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* 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.hdfs.server.protocol;
import java.io.*;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.ipc.VersionedProtocol;
import org.apache.hadoop.security.KerberosInfo;
import org.apache.avro.reflect.Nullable;
/**********************************************************************
* Protocol that a DFS datanode uses to communicate with the NameNode.
* It's used to upload current load information and block reports.
*
* The only way a NameNode can communicate with a DataNode is by
* returning values from these functions.
*
**********************************************************************/
@KerberosInfo(
serverPrincipal = DFSConfigKeys.DFS_NAMENODE_USER_NAME_KEY,
clientPrincipal = DFSConfigKeys.DFS_DATANODE_USER_NAME_KEY)
@InterfaceAudience.Private
public interface DatanodeProtocol extends VersionedProtocol {
/**
* 26: remove getBlockLocations optimization
*/
public static final long versionID = 26;
// error code
final static int NOTIFY = 0;
final static int DISK_ERROR = 1; // there are still valid volumes on DN
final static int INVALID_BLOCK = 2;
final static int FATAL_DISK_ERROR = 3; // no valid volumes left on DN
/**
* Determines actions that data node should perform
* when receiving a datanode command.
*/
final static int DNA_UNKNOWN = 0; // unknown action
final static int DNA_TRANSFER = 1; // transfer blocks to another datanode
final static int DNA_INVALIDATE = 2; // invalidate blocks
final static int DNA_SHUTDOWN = 3; // shutdown node
final static int DNA_REGISTER = 4; // re-register
final static int DNA_FINALIZE = 5; // finalize previous upgrade
final static int DNA_RECOVERBLOCK = 6; // request a block recovery
final static int DNA_ACCESSKEYUPDATE = 7; // update access key
/**
* Register Datanode.
*
* @see org.apache.hadoop.hdfs.server.datanode.DataNode#dnRegistration
* @see org.apache.hadoop.hdfs.server.namenode.FSNamesystem#registerDatanode(DatanodeRegistration)
*
* @return updated {@link org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration}, which contains
* new storageID if the datanode did not have one and
* registration ID for further communication.
*/
public DatanodeRegistration registerDatanode(DatanodeRegistration registration
) throws IOException;
/**
* sendHeartbeat() tells the NameNode that the DataNode is still
* alive and well. Includes some status info, too.
* It also gives the NameNode a chance to return
* an array of "DatanodeCommand" objects.
* A DatanodeCommand tells the DataNode to invalidate local block(s),
* or to copy them to other DataNodes, etc.
*/
@Nullable
public DatanodeCommand[] sendHeartbeat(DatanodeRegistration registration,
long capacity,
long dfsUsed, long remaining,
int xmitsInProgress, int xceiverCount,
int failedVolumes) throws IOException;
/**
* blockReport() tells the NameNode about all the locally-stored blocks.
* The NameNode returns an array of Blocks that have become obsolete
* and should be deleted. This function is meant to upload *all*
* the locally-stored blocks. It's invoked upon startup and then
* infrequently afterwards.
* @param registration
* @param blocks - the block list as an array of longs.
* Each block is represented as 2 longs.
* This is done instead of Block[] to reduce memory used by block reports.
*
* @return - the next command for DN to process.
* @throws IOException
*/
public DatanodeCommand blockReport(DatanodeRegistration registration,
long[] blocks) throws IOException;
/**
* blockReceived() allows the DataNode to tell the NameNode about
* recently-received block data, with a hint for pereferred replica
* to be deleted when there is any excessive blocks.
* For example, whenever client code
* writes a new Block here, or another DataNode copies a Block to
* this DataNode, it will call blockReceived().
*/
public void blockReceived(DatanodeRegistration registration,
Block blocks[],
String[] delHints) throws IOException;
/**
* errorReport() tells the NameNode about something that has gone
* awry. Useful for debugging.
*/
public void errorReport(DatanodeRegistration registration,
int errorCode,
String msg) throws IOException;
public NamespaceInfo versionRequest() throws IOException;
/**
* This is a very general way to send a command to the name-node during
* distributed upgrade process.
*
* The generosity is because the variety of upgrade commands is unpredictable.
* The reply from the name-node is also received in the form of an upgrade
* command.
*
* @return a reply in the form of an upgrade command
*/
UpgradeCommand processUpgradeCommand(UpgradeCommand comm) throws IOException;
/**
* same as {@link org.apache.hadoop.hdfs.protocol.ClientProtocol#reportBadBlocks(LocatedBlock[])}
* }
*/
public void reportBadBlocks(LocatedBlock[] blocks) throws IOException;
/**
* Commit block synchronization in lease recovery
*/
public void commitBlockSynchronization(Block block,
long newgenerationstamp, long newlength,
boolean closeFile, boolean deleteblock, DatanodeID[] newtargets
) throws IOException;
}