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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.schema;
import java.util.Iterator;
import java.util.Optional;
import javax.annotation.Nullable;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.collect.MapDifference;
import com.google.common.collect.Maps;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.config.ViewDefinition;
import static com.google.common.collect.Iterables.filter;
public final class Views implements Iterable
{
private final ImmutableMap views;
private Views(Builder builder)
{
views = builder.views.build();
}
public static Builder builder()
{
return new Builder();
}
public static Views none()
{
return builder().build();
}
public Iterator iterator()
{
return views.values().iterator();
}
public Iterable metadatas()
{
return Iterables.transform(views.values(), view -> view.metadata);
}
public int size()
{
return views.size();
}
public boolean isEmpty()
{
return views.isEmpty();
}
/**
* Get the materialized view with the specified name
*
* @param name a non-qualified materialized view name
* @return an empty {@link Optional} if the materialized view name is not found; a non-empty optional of {@link ViewDefinition} otherwise
*/
public Optional get(String name)
{
return Optional.ofNullable(views.get(name));
}
/**
* Get the view with the specified name
*
* @param name a non-qualified view name
* @return null if the view name is not found; the found {@link ViewDefinition} otherwise
*/
@Nullable
public ViewDefinition getNullable(String name)
{
return views.get(name);
}
/**
* Create a MaterializedViews instance with the provided materialized view added
*/
public Views with(ViewDefinition view)
{
if (get(view.viewName).isPresent())
throw new IllegalStateException(String.format("Materialized View %s already exists", view.viewName));
return builder().add(this).add(view).build();
}
/**
* Creates a MaterializedViews instance with the materializedView with the provided name removed
*/
public Views without(String name)
{
ViewDefinition materializedView =
get(name).orElseThrow(() -> new IllegalStateException(String.format("Materialized View %s doesn't exists", name)));
return builder().add(filter(this, v -> v != materializedView)).build();
}
/**
* Creates a MaterializedViews instance which contains an updated materialized view
*/
public Views replace(ViewDefinition view, CFMetaData cfm)
{
return without(view.viewName).with(view);
}
MapDifference diff(Views other)
{
return Maps.difference(views, other.views);
}
@Override
public boolean equals(Object o)
{
return this == o || (o instanceof Views && views.equals(((Views) o).views));
}
@Override
public int hashCode()
{
return views.hashCode();
}
@Override
public String toString()
{
return views.values().toString();
}
public static final class Builder
{
final ImmutableMap.Builder views = new ImmutableMap.Builder<>();
private Builder()
{
}
public Views build()
{
return new Views(this);
}
public Builder add(ViewDefinition view)
{
views.put(view.viewName, view);
return this;
}
public Builder add(Iterable views)
{
views.forEach(this::add);
return this;
}
}
}