BlockLocation.java
/**
* 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.fs;
import java.io.IOException;
import java.io.Serializable;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.util.StringInterner;
/**
* Represents the network location of a block, information about the hosts
* that contain block replicas, and other block metadata (E.g. the file
* offset associated with the block, length, whether it is corrupt, etc).
*
* For a single BlockLocation, it will have different meanings for replicated
* and erasure coded files.
*
* If the file is 3-replicated, offset and length of a BlockLocation represent
* the absolute value in the file and the hosts are the 3 datanodes that
* holding the replicas. Here is an example:
* <pre>
* BlockLocation(offset: 0, length: BLOCK_SIZE,
* hosts: {"host1:9866", "host2:9866, host3:9866"})
* </pre>
*
* And if the file is erasure-coded, each BlockLocation represents a logical
* block groups. Value offset is the offset of a block group in the file and
* value length is the total length of a block group. Hosts of a BlockLocation
* are the datanodes that holding all the data blocks and parity blocks of a
* block group.
* Suppose we have a RS_3_2 coded file (3 data units and 2 parity units).
* A BlockLocation example will be like:
* <pre>
* BlockLocation(offset: 0, length: 3 * BLOCK_SIZE, hosts: {"host1:9866",
* "host2:9866","host3:9866","host4:9866","host5:9866"})
* </pre>
*
* Please refer to
* {@link FileSystem#getFileBlockLocations(FileStatus, long, long)} or
* {@link FileContext#getFileBlockLocations(Path, long, long)}
* for more examples.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class BlockLocation implements Serializable {
private static final long serialVersionUID = 0x22986f6d;
private String[] hosts; // Datanode hostnames
private String[] cachedHosts; // Datanode hostnames with a cached replica
private String[] names; // Datanode IP:xferPort for accessing the block
private String[] topologyPaths; // Full path name in network topology
private String[] storageIds; // Storage ID of each replica
private StorageType[] storageTypes; // Storage type of each replica
private long offset; // Offset of the block in the file
private long length;
private boolean corrupt;
private static final String[] EMPTY_STR_ARRAY = new String[0];
private static final StorageType[] EMPTY_STORAGE_TYPE_ARRAY =
StorageType.EMPTY_ARRAY;
/**
* Default Constructor.
*/
public BlockLocation() {
this(EMPTY_STR_ARRAY, EMPTY_STR_ARRAY, 0L, 0L);
}
/**
* Copy constructor.
* @param that blocklocation.
*/
public BlockLocation(BlockLocation that) {
this.hosts = that.hosts;
this.cachedHosts = that.cachedHosts;
this.names = that.names;
this.topologyPaths = that.topologyPaths;
this.offset = that.offset;
this.length = that.length;
this.corrupt = that.corrupt;
this.storageIds = that.storageIds;
this.storageTypes = that.storageTypes;
}
/**
* Constructor with host, name, offset and length.
* @param names names array.
* @param hosts host array.
* @param offset offset.
* @param length length.
*/
public BlockLocation(String[] names, String[] hosts, long offset,
long length) {
this(names, hosts, offset, length, false);
}
/**
* Constructor with host, name, offset, length and corrupt flag.
* @param names names.
* @param hosts hosts.
* @param offset offset.
* @param length length.
* @param corrupt corrupt.
*/
public BlockLocation(String[] names, String[] hosts, long offset,
long length, boolean corrupt) {
this(names, hosts, null, offset, length, corrupt);
}
/**
* Constructor with host, name, network topology, offset and length.
* @param names names.
* @param hosts hosts.
* @param topologyPaths topologyPaths.
* @param offset offset.
* @param length length.
*/
public BlockLocation(String[] names, String[] hosts, String[] topologyPaths,
long offset, long length) {
this(names, hosts, topologyPaths, offset, length, false);
}
/**
* Constructor with host, name, network topology, offset, length
* and corrupt flag.
* @param names names.
* @param hosts hosts.
* @param topologyPaths topologyPaths.
* @param offset offset.
* @param length length.
* @param corrupt corrupt.
*/
public BlockLocation(String[] names, String[] hosts, String[] topologyPaths,
long offset, long length, boolean corrupt) {
this(names, hosts, null, topologyPaths, offset, length, corrupt);
}
public BlockLocation(String[] names, String[] hosts, String[] cachedHosts,
String[] topologyPaths, long offset, long length, boolean corrupt) {
this(names, hosts, cachedHosts, topologyPaths, null, null, offset, length,
corrupt);
}
public BlockLocation(String[] names, String[] hosts, String[] cachedHosts,
String[] topologyPaths, String[] storageIds, StorageType[] storageTypes,
long offset, long length, boolean corrupt) {
if (names == null) {
this.names = EMPTY_STR_ARRAY;
} else {
this.names = StringInterner.internStringsInArray(names);
}
if (hosts == null) {
this.hosts = EMPTY_STR_ARRAY;
} else {
this.hosts = StringInterner.internStringsInArray(hosts);
}
if (cachedHosts == null) {
this.cachedHosts = EMPTY_STR_ARRAY;
} else {
this.cachedHosts = StringInterner.internStringsInArray(cachedHosts);
}
if (topologyPaths == null) {
this.topologyPaths = EMPTY_STR_ARRAY;
} else {
this.topologyPaths = StringInterner.internStringsInArray(topologyPaths);
}
if (storageIds == null) {
this.storageIds = EMPTY_STR_ARRAY;
} else {
this.storageIds = StringInterner.internStringsInArray(storageIds);
}
if (storageTypes == null) {
this.storageTypes = EMPTY_STORAGE_TYPE_ARRAY;
} else {
this.storageTypes = storageTypes;
}
this.offset = offset;
this.length = length;
this.corrupt = corrupt;
}
/**
* Get the list of hosts (hostname) hosting this block.
* @return hosts array.
* @throws IOException If an I/O error occurred.
*/
public String[] getHosts() throws IOException {
return hosts;
}
/**
* Get the list of hosts (hostname) hosting a cached replica of the block.
* @return cached hosts.
*/
public String[] getCachedHosts() {
return cachedHosts;
}
/**
* Get the list of names (IP:xferPort) hosting this block.
* @return names array.
* @throws IOException If an I/O error occurred.
*/
public String[] getNames() throws IOException {
return names;
}
/**
* Get the list of network topology paths for each of the hosts.
* The last component of the path is the "name" (IP:xferPort).
* @return topology paths.
* @throws IOException If an I/O error occurred.
*/
public String[] getTopologyPaths() throws IOException {
return topologyPaths;
}
/**
* Get the storageID of each replica of the block.
* @return storage ids.
*/
public String[] getStorageIds() {
return storageIds;
}
/**
* Get the storage type of each replica of the block.
* @return storage type of each replica of the block.
*/
public StorageType[] getStorageTypes() {
return storageTypes;
}
/**
* Get the start offset of file associated with this block.
* @return start offset of file associated with this block.
*/
public long getOffset() {
return offset;
}
/**
* Get the length of the block.
* @return length of the block.
*/
public long getLength() {
return length;
}
/**
* Get the corrupt flag.
* @return corrupt flag.
*/
public boolean isCorrupt() {
return corrupt;
}
/**
* Return true if the block is striped (erasure coded).
* @return if the block is striped true, not false.
*/
public boolean isStriped() {
return false;
}
/**
* Set the start offset of file associated with this block.
* @param offset start offset.
*/
public void setOffset(long offset) {
this.offset = offset;
}
/**
* Set the length of block.
* @param length length of block.
*/
public void setLength(long length) {
this.length = length;
}
/**
* Set the corrupt flag.
* @param corrupt corrupt flag.
*/
public void setCorrupt(boolean corrupt) {
this.corrupt = corrupt;
}
/**
* Set the hosts hosting this block.
* @param hosts hosts array.
* @throws IOException If an I/O error occurred.
*/
public void setHosts(String[] hosts) throws IOException {
if (hosts == null) {
this.hosts = EMPTY_STR_ARRAY;
} else {
this.hosts = StringInterner.internStringsInArray(hosts);
}
}
/**
* Set the hosts hosting a cached replica of this block.
* @param cachedHosts cached hosts.
*/
public void setCachedHosts(String[] cachedHosts) {
if (cachedHosts == null) {
this.cachedHosts = EMPTY_STR_ARRAY;
} else {
this.cachedHosts = StringInterner.internStringsInArray(cachedHosts);
}
}
/**
* Set the names (host:port) hosting this block.
* @param names names.
* @throws IOException If an I/O error occurred.
*/
public void setNames(String[] names) throws IOException {
if (names == null) {
this.names = EMPTY_STR_ARRAY;
} else {
this.names = StringInterner.internStringsInArray(names);
}
}
/**
* Set the network topology paths of the hosts.
*
* @param topologyPaths topology paths.
* @throws IOException If an I/O error occurred.
*/
public void setTopologyPaths(String[] topologyPaths) throws IOException {
if (topologyPaths == null) {
this.topologyPaths = EMPTY_STR_ARRAY;
} else {
this.topologyPaths = StringInterner.internStringsInArray(topologyPaths);
}
}
public void setStorageIds(String[] storageIds) {
if (storageIds == null) {
this.storageIds = EMPTY_STR_ARRAY;
} else {
this.storageIds = StringInterner.internStringsInArray(storageIds);
}
}
public void setStorageTypes(StorageType[] storageTypes) {
if (storageTypes == null) {
this.storageTypes = EMPTY_STORAGE_TYPE_ARRAY;
} else {
this.storageTypes = storageTypes;
}
}
@Override
public String toString() {
StringBuilder result = new StringBuilder();
result.append(offset)
.append(',')
.append(length);
if (corrupt) {
result.append("(corrupt)");
}
for(String h: hosts) {
result.append(',');
result.append(h);
}
return result.toString();
}
}