/**
*
* 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.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.NavigableSet;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.io.TimeRange;
import org.apache.hadoop.hbase.util.Bytes;
/**
* Used to perform Get operations on a single row.
* <p>
* To get everything for a row, instantiate a Get object with the row to get.
* To further narrow the scope of what to Get, use the methods below.
* <p>
* To get all columns from specific families, execute {@link #addFamily(byte[]) addFamily}
* for each family to retrieve.
* <p>
* To get specific columns, execute {@link #addColumn(byte[], byte[]) addColumn}
* for each column to retrieve.
* <p>
* To only retrieve columns within a specific range of version timestamps,
* execute {@link #setTimeRange(long, long) setTimeRange}.
* <p>
* To only retrieve columns with a specific timestamp, execute
* {@link #setTimeStamp(long) setTimestamp}.
* <p>
* To limit the number of versions of each column to be returned, execute
* {@link #setMaxVersions(int) setMaxVersions}.
* <p>
* To add a filter, call {@link #setFilter(Filter) setFilter}.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class Get extends Query
implements Row, Comparable<Row> {
private byte [] row = null;
private int maxVersions = 1;
private boolean cacheBlocks = true;
private int storeLimit = -1;
private int storeOffset = 0;
private TimeRange tr = new TimeRange();
private boolean checkExistenceOnly = false;
private boolean closestRowBefore = false;
private Map<byte [], NavigableSet<byte []>> familyMap =
new TreeMap<byte [], NavigableSet<byte []>>(Bytes.BYTES_COMPARATOR);
/**
* Create a Get operation for the specified row.
* <p>
* If no further operations are done, this will get the latest version of
* all columns in all families of the specified row.
* @param row row key
*/
public Get(byte [] row) {
Mutation.checkRow(row);
this.row = row;
}
public boolean isCheckExistenceOnly() {
return checkExistenceOnly;
}
public void setCheckExistenceOnly(boolean checkExistenceOnly) {
this.checkExistenceOnly = checkExistenceOnly;
}
public boolean isClosestRowBefore() {
return closestRowBefore;
}
public void setClosestRowBefore(boolean closestRowBefore) {
this.closestRowBefore = closestRowBefore;
}
/**
* Get all columns from the specified family.
* <p>
* Overrides previous calls to addColumn for this family.
* @param family family name
* @return the Get object
*/
public Get addFamily(byte [] family) {
familyMap.remove(family);
familyMap.put(family, null);
return this;
}
/**
* Get the column from the specific family with the specified qualifier.
* <p>
* Overrides previous calls to addFamily for this family.
* @param family family name
* @param qualifier column qualifier
* @return the Get objec
*/
public Get addColumn(byte [] family, byte [] qualifier) {
NavigableSet<byte []> set = familyMap.get(family);
if(set == null) {
set = new TreeSet<byte []>(Bytes.BYTES_COMPARATOR);
}
if (qualifier == null) {
qualifier = HConstants.EMPTY_BYTE_ARRAY;
}
set.add(qualifier);
familyMap.put(family, set);
return this;
}
/**
* Get versions of columns only within the specified timestamp range,
* [minStamp, maxStamp).
* @param minStamp minimum timestamp value, inclusive
* @param maxStamp maximum timestamp value, exclusive
* @throws IOException if invalid time range
* @return this for invocation chaining
*/
public Get setTimeRange(long minStamp, long maxStamp)
throws IOException {
tr = new TimeRange(minStamp, maxStamp);
return this;
}
/**
* Get versions of columns with the specified timestamp.
* @param timestamp version timestamp
* @return this for invocation chaining
*/
public Get setTimeStamp(long timestamp) {
try {
tr = new TimeRange(timestamp, timestamp+1);
} catch(IOException e) {
// Will never happen
}
return this;
}
/**
* Get all available versions.
* @return this for invocation chaining
*/
public Get setMaxVersions() {
this.maxVersions = Integer.MAX_VALUE;
return this;
}
/**
* Get up to the specified number of versions of each column.
* @param maxVersions maximum versions for each column
* @throws IOException if invalid number of versions
* @return this for invocation chaining
*/
public Get setMaxVersions(int maxVersions) throws IOException {
if(maxVersions <= 0) {
throw new IOException("maxVersions must be positive");
}
this.maxVersions = maxVersions;
return this;
}
/**
* Set the maximum number of values to return per row per Column Family
* @param limit the maximum number of values returned / row / CF
* @return this for invocation chaining
*/
public Get setMaxResultsPerColumnFamily(int limit) {
this.storeLimit = limit;
return this;
}
/**
* Set offset for the row per Column Family. This offset is only within a particular row/CF
* combination. It gets reset back to zero when we move to the next row or CF.
* @param offset is the number of kvs that will be skipped.
* @return this for invocation chaining
*/
public Get setRowOffsetPerColumnFamily(int offset) {
this.storeOffset = offset;
return this;
}
@Override
public Get setFilter(Filter filter) {
super.setFilter(filter);
return this;
}
/* Accessors */
/**
* Set whether blocks should be cached for this Get.
* <p>
* This is true by default. When true, default settings of the table and
* family are used (this will never override caching blocks if the block
* cache is disabled for that family or entirely).
*
* @param cacheBlocks if false, default settings are overridden and blocks
* will not be cached
*/
public void setCacheBlocks(boolean cacheBlocks) {
this.cacheBlocks = cacheBlocks;
}
/**
* Get whether blocks should be cached for this Get.
* @return true if default caching should be used, false if blocks should not
* be cached
*/
public boolean getCacheBlocks() {
return cacheBlocks;
}
/**
* Method for retrieving the get's row
* @return row
*/
public byte [] getRow() {
return this.row;
}
/**
* Method for retrieving the get's maximum number of version
* @return the maximum number of version to fetch for this get
*/
public int getMaxVersions() {
return this.maxVersions;
}
/**
* Method for retrieving the get's maximum number of values
* to return per Column Family
* @return the maximum number of values to fetch per CF
*/
public int getMaxResultsPerColumnFamily() {
return this.storeLimit;
}
/**
* Method for retrieving the get's offset per row per column
* family (#kvs to be skipped)
* @return the row offset
*/
public int getRowOffsetPerColumnFamily() {
return this.storeOffset;
}
/**
* Method for retrieving the get's TimeRange
* @return timeRange
*/
public TimeRange getTimeRange() {
return this.tr;
}
/**
* Method for retrieving the keys in the familyMap
* @return keys in the current familyMap
*/
public Set<byte[]> familySet() {
return this.familyMap.keySet();
}
/**
* Method for retrieving the number of families to get from
* @return number of families
*/
public int numFamilies() {
return this.familyMap.size();
}
/**
* Method for checking if any families have been inserted into this Get
* @return true if familyMap is non empty false otherwise
*/
public boolean hasFamilies() {
return !this.familyMap.isEmpty();
}
/**
* Method for retrieving the get's familyMap
* @return familyMap
*/
public Map<byte[],NavigableSet<byte[]>> getFamilyMap() {
return this.familyMap;
}
/**
* Compile the table and column family (i.e. schema) information
* into a String. Useful for parsing and aggregation by debugging,
* logging, and administration tools.
* @return Map
*/
@Override
public Map<String, Object> getFingerprint() {
Map<String, Object> map = new HashMap<String, Object>();
List<String> families = new ArrayList<String>();
map.put("families", families);
for (Map.Entry<byte [], NavigableSet<byte[]>> entry :
this.familyMap.entrySet()) {
families.add(Bytes.toStringBinary(entry.getKey()));
}
return map;
}
/**
* Compile the details beyond the scope of getFingerprint (row, columns,
* timestamps, etc.) into a Map along with the fingerprinted information.
* Useful for debugging, logging, and administration tools.
* @param maxCols a limit on the number of columns output prior to truncation
* @return Map
*/
@Override
public Map<String, Object> toMap(int maxCols) {
// we start with the fingerprint map and build on top of it.
Map<String, Object> map = getFingerprint();
// replace the fingerprint's simple list of families with a
// map from column families to lists of qualifiers and kv details
Map<String, List<String>> columns = new HashMap<String, List<String>>();
map.put("families", columns);
// add scalar information first
map.put("row", Bytes.toStringBinary(this.row));
map.put("maxVersions", this.maxVersions);
map.put("cacheBlocks", this.cacheBlocks);
List<Long> timeRange = new ArrayList<Long>();
timeRange.add(this.tr.getMin());
timeRange.add(this.tr.getMax());
map.put("timeRange", timeRange);
int colCount = 0;
// iterate through affected families and add details
for (Map.Entry<byte [], NavigableSet<byte[]>> entry :
this.familyMap.entrySet()) {
List<String> familyList = new ArrayList<String>();
columns.put(Bytes.toStringBinary(entry.getKey()), familyList);
if(entry.getValue() == null) {
colCount++;
--maxCols;
familyList.add("ALL");
} else {
colCount += entry.getValue().size();
if (maxCols <= 0) {
continue;
}
for (byte [] column : entry.getValue()) {
if (--maxCols <= 0) {
continue;
}
familyList.add(Bytes.toStringBinary(column));
}
}
}
map.put("totalColumns", colCount);
if (this.filter != null) {
map.put("filter", this.filter.toString());
}
// add the id if set
if (getId() != null) {
map.put("id", getId());
}
return map;
}
//Row
@Override
public int compareTo(Row other) {
// TODO: This is wrong. Can't have two gets the same just because on same row.
return Bytes.compareTo(this.getRow(), other.getRow());
}
@Override
public int hashCode() {
// TODO: This is wrong. Can't have two gets the same just because on same row. But it
// matches how equals works currently and gets rid of the findbugs warning.
return Bytes.hashCode(this.getRow());
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
Row other = (Row) obj;
// TODO: This is wrong. Can't have two gets the same just because on same row.
return compareTo(other) == 0;
}
}