/**
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.rwstore;
import java.io.*;
import java.nio.ByteBuffer;
import com.bigdata.rwstore.sector.IMemoryManager;
import com.bigdata.rwstore.sector.MemoryManager;
import com.bigdata.rwstore.sector.SectorAllocator;
/************************************************************************
* PSInputStream
*
* Unlike the original PSInputStream this does not incrementally read
* from the store but rather immediate maps the ByteBuffers to the
* in-memory storage.
**/
public class PSInputStream extends InputStream {
final RWStore m_store;
final byte[] m_buffer;
final int m_maxCursor;
final DataInputStream m_hdrIn;
final int m_blobBuffers;
int m_cursor = 0;
int m_size = 0;
public PSInputStream(final RWStore store, long addr) {
m_store = store;
m_size = (int) (addr & 0xFFFFFFFF);
if (m_size < (store.m_maxFixedAlloc-4)) {
m_buffer = new byte[m_size+4]; // allow for checksum
store.getData((addr >> 32), m_buffer);
m_hdrIn = null;
m_blobBuffers = 0;
m_maxCursor = m_size;
} else {
m_buffer = new byte[store.m_maxFixedAlloc];
m_maxCursor = store.m_maxFixedAlloc-4;
final int alloc = m_maxCursor;
final int nblocks = (alloc - 1 + (m_size-4))/alloc;
final int hdrsize = 4 * (nblocks + 1) + 4; // plus 4 for checksum
// FIXME: if hdrsize is blob then use recursive stream!
if (hdrsize > store.m_maxFixedAlloc) {
throw new UnsupportedOperationException("Header is a blob not yet supported");
}
final byte[] hdrbuf = new byte[hdrsize]; // plus 4 bytes for checksum
store.getData((addr >> 32), hdrbuf);
m_hdrIn = new DataInputStream(new ByteArrayInputStream(hdrbuf));
try {
m_blobBuffers = m_hdrIn.readInt();
} catch (IOException e) {
throw new RuntimeException("Unable to initialize blob header", e);
}
m_cursor = m_maxCursor; // force lazy read
}
}
@Override
public int read() throws IOException {
if (m_size == 0) {
return -1;
}
if (m_cursor >= m_maxCursor) {
loadBuffer();
}
m_size--;
return 0xFF & m_buffer[m_cursor++];
}
private int loadBuffer() throws IOException {
final int nxtaddr = m_hdrIn.readInt();
final int rdlen = m_size > m_maxCursor ? m_maxCursor : m_size;
m_store.getData(nxtaddr, m_buffer, 0, rdlen+4);
m_cursor = 0;
return rdlen;
}
public synchronized int read(final byte dst[], final int off, final int len) throws IOException {
if (m_size == 0) {
return -1;
}
if (m_cursor >= m_maxCursor) {
loadBuffer();
}
final int rdlen = len > m_size ? m_size : len;
int avail = m_maxCursor - m_cursor;
int delta = 0;
while (avail < (rdlen-delta)) {
System.arraycopy(m_buffer, m_cursor, dst, off+delta, avail);
m_cursor += avail;
delta += avail;
m_size -= avail;
avail = loadBuffer();
}
final int lastRead = (rdlen-delta);
System.arraycopy(m_buffer, m_cursor, dst, off+delta, lastRead);
m_size -= lastRead;
m_cursor += lastRead;
return rdlen;
}
}