org.apache.hadoop.hbase.client.Result Maven / Gradle / Ivy
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* 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.client;
import java.io.IOException;
import java.nio.BufferOverflowException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NoSuchElementException;
import java.util.TreeMap;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellComparator;
import org.apache.hadoop.hbase.CellScannable;
import org.apache.hadoop.hbase.CellScanner;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.KeyValueUtil;
import org.apache.hadoop.hbase.PrivateCellUtil;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.yetus.audience.InterfaceAudience;
/**
* Single row result of a {@link Get} or {@link Scan} query.
*
* This class is NOT THREAD SAFE.
*
* Convenience methods are available that return various {@link Map} structures and values directly.
*
* To get a complete mapping of all cells in the Result, which can include multiple families and
* multiple versions, use {@link #getMap()}.
*
* To get a mapping of each family to its columns (qualifiers and values), including only the latest
* version of each, use {@link #getNoVersionMap()}. To get a mapping of qualifiers to latest values
* for an individual family use {@link #getFamilyMap(byte[])}.
*
* To get the latest value for a specific family and qualifier use
* {@link #getValue(byte[], byte[])}. A Result is backed by an array of {@link Cell} objects, each
* representing an HBase cell defined by the row, family, qualifier, timestamp, and value.
*
* The underlying {@link Cell} objects can be accessed through the method {@link #listCells()}. This
* will create a List from the internal Cell []. Better is to exploit the fact that a new Result
* instance is a primed {@link CellScanner}; just call {@link #advance()} and {@link #current()} to
* iterate over Cells as you would any {@link CellScanner}. Call {@link #cellScanner()} to reset
* should you need to iterate the same Result over again ({@link CellScanner}s are one-shot). If you
* need to overwrite a Result with another Result instance -- as in the old 'mapred' RecordReader
* next invocations -- then create an empty Result with the null constructor and in then use
* {@link #copyFrom(Result)}
*/
@InterfaceAudience.Public
public class Result implements CellScannable, CellScanner {
private Cell[] cells;
private Boolean exists; // if the query was just to check existence.
private boolean stale = false;
/**
* See {@link #mayHaveMoreCellsInRow()}.
*/
private boolean mayHaveMoreCellsInRow = false;
// We're not using java serialization. Transient here is just a marker to say
// that this is where we cache row if we're ever asked for it.
private transient byte[] row = null;
// Ditto for familyMap. It can be composed on fly from passed in kvs.
private transient NavigableMap>> familyMap = null;
private static ThreadLocal localBuffer = new ThreadLocal<>();
private static final int PAD_WIDTH = 128;
public static final Result EMPTY_RESULT = new Result(true);
private final static int INITIAL_CELLSCANNER_INDEX = -1;
/**
* Index for where we are when Result is acting as a {@link CellScanner}.
*/
private int cellScannerIndex = INITIAL_CELLSCANNER_INDEX;
private RegionLoadStats stats;
private final boolean readonly;
private Cursor cursor = null;
/**
* 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 to
* 'mapreduce' package MapReduce where you need to overwrite a Result instance with a
* {@link #copyFrom(Result)} call.
*/
public Result() {
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;
}
/**
* Instantiate a Result with the specified List of KeyValues.
* Note: You must ensure that the keyvalues are already sorted.
* @param cells List of cells
*/
public static Result create(List cells) {
return create(cells, null);
}
public static Result create(List cells, Boolean exists) {
return create(cells, exists, false);
}
public static Result create(List cells, Boolean exists, boolean stale) {
return create(cells, exists, stale, false);
}
public static Result create(List cells, Boolean exists, boolean stale,
boolean mayHaveMoreCellsInRow) {
if (exists != null) {
return new Result(null, exists, stale, mayHaveMoreCellsInRow);
}
return new Result(cells.toArray(new Cell[cells.size()]), null, stale, mayHaveMoreCellsInRow);
}
/**
* Instantiate a Result with the specified array of KeyValues.
* Note: You must ensure that the keyvalues are already sorted.
* @param cells array of cells
*/
public static Result create(Cell[] cells) {
return create(cells, null, false);
}
public static Result create(Cell[] cells, Boolean exists, boolean stale) {
return create(cells, exists, stale, false);
}
public static Result create(Cell[] cells, Boolean exists, boolean stale,
boolean mayHaveMoreCellsInRow) {
if (exists != null) {
return new Result(null, exists, stale, mayHaveMoreCellsInRow);
}
return new Result(cells, null, stale, mayHaveMoreCellsInRow);
}
public static Result createCursorResult(Cursor cursor) {
return new Result(cursor);
}
private Result(Cursor cursor) {
this.cursor = cursor;
this.readonly = false;
}
/** Private ctor. Use {@link #create(Cell[])}. */
private Result(Cell[] cells, Boolean exists, boolean stale, boolean mayHaveMoreCellsInRow) {
this.cells = cells;
this.exists = exists;
this.stale = stale;
this.mayHaveMoreCellsInRow = mayHaveMoreCellsInRow;
this.readonly = false;
}
/**
* Method for retrieving the row key that corresponds to the row from which this Result was
* created.
*/
public byte[] getRow() {
if (this.row == null) {
this.row =
(this.cells == null || this.cells.length == 0) ? null : CellUtil.cloneRow(this.cells[0]);
}
return this.row;
}
/**
* Return the array of Cells backing this Result instance. The array is sorted from smallest ->
* largest using the {@link CellComparator}. The array only contains what your Get or Scan
* specifies and no more. For example if you request column "A" 1 version you will have at most 1
* Cell in the array. If you request column "A" with 2 version you will have at most 2 Cells, with
* the first one being the newer timestamp and the second being the older timestamp (this is the
* sort order defined by {@link CellComparator}). If columns don't exist, they won't be present in
* the result. Therefore if you ask for 1 version all columns, it is safe to iterate over this
* array and expect to see 1 Cell for each column and no more. This API is faster than using
* getFamilyMap() and getMap()
* @return array of Cells; can be null if nothing in the result
*/
public Cell[] rawCells() {
return cells;
}
/**
* Create a sorted list of the Cell's in this result. Since HBase 0.20.5 this is equivalent to
* raw().
* @return sorted List of Cells; can be null if no cells in the result
*/
public List listCells() {
return isEmpty() ? null : Arrays.asList(rawCells());
}
/**
* Return the Cells for the specific column. The Cells are sorted in the {@link CellComparator}
* order. That implies the first entry in the list is the most recent column. If the query (Scan
* or Get) only requested 1 version the list will contain at most 1 entry. If the column did not
* exist in the result set (either the column does not exist or the column was not selected in the
* query) the list will be empty. Also see getColumnLatest which returns just a Cell
* @param family the family
* @return a list of Cells for this column or empty list if the column did not exist in the result
* set
*/
public List getColumnCells(byte[] family, byte[] qualifier) {
List result = new ArrayList<>();
Cell[] kvs = rawCells();
if (kvs == null || kvs.length == 0) {
return result;
}
int pos = binarySearch(kvs, family, qualifier);
if (pos == -1) {
return result; // cant find it
}
for (int i = pos; i < kvs.length; i++) {
if (CellUtil.matchingColumn(kvs[i], family, qualifier)) {
result.add(kvs[i]);
} else {
break;
}
}
return result;
}
private byte[] notNullBytes(final byte[] bytes) {
if (bytes == null) {
return HConstants.EMPTY_BYTE_ARRAY;
} else {
return bytes;
}
}
protected int binarySearch(final Cell[] kvs, final byte[] family, final byte[] qualifier) {
byte[] familyNotNull = notNullBytes(family);
byte[] qualifierNotNull = notNullBytes(qualifier);
Cell searchTerm = PrivateCellUtil.createFirstOnRow(kvs[0].getRowArray(), kvs[0].getRowOffset(),
kvs[0].getRowLength(), familyNotNull, 0, (byte) familyNotNull.length, qualifierNotNull, 0,
qualifierNotNull.length);
// pos === ( -(insertion point) - 1)
int pos = Arrays.binarySearch(kvs, searchTerm, CellComparator.getInstance());
// never will exact match
if (pos < 0) {
pos = (pos + 1) * -1;
// pos is now insertion point
}
if (pos == kvs.length) {
return -1; // doesn't exist
}
return pos;
}
/**
* Searches for the latest value for the specified column.
* @param kvs the array to search
* @param family family name
* @param foffset family offset
* @param flength family length
* @param qualifier column qualifier
* @param qoffset qualifier offset
* @param qlength qualifier length
* @return the index where the value was found, or -1 otherwise
*/
protected int binarySearch(final Cell[] kvs, final byte[] family, final int foffset,
final int flength, final byte[] qualifier, final int qoffset, final int qlength) {
double keyValueSize =
(double) KeyValue.getKeyValueDataStructureSize(kvs[0].getRowLength(), flength, qlength, 0);
byte[] buffer = localBuffer.get();
if (buffer == null || keyValueSize > buffer.length) {
// pad to the smallest multiple of the pad width
buffer = new byte[(int) Math.ceil(keyValueSize / PAD_WIDTH) * PAD_WIDTH];
localBuffer.set(buffer);
}
Cell searchTerm =
KeyValueUtil.createFirstOnRow(buffer, 0, kvs[0].getRowArray(), kvs[0].getRowOffset(),
kvs[0].getRowLength(), family, foffset, flength, qualifier, qoffset, qlength);
// pos === ( -(insertion point) - 1)
int pos = Arrays.binarySearch(kvs, searchTerm, CellComparator.getInstance());
// never will exact match
if (pos < 0) {
pos = (pos + 1) * -1;
// pos is now insertion point
}
if (pos == kvs.length) {
return -1; // doesn't exist
}
return pos;
}
/**
* The Cell for the most recent timestamp for a given column.
* @return the Cell for the column, or null if no value exists in the row or none have been
* selected in the query (Get/Scan)
*/
public Cell getColumnLatestCell(byte[] family, byte[] qualifier) {
Cell[] kvs = rawCells(); // side effect possibly.
if (kvs == null || kvs.length == 0) {
return null;
}
int pos = binarySearch(kvs, family, qualifier);
if (pos == -1) {
return null;
}
if (CellUtil.matchingColumn(kvs[pos], family, qualifier)) {
return kvs[pos];
}
return null;
}
/**
* The Cell for the most recent timestamp for a given column.
* @param family family name
* @param foffset family offset
* @param flength family length
* @param qualifier column qualifier
* @param qoffset qualifier offset
* @param qlength qualifier length
* @return the Cell for the column, or null if no value exists in the row or none have been
* selected in the query (Get/Scan)
*/
public Cell getColumnLatestCell(byte[] family, int foffset, int flength, byte[] qualifier,
int qoffset, int qlength) {
Cell[] kvs = rawCells(); // side effect possibly.
if (kvs == null || kvs.length == 0) {
return null;
}
int pos = binarySearch(kvs, family, foffset, flength, qualifier, qoffset, qlength);
if (pos == -1) {
return null;
}
if (
PrivateCellUtil.matchingColumn(kvs[pos], family, foffset, flength, qualifier, qoffset,
qlength)
) {
return kvs[pos];
}
return null;
}
/**
* Get the latest version of the specified column. Note: this call clones the value content of the
* hosting Cell. See {@link #getValueAsByteBuffer(byte[], byte[])}, etc., or {@link #listCells()}
* if you would avoid the cloning.
* @param family family name
* @param qualifier column qualifier
* @return value of latest version of column, null if none found
*/
public byte[] getValue(byte[] family, byte[] qualifier) {
Cell kv = getColumnLatestCell(family, qualifier);
if (kv == null) {
return null;
}
return CellUtil.cloneValue(kv);
}
/**
* Returns the value wrapped in a new ByteBuffer.
* @param family family name
* @param qualifier column qualifier
* @return the latest version of the column, or null if none found
*/
public ByteBuffer getValueAsByteBuffer(byte[] family, byte[] qualifier) {
Cell kv = getColumnLatestCell(family, 0, family.length, qualifier, 0, qualifier.length);
if (kv == null) {
return null;
}
return ByteBuffer.wrap(kv.getValueArray(), kv.getValueOffset(), kv.getValueLength())
.asReadOnlyBuffer();
}
/**
* Returns the value wrapped in a new ByteBuffer.
* @param family family name
* @param foffset family offset
* @param flength family length
* @param qualifier column qualifier
* @param qoffset qualifier offset
* @param qlength qualifier length
* @return the latest version of the column, or null if none found
*/
public ByteBuffer getValueAsByteBuffer(byte[] family, int foffset, int flength, byte[] qualifier,
int qoffset, int qlength) {
Cell kv = getColumnLatestCell(family, foffset, flength, qualifier, qoffset, qlength);
if (kv == null) {
return null;
}
return ByteBuffer.wrap(kv.getValueArray(), kv.getValueOffset(), kv.getValueLength())
.asReadOnlyBuffer();
}
/**
* Loads the latest version of the specified column into the provided ByteBuffer.
*
* Does not clear or flip the buffer.
* @param family family name
* @param qualifier column qualifier
* @param dst the buffer where to write the value
* @return true if a value was found, false otherwise
* @throws BufferOverflowException there is insufficient space remaining in the buffer
*/
public boolean loadValue(byte[] family, byte[] qualifier, ByteBuffer dst)
throws BufferOverflowException {
return loadValue(family, 0, family.length, qualifier, 0, qualifier.length, dst);
}
/**
* Loads the latest version of the specified column into the provided ByteBuffer.
*
* Does not clear or flip the buffer.
* @param family family name
* @param foffset family offset
* @param flength family length
* @param qualifier column qualifier
* @param qoffset qualifier offset
* @param qlength qualifier length
* @param dst the buffer where to write the value
* @return true if a value was found, false otherwise
* @throws BufferOverflowException there is insufficient space remaining in the buffer
*/
public boolean loadValue(byte[] family, int foffset, int flength, byte[] qualifier, int qoffset,
int qlength, ByteBuffer dst) throws BufferOverflowException {
Cell kv = getColumnLatestCell(family, foffset, flength, qualifier, qoffset, qlength);
if (kv == null) {
return false;
}
dst.put(kv.getValueArray(), kv.getValueOffset(), kv.getValueLength());
return true;
}
/**
* Checks if the specified column contains a non-empty value (not a zero-length byte array).
* @param family family name
* @param qualifier column qualifier
* @return whether or not a latest value exists and is not empty
*/
public boolean containsNonEmptyColumn(byte[] family, byte[] qualifier) {
return containsNonEmptyColumn(family, 0, family.length, qualifier, 0, qualifier.length);
}
/**
* Checks if the specified column contains a non-empty value (not a zero-length byte array).
* @param family family name
* @param foffset family offset
* @param flength family length
* @param qualifier column qualifier
* @param qoffset qualifier offset
* @param qlength qualifier length
* @return whether or not a latest value exists and is not empty
*/
public boolean containsNonEmptyColumn(byte[] family, int foffset, int flength, byte[] qualifier,
int qoffset, int qlength) {
Cell kv = getColumnLatestCell(family, foffset, flength, qualifier, qoffset, qlength);
return (kv != null) && (kv.getValueLength() > 0);
}
/**
* Checks if the specified column contains an empty value (a zero-length byte array).
* @param family family name
* @param qualifier column qualifier
* @return whether or not a latest value exists and is empty
*/
public boolean containsEmptyColumn(byte[] family, byte[] qualifier) {
return containsEmptyColumn(family, 0, family.length, qualifier, 0, qualifier.length);
}
/**
* Checks if the specified column contains an empty value (a zero-length byte array).
* @param family family name
* @param foffset family offset
* @param flength family length
* @param qualifier column qualifier
* @param qoffset qualifier offset
* @param qlength qualifier length
* @return whether or not a latest value exists and is empty
*/
public boolean containsEmptyColumn(byte[] family, int foffset, int flength, byte[] qualifier,
int qoffset, int qlength) {
Cell kv = getColumnLatestCell(family, foffset, flength, qualifier, qoffset, qlength);
return (kv != null) && (kv.getValueLength() == 0);
}
/**
* Checks for existence of a value for the specified column (empty or not).
* @param family family name
* @param qualifier column qualifier
* @return true if at least one value exists in the result, false if not
*/
public boolean containsColumn(byte[] family, byte[] qualifier) {
Cell kv = getColumnLatestCell(family, qualifier);
return kv != null;
}
/**
* Checks for existence of a value for the specified column (empty or not).
* @param family family name
* @param foffset family offset
* @param flength family length
* @param qualifier column qualifier
* @param qoffset qualifier offset
* @param qlength qualifier length
* @return true if at least one value exists in the result, false if not
*/
public boolean containsColumn(byte[] family, int foffset, int flength, byte[] qualifier,
int qoffset, int qlength) {
return getColumnLatestCell(family, foffset, flength, qualifier, qoffset, qlength) != null;
}
/**
* Map of families to all versions of its qualifiers and values.
*
* Returns a three level Map of the form:
* Map&family,Map<qualifier,Map<timestamp,value>>>
*
* Note: All other map returning methods make use of this map internally.
* @return map from families to qualifiers to versions
*/
public NavigableMap>> getMap() {
if (this.familyMap != null) {
return this.familyMap;
}
if (isEmpty()) {
return null;
}
this.familyMap = new TreeMap<>(Bytes.BYTES_COMPARATOR);
for (Cell kv : this.cells) {
byte[] family = CellUtil.cloneFamily(kv);
NavigableMap> columnMap = familyMap.get(family);
if (columnMap == null) {
columnMap = new TreeMap<>(Bytes.BYTES_COMPARATOR);
familyMap.put(family, columnMap);
}
byte[] qualifier = CellUtil.cloneQualifier(kv);
NavigableMap versionMap = columnMap.get(qualifier);
if (versionMap == null) {
versionMap = new TreeMap<>(new Comparator() {
@Override
public int compare(Long l1, Long l2) {
return l2.compareTo(l1);
}
});
columnMap.put(qualifier, versionMap);
}
Long timestamp = kv.getTimestamp();
byte[] value = CellUtil.cloneValue(kv);
versionMap.put(timestamp, value);
}
return this.familyMap;
}
/**
* Map of families to their most recent qualifiers and values.
*
* Returns a two level Map of the form: Map&family,Map<qualifier,value>>
*
* The most recent version of each qualifier will be used.
* @return map from families to qualifiers and value
*/
public NavigableMap> getNoVersionMap() {
if (this.familyMap == null) {
getMap();
}
if (isEmpty()) {
return null;
}
NavigableMap> returnMap =
new TreeMap<>(Bytes.BYTES_COMPARATOR);
for (Map.Entry>> familyEntry : familyMap
.entrySet()) {
NavigableMap qualifierMap = new TreeMap<>(Bytes.BYTES_COMPARATOR);
for (Map.Entry> qualifierEntry : familyEntry.getValue()
.entrySet()) {
byte[] value = qualifierEntry.getValue().get(qualifierEntry.getValue().firstKey());
qualifierMap.put(qualifierEntry.getKey(), value);
}
returnMap.put(familyEntry.getKey(), qualifierMap);
}
return returnMap;
}
/**
* Map of qualifiers to values.
*
* Returns a Map of the form: Map<qualifier,value>
* @param family column family to get
* @return map of qualifiers to values
*/
public NavigableMap getFamilyMap(byte[] family) {
if (this.familyMap == null) {
getMap();
}
if (isEmpty()) {
return null;
}
NavigableMap returnMap = new TreeMap<>(Bytes.BYTES_COMPARATOR);
NavigableMap> qualifierMap = familyMap.get(family);
if (qualifierMap == null) {
return returnMap;
}
for (Map.Entry> entry : qualifierMap.entrySet()) {
byte[] value = entry.getValue().get(entry.getValue().firstKey());
returnMap.put(entry.getKey(), value);
}
return returnMap;
}
/**
* Returns the value of the first column in the Result.
* @return value of the first column
*/
public byte[] value() {
if (isEmpty()) {
return null;
}
return CellUtil.cloneValue(cells[0]);
}
/**
* Check if the underlying Cell [] is empty or not
* @return true if empty
*/
public boolean isEmpty() {
return this.cells == null || this.cells.length == 0;
}
/** Returns the size of the underlying Cell [] */
public int size() {
return this.cells == null ? 0 : this.cells.length;
}
/**
* */
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("keyvalues=");
if (isEmpty()) {
sb.append("NONE");
return sb.toString();
}
sb.append("{");
boolean moreThanOne = false;
for (Cell kv : this.cells) {
if (moreThanOne) {
sb.append(", ");
} else {
moreThanOne = true;
}
sb.append(kv.toString());
}
sb.append("}");
return sb.toString();
}
/**
* Does a deep comparison of two Results, down to the byte arrays.
* @param res1 first result to compare
* @param res2 second result to compare
* @throws Exception Every difference is throwing an exception
*/
public static void compareResults(Result res1, Result res2) throws Exception {
compareResults(res1, res2, true);
}
/**
* Does a deep comparison of two Results, down to the byte arrays.
* @param res1 first result to compare
* @param res2 second result to compare
* @param verbose includes string representation for all cells in the exception if true; otherwise
* include rowkey only
* @throws Exception Every difference is throwing an exception
*/
public static void compareResults(Result res1, Result res2, boolean verbose) throws Exception {
if (res2 == null) {
throw new Exception(
"There wasn't enough rows, we stopped at " + Bytes.toStringBinary(res1.getRow()));
}
if (res1.size() != res2.size()) {
if (verbose) {
throw new Exception(
"This row doesn't have the same number of KVs: " + res1 + " compared to " + res2);
} else {
throw new Exception(
"This row doesn't have the same number of KVs: row=" + Bytes.toStringBinary(res1.getRow())
+ ", " + res1.size() + " cells are compared to " + res2.size() + " cells");
}
}
Cell[] ourKVs = res1.rawCells();
Cell[] replicatedKVs = res2.rawCells();
for (int i = 0; i < res1.size(); i++) {
if (
!ourKVs[i].equals(replicatedKVs[i]) || !CellUtil.matchingValue(ourKVs[i], replicatedKVs[i])
|| !CellUtil.matchingTags(ourKVs[i], replicatedKVs[i])
) {
if (verbose) {
throw new Exception("This result was different: " + res1 + " compared to " + res2);
} else {
throw new Exception(
"This result was different: row=" + Bytes.toStringBinary(res1.getRow()));
}
}
}
}
/**
* Forms a single result from the partial results in the partialResults list. This method is
* useful for reconstructing partial results on the client side.
* @param partialResults list of partial results
* @return The complete result that is formed by combining all of the partial results together
* @throws IOException A complete result cannot be formed because the results in the partial list
* come from different rows
*/
public static Result createCompleteResult(Iterable partialResults) throws IOException {
if (partialResults == null) {
return Result.create(Collections.emptyList(), null, false);
}
List cells = new ArrayList<>();
boolean stale = false;
byte[] prevRow = null;
byte[] currentRow = null;
for (Iterator iter = partialResults.iterator(); iter.hasNext();) {
Result r = iter.next();
currentRow = r.getRow();
if (prevRow != null && !Bytes.equals(prevRow, currentRow)) {
throw new IOException("Cannot form complete result. Rows of partial results do not match."
+ " Partial Results: " + partialResults);
}
// Ensure that all Results except the last one are marked as partials. The last result
// may not be marked as a partial because Results are only marked as partials when
// the scan on the server side must be stopped due to reaching the maxResultSize.
// Visualizing it makes it easier to understand:
// maxResultSize: 2 cells
// (-x-) represents cell number x in a row
// Example: row1: -1- -2- -3- -4- -5- (5 cells total)
// How row1 will be returned by the server as partial Results:
// Result1: -1- -2- (2 cells, size limit reached, mark as partial)
// Result2: -3- -4- (2 cells, size limit reached, mark as partial)
// Result3: -5- (1 cell, size limit NOT reached, NOT marked as partial)
if (iter.hasNext() && !r.mayHaveMoreCellsInRow()) {
throw new IOException("Cannot form complete result. Result is missing partial flag. "
+ "Partial Results: " + partialResults);
}
prevRow = currentRow;
stale = stale || r.isStale();
for (Cell c : r.rawCells()) {
cells.add(c);
}
}
return Result.create(cells, null, stale);
}
/**
* Get total size of raw cells
* @return Total size.
*/
public static long getTotalSizeOfCells(Result result) {
long size = 0;
if (result.isEmpty()) {
return size;
}
for (Cell c : result.rawCells()) {
size += c.heapSize();
}
return size;
}
/**
* 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).
*/
public void copyFrom(Result other) {
checkReadonly();
this.row = null;
this.familyMap = null;
this.cells = other.cells;
}
@Override
public CellScanner cellScanner() {
// Reset
this.cellScannerIndex = INITIAL_CELLSCANNER_INDEX;
return this;
}
@Override
public Cell current() {
if (
isEmpty() || cellScannerIndex == INITIAL_CELLSCANNER_INDEX || cellScannerIndex >= cells.length
) {
return null;
}
return this.cells[cellScannerIndex];
}
@Override
public boolean advance() {
if (isEmpty()) {
return false;
}
cellScannerIndex++;
if (cellScannerIndex < this.cells.length) {
return true;
} else if (cellScannerIndex == this.cells.length) {
return false;
}
throw new NoSuchElementException("Cannot advance beyond the last cell");
}
public Boolean getExists() {
return exists;
}
public void setExists(Boolean exists) {
checkReadonly();
this.exists = exists;
}
/**
* Whether or not the results are coming from possibly stale data. Stale results might be returned
* if {@link Consistency} is not STRONG for the query.
* @return Whether or not the results are coming from possibly stale data.
*/
public boolean isStale() {
return stale;
}
/**
* Whether or not the results are partial.
* @deprecated the word 'partial' ambiguous, use {@link #mayHaveMoreCellsInRow()} instead.
* Deprecated since 1.4.0.
* @see #mayHaveMoreCellsInRow()
*/
@Deprecated
public boolean isPartial() {
return mayHaveMoreCellsInRow;
}
/**
* For scanning large rows, the RS may choose to return the cells chunk by chunk to prevent OOM or
* timeout. This flag is used to tell you if the current Result is the last one of the current
* row. False means this Result is the last one. True means there MAY be more cells belonging to
* the current row. If you don't use {@link Scan#setAllowPartialResults(boolean)} or
* {@link Scan#setBatch(int)}, this method will always return false because the Result must
* contains all cells in one Row.
*/
public boolean mayHaveMoreCellsInRow() {
return mayHaveMoreCellsInRow;
}
/**
* Set load information about the region to the information about the result
* @param loadStats statistics about the current region from which this was returned
*/
@InterfaceAudience.Private
public void setStatistics(RegionLoadStats loadStats) {
this.stats = loadStats;
}
/**
* Returns the associated statistics about the region from which this was returned. Can be
* null if stats are disabled.
*/
public 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!");
}
}
/**
* Return true if this Result is a cursor to tell users where the server has scanned. In this
* Result the only meaningful method is {@link #getCursor()}. {@code
* while (r = scanner.next() && r != null) {
* if(r.isCursor()){
* // scanning is not end, it is a cursor, save its row key and close scanner if you want, or
* // just continue the loop to call next(). } else { // just like before } } // scanning is end }
* {@link Scan#setNeedCursorResult(boolean)} {@link Cursor} {@link #getCursor()}
*/
public boolean isCursor() {
return cursor != null;
}
/**
* Return the cursor if this Result is a cursor result. {@link Scan#setNeedCursorResult(boolean)}
* {@link Cursor} {@link #isCursor()}
*/
public Cursor getCursor() {
return cursor;
}
}
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