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db derby 10.2 » org » apache » derby » client » am » CachingLogicalConnection.java
/*

   Derby - Class org.apache.derby.client.am.CachingLogicalConnection

   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.derby.client.am;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import org.apache.derby.client.ClientPooledConnection;
import org.apache.derby.client.am.stmtcache.JDBCStatementCache;

import org.apache.derby.shared.common.sanity.SanityManager;

/**
 * A logical connection used in a connection pool with capabilities for
 * caching prepared statements.
 * <p>
 * An instance of this class is what is passed out the the client. It uses a
 * JDBC statement object cache to avoid re-preparing commonly used queries.
 * The cache has scope of a physical connection, and is lost when the pooled
 * connection is closed (which includes closing the physical connection).
 *
 * @see StatementCacheInteractor
 */
public class CachingLogicalConnection
    extends LogicalConnection {

    /** JDBC statement cache interactor used to prepare statements and calls. */
    private StatementCacheInteractor cacheInteractor;

    /**
     * Creates a new logical connection which caches prepared statements.
     *
     * @param physicalConnection underlying physical database connection
     * @param pooledConnection associated pooled connection
     * @param stmtCache associated statement cache
     *
     * @throws SqlException if creating the logical connection fails
     */
    public CachingLogicalConnection(Connection physicalConnection,
                                    ClientPooledConnection pooledConnection,
                                    JDBCStatementCache stmtCache)
            throws SqlException {
        super(physicalConnection, pooledConnection);
        this.cacheInteractor =
                new StatementCacheInteractor(stmtCache, physicalConnection);
    }

    public synchronized void close()
            throws SQLException {
        if (this.cacheInteractor != null) {
            this.cacheInteractor.closeOpenLogicalStatements();
            // Nullify reference to cache interactor to allow it to be GC'ed.
            // It should not be used again when, logical connection is closed.
            this.cacheInteractor = null;
            super.close();
        }
    }

    public synchronized PreparedStatement prepareStatement(String sql)
            throws SQLException {
        checkForNullPhysicalConnection();
        return cacheInteractor.prepareStatement(sql);
    }

    public synchronized PreparedStatement prepareStatement(
                                                String sql,
                                                int resultSetType,
                                                int resultSetConcurrency)
            throws SQLException {
        checkForNullPhysicalConnection();
        return cacheInteractor.prepareStatement(
                    sql, resultSetType, resultSetConcurrency);
    }

    public synchronized PreparedStatement prepareStatement(
                                                String sql,
                                                int resultSetType,
                                                int resultSetConcurrency,
                                                int resultSetHoldability)
            throws SQLException {
        checkForNullPhysicalConnection();
        return cacheInteractor.prepareStatement(
                sql, resultSetType,resultSetConcurrency, resultSetHoldability);
    }

    public synchronized PreparedStatement prepareStatement(
                                                String sql,
                                                int autoGeneratedKeys)
            throws SQLException {
        checkForNullPhysicalConnection();
        return cacheInteractor.prepareStatement(sql, autoGeneratedKeys);
    }

    public synchronized PreparedStatement prepareStatement(
                                                String sql,
                                                int[] columnIndexes)
            throws SQLException {
        checkForNullPhysicalConnection();
        PreparedStatement ps = null;
        if (columnIndexes != null && columnIndexes.length > 1) {
            // This should probably be extended to use a separate type of
            // statement key (instead of just saying its a statement which
            // returns auto-generated keys), to force it throught the driver
            // validation code.
            // For now, disable statement pooling and fail in sane builds only,
            // or in the relevant parts of the driver if still not supported.
            ps = super.prepareStatement(sql, columnIndexes);
            // If we get this far, the rest of the driver has extended
            // its capabilities and this class is lagging behind...
            if (SanityManager.DEBUG) {
                SanityManager.THROWASSERT("CachingLogicalConnection is " +
                        "missing the capability to handle prepareStatement " +
                        "with an int array with more than one elemenet.");
            }
            // No caching being done, but we are able to continue.
        } else {
            int generatedKeys = Statement.RETURN_GENERATED_KEYS;
            // If indexes is null or empty, don't return autogenerated keys.
            if (columnIndexes == null || columnIndexes.length == 0) {
                generatedKeys = Statement.NO_GENERATED_KEYS;
            }
            ps = cacheInteractor.prepareStatement(sql, generatedKeys);
        }
        return ps;
    }

    public synchronized PreparedStatement prepareStatement(
                                                String sql,
                                                String[] columnNames)
            throws SQLException {
        checkForNullPhysicalConnection();
        PreparedStatement ps = null;
        if (columnNames != null && columnNames.length > 1) {
            // This should probably be extended to use a separate type of
            // statement key (instead of just saying its a statement which
            // returns auto-generated keys), to force it throught the driver
            // validation code.
            // For now, disable statement pooling and fail in sane builds only,
            // or in the relevant parts of the driver if still not supported.
            ps = super.prepareStatement(sql, columnNames);
            // If we get this far, the rest of the driver has extended
            // its capabilities and this class is lagging behind...
            if (SanityManager.DEBUG) {
                SanityManager.THROWASSERT("CachingLogicalConnection is " +
                        "missing the capability to handle prepareStatement " +
                        "with a string array with more than one elemenet.");
            }
            // No caching being done, but we are able to continue.
        } else {
            int generatedKeys = Statement.RETURN_GENERATED_KEYS;
            // If names is null or empty, don't return autogenerated keys.
            if (columnNames == null || columnNames.length == 0) {
                generatedKeys = Statement.NO_GENERATED_KEYS;
            }
            ps = cacheInteractor.prepareStatement(sql, generatedKeys);
        }
        return ps;
    }

    public synchronized CallableStatement prepareCall(String sql)
            throws SQLException {
        checkForNullPhysicalConnection();
        return cacheInteractor.prepareCall(sql);
    }

    public synchronized CallableStatement prepareCall(String sql,
                                                      int resultSetType,
                                                      int resultSetConcurrency)
            throws SQLException {
        checkForNullPhysicalConnection();
        return cacheInteractor.prepareCall(
                sql, resultSetType, resultSetConcurrency);
    }

    public synchronized CallableStatement prepareCall(String sql,
                                                      int resultSetType,
                                                      int resultSetConcurrency,
                                                      int resultSetHoldability)
            throws SQLException {
        checkForNullPhysicalConnection();
        return cacheInteractor.prepareCall(
                sql, resultSetType, resultSetConcurrency, resultSetHoldability);
    }
}
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