/*
* Copyright 2010 The Apache Software Foundation
*
* 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.hadoop.hbase.stargate;
import java.io.IOException;
import java.util.Iterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.UnknownScannerException;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.HTablePool;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.stargate.model.ScannerModel;
import org.apache.hadoop.util.StringUtils;
public class ScannerResultGenerator extends ResultGenerator {
private static final Log LOG =
LogFactory.getLog(ScannerResultGenerator.class);
public static Filter buildFilterFromModel(final ScannerModel model)
throws Exception {
String filter = model.getFilter();
if (filter == null || filter.length() == 0) {
return null;
}
return buildFilter(filter);
}
private String id;
private Iterator<KeyValue> rowI;
private KeyValue cache;
private ResultScanner scanner;
private Result cached;
public ScannerResultGenerator(final String tableName, final RowSpec rowspec,
final Filter filter) throws IllegalArgumentException, IOException {
HTablePool pool = RESTServlet.getInstance().getTablePool();
HTable table = pool.getTable(tableName);
try {
Scan scan;
if (rowspec.hasEndRow()) {
scan = new Scan(rowspec.getStartRow(), rowspec.getEndRow());
} else {
scan = new Scan(rowspec.getStartRow());
}
if (rowspec.hasColumns()) {
byte[][] columns = rowspec.getColumns();
for (byte[] column: columns) {
byte[][] split = KeyValue.parseColumn(column);
if (split.length > 1 && (split[1] != null && split[1].length != 0)) {
scan.addColumn(split[0], split[1]);
} else {
scan.addFamily(split[0]);
}
}
} else {
for (HColumnDescriptor family:
table.getTableDescriptor().getFamilies()) {
scan.addFamily(family.getName());
}
}
scan.setTimeRange(rowspec.getStartTime(), rowspec.getEndTime());
scan.setMaxVersions(rowspec.getMaxVersions());
if (filter != null) {
scan.setFilter(filter);
}
// always disable block caching on the cluster when scanning
scan.setCacheBlocks(false);
scanner = table.getScanner(scan);
cached = null;
id = Long.toString(System.currentTimeMillis()) +
Integer.toHexString(scanner.hashCode());
} finally {
pool.putTable(table);
}
}
public String getID() {
return id;
}
public void close() {
}
public boolean hasNext() {
if (cache != null) {
return true;
}
if (rowI != null && rowI.hasNext()) {
return true;
}
if (cached != null) {
return true;
}
try {
Result result = scanner.next();
if (result != null && !result.isEmpty()) {
cached = result;
}
} catch (UnknownScannerException e) {
throw new IllegalArgumentException(e);
} catch (IOException e) {
LOG.error(StringUtils.stringifyException(e));
}
return cached != null;
}
public KeyValue next() {
if (cache != null) {
KeyValue kv = cache;
cache = null;
return kv;
}
boolean loop;
do {
loop = false;
if (rowI != null) {
if (rowI.hasNext()) {
return rowI.next();
} else {
rowI = null;
}
}
if (cached != null) {
rowI = cached.list().iterator();
loop = true;
cached = null;
} else {
Result result = null;
try {
result = scanner.next();
} catch (UnknownScannerException e) {
throw new IllegalArgumentException(e);
} catch (IOException e) {
LOG.error(StringUtils.stringifyException(e));
}
if (result != null && !result.isEmpty()) {
rowI = result.list().iterator();
loop = true;
}
}
} while (loop);
return null;
}
public void putBack(KeyValue kv) {
this.cache = kv;
}
public void remove() {
throw new UnsupportedOperationException("remove not supported");
}
}