/*
* 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.jackrabbit.oak.plugins.mongomk.blob.gridfs;
import java.io.InputStream;
import org.apache.jackrabbit.mk.util.IOUtils;
import com.mongodb.BasicDBObject;
import com.mongodb.gridfs.GridFS;
import com.mongodb.gridfs.GridFSDBFile;
/**
* {@code Command} for {@code MongoMicroKernel#read(String, long, byte[], int, int)}
* FIXME - Reading from large blobs with small increments is slow in this implementation.
* See if this could be improved with some kind of cache mechanism.
*/
public class ReadBlobCommandGridFS extends BaseCommand<Integer> {
private final GridFS gridFS;
private final String blobId;
private final long blobOffset;
private final byte[] buffer;
private final int bufferOffset;
private int length;
/**
* Constructs a new {@code ReadBlobCommandMongo}.
*
* @param gridFS GridFS instance.
* @param blobId Blob id.
* @param blobOffset Blob offset.
* @param buffer Buffer.
* @param bufferOffset Buffer offset.
* @param length Length.
*/
public ReadBlobCommandGridFS(GridFS gridFS, String blobId, long blobOffset,
byte[] buffer, int bufferOffset, int length) {
super();
this.gridFS = gridFS;
this.blobId = blobId;
this.blobOffset = blobOffset;
this.buffer = buffer;
this.bufferOffset = bufferOffset;
this.length = length;
}
@Override
public Integer execute() throws Exception {
return fetchBlobFromMongo();
}
private int fetchBlobFromMongo() throws Exception {
GridFSDBFile gridFile = gridFS.findOne(new BasicDBObject("md5", blobId));
long fileLength = gridFile.getLength();
long start = blobOffset;
long end = blobOffset + length;
if (end > fileLength) {
end = fileLength;
}
length = (int) (end - start);
if (start < end) {
InputStream is = gridFile.getInputStream();
if (blobOffset > 0) {
IOUtils.skipFully(is, blobOffset);
}
IOUtils.readFully(is, buffer, bufferOffset, length);
is.close();
return length;
}
return -1;
}
}