org.apache.phoenix.hbase.index.covered.data.LazyValueGetter Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* 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
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*/
package org.apache.phoenix.hbase.index.covered.data;
import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.hbase.index.AbstractValueGetter;
import org.apache.phoenix.hbase.index.ValueGetter;
import org.apache.phoenix.hbase.index.covered.filter.ApplyAndFilterDeletesFilter.DeleteTracker;
import org.apache.phoenix.hbase.index.covered.update.ColumnReference;
import org.apache.phoenix.hbase.index.scanner.Scanner;
import org.apache.phoenix.hbase.index.scanner.ScannerBuilder.CoveredDeleteScanner;
import org.apache.phoenix.hbase.index.util.ImmutableBytesPtr;
/**
* {@link ValueGetter} that uses lazy initialization to get the value for the given
* {@link ColumnReference}. Once stored, the mapping for that reference is retained.
*/
public class LazyValueGetter extends AbstractValueGetter {
private CoveredDeleteScanner scan;
private volatile Map values;
private byte[] row;
/**
* Back the getter with a {@link Scanner} to actually access the local data.
* @param scan backing scanner
* @param currentRow row key for the row to seek in the scanner
*/
public LazyValueGetter(CoveredDeleteScanner scan, byte[] currentRow) {
this.scan = scan;
this.row = currentRow;
}
@Override
public ImmutableBytesWritable getLatestValue(ColumnReference ref, long ts) throws IOException {
Map v = values;
// ensure we have a backing map
if (v == null) {
synchronized (this) {
v = values;
if (v == null) {
v = values = Collections.synchronizedMap(new HashMap());
}
}
}
// check the value in the map
ImmutableBytesWritable value = v.get(ref);
if (value == null) {
value = get(ref);
DeleteTracker deleteTracker = scan.getDeleteTracker();
if (value == null) {
// Delete family is used for row deletion. Family won't necessarily match as we'll be at
// the delete family marker on the last column family if there is one.
if (deleteTracker.deleteFamily != null && deleteTracker.deleteFamily.getTimestamp() == ts) {
value = HIDDEN_BY_DELETE;
}
}
v.put(ref, value);
}
return value;
}
/**
* @param ref
* @return the first value on the scanner for the given column
*/
private ImmutableBytesPtr get(ColumnReference ref) throws IOException {
KeyValue first = ref.getFirstKeyValueForRow(row);
if (!scan.seek(first)) {
return null;
}
// there is a next value - we only care about the current value, so we can just snag that
Cell next = scan.next();
if (ref.matches(next)) {
return new ImmutableBytesPtr(next.getValueArray(), next.getValueOffset(), next.getValueLength());
}
return null;
}
@Override
public byte[] getRowKey() {
return this.row;
}
}