org.apache.hadoop.hbase.io.Reference Maven / Gradle / Ivy
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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.hbase.io;
import java.io.BufferedInputStream;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.KeyValueUtil;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hbase.thirdparty.com.google.protobuf.UnsafeByteOperations;
import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.shaded.protobuf.generated.FSProtos;
/**
* A reference to the top or bottom half of a store file where 'bottom' is the first half of the
* file containing the keys that sort lowest and 'top' is the second half of the file with keys that
* sort greater than those of the bottom half. The file referenced lives under a different region.
* References are made at region split time.
*
* References work with a special half store file type. References know how to write out the
* reference format in the file system and are what is juggled when references are mixed in with
* direct store files. The half store file type is used reading the referred to file.
*
* References to store files located over in some other region look like this in the file system
* 1278437856009925445.3323223323: i.e. an id followed by hash of the referenced
* region. Note, a region is itself not splittable if it has instances of store file references.
* References are cleaned up by compactions.
*/
@InterfaceAudience.Private
public class Reference {
private byte[] splitkey;
private Range region;
/**
* For split HStoreFiles, it specifies if the file covers the lower half or the upper half of the
* key range
*/
static enum Range {
/** HStoreFile contains upper half of key range */
top,
/** HStoreFile contains lower half of key range */
bottom
}
/**
* n * @return A {@link Reference} that points at top half of a an hfile
*/
public static Reference createTopReference(final byte[] splitRow) {
return new Reference(splitRow, Range.top);
}
/**
* n * @return A {@link Reference} that points at the bottom half of a an hfile
*/
public static Reference createBottomReference(final byte[] splitRow) {
return new Reference(splitRow, Range.bottom);
}
/**
* Constructor
* @param splitRow This is row we are splitting around. n
*/
Reference(final byte[] splitRow, final Range fr) {
this.splitkey = splitRow == null ? null : KeyValueUtil.createFirstOnRow(splitRow).getKey();
this.region = fr;
}
/**
* Used by serializations.
* @deprecated need by pb serialization
*/
@Deprecated
// Make this private when it comes time to let go of this constructor.
// Needed by pb serialization.
public Reference() {
this(null, Range.bottom);
}
/**
* n
*/
public Range getFileRegion() {
return this.region;
}
/**
* n
*/
public byte[] getSplitKey() {
return splitkey;
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return "" + this.region;
}
public static boolean isTopFileRegion(final Range r) {
return r.equals(Range.top);
}
/**
* @deprecated Writables are going away. Use the pb serialization methods instead. Remove in a
* release after 0.96 goes out. This is here only to migrate old Reference files
* written with Writables before 0.96.
*/
@Deprecated
public void readFields(DataInput in) throws IOException {
boolean tmp = in.readBoolean();
// If true, set region to top.
this.region = tmp ? Range.top : Range.bottom;
this.splitkey = Bytes.readByteArray(in);
}
public Path write(final FileSystem fs, final Path p) throws IOException {
FSDataOutputStream out = fs.create(p, false);
try {
out.write(toByteArray());
} finally {
out.close();
}
return p;
}
/**
* Read a Reference from FileSystem. nn * @return New Reference made from passed p n
*/
public static Reference read(final FileSystem fs, final Path p) throws IOException {
InputStream in = fs.open(p);
try {
// I need to be able to move back in the stream if this is not a pb serialization so I can
// do the Writable decoding instead.
in = in.markSupported() ? in : new BufferedInputStream(in);
int pblen = ProtobufUtil.lengthOfPBMagic();
in.mark(pblen);
byte[] pbuf = new byte[pblen];
IOUtils.readFully(in, pbuf, 0, pblen);
// WATCHOUT! Return in middle of function!!!
if (ProtobufUtil.isPBMagicPrefix(pbuf)) return convert(FSProtos.Reference.parseFrom(in));
// Else presume Writables. Need to reset the stream since it didn't start w/ pb.
// We won't bother rewriting thie Reference as a pb since Reference is transitory.
in.reset();
Reference r = new Reference();
DataInputStream dis = new DataInputStream(in);
// Set in = dis so it gets the close below in the finally on our way out.
in = dis;
r.readFields(dis);
return r;
} finally {
in.close();
}
}
public FSProtos.Reference convert() {
FSProtos.Reference.Builder builder = FSProtos.Reference.newBuilder();
builder.setRange(isTopFileRegion(getFileRegion())
? FSProtos.Reference.Range.TOP
: FSProtos.Reference.Range.BOTTOM);
builder.setSplitkey(UnsafeByteOperations.unsafeWrap(getSplitKey()));
return builder.build();
}
public static Reference convert(final FSProtos.Reference r) {
Reference result = new Reference();
result.splitkey = r.getSplitkey().toByteArray();
result.region = r.getRange() == FSProtos.Reference.Range.TOP ? Range.top : Range.bottom;
return result;
}
/**
* Use this when writing to a stream and you want to use the pb mergeDelimitedFrom (w/o the
* delimiter, pb reads to EOF which may not be what you want).
* @return This instance serialized as a delimited protobuf w/ a magic pb prefix. n
*/
byte[] toByteArray() throws IOException {
return ProtobufUtil.prependPBMagic(convert().toByteArray());
}
@Override
public int hashCode() {
return Arrays.hashCode(splitkey) + region.hashCode();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null) return false;
if (!(o instanceof Reference)) return false;
Reference r = (Reference) o;
if (splitkey != null && r.splitkey == null) return false;
if (splitkey == null && r.splitkey != null) return false;
if (splitkey != null && !Arrays.equals(splitkey, r.splitkey)) return false;
return region.equals(r.region);
}
}