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Cassandra support for Spring Data
/*
* Copyright 2017-2020 the original author or authors.
*
* 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
*
* https://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.springframework.data.cassandra.core;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import org.springframework.data.cassandra.core.mapping.CassandraMappingContext;
import org.springframework.data.cassandra.core.mapping.CassandraPersistentEntity;
import org.springframework.util.Assert;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import com.datastax.oss.driver.api.core.CqlIdentifier;
import com.datastax.oss.driver.api.core.metadata.schema.RelationMetadata;
import com.datastax.oss.driver.api.core.type.DataType;
import com.datastax.oss.driver.api.core.type.ListType;
import com.datastax.oss.driver.api.core.type.MapType;
import com.datastax.oss.driver.api.core.type.SetType;
import com.datastax.oss.driver.api.core.type.TupleType;
import com.datastax.oss.driver.api.core.type.UserDefinedType;
/**
* Schema drop support for Cassandra based on {@link CassandraMappingContext} and {@link CassandraPersistentEntity}.
* This class generates CQL to drop user types (UDT) and tables.
*
* @author Mark Paluch
* @since 1.5
* @see org.springframework.data.cassandra.core.mapping.Table
* @see org.springframework.data.cassandra.core.mapping.UserDefinedType
* @see org.springframework.data.cassandra.core.mapping.CassandraType
*/
public class CassandraPersistentEntitySchemaDropper {
private final CassandraAdminOperations cassandraAdminOperations;
private final CassandraMappingContext mappingContext;
/**
* Create a new {@link CassandraPersistentEntitySchemaDropper} for the given {@link CassandraMappingContext} and
* {@link CassandraAdminOperations}.
*
* @param mappingContext must not be {@literal null}.
* @param cassandraAdminOperations must not be {@literal null}.
*/
public CassandraPersistentEntitySchemaDropper(CassandraMappingContext mappingContext,
CassandraAdminOperations cassandraAdminOperations) {
Assert.notNull(cassandraAdminOperations, "CassandraAdminOperations must not be null");
Assert.notNull(mappingContext, "CassandraMappingContext must not be null");
this.cassandraAdminOperations = cassandraAdminOperations;
this.mappingContext = mappingContext;
}
/**
* Drop tables that exist in the keyspace.
*
* @param dropUnused {@literal true} to drop unused tables. Table usage is determined by existing table mappings.
*/
public void dropTables(boolean dropUnused) {
this.cassandraAdminOperations.getKeyspaceMetadata() //
.getTables() //
.values() //
.stream() //
.map(RelationMetadata::getName) //
.filter(table -> dropUnused || this.mappingContext.usesTable(table)) //
.forEach(this.cassandraAdminOperations::dropTable);
}
/**
* Drop user types that exist in the keyspace.
*
* @param dropUnused {@literal true} to drop unused types before creation. Type usage is determined from existing
* mapped {@link org.springframework.data.cassandra.core.mapping.UserDefinedType}s and UDT names on field
* specifications.
*/
public void dropUserTypes(boolean dropUnused) {
Set canRecreate = this.mappingContext.getUserDefinedTypeEntities().stream()
.map(CassandraPersistentEntity::getTableName).collect(Collectors.toSet());
Collection userTypes = this.cassandraAdminOperations.getKeyspaceMetadata().getUserDefinedTypes()
.values();
getUserTypesToDrop(userTypes) //
.stream() //
.filter(it -> canRecreate.contains(it) || (dropUnused && !mappingContext.usesUserType(it))) //
.forEach(this.cassandraAdminOperations::dropUserType);
}
/**
* Create {@link List} of {@link CqlIdentifier} with User-Defined type names to drop considering dependencies between
* UDTs.
*
* @return {@link List} of {@link CqlIdentifier}.
*/
private List getUserTypesToDrop(Collection knownUserTypes) {
List toDrop = new ArrayList<>();
UserTypeDependencyGraphBuilder builder = new UserTypeDependencyGraphBuilder();
knownUserTypes.forEach(builder::addUserType);
UserTypeDependencyGraph dependencyGraph = builder.build();
Set globalSeen = new LinkedHashSet<>();
knownUserTypes.forEach(userType -> {
toDrop.addAll(dependencyGraph.getDropOrder(userType.getName(), globalSeen::add));
});
return toDrop;
}
/**
* Builder for {@link UserTypeDependencyGraph}. Introspects {@link UserType} for dependencies to other user types to
* build a dependency graph between user types.
*
* @author Mark Paluch
* @since 2.0.7
*/
static class UserTypeDependencyGraphBuilder {
// Maps user types to other types they are referenced in.
private final MultiValueMap dependencies = new LinkedMultiValueMap<>();
/**
* Add {@link UserType} to the builder and inspect its dependencies.
*
* @param userType must not be {@literal null.}
*/
void addUserType(UserDefinedType userType) {
Set seen = new LinkedHashSet<>();
visitTypes(userType, seen::add);
}
/**
* Build the {@link UserTypeDependencyGraph}.
*
* @return the {@link UserTypeDependencyGraph}.
*/
UserTypeDependencyGraph build() {
return new UserTypeDependencyGraph(new LinkedMultiValueMap<>(dependencies));
}
/**
* Visit a {@link UserType} and its fields.
*
* @param userType
* @param typeFilter
*/
private void visitTypes(UserDefinedType userType, Predicate typeFilter) {
CqlIdentifier typeName = userType.getName();
if (!typeFilter.test(typeName)) {
return;
}
for (DataType fieldType : userType.getFieldTypes()) {
if (fieldType instanceof UserDefinedType) {
addDependency((UserDefinedType) fieldType, typeName, typeFilter);
return;
}
doWithTypeArguments(fieldType, it -> {
if (it instanceof UserDefinedType) {
addDependency((UserDefinedType) it, typeName, typeFilter);
}
});
}
}
private void addDependency(UserDefinedType userType, CqlIdentifier requiredBy,
Predicate typeFilter) {
dependencies.add(userType.getName(), requiredBy);
visitTypes(userType, typeFilter);
}
private static void doWithTypeArguments(DataType type, Consumer callback) {
if (type instanceof MapType) {
MapType mapType = (MapType) type;
callback.accept(mapType.getKeyType());
doWithTypeArguments(mapType.getKeyType(), callback);
callback.accept(mapType.getValueType());
doWithTypeArguments(mapType.getValueType(), callback);
}
if (type instanceof ListType) {
ListType listType = (ListType) type;
callback.accept(listType.getElementType());
doWithTypeArguments(listType.getElementType(), callback);
}
if (type instanceof SetType) {
SetType setType = (SetType) type;
callback.accept(setType.getElementType());
doWithTypeArguments(setType.getElementType(), callback);
}
if (type instanceof TupleType) {
TupleType tupleType = (TupleType) type;
tupleType.getComponentTypes().forEach(nested -> {
callback.accept(nested);
doWithTypeArguments(nested, callback);
});
}
}
}
/**
* Dependency graph representing user type field dependencies to other user types.
*
* @author Mark Paluch
* @since 2.0.7
*/
static class UserTypeDependencyGraph {
private final MultiValueMap dependencies;
UserTypeDependencyGraph(MultiValueMap dependencies) {
this.dependencies = dependencies;
}
/**
* Returns the names of user types in the order they need to be dropped including type {@code typeName}.
*
* @param typeName
* @param typeFilter
* @return
*/
List getDropOrder(CqlIdentifier typeName, Predicate typeFilter) {
List toDrop = new ArrayList<>();
if (typeFilter.test(typeName)) {
List dependants = dependencies.getOrDefault(typeName, Collections.emptyList());
dependants.stream().map(dependant -> getDropOrder(dependant, typeFilter)).forEach(toDrop::addAll);
toDrop.add(typeName);
}
return toDrop;
}
}
}