/**
* 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.IOException;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
import org.apache.hadoop.hdfs.protocol.LocatedBlocksWithMetaInfo;
import org.apache.hadoop.hdfs.server.namenode.CheckpointSignature;
import org.apache.hadoop.ipc.VersionedProtocol;
/*****************************************************************************
* Protocol that a secondary NameNode and the Snapshot Node use to
* communicate with the NameNode.
* It's used to get part of the name node state
*****************************************************************************/
public interface NamenodeProtocol extends VersionedProtocol {
/**
* 3: Added a parameter to rollFSImage() and
* changed the definition of CheckpointSignature
*/
public static final long versionID = 3L;
/** Get a list of blocks belonged to <code>datanode</code>
* whose total size is equal to <code>size</code>
* @param datanode a data node
* @param size requested size
* @return a list of blocks & their locations
* @throws RemoteException if size is less than or equal to 0 or
datanode does not exist
*/
public BlocksWithLocations getBlocks(DatanodeInfo datanode, long size)
throws IOException;
/**
* @return The most recent transaction ID that has been synced to
* persistent storage.
* @throws IOException
*/
public long getTransactionID() throws IOException;
/**
* Closes the current edit log and opens a new one. The
* call fails if the file system is in SafeMode.
* @throws IOException
* @return a unique token to identify this transaction.
*/
public CheckpointSignature rollEditLog() throws IOException;
/**
* Rolls the fsImage log. It removes the old fsImage, copies the
* new image to fsImage, removes the old edits and renames edits.new
* to edits. The call fails if any of the four files are missing.
*
* @param newImageSignature the signature of the new fsimage
* @throws IOException
*/
public void rollFsImage(CheckpointSignature newImageSignature)
throws IOException;
/**
* Gets the length of the blocks with ids in blockIds
* @param blockIds the ids of block for which the lengths are being requested
* @return the lengths of the blocks. -1 for blocks which couldn't be resolved.
*/
public long[] getBlockLengths(long[] blockIds);
/**
* Gets the CheckpointSignature at the time the call was made
* @return the CheckpointSignature
* @throws IOException
*/
public CheckpointSignature getCheckpointSignature() throws IOException;
/***
* Updates the DatanodeInfo for each LocatedBlock in locatedBlocks. Used
* by SnapshotShell to read data for a file from a snapshot.
* @param locatedBlocks the LocatedBlocks stored in the snapshot for the file
* @return LocatedBlocks for same block set with updated DatanodeInfo
* @throws IOException
*/
public LocatedBlocksWithMetaInfo updateDatanodeInfo(
LocatedBlocks locatedBlocks) throws IOException;
/**
* Return a structure containing details about all edit logs available to be
* fetched from the NameNode.
*
* @param sinceTxId return only logs that contain transactions >= sinceTxId
*/
public RemoteEditLogManifest getEditLogManifest(long l) throws IOException;
/**
* Issued by standby to validate that it is allowed to talk to the primary.
*
* @return data transfer version supported by NameNode
*/
public int register() throws IOException;
}