package com.bigdata.io;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;
import org.apache.log4j.Logger;
public class MergeStreamWithSortedSet {
private static final transient Logger log = Logger
.getLogger(MergeStreamWithSortedSet.class);
static public void process(final InputStream in, final Set<Entry<Long, byte[]>> snapshotData, final OutputStream out) throws IOException {
final byte[] bb = new byte[4096];
final Iterator<Entry<Long, byte[]>> bbs = snapshotData.iterator();
long curs = 0;
while (bbs.hasNext()) {
final Entry<Long, byte[]> e = bbs.next();
final long pos = e.getKey();
final byte[] buf = e.getValue();
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);
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);
}
}