HDFS-11133. Ozone: Add allocateContainer RPC. Contributed by Anu Engineer

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/container/common/utils/LevelDBStore.java

@@ -52,6 +52,22 @@ public class LevelDBStore {
     this.dbFile = dbPath;
   }
 
+  /**
+   * Opens a DB file.
+   *
+   * @param dbPath          - DB File path
+   * @throws IOException
+   */
+  public LevelDBStore(File dbPath, Options options)
+      throws IOException {
+    db = JniDBFactory.factory.open(dbPath, options);
+    if (db == null) {
+      throw new IOException("Db is null");
+    }
+    this.dbFile = dbPath;
+  }
+
+
   /**
    * Puts a Key into file.
    *

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/protocol/StorageContainerLocationProtocol.java

@@ -22,6 +22,7 @@ import java.io.IOException;
 import java.util.Set;
 
 import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.scm.container.common.helpers.Pipeline;
 
 /**
  * ContainerLocationProtocol is used by an HDFS node to find the set of nodes
@@ -41,4 +42,13 @@ public interface StorageContainerLocationProtocol {
    */
   Set<LocatedContainer> getStorageContainerLocations(Set<String> keys)
       throws IOException;
+
+  /**
+   * Asks SCM where a container should be allocated. SCM responds with the
+   * set of datanodes that should be used creating this container.
+   * @param containerName - Name of the container.
+   * @return Pipeline.
+   * @throws IOException
+   */
+  Pipeline allocateContainer(String containerName) throws IOException;
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/protocolPB/StorageContainerLocationProtocolClientSideTranslatorPB.java

@@ -1,42 +1,44 @@
 /**
- * Licensed to the Apache Software Foundation (ASF) under one
+ * Licensed to the Apache Software Foundation (ASF) under one or more
- * or more contributor license agreements.  See the NOTICE file
+ * contributor license agreements.  See the NOTICE file distributed with this
- * distributed with this work for additional information
+ * work for additional information regarding copyright ownership.  The ASF
- * regarding copyright ownership.  The ASF licenses this file
+ * licenses this file to you under the Apache License, Version 2.0 (the
- * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
- * "License"); you may not use this file except in compliance
+ * You may obtain a copy of the License at
- * with the License.  You may obtain a copy of the License at
+ * <p>
- *
+ * http://www.apache.org/licenses/LICENSE-2.0
- *     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,
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * See the License for the specific language governing permissions and
+ * License for the specific language governing permissions and limitations under
- * limitations under the License.
+ * the License.
  */
 package org.apache.hadoop.ozone.protocolPB;
 
-import java.io.Closeable;
+import com.google.common.base.Preconditions;
-import java.io.IOException;
-import java.util.Set;
-
 import com.google.common.collect.Sets;
 import com.google.protobuf.RpcController;
 import com.google.protobuf.ServiceException;
-
 import org.apache.hadoop.classification.InterfaceAudience;
-import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeInfoProto;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
+import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeInfoProto;
 import org.apache.hadoop.hdfs.protocolPB.PBHelperClient;
 import org.apache.hadoop.ipc.ProtobufHelper;
 import org.apache.hadoop.ipc.ProtocolTranslator;
 import org.apache.hadoop.ipc.RPC;
 import org.apache.hadoop.ozone.protocol.LocatedContainer;
 import org.apache.hadoop.ozone.protocol.StorageContainerLocationProtocol;
+import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.ContainerRequestProto;
+import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.ContainerResponseProto;
 import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.GetStorageContainerLocationsRequestProto;
 import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.GetStorageContainerLocationsResponseProto;
 import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.LocatedContainerProto;
+import org.apache.hadoop.scm.container.common.helpers.Pipeline;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.Set;
 
 /**
  * This class is the client-side translator to translate the requests made on
@@ -47,7 +49,9 @@ import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolPr
 public final class StorageContainerLocationProtocolClientSideTranslatorPB
     implements StorageContainerLocationProtocol, ProtocolTranslator, Closeable {
 
-  /** RpcController is not used and hence is set to null. */
+  /**
+   * RpcController is not used and hence is set to null.
+   */
   private static final RpcController NULL_RPC_CONTROLLER = null;
 
   private final StorageContainerLocationProtocolPB rpcProxy;
@@ -67,7 +71,7 @@ public final class StorageContainerLocationProtocolClientSideTranslatorPB
       throws IOException {
     GetStorageContainerLocationsRequestProto.Builder req =
         GetStorageContainerLocationsRequestProto.newBuilder();
-    for (String key: keys) {
+    for (String key : keys) {
       req.addKeys(key);
     }
     final GetStorageContainerLocationsResponseProto resp;
@@ -79,11 +83,11 @@ public final class StorageContainerLocationProtocolClientSideTranslatorPB
     }
     Set<LocatedContainer> locatedContainers =
         Sets.newLinkedHashSetWithExpectedSize(resp.getLocatedContainersCount());
-    for (LocatedContainerProto locatedContainer:
+    for (LocatedContainerProto locatedContainer :
         resp.getLocatedContainersList()) {
       Set<DatanodeInfo> locations = Sets.newLinkedHashSetWithExpectedSize(
           locatedContainer.getLocationsCount());
-      for (DatanodeInfoProto location: locatedContainer.getLocationsList()) {
+      for (DatanodeInfoProto location : locatedContainer.getLocationsList()) {
         locations.add(PBHelperClient.convert(location));
       }
       locatedContainers.add(new LocatedContainer(locatedContainer.getKey(),
@@ -94,6 +98,37 @@ public final class StorageContainerLocationProtocolClientSideTranslatorPB
     return locatedContainers;
   }
 
+  /**
+   * Asks SCM where a container should be allocated. SCM responds with the set
+   * of datanodes that should be used creating this container.
+   *
+   * @param containerName - Name of the container.
+   * @return Pipeline.
+   * @throws IOException
+   */
+  @Override
+  public Pipeline allocateContainer(String containerName) throws IOException {
+
+    Preconditions.checkNotNull(containerName, "Container Name cannot be Null");
+    Preconditions.checkState(!containerName.isEmpty(), "Container name cannot" +
+        " be empty");
+
+    ContainerRequestProto request = ContainerRequestProto.newBuilder()
+        .setContainerName(containerName).build();
+
+    final  ContainerResponseProto response;
+    try {
+      response = rpcProxy.allocateContainer(NULL_RPC_CONTROLLER, request);
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+    if (response.getErrorCode() != ContainerResponseProto.Error.success) {
+      throw new IOException(response.hasErrorMessage() ?
+          response.getErrorMessage() : "Allocate container failed.");
+    }
+    return Pipeline.getFromProtoBuf(response.getPipeline());
+  }
+
   @Override
   public Object getUnderlyingProxyObject() {
     return rpcProxy;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/protocolPB/StorageContainerLocationProtocolServerSideTranslatorPB.java

@@ -29,9 +29,12 @@ import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocolPB.PBHelperClient;
 import org.apache.hadoop.ozone.protocol.LocatedContainer;
 import org.apache.hadoop.ozone.protocol.StorageContainerLocationProtocol;
+import org.apache.hadoop.ozone.protocol.proto
+    .StorageContainerLocationProtocolProtos;
 import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.GetStorageContainerLocationsRequestProto;
 import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.GetStorageContainerLocationsResponseProto;
 import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.LocatedContainerProto;
+import org.apache.hadoop.ozone.protocol.proto.StorageContainerLocationProtocolProtos.ContainerResponseProto;
 
 /**
  * This class is the server-side translator that forwards requests received on
@@ -86,4 +89,11 @@ public final class StorageContainerLocationProtocolServerSideTranslatorPB
     }
     return resp.build();
   }
+
+  @Override
+  public ContainerResponseProto allocateContainer(RpcController unused,
+      StorageContainerLocationProtocolProtos.ContainerRequestProto request)
+      throws ServiceException {
+    return null;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/scm/container/ContainerMapping.java

@@ -0,0 +1,199 @@
+/**
+ * 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.ozone.scm.container;
+
+import com.google.common.base.Preconditions;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.ozone.protocol.proto.ContainerProtos;
+import org.apache.hadoop.hdfs.protocol.DatanodeID;
+import org.apache.hadoop.ozone.OzoneConfigKeys;
+import org.apache.hadoop.ozone.container.common.utils.LevelDBStore;
+import org.apache.hadoop.ozone.scm.node.NodeManager;
+import org.apache.hadoop.scm.container.common.helpers.Pipeline;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+import org.iq80.leveldb.Options;
+
+/**
+ * Mapping class contains the mapping from a name to a pipeline mapping. This is
+ * used by SCM when allocating new locations and when looking up a key.
+ */
+public class ContainerMapping implements Mapping {
+  private static final Logger LOG =
+      LoggerFactory.getLogger(ContainerMapping.class);
+
+  private final NodeManager nodeManager;
+  private final int cacheSize;
+  private final Lock lock;
+  private final Charset encoding = Charset.forName("UTF-8");
+  private final LevelDBStore store;
+  private final Random rand;
+
+  /**
+   * Constructs a mapping class that creates mapping between container names and
+   * pipelines.
+   *
+   * @param nodeManager - NodeManager so that we can get the nodes that are
+   * healthy to place new containers.
+   * @param cacheSizeMB - Amount of memory reserved for the LSM tree to cache
+   * its nodes. This is passed to LevelDB and this memory is allocated in Native
+   * code space. CacheSize is specified in MB.
+   */
+  @SuppressWarnings("unchecked")
+  public ContainerMapping(Configuration conf, NodeManager nodeManager,
+      int cacheSizeMB) throws IOException {
+    this.nodeManager = nodeManager;
+    this.cacheSize = cacheSizeMB;
+
+    // TODO: Fix this checking.
+    String scmMetaDataDir = conf.get(OzoneConfigKeys
+        .OZONE_CONTAINER_METADATA_DIRS);
+    if ((scmMetaDataDir == null) || (scmMetaDataDir.isEmpty())) {
+      throw
+          new IllegalArgumentException("SCM metadata directory is not valid.");
+    }
+    File dbPath = new File(scmMetaDataDir, "SCM.db");
+    Options options = new Options();
+    options.cacheSize(this.cacheSize * (1024 * 1024));
+    options.createIfMissing();
+    store = new LevelDBStore(dbPath, options);
+    this.lock = new ReentrantLock();
+    rand = new Random();
+  }
+
+  /**
+   * Translates a list of nodes, ordered such that the first is the leader, into
+   * a corresponding {@link Pipeline} object.
+   *
+   * @param node datanode on which we will allocate the contianer.
+   * @param containerName container name
+   * @return pipeline corresponding to nodes
+   */
+  private static Pipeline newPipelineFromNodes(DatanodeID node, String
+      containerName) {
+    Preconditions.checkNotNull(node);
+    String leaderId = node.getDatanodeUuid();
+    Pipeline pipeline = new Pipeline(leaderId);
+    pipeline.addMember(node);
+    pipeline.setContainerName(containerName);
+    return pipeline;
+  }
+
+  /**
+   * Returns the Pipeline from the container name.
+   *
+   * @param containerName - Name
+   * @return - Pipeline that makes up this container.
+   */
+  @Override
+  public Pipeline getContainer(String containerName) throws IOException {
+    Pipeline pipeline = null;
+    lock.lock();
+    try {
+      byte[] pipelineBytes = store.get(containerName.getBytes(encoding));
+      if (pipelineBytes == null) {
+        throw new IOException("Specified key does not exist. key : " +
+            containerName);
+      }
+      pipeline = Pipeline.getFromProtoBuf(
+          ContainerProtos.Pipeline.PARSER.parseFrom(pipelineBytes));
+      return pipeline;
+    } finally {
+      lock.unlock();
+    }
+  }
+
+  /**
+   * Allocates a new container.
+   *
+   * @param containerName - Name of the container.
+   * @return - Pipeline that makes up this container.
+   * @throws IOException
+   */
+  @Override
+  public Pipeline allocateContainer(String containerName) throws IOException {
+    Preconditions.checkNotNull(containerName);
+    Preconditions.checkState(!containerName.isEmpty());
+    Pipeline pipeline = null;
+    if (!nodeManager.isOutOfNodeChillMode()) {
+      throw new IOException("Unable to create container while in chill mode");
+    }
+
+    lock.lock();
+    try {
+      byte[] pipelineBytes = store.get(containerName.getBytes(encoding));
+      if (pipelineBytes != null) {
+        throw new IOException("Specified container already exists. key : " +
+            containerName);
+      }
+      DatanodeID id = getDatanodeID();
+      if (id != null) {
+        pipeline = newPipelineFromNodes(id, containerName);
+        store.put(containerName.getBytes(encoding),
+            pipeline.getProtobufMessage().toByteArray());
+      }
+    } finally {
+      lock.unlock();
+    }
+    return pipeline;
+  }
+
+  /**
+   * Returns a random Datanode ID from the list of healthy nodes.
+   *
+   * @return Datanode ID
+   * @throws IOException
+   */
+  private DatanodeID getDatanodeID() throws IOException {
+    List<DatanodeID> healthyNodes =
+        nodeManager.getNodes(NodeManager.NODESTATE.HEALTHY);
+
+    if (healthyNodes.size() == 0) {
+      throw new IOException("No healthy node found to allocate container.");
+    }
+
+    int index = rand.nextInt() % healthyNodes.size();
+    return healthyNodes.get(Math.abs(index));
+  }
+
+  /**
+   * Closes this stream and releases any system resources associated with it. If
+   * the stream is already closed then invoking this method has no effect.
+   * <p>
+   * <p> As noted in {@link AutoCloseable#close()}, cases where the close may
+   * fail require careful attention. It is strongly advised to relinquish the
+   * underlying resources and to internally <em>mark</em> the {@code Closeable}
+   * as closed, prior to throwing the {@code IOException}.
+   *
+   * @throws IOException if an I/O error occurs
+   */
+  @Override
+  public void close() throws IOException {
+    if (store != null) {
+      store.close();
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/scm/container/Mapping.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.ozone.scm.container;
+
+
+import org.apache.hadoop.scm.container.common.helpers.Pipeline;
+
+import java.io.Closeable;
+import java.io.IOException;
+
+/**
+ * Mapping class contains the mapping from a name to a pipeline mapping. This is
+ * used by SCM when allocating new locations and when looking up a key.
+ */
+public interface Mapping extends Closeable {
+  /**
+   * Returns the Pipeline from the container name.
+   *
+   * @param containerName - Name
+   * @return - Pipeline that makes up this container.
+   * @throws IOException
+   */
+  Pipeline getContainer(String containerName) throws IOException;
+
+  /**
+   * Allocates a new container for a given keyName.
+   *
+   * @param containerName - Name
+   * @return - Pipeline that makes up this container.
+   * @throws IOException
+   */
+  Pipeline allocateContainer(String containerName) throws IOException;
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/scm/container/package-info.java

@@ -0,0 +1,22 @@
+/**
+ * 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.ozone.scm.container;
+/**
+ * This package contains routines to manage the container location and
+ * mapping inside SCM
+ */

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/storage/StorageContainerManager.java

@@ -199,6 +199,21 @@ public class StorageContainerManager
     return locatedContainers;
   }
 
+  /**
+   * Asks SCM where a container should be allocated. SCM responds with the set
+   * of datanodes that should be used creating this container.
+   *
+   * @param containerName - Name of the container.
+   * @return Pipeline.
+   * @throws IOException
+   */
+  @Override
+  public Pipeline allocateContainer(String containerName) throws IOException {
+    // TODO : This whole file will be replaced when we switch over to using
+    // the new protocol. So skipping connecting this code for now.
+    return null;
+  }
+
   @Override
   public DatanodeRegistration registerDatanode(
       DatanodeRegistration registration) throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/StorageContainerLocationProtocol.proto

@@ -29,6 +29,7 @@ option java_generate_equals_and_hash = true;
 package hadoop.hdfs;
 
 import "hdfs.proto";
+import "DatanodeContainerProtocol.proto";
 
 /**
  * keys - batch of object keys to find
@@ -56,6 +57,27 @@ message LocatedContainerProto {
   required DatanodeInfoProto leader = 5;
 }
 
+/**
+* Request send to SCM asking where the container should be created.
+*/
+message ContainerRequestProto {
+  required string containerName = 1;
+}
+
+/**
+ * Reply from SCM indicating that the container.
+ */
+message ContainerResponseProto {
+  enum Error {
+    success = 1;
+    errorContainerAlreadyExists = 2;
+    errorContainerMissing = 3;
+  }
+  required Error errorCode = 1;
+  required hadoop.hdfs.ozone.Pipeline pipeline = 2;
+  optional string errorMessage = 3;
+}
+
 /**
  * Protocol used from an HDFS node to StorageContainerManager.  See the request
  * and response messages for details of the RPC calls.
@@ -68,4 +90,10 @@ service StorageContainerLocationProtocolService {
    */
   rpc getStorageContainerLocations(GetStorageContainerLocationsRequestProto)
       returns(GetStorageContainerLocationsResponseProto);
+
+  /**
+   Creates a container entry in SCM.
+   */
+  rpc allocateContainer(ContainerRequestProto) returns (ContainerResponseProto);
+
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/ozone/scm/container/MockNodeManager.java

@@ -0,0 +1,201 @@
+/**
+ * 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.ozone.scm.container;
+
+import org.apache.hadoop.hdfs.protocol.DatanodeID;
+import org.apache.hadoop.hdfs.protocol.UnregisteredNodeException;
+import org.apache.hadoop.ozone.container.common.SCMTestUtils;
+import org.apache.hadoop.ozone.scm.node.NodeManager;
+
+import java.io.IOException;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Test Helper for testing container Mapping.
+ */
+public class MockNodeManager implements NodeManager {
+  private final List<DatanodeID> healthyNodes;
+  private static final int HEALTHY_NODE_COUNT = 10;
+  private boolean chillmode;
+
+  public MockNodeManager() {
+    this.healthyNodes = new LinkedList<>();
+    for (int x = 0; x < 10; x++) {
+      healthyNodes.add(SCMTestUtils.getDatanodeID());
+    }
+    chillmode = false;
+  }
+
+  /**
+   * Sets the chill mode value.
+   * @param chillmode
+   */
+  public void setChillmode(boolean chillmode) {
+    this.chillmode = chillmode;
+  }
+
+  /**
+   * Removes a data node from the management of this Node Manager.
+   *
+   * @param node - DataNode.
+   * @throws UnregisteredNodeException
+   */
+  @Override
+  public void removeNode(DatanodeID node) throws UnregisteredNodeException {
+
+  }
+
+  /**
+   * Gets all Live Datanodes that is currently communicating with SCM.
+   *
+   * @param nodestate - State of the node
+   * @return List of Datanodes that are Heartbeating SCM.
+   */
+  @Override
+  public List<DatanodeID> getNodes(NODESTATE nodestate) {
+    if (nodestate == NODESTATE.HEALTHY) {
+      return healthyNodes;
+    }
+    return null;
+  }
+
+  /**
+   * Returns the Number of Datanodes that are communicating with SCM.
+   *
+   * @param nodestate - State of the node
+   * @return int -- count
+   */
+  @Override
+  public int getNodeCount(NODESTATE nodestate) {
+    if (nodestate == NODESTATE.HEALTHY) {
+      return HEALTHY_NODE_COUNT;
+    }
+    return 0;
+  }
+
+  /**
+   * Get all datanodes known to SCM.
+   *
+   * @return List of DatanodeIDs known to SCM.
+   */
+  @Override
+  public List<DatanodeID> getAllNodes() {
+    return null;
+  }
+
+  /**
+   * Get the minimum number of nodes to get out of chill mode.
+   *
+   * @return int
+   */
+  @Override
+  public int getMinimumChillModeNodes() {
+    return 0;
+  }
+
+  /**
+   * Reports if we have exited out of chill mode by discovering enough nodes.
+   *
+   * @return True if we are out of Node layer chill mode, false otherwise.
+   */
+  @Override
+  public boolean isOutOfNodeChillMode() {
+    return !chillmode;
+  }
+
+  /**
+   * Chill mode is the period when node manager waits for a minimum configured
+   * number of datanodes to report in. This is called chill mode to indicate the
+   * period before node manager gets into action.
+   * <p>
+   * Forcefully exits the chill mode, even if we have not met the minimum
+   * criteria of the nodes reporting in.
+   */
+  @Override
+  public void forceExitChillMode() {
+
+  }
+
+  /**
+   * Forcefully enters chill mode, even if all minimum node conditions are met.
+   */
+  @Override
+  public void forceEnterChillMode() {
+
+  }
+
+  /**
+   * Clears the manual chill mode flag.
+   */
+  @Override
+  public void clearChillModeFlag() {
+
+  }
+
+  /**
+   * Returns a chill mode status string.
+   *
+   * @return String
+   */
+  @Override
+  public String getChillModeStatus() {
+    return null;
+  }
+
+  /**
+   * Returns the status of manual chill mode flag.
+   *
+   * @return true if forceEnterChillMode has been called, false if
+   * forceExitChillMode or status is not set. eg. clearChillModeFlag.
+   */
+  @Override
+  public boolean isInManualChillMode() {
+    return false;
+  }
+
+  /**
+   * Closes this stream and releases any system resources associated with it. If
+   * the stream is already closed then invoking this method has no effect.
+   * <p>
+   * <p> As noted in {@link AutoCloseable#close()}, cases where the close may
+   * fail require careful attention. It is strongly advised to relinquish the
+   * underlying resources and to internally <em>mark</em> the {@code Closeable}
+   * as closed, prior to throwing the {@code IOException}.
+   *
+   * @throws IOException if an I/O error occurs
+   */
+  @Override
+  public void close() throws IOException {
+
+  }
+
+  /**
+   * When an object implementing interface <code>Runnable</code> is used to
+   * create a thread, starting the thread causes the object's <code>run</code>
+   * method to be called in that separately executing thread.
+   * <p>
+   * The general contract of the method <code>run</code> is that it may take any
+   * action whatsoever.
+   *
+   * @see Thread#run()
+   */
+  @Override
+  public void run() {
+
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/ozone/scm/container/TestContainerMapping.java

@@ -0,0 +1,133 @@
+/**
+ * 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.ozone.scm.container;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.ozone.OzoneConfigKeys;
+import org.apache.hadoop.ozone.container.common.SCMTestUtils;
+import org.apache.hadoop.scm.container.common.helpers.Pipeline;
+import org.junit.AfterClass;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URL;
+import java.nio.file.Paths;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.UUID;
+
+/**
+ * Tests for Container Mapping.
+ */
+public class TestContainerMapping {
+  private static ContainerMapping mapping;
+  private static MockNodeManager nodeManager;
+  @Rule
+  public ExpectedException thrown = ExpectedException.none();
+  @BeforeClass
+  public static void setUp() throws Exception {
+    Configuration conf = SCMTestUtils.getConf();
+
+    URL p = conf.getClass().getResource("");
+    String path = p.getPath().concat(
+        TestContainerMapping.class.getSimpleName());
+
+    conf.set(OzoneConfigKeys.OZONE_CONTAINER_METADATA_DIRS, path);
+    File testDir = Paths.get(path).toFile();
+    boolean folderExisted = testDir.exists() || testDir.mkdirs();
+    if (!folderExisted) {
+      throw new IOException("Unable to create test diectory path");
+    }
+    nodeManager = new MockNodeManager();
+    mapping = new ContainerMapping(conf, nodeManager, 128);
+  }
+
+  @AfterClass
+  public static void cleanup() throws IOException {
+    mapping.close();
+  }
+
+  @Before
+  public void clearChillMode() {
+    nodeManager.setChillmode(false);
+  }
+
+  @Test
+  public void testallocateContainer() throws Exception {
+    Pipeline pipeline = mapping.allocateContainer(UUID.randomUUID().toString());
+    Assert.assertNotNull(pipeline);
+  }
+
+  @Test
+  public void testallocateContainerDistributesAllocation() throws Exception {
+    /* This is a lame test, we should really be testing something like
+    z-score or make sure that we don't have 3sigma kind of events. Too lazy
+    to write all that code. This test very lamely tests if we have more than
+    5 separate nodes  from the list of 10 datanodes that got allocated a
+    container.
+     */
+    Set<String> pipelineList = new TreeSet<>();
+    for (int x = 0; x < 30; x++) {
+      Pipeline pipeline = mapping.allocateContainer(UUID.randomUUID()
+          .toString());
+
+      Assert.assertNotNull(pipeline);
+      pipelineList.add(pipeline.getLeader().getDatanodeUuid());
+    }
+    Assert.assertTrue(pipelineList.size() > 5);
+  }
+
+  @Test
+  public void testGetContainer() throws IOException {
+    String containerName = UUID.randomUUID().toString();
+    Pipeline pipeline = mapping.allocateContainer(containerName);
+    Assert.assertNotNull(pipeline);
+    Pipeline newPipeline = mapping.getContainer(containerName);
+    Assert.assertEquals(pipeline.getLeader().getDatanodeUuid(),
+        newPipeline.getLeader().getDatanodeUuid());
+  }
+
+  @Test
+  public void testDuplicateAllocateContainerFails() throws IOException {
+    String containerName = UUID.randomUUID().toString();
+    Pipeline pipeline = mapping.allocateContainer(containerName);
+    Assert.assertNotNull(pipeline);
+    thrown.expectMessage("Specified container already exists.");
+    mapping.allocateContainer(containerName);
+  }
+
+  @Test
+  public void testgetNoneExistentContainer() throws IOException {
+    String containerName = UUID.randomUUID().toString();
+    thrown.expectMessage("Specified key does not exist.");
+    mapping.getContainer(containerName);
+  }
+
+  @Test
+  public void testChillModeAllocateContainerFails() throws IOException {
+    String containerName = UUID.randomUUID().toString();
+    nodeManager.setChillmode(true);
+    thrown.expectMessage("Unable to create container while in chill mode");
+    mapping.allocateContainer(containerName);
+  }
+}