/**
*
* 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 org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.protobuf.generated.FSProtos;
import org.apache.hadoop.hbase.util.Bytes;
import com.google.protobuf.ByteString;
import com.google.protobuf.ZeroCopyLiteralByteString;
/**
* 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.
*
* <p>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.
*
* <p>References to store files located over in some other region look like
* this in the file system
* <code>1278437856009925445.3323223323</code>:
* 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
}
/**
* @param splitRow
* @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);
}
/**
* @param splitRow
* @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.
* @param fr
*/
Reference(final byte [] splitRow, final Range fr) {
this.splitkey = splitRow == null? null: KeyValue.createFirstOnRow(splitRow).getKey();
this.region = fr;
}
/**
* Used by serializations.
*/
@Deprecated
// Make this private when it comes time to let go of this constructor. Needed by pb serialization.
public Reference() {
this(null, Range.bottom);
}
/**
*
* @return Range
*/
public Range getFileRegion() {
return this.region;
}
/**
* @return splitKey
*/
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.
* @param fs
* @param p
* @return New Reference made from passed <code>p</code>
* @throws IOException
*/
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];
int read = in.read(pbuf);
if (read != pblen) throw new IOException("read=" + read + ", wanted=" + 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();
}
}
FSProtos.Reference convert() {
FSProtos.Reference.Builder builder = FSProtos.Reference.newBuilder();
builder.setRange(isTopFileRegion(getFileRegion())?
FSProtos.Reference.Range.TOP: FSProtos.Reference.Range.BOTTOM);
builder.setSplitkey(ZeroCopyLiteralByteString.wrap(getSplitKey()));
return builder.build();
}
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.
* @throws IOException
*/
byte [] toByteArray() throws IOException {
return ProtobufUtil.prependPBMagic(convert().toByteArray());
}
}