hadoop XAttrFormat 源码
haddop XAttrFormat 代码
文件路径：/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/XAttrFormat.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.hdfs.server.namenode;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.fs.XAttr;
import org.apache.hadoop.hdfs.XAttrHelper;
import org.apache.hadoop.util.Preconditions;
import org.apache.hadoop.thirdparty.com.google.common.primitives.Ints;
import org.apache.hadoop.hdfs.util.LongBitFormat;
/**
* Class to pack XAttrs into byte[].<br>
*
* Note: this format is used both in-memory and on-disk. Changes will be
* incompatible.
*
*/
public enum XAttrFormat implements LongBitFormat.Enum {
RESERVED(null, 5),
NS_EXT(RESERVED.BITS, 1),
NAME(NS_EXT.BITS, 24),
NS(NAME.BITS, 2);
private static final int NS_EXT_SHIFT = NS.BITS.getLength();
private static final int NS_MASK = (1 << NS_EXT_SHIFT) - 1;
private static final int XATTR_VALUE_LEN_MAX = 1 << 16;
private static final XAttr.NameSpace[] XATTR_NAMESPACE_VALUES =
XAttr.NameSpace.values();
private final LongBitFormat BITS;
XAttrFormat(LongBitFormat previous, int length) {
BITS = new LongBitFormat(name(), previous, length, 0);
}
@Override
public int getLength() {
return BITS.getLength();
}
static XAttr.NameSpace getNamespace(int record) {
long nid = NS.BITS.retrieve(record);
nid |= NS_EXT.BITS.retrieve(record) << NS_EXT_SHIFT;
return XATTR_NAMESPACE_VALUES[(int) nid];
}
public static String getName(int record) {
int nid = (int)NAME.BITS.retrieve(record);
return SerialNumberManager.XATTR.getString(nid);
}
static int toInt(XAttr a) {
int nid = SerialNumberManager.XATTR.getSerialNumber(a.getName());
int nsOrd = a.getNameSpace().ordinal();
long value = NS.BITS.combine(nsOrd & NS_MASK, 0L);
value = NS_EXT.BITS.combine(nsOrd >>> NS_EXT_SHIFT, value);
value = NAME.BITS.combine(nid, value);
return (int)value;
}
static XAttr toXAttr(int record, byte[] value,
SerialNumberManager.StringTable stringTable) {
int nid = (int)NAME.BITS.retrieve(record);
String name = SerialNumberManager.XATTR.getString(nid, stringTable);
return new XAttr.Builder()
.setNameSpace(getNamespace(record))
.setName(name)
.setValue(value)
.build();
}
/**
* Unpack byte[] to XAttrs.
*
* @param attrs the packed bytes of XAttrs
* @return XAttrs list
*/
static List<XAttr> toXAttrs(byte[] attrs) {
List<XAttr> xAttrs = new ArrayList<>();
if (attrs == null || attrs.length == 0) {
return xAttrs;
}
for (int i = 0; i < attrs.length;) {
XAttr.Builder builder = new XAttr.Builder();
// big-endian
int v = Ints.fromBytes(attrs[i], attrs[i + 1],
attrs[i + 2], attrs[i + 3]);
i += 4;
builder.setNameSpace(XAttrFormat.getNamespace(v));
builder.setName(XAttrFormat.getName(v));
int vlen = ((0xff & attrs[i]) << 8) | (0xff & attrs[i + 1]);
i += 2;
if (vlen > 0) {
byte[] value = new byte[vlen];
System.arraycopy(attrs, i, value, 0, vlen);
builder.setValue(value);
i += vlen;
}
xAttrs.add(builder.build());
}
return xAttrs;
}
/**
* Get XAttr by name with prefix.
* Will unpack the byte[] until find the specific XAttr
*
* @param attrs the packed bytes of XAttrs
* @param prefixedName the XAttr name with prefix
* @return the XAttr
*/
static XAttr getXAttr(byte[] attrs, String prefixedName) {
if (prefixedName == null || attrs == null) {
return null;
}
XAttr xAttr = XAttrHelper.buildXAttr(prefixedName);
for (int i = 0; i < attrs.length;) {
// big-endian
int v = Ints.fromBytes(attrs[i], attrs[i + 1],
attrs[i + 2], attrs[i + 3]);
i += 4;
XAttr.NameSpace namespace = XAttrFormat.getNamespace(v);
String name = XAttrFormat.getName(v);
int vlen = ((0xff & attrs[i]) << 8) | (0xff & attrs[i + 1]);
i += 2;
if (xAttr.getNameSpace() == namespace &&
xAttr.getName().equals(name)) {
if (vlen > 0) {
byte[] value = new byte[vlen];
System.arraycopy(attrs, i, value, 0, vlen);
return new XAttr.Builder().setNameSpace(namespace).
setName(name).setValue(value).build();
}
return xAttr;
}
i += vlen;
}
return null;
}
/**
* Pack the XAttrs to byte[].
*
* @param xAttrs the XAttrs
* @return the packed bytes
*/
static byte[] toBytes(List<XAttr> xAttrs) {
if (xAttrs == null || xAttrs.isEmpty()) {
return null;
}
ByteArrayOutputStream out = new ByteArrayOutputStream();
try {
for (XAttr a : xAttrs) {
// big-endian
int v = XAttrFormat.toInt(a);
out.write(Ints.toByteArray(v));
int vlen = a.getValue() == null ? 0 : a.getValue().length;
Preconditions.checkArgument(vlen < XATTR_VALUE_LEN_MAX,
"The length of xAttr values is too long.");
out.write((byte)(vlen >> 8));
out.write((byte)(vlen));
if (vlen > 0) {
out.write(a.getValue());
}
}
} catch (IOException e) {
// in fact, no exception
}
return out.toByteArray();
}
}
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