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The Kite Data Core module provides simple, intuitive APIs for working with
datasets in the Hadoop Platform.
/**
* Copyright 2013 Cloudera Inc.
*
* Licensed 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.kitesdk.data;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import org.kitesdk.data.spi.ColumnMappingParser;
/**
* A descriptor for an entity's column mappings, which defines how an entity
* maps to a columnar store.
*
* @since 0.14.0
*/
@Immutable
public class ColumnMapping {
private final Collection fieldMappings;
private ColumnMapping(Collection mappings) {
fieldMappings = ImmutableList.copyOf(mappings);
}
public Collection getFieldMappings() {
return fieldMappings;
}
public FieldMapping getFieldMapping(String fieldName) {
for (FieldMapping fm : fieldMappings) {
if (fm.getFieldName().equals(fieldName)) {
return fm;
}
}
return null;
}
/**
* Get the columns required by this schema.
*
* @return The set of columns
*/
public Set getRequiredColumns() {
Set set = new HashSet();
for (FieldMapping fieldMapping : fieldMappings) {
if (FieldMapping.MappingType.KEY == fieldMapping.getMappingType()) {
continue;
} else if (FieldMapping.MappingType.KEY_AS_COLUMN == fieldMapping.getMappingType()) {
set.add(fieldMapping.getFamilyAsString() + ":");
} else {
set.add(fieldMapping.getFamilyAsString() + ":"
+ fieldMapping.getQualifierAsString());
}
}
return set;
}
/**
* Get the column families required by this schema.
*
* @return The set of column families.
*/
public Set getRequiredColumnFamilies() {
Set set = new HashSet();
for (FieldMapping mapping : fieldMappings) {
if (FieldMapping.MappingType.KEY != mapping.getMappingType())
set.add(mapping.getFamilyAsString());
}
return set;
}
@Override
@edu.umd.cs.findbugs.annotations.SuppressWarnings(
value="NP_METHOD_PARAMETER_TIGHTENS_ANNOTATION",
justification="Default annotation is not correct for equals")
public boolean equals(@Nullable Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ColumnMapping that = (ColumnMapping) o;
return Objects.equal(fieldMappings, that.fieldMappings);
}
@Override
public int hashCode() {
return Objects.hashCode(fieldMappings.hashCode());
}
@Override
public String toString() {
return ColumnMappingParser.toString(this, false);
}
public String toString(boolean pretty) {
return ColumnMappingParser.toString(this, pretty);
}
/**
* A fluent builder to aid in constructing a {@link ColumnMapping}.
*
* @since 0.14.0
*/
public static class Builder {
boolean hasOCCVersion = false;
boolean hasCounter = false;
private Collection fieldMappings = new ArrayList();
/**
* Adds a mapping to store the record field {@code name} in the record key.
*
* The underlying dataset's {@link PartitionStrategy} must have an identity
* partitioner for the record field {@code name} so that the value can be
* recovered.
*
* @param name The name of a record field
* @return This Builder for method chaining
*/
public Builder key(String name) {
addField(FieldMapping.key(name));
return this;
}
/**
* Adds a mapping to store the record field {@code name} in a column using
* the {@code family} and {@code qualifier}.
*
* @param name The name of a record field
* @param family The column family for storing the record field value
* @param qualifier The column qualifier for storing the record field value
* @return This Builder for method chaining
*/
public Builder column(String name, String family, String qualifier) {
addField(FieldMapping.column(name, family, qualifier));
return this;
}
/**
* Adds a key-as-column mapping to store the record field {@code name} in
* the given {@code family}, using its keys or fields as column qualifiers.
*
* The record field must be a map or a record.
*
* @param name The name of a record field
* @param family The column family for storing the map or record values
* @return This Builder for method chaining
*/
public Builder keyAsColumn(String name, String family) {
addField(FieldMapping.keyAsColumn(name, family));
return this;
}
/**
* Adds a key-as-column mapping to store the record field {@code name} in
* the given {@code family}, using column qualifiers built from its keys or
* field names appended to the {@code qualifierPrefix}.
*
* The record field must be a map or a record.
*
* @param name The name of a record field
* @param family The column family for storing the map or record values
* @param qualifierPrefix A prefix to add when building column qualifiers
* @return This Builder for method chaining
*/
public Builder keyAsColumn(String name, String family, String qualifierPrefix) {
addField(FieldMapping.keyAsColumn(name, family, qualifierPrefix));
return this;
}
/**
* Adds a counter mapping to store record field {@code name} in a column
* using the {@code family} and {@code qualifier}. The record field can be
* updated atomically using
* {@link RandomAccessDataset#increment(Key, String, long)}
*
* The record field must be an int or a long.
*
* Counters cannot be used in combination with optimistic concurrency (OCC).
*
* @param name The name of a record field
* @param family The column family for storing the record counter value
* @param qualifier The column qualifier for storing the record field value
* @return This Builder for method chaining
*/
public Builder counter(String name, String family, String qualifier) {
addField(FieldMapping.counter(name, family, qualifier));
return this;
}
/**
* Adds an OCC version mapping for the record field {@code name}. The
* record field will contain the current version number of the record.
*
* Using this mapping enables optimistic concurrency (OCC), where the
* underlying {@link RandomAccessDataset} will only persist changes to a
* record if it has not changed by another process.
*
* The record field must be an int or a long.
*
* Optimistic concurrency (OCC) cannot be used in combination with counters.
*
* @param name The name of a record field to use for an OCC version
* @return This Builder for method chaining
*/
public Builder occ(String name) {
addField(FieldMapping.occ(name));
return this;
}
/**
* Adds an OCC version mapping for the record field {@code name}. The
* record field will contain the current version number of the record.
*
* Using this mapping enables optimistic concurrency (OCC), where the
* underlying {@link RandomAccessDataset} will only persist changes to a
* record if it has not changed by another process.
*
* The record field must be an int or a long.
*
* Optimistic concurrency (OCC) cannot be used in combination with counters.
*
* @param name The name of a record field to use for an OCC version
* @return This Builder for method chaining
*/
public Builder version(String name) {
return occ(name);
}
/**
* Adds a {@link FieldMapping}.
*
* @param fieldMapping A {@code FieldMapping}
* @return This Builder for method chaining
*/
public Builder fieldMapping(FieldMapping fieldMapping) {
addField(fieldMapping);
return this;
}
/**
* Adds each {@link FieldMapping} from a collection.
*
* @param fieldMappings A collection of {@code FieldMapping} objects
* @return This Builder for method chaining
*/
public Builder fieldMappings(Collection fieldMappings) {
for (FieldMapping fieldMapping : fieldMappings) {
addField(fieldMapping);
}
return this;
}
/**
* Builds and returns a {@link ColumnMapping} from the fields
* mappings added to this builder.
*
* @return a ColumnMapping
*/
public ColumnMapping build() {
return new ColumnMapping(fieldMappings);
}
/**
* Validate that a {@link FieldMapping} is compatible with this builder's
* current set of mappings and add it to the set of mappings.
*
* A mapping is not compatible if it results in:
*
* 1. Multiple occVersion mappings in the mapping set
* 2. Both a counter and an occVersion mapping in the mapping set
*
*
* @param fm a {@code FieldMapping} to add to this builder
*/
private void addField(FieldMapping fm) {
// validate!
if (fm.getMappingType() == FieldMapping.MappingType.OCC_VERSION) {
ValidationException.check(!hasOCCVersion,
"Cannot use multiple occVersion fields");
ValidationException.check(!hasCounter,
"Cannot use both counter and occVersion fields");
hasOCCVersion = true;
} else if (fm.getMappingType() == FieldMapping.MappingType.COUNTER) {
ValidationException.check(!hasOCCVersion,
"Cannot use both counter and occVersion fields");
hasCounter = true;
}
fieldMappings.add(fm);
}
}
}