HBASE-13273 Make Result.EMPTY_RESULT read-only; currently it can be modified

Signed-off-by: Sean Busbey <busbey@cloudera.com>
This commit is contained in:
Mikhail Antonov 2015-03-20 16:24:54 -07:00 committed by Sean Busbey
parent fcc09dcd38
commit 8cb4f89c01
2 changed files with 58 additions and 2 deletions

View File

@ -102,7 +102,7 @@ public class Result implements CellScannable, CellScanner {
private static ThreadLocal<byte[]> localBuffer = new ThreadLocal<byte[]>();
private static final int PAD_WIDTH = 128;
public static final Result EMPTY_RESULT = new Result();
public static final Result EMPTY_RESULT = new Result(true);
private final static int INITIAL_CELLSCANNER_INDEX = -1;
@ -112,6 +112,8 @@ public class Result implements CellScannable, CellScanner {
private int cellScannerIndex = INITIAL_CELLSCANNER_INDEX;
private ClientProtos.RegionLoadStats stats;
private final boolean readonly;
/**
* Creates an empty Result w/ no KeyValue payload; returns null if you call {@link #rawCells()}.
* Use this to represent no results if {@code null} won't do or in old 'mapred' as opposed
@ -119,7 +121,16 @@ public class Result implements CellScannable, CellScanner {
* {@link #copyFrom(Result)} call.
*/
public Result() {
super();
this(false);
}
/**
* Allows to construct special purpose immutable Result objects,
* such as EMPTY_RESULT.
* @param readonly whether this Result instance is readonly
*/
private Result(boolean readonly) {
this.readonly = readonly;
}
/**
@ -172,6 +183,7 @@ public class Result implements CellScannable, CellScanner {
this.exists = exists;
this.stale = stale;
this.partial = partial;
this.readonly = false;
}
/**
@ -834,9 +846,12 @@ public class Result implements CellScannable, CellScanner {
/**
* Copy another Result into this one. Needed for the old Mapred framework
* @throws UnsupportedOperationException if invoked on instance of EMPTY_RESULT
* (which is supposed to be immutable).
* @param other
*/
public void copyFrom(Result other) {
checkReadonly();
this.row = null;
this.familyMap = null;
this.cells = other.cells;
@ -866,6 +881,7 @@ public class Result implements CellScannable, CellScanner {
}
public void setExists(Boolean exists) {
checkReadonly();
this.exists = exists;
}
@ -891,8 +907,11 @@ public class Result implements CellScannable, CellScanner {
/**
* Add load information about the region to the information about the result
* @param loadStats statistics about the current region from which this was returned
* @throws UnsupportedOperationException if invoked on instance of EMPTY_RESULT
* (which is supposed to be immutable).
*/
public void addResults(ClientProtos.RegionLoadStats loadStats) {
checkReadonly();
this.stats = loadStats;
}
@ -903,4 +922,14 @@ public class Result implements CellScannable, CellScanner {
public ClientProtos.RegionLoadStats getStats() {
return stats;
}
/**
* All methods modifying state of Result object must call this method
* to ensure that special purpose immutable Results can't be accidentally modified.
*/
private void checkReadonly() {
if (readonly == true) {
throw new UnsupportedOperationException("Attempting to modify readonly EMPTY_RESULT!");
}
}
}

View File

@ -34,6 +34,7 @@ import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellScanner;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.protobuf.generated.ClientProtos;
import org.apache.hadoop.hbase.testclassification.ClientTests;
import org.apache.hadoop.hbase.testclassification.SmallTests;
import org.apache.hadoop.hbase.util.Bytes;
@ -229,6 +230,32 @@ public class TestResult extends TestCase {
}
}
/**
* Verifies that one can't modify instance of EMPTY_RESULT.
*/
public void testEmptyResultIsReadonly() {
Result emptyResult = Result.EMPTY_RESULT;
Result otherResult = new Result();
try {
emptyResult.copyFrom(otherResult);
fail("UnsupportedOperationException should have been thrown!");
} catch (UnsupportedOperationException ex) {
LOG.debug("As expected: " + ex.getMessage());
}
try {
emptyResult.addResults(ClientProtos.RegionLoadStats.getDefaultInstance());
fail("UnsupportedOperationException should have been thrown!");
} catch (UnsupportedOperationException ex) {
LOG.debug("As expected: " + ex.getMessage());
}
try {
emptyResult.setExists(true);
fail("UnsupportedOperationException should have been thrown!");
} catch (UnsupportedOperationException ex) {
LOG.debug("As expected: " + ex.getMessage());
}
}
/**
* Microbenchmark that compares {@link Result#getValue} and {@link Result#loadValue} performance.