/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.bigdata.io;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Iterator;
import org.apache.log4j.Logger;
import com.bigdata.journal.AbstractJournal.ISnapshotData;
import com.bigdata.journal.AbstractJournal.ISnapshotEntry;
/**
* This utility class provide a method to write an InputStream to an OutputStream, merging with
* the ISnapshotData.
* <p>
* The ISnapshotData provides access to an ordered iteration of [Address,Data] that is processed
* with the InputStream to determine which data to write to the OutputStream, alternately transferring
* bytes from the InputStream and the ISnapshotData.
*
* @author Martyn Cutcher
*
*/
public class MergeStreamWithSnapshotData {
private static final transient Logger log = Logger
.getLogger(MergeStreamWithSnapshotData.class);
static public void process(final InputStream in, final ISnapshotData snapshotData, final OutputStream out) throws IOException {
final byte[] bb = new byte[4096];
final Iterator<ISnapshotEntry> bbs = snapshotData.entries();
long curs = 0;
while (bbs.hasNext()) {
final ISnapshotEntry e = bbs.next();
final long pos = e.getAddress();
final byte[] buf = e.getData();
final long blen = buf.length;
// transfer Input to Output until start of buffer
if (curs < pos) {
transfer(in, (pos-curs), bb, out);
curs = pos;
}
// transfer buffer
out.write(buf);
if (log.isInfoEnabled())
log.info("Write ByteBuffer at " + pos +", length: " + blen);
curs += blen;
// skip input over size of buffer
in.skip(blen);
}
// Now transfer remainder of stream
transfer(in, Long.MAX_VALUE, bb, out);
}
private static void transfer(final InputStream in, final long len, final byte[] buf, final OutputStream out) throws IOException {
long rem = len;
while (rem > buf.length) {
int rdlen = in.read(buf);
if (rdlen == -1)
return; // eof
out.write(buf, 0, rdlen);
rem -= rdlen;
}
// now read in what's left
int rdlen = in.read(buf, 0, (int) rem);
if (rdlen == -1)
return; // eof
out.write(buf, 0, rdlen);
}
}