org.springframework.data.cassandra.core.cql.CachedPreparedStatementCreator Maven / Gradle / Ivy
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/*
* Copyright 2013-2019 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.cql;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.Assert;
import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.exceptions.DriverException;
/**
* This {@link PreparedStatementCreator} maintains a static cache of all prepared statements for the duration of the JVM
* runtime, more specific the lifecycle of the associated {@link ClassLoader}. When preparing statements with Cassandra,
* each Statement should be prepared once and only once due to the overhead of preparing the statement.
*
* {@link CachedPreparedStatementCreator} is thread-safe and does not require external synchronization when used by
* concurrent threads.
*
* @author David Webb
* @author Mark Paluch
* @deprecated since 2.0. This class uses an unsafe, static held cache and is not able to prepare
* {@link com.datastax.driver.core.querybuilder.BuiltStatement}. Use
* {@link org.springframework.data.cassandra.core.cql.support.CachedPreparedStatementCreator}.
*/
@Deprecated
public class CachedPreparedStatementCreator implements PreparedStatementCreator {
private static final Map> CACHE = new ConcurrentHashMap<>();
protected final Logger log = LoggerFactory.getLogger(getClass());
private final String cql;
/**
* Create a {@link PreparedStatementCreator} from the provided CQL.
*
* @param cql must not be empty or {@literal null}.
*/
public CachedPreparedStatementCreator(String cql) {
Assert.hasText(cql, "CQL is required to create a PreparedStatement");
this.cql = cql;
}
/**
* Returns the CQL statement on which the {@link PreparedStatement} will be based.
*
* @return a String containing the CQL of the {@link PreparedStatement}.
*/
public String getCql() {
return this.cql;
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.cql.PreparedStatementCreator#createPreparedStatement(com.datastax.driver.core.Session)
*/
@Override
public PreparedStatement createPreparedStatement(Session session) throws DriverException {
String cacheKey = String.valueOf(session.getLoggedKeyspace()).concat("|").concat(this.cql);
log.debug("Cacheable PreparedStatement in Keyspace {}", session.getLoggedKeyspace());
Map sessionCache = getOrCreateSessionLocalCache(session);
return getOrPrepareStatement(session, cacheKey, sessionCache);
}
@SuppressWarnings("all")
private Map getOrCreateSessionLocalCache(Session session) {
Map sessionMap = CACHE.get(session);
if (sessionMap == null) {
synchronized (session) {
if (CACHE.containsKey(session)) {
sessionMap = CACHE.get(session);
} else {
sessionMap = new ConcurrentHashMap();
CACHE.put(session, sessionMap);
}
}
}
return sessionMap;
}
@SuppressWarnings("all")
private PreparedStatement getOrPrepareStatement(Session session, String cacheKey,
Map sessionCache) {
PreparedStatement preparedStatement = sessionCache.get(cacheKey);
if (preparedStatement == null) {
synchronized (sessionCache) {
if (sessionCache.containsKey(cacheKey)) {
log.debug("Found cached PreparedStatement");
preparedStatement = sessionCache.get(cacheKey);
} else {
log.debug("No cached PreparedStatement found... creating and caching");
preparedStatement = session.prepare(this.cql);
sessionCache.put(cacheKey, preparedStatement);
}
}
}
return preparedStatement;
}
}