY)) {
+          return 1;
+        } else if (key2Str.equals(CONF_VERSION_KEY)) {
+          return -1;
         }
         return key1Str.compareTo(key2Str);
       }
@@ -146,6 +151,10 @@ public byte[] findShortSuccessor(byte[] key) {
     File dbfile = new File(storeRoot.toString());
     try {
       db = JniDBFactory.factory.open(dbfile, options);
+      if (db.get(bytes(CONF_VERSION_KEY)) == null) {
+        db.put(bytes(CONF_VERSION_KEY),
+            bytes(String.valueOf(System.currentTimeMillis())));
+      }
     } catch (NativeDB.DBException e) {
       if (e.isNotFound() || e.getMessage().contains(" does not exist ")) {
         LOG.info("Creating conf database at " + dbfile);
@@ -158,6 +167,8 @@ public byte[] findShortSuccessor(byte[] key) {
             initBatch.put(bytes(kv.getKey()), bytes(kv.getValue()));
           }
           db.write(initBatch);
+          db.put(bytes(CONF_VERSION_KEY),
+              bytes(String.valueOf(System.currentTimeMillis())));
         } catch (DBException dbErr) {
           throw new IOException(dbErr.getMessage(), dbErr);
         }
@@ -215,6 +226,8 @@ public void confirmMutation(boolean isValid) throws IOException {
       }
     }
     db.write(updateBatch);
+    db.put(bytes(CONF_VERSION_KEY),
+        bytes(String.valueOf(System.currentTimeMillis())));
     pendingMutation = null;
   }
 
@@ -250,7 +263,8 @@ public synchronized Configuration retrieve() {
       Map.Entry<byte[], byte[]> entry = itr.next();
       String key = new String(entry.getKey(), StandardCharsets.UTF_8);
       String value = new String(entry.getValue(), StandardCharsets.UTF_8);
-      if (key.equals(LOG_KEY) || key.equals(VERSION_KEY)) {
+      if (key.equals(LOG_KEY) || key.equals(VERSION_KEY) ||
+          key.equals(CONF_VERSION_KEY)) {
         break;
       }
       config.set(key, value);
@@ -258,6 +272,13 @@ public synchronized Configuration retrieve() {
     return config;
   }
 
+  @Override
+  public long getConfigVersion() throws Exception {
+    String version = new String(db.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

@@ -134,6 +134,11 @@ public Configuration getConfiguration() {
     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

@@ -132,6 +132,12 @@ public void close() throws IOException {}
    */
   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 void initialize(Configuration config, Configuration schedConf,
     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 +102,12 @@ public void initialize(Configuration config, Configuration schedConf,
           serializeObject(new LinkedList<LogMutation>()), -1);
     }
 
+    if (!zkManager.exists(confVersionPath)) {
+      zkManager.create(confVersionPath);
+      zkManager.setData(confVersionPath,
+          String.valueOf(System.currentTimeMillis()), -1);
+    }
+
     if (!zkManager.exists(confStorePath)) {
       zkManager.create(confStorePath);
       HashMap<String, String> mapSchedConf = new HashMap<>();
@@ -106,6 +115,8 @@ public void initialize(Configuration config, Configuration schedConf,
         mapSchedConf.put(entry.getKey(), entry.getValue());
       }
       zkManager.setData(confStorePath, serializeObject(mapSchedConf), -1);
+      zkManager.setData(confVersionPath,
+          String.valueOf(System.currentTimeMillis()), -1);
     }
   }
 
@@ -185,6 +196,9 @@ public void confirmMutation(boolean isValid)
       }
       zkManager.safeSetData(confStorePath, serializeObject(mapConf), -1,
           zkAcl, fencingNodePath);
+      zkManager.setData(confVersionPath,
+          String.valueOf(System.currentTimeMillis()), -1);
+
     }
     pendingMutation = null;
   }
@@ -213,6 +227,11 @@ public synchronized Configuration retrieve() {
     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

@@ -2590,7 +2590,7 @@ public Response formatSchedulerConfiguration(@Context HttpServletRequest hsr)
       }
     } else {
       return Response.status(Status.BAD_REQUEST)
-          .entity("Configuration change only supported by " +
+          .entity("Scheduler Configuration format only supported by " +
           "MutableConfScheduler.").build();
     }
   }
@@ -2680,6 +2680,38 @@ public Response getSchedulerConfiguration(@Context HttpServletRequest hsr)
     }
   }
 
+  @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(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/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/TestZKConfigurationStore.java

@@ -137,6 +137,21 @@ public void testFormatConfiguration() throws Exception {
     assertNull(confStore.retrieve());
   }
 
+  @Test
+  public void testGetConfigurationVersion() throws Exception {
+    confStore.initialize(conf, schedConf, rmContext);
+    long v1 = confStore.getConfigVersion();
+    Thread.sleep(2000);
+    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();
+    assertTrue(v2 > v1);
+  }
+
   @Test
   public void testPersistUpdatedConfiguration() throws Exception {
     confStore.initialize(conf, schedConf, rmContext);