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Cassandra support for Spring Data
/*
* Copyright 2018-2020 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 lombok.AccessLevel;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.experimental.FieldDefaults;
import java.util.List;
import java.util.stream.Stream;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.data.cassandra.core.cql.CqlIdentifier;
import org.springframework.data.cassandra.core.query.Query;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
/**
* Implementation of {@link ExecutableSelectOperation}.
*
* @author Mark Paluch
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation
* @see org.springframework.data.cassandra.core.query.Query
* @since 2.1
*/
@RequiredArgsConstructor
class ExecutableSelectOperationSupport implements ExecutableSelectOperation {
private final @NonNull CassandraTemplate template;
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation#query(java.lang.Class)
*/
@Override
public ExecutableSelect query(Class domainType) {
Assert.notNull(domainType, "DomainType must not be null");
return new ExecutableSelectSupport<>(this.template, domainType, domainType, Query.empty(), null);
}
// TODO: rethink the implementation
// While the use of final fields and construction on mutation effectively makes this class Thread-safe,
// it is possible this implementation could generate a high-level of young-gen garbage on the JVM heap,
// particularly if the template query(..) (and this class) are used inside of a loop for a large number
// of domain types. Of course, this assumption is highly contingent on the user's `Query`
// in addition to his/her application design.
@RequiredArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
static class ExecutableSelectSupport implements ExecutableSelect {
@NonNull CassandraTemplate template;
@NonNull Class domainType;
@NonNull Class returnType;
@NonNull Query query;
@Nullable CqlIdentifier tableName;
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.SelectWithTable#inTable(org.springframework.data.cassandra.core.cql.CqlIdentifier)
*/
@Override
public SelectWithProjection inTable(CqlIdentifier tableName) {
Assert.notNull(tableName, "Table name must not be null");
return new ExecutableSelectSupport<>(this.template, this.domainType, this.returnType, this.query, tableName);
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.SelectWithProjection#as(java.lang.Class)
*/
@Override
public SelectWithQuery as(Class returnType) {
Assert.notNull(returnType, "ReturnType must not be null");
return new ExecutableSelectSupport<>(this.template, this.domainType, returnType, this.query, this.tableName);
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.SelectWithQuery#matching(org.springframework.data.cassandra.core.query.Query)
*/
@Override
public TerminatingSelect matching(Query query) {
Assert.notNull(query, "Query must not be null");
return new ExecutableSelectSupport<>(this.template, this.domainType, this.returnType, query, this.tableName);
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.TerminatingSelect#count()
*/
@Override
public long count() {
return this.template.doCount(this.query, this.domainType, getTableName());
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.TerminatingSelect#exists()
*/
@Override
public boolean exists() {
return this.template.doExists(this.query, this.domainType, getTableName());
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.TerminatingSelect#firstValue()
*/
@Override
public T firstValue() {
List result = this.template.doSelect(this.query.limit(1), this.domainType, getTableName(), this.returnType);
return ObjectUtils.isEmpty(result) ? null : result.iterator().next();
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.TerminatingSelect#oneValue()
*/
@Override
public T oneValue() {
List result = this.template.doSelect(this.query.limit(2), this.domainType, getTableName(), this.returnType);
if (ObjectUtils.isEmpty(result)) {
return null;
}
if (result.size() > 1) {
throw new IncorrectResultSizeDataAccessException(
String.format("Query [%s] returned non unique result.", this.query), 1);
}
return result.iterator().next();
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.TerminatingSelect#all()
*/
@Override
public List all() {
return this.template.doSelect(this.query, this.domainType, getTableName(), this.returnType);
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.ExecutableSelectOperation.TerminatingSelect#stream()
*/
@Override
public Stream stream() {
return this.template.doStream(this.query, this.domainType, getTableName(), this.returnType);
}
private CqlIdentifier getTableName() {
return this.tableName != null ? this.tableName : this.template.getTableName(this.domainType);
}
}
}