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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cassandra.cql3.selection;
import java.util.*;
import com.google.common.collect.Lists;
import org.apache.cassandra.schema.ColumnMetadata;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.cql3.QueryOptions;
import org.apache.cassandra.cql3.VariableSpecifications;
import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.cql3.selection.Selector.Factory;
import org.apache.cassandra.db.filter.ColumnFilter.Builder;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.exceptions.InvalidRequestException;
/**
* A set of {@code Selector} factories.
*/
final class SelectorFactories implements Iterable
{
/**
* The {@code Selector} factories.
*/
private final List factories;
/**
* {@code true} if one of the factories creates writetime selectors.
*/
private boolean containsWritetimeFactory;
/**
* {@code true} if one of the factories creates maxWritetime selectors.
*/
private boolean containsMaxWritetimeFactory;
/**
* {@code true} if one of the factories creates TTL selectors.
*/
private boolean containsTTLFactory;
/**
* The number of factories creating aggregates.
*/
private int numberOfAggregateFactories;
/**
* Creates a new SelectorFactories instance and collect the column definitions.
*
* @param selectables the Selectables for which the factories must be created
* @param expectedTypes the returned types expected for each of the {@code selectables}, if there
* is any such expectations, or {@code null} otherwise. This will be {@code null} when called on
* the top-level selectables, but may not be for selectable nested within a function for instance
* (as the argument selectable will be expected to be of the type expected by the function).
* @param table the table Definition
* @param defs the collector parameter for the column definitions
* @param boundNames the collector for the specification of bound markers in the selection
* @return a new SelectorFactories instance
* @throws InvalidRequestException if a problem occurs while creating the factories
*/
public static SelectorFactories createFactoriesAndCollectColumnDefinitions(List selectables,
List> expectedTypes,
TableMetadata table,
List defs,
VariableSpecifications boundNames)
throws InvalidRequestException
{
return new SelectorFactories(selectables, expectedTypes, table, defs, boundNames);
}
private SelectorFactories(List selectables,
List> expectedTypes,
TableMetadata table,
List defs,
VariableSpecifications boundNames)
throws InvalidRequestException
{
factories = new ArrayList<>(selectables.size());
for (int i = 0; i < selectables.size(); i++)
{
Selectable selectable = selectables.get(i);
AbstractType expectedType = expectedTypes == null ? null : expectedTypes.get(i);
Factory factory = selectable.newSelectorFactory(table, expectedType, defs, boundNames);
containsWritetimeFactory |= factory.isWritetimeSelectorFactory();
containsTTLFactory |= factory.isTTLSelectorFactory();
containsMaxWritetimeFactory |= factory.isMaxWritetimeSelectorFactory();
if (factory.isAggregateSelectorFactory())
++numberOfAggregateFactories;
factories.add(factory);
}
}
public void addFunctionsTo(List functions)
{
factories.forEach(p -> p.addFunctionsTo(functions));
}
/**
* Returns the factory with the specified index.
*
* @param i the factory index
* @return the factory with the specified index
*/
public Selector.Factory get(int i)
{
return factories.get(i);
}
/**
* Returns the index of the {@code SimpleSelector.Factory} for the specified column.
*
* @param columnIndex the index of the column
* @return the index of the {@code SimpleSelector.Factory} for the specified column or -1 if it does not exist.
*/
public int indexOfSimpleSelectorFactory(int columnIndex)
{
for (int i = 0, m = factories.size(); i < m; i++)
{
if (factories.get(i).isSimpleSelectorFactoryFor(columnIndex))
return i;
}
return -1;
}
/**
* Adds a new Selector.Factory for a column that is needed only for ORDER BY purposes.
* @param def the column that is needed for ordering
* @param index the index of the column definition in the Selection's list of columns
*/
public void addSelectorForOrdering(ColumnMetadata def, int index)
{
factories.add(SimpleSelector.newFactory(def, index, true));
}
/**
* Whether the selector built by this factory does aggregation or not (either directly or in a sub-selector).
*
* @return true if the selector built by this factor does aggregation, false otherwise.
*/
public boolean doesAggregation()
{
return numberOfAggregateFactories > 0;
}
/**
* Checks if this SelectorFactories contains at least one factory for writetime selectors.
*
* @return true if this SelectorFactories contains at least one factory for writetime
* selectors, false otherwise.
*/
public boolean containsWritetimeSelectorFactory()
{
return containsWritetimeFactory;
}
/**
* Checks if this {@code SelectorFactories} contains at least one factory for maxWritetime selectors.
*
* @return {@link true} if this {@link SelectorFactories} contains at least one factory for maxWritetime
* selectors, {@link false} otherwise.
*/
public boolean containsMaxWritetimeSelectorFactory()
{
return containsMaxWritetimeFactory;
}
/**
* Checks if this SelectorFactories contains at least one factory for TTL selectors.
*
* @return true if this SelectorFactories contains at least one factory for TTL
* selectors, false otherwise.
*/
public boolean containsTTLSelectorFactory()
{
return containsTTLFactory;
}
/**
* Creates a list of new Selector instances.
*
* @param options the query options for the query being executed.
* @return a list of new Selector instances.
*/
public List newInstances(QueryOptions options) throws InvalidRequestException
{
List selectors = new ArrayList<>(factories.size());
for (Selector.Factory factory : factories)
selectors.add(factory.newInstance(options));
return selectors;
}
public Iterator iterator()
{
return factories.iterator();
}
/**
* Returns the names of the columns corresponding to the output values of the selector instances created by
* these factories.
*
* @return a list of column names
*/
public List getColumnNames()
{
return Lists.transform(factories, new com.google.common.base.Function()
{
public String apply(Selector.Factory factory)
{
return factory.getColumnName();
}
});
}
/**
* Returns a list of the return types of the selector instances created by these factories.
*
* @return a list of types
*/
public List> getReturnTypes()
{
return Lists.transform(factories, new com.google.common.base.Function>()
{
public AbstractType apply(Selector.Factory factory)
{
return factory.getReturnType();
}
});
}
boolean areAllFetchedColumnsKnown()
{
for (Factory factory : factories)
{
if (!factory.areAllFetchedColumnsKnown())
return false;
}
return true;
}
void addFetchedColumns(Builder builder)
{
for (Factory factory : factories)
factory.addFetchedColumns(builder);
}
/**
* Returns the number of factories.
* @return the number of factories
*/
public int size()
{
return factories.size();
}
}