org.h2.store.PageInputStream Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.store;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import org.h2.message.DbException;
import org.h2.message.Trace;
import org.h2.util.BitField;
/**
* An input stream that reads from a page store.
*/
public class PageInputStream extends InputStream {
private final PageStore store;
private final Trace trace;
private final int firstTrunkPage;
private final PageStreamTrunk.Iterator trunkIterator;
private int dataPage;
private PageStreamTrunk trunk;
private int trunkIndex;
private PageStreamData data;
private int dataPos;
private boolean endOfFile;
private int remaining;
private final byte[] buffer = { 0 };
private int logKey;
PageInputStream(PageStore store, int logKey, int firstTrunkPage, int dataPage) {
this.store = store;
this.trace = store.getTrace();
// minus one because we increment before comparing
this.logKey = logKey - 1;
this.firstTrunkPage = firstTrunkPage;
trunkIterator = new PageStreamTrunk.Iterator(store, firstTrunkPage);
this.dataPage = dataPage;
}
@Override
public int read() throws IOException {
int len = read(buffer);
return len < 0 ? -1 : (buffer[0] & 255);
}
@Override
public int read(byte[] b) throws IOException {
return read(b, 0, b.length);
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (len == 0) {
return 0;
}
int read = 0;
while (len > 0) {
int r = readBlock(b, off, len);
if (r < 0) {
break;
}
read += r;
off += r;
len -= r;
}
return read == 0 ? -1 : read;
}
private int readBlock(byte[] buff, int off, int len) throws IOException {
try {
fillBuffer();
if (endOfFile) {
return -1;
}
int l = Math.min(remaining, len);
data.read(dataPos, buff, off, l);
remaining -= l;
dataPos += l;
return l;
} catch (DbException e) {
throw new EOFException();
}
}
private void fillBuffer() {
if (remaining > 0 || endOfFile) {
return;
}
int next;
while (true) {
if (trunk == null) {
trunk = trunkIterator.next();
trunkIndex = 0;
logKey++;
if (trunk == null || trunk.getLogKey() != logKey) {
endOfFile = true;
return;
}
}
if (trunk != null) {
next = trunk.getPageData(trunkIndex++);
if (next == -1) {
trunk = null;
} else if (dataPage == -1 || dataPage == next) {
break;
}
}
}
if (trace.isDebugEnabled()) {
trace.debug("pageIn.readPage " + next);
}
dataPage = -1;
data = null;
Page p = store.getPage(next);
if (p instanceof PageStreamData) {
data = (PageStreamData) p;
}
if (data == null || data.getLogKey() != logKey) {
endOfFile = true;
return;
}
dataPos = PageStreamData.getReadStart();
remaining = store.getPageSize() - dataPos;
}
/**
* Set all pages as 'allocated' in the page store.
*
* @return the bit set
*/
BitField allocateAllPages() {
BitField pages = new BitField();
int key = logKey;
PageStreamTrunk.Iterator it = new PageStreamTrunk.Iterator(
store, firstTrunkPage);
while (true) {
PageStreamTrunk t = it.next();
key++;
if (it.canDelete()) {
store.allocatePage(it.getCurrentPageId());
}
if (t == null || t.getLogKey() != key) {
break;
}
pages.set(t.getPos());
for (int i = 0;; i++) {
int n = t.getPageData(i);
if (n == -1) {
break;
}
pages.set(n);
store.allocatePage(n);
}
}
return pages;
}
int getDataPage() {
return data.getPos();
}
@Override
public void close() {
// nothing to do
}
}