org.luciddb.session.LucidDbTxnMgr.java Source code

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Here is the source code for org.luciddb.session.LucidDbTxnMgr.java

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/*
// Licensed to DynamoBI Corporation (DynamoBI) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  DynamoBI 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.luciddb.session;

import java.util.*;
import java.util.logging.*;

import net.sf.farrago.catalog.*;
import net.sf.farrago.db.*;
import net.sf.farrago.resource.*;
import net.sf.farrago.session.*;

import org.apache.commons.transaction.locking.*;
import org.apache.commons.transaction.util.*;

import org.eigenbase.relopt.*;
import org.eigenbase.sql.*;
import org.eigenbase.sql.parser.*;
import org.eigenbase.util.*;

/**
 * LucidDbTxnMgr implements the {@link FarragoSessionTxnMgr} interface with
 * locking semantics customized for LucidDB.
 *
 * @author John V. Sichi
 * @version $Id$
 */
class LucidDbTxnMgr extends FarragoDbNullTxnMgr {
    //~ Static fields/initializers ---------------------------------------------

    // TODO jvs 15-Mar-2006:  start a new LucidDbTrace.java file?
    private static final Logger tracer = Logger.getLogger(LucidDbTxnMgr.class.getName());

    //~ Instance fields --------------------------------------------------------

    private final LockManager2 lockMgr;

    //~ Constructors -----------------------------------------------------------

    LucidDbTxnMgr() {
        // NOTE jvs 8-Feb-2007:  This does nothing unless someone
        // actually enables the corresponding log4j settings AND
        // java.util.logging settings
        LoggerFacade loggerFacade = new Jdk14Logger(tracer);
        lockMgr = new GenericLockManager(2, loggerFacade);
    }

    //~ Methods ----------------------------------------------------------------

    // implement FarragoSessionTxnMgr
    public FarragoSessionTxnId beginTxn(FarragoSession session) {
        return super.beginTxn(session);
    }

    // override FarragoDbNullTxnMgr
    protected void accessTable(FarragoSessionTxnId txnId, List<String> localTableName,
            TableAccessMap.Mode accessType) {
        super.accessTable(txnId, localTableName, accessType);

        SqlIdentifier sqlId = new SqlIdentifier((String[]) localTableName.toArray(Util.emptyStringArray),
                SqlParserPos.ZERO);
        String renderedTableName = sqlId.toString();

        if (accessType != TableAccessMap.Mode.READ_ACCESS) {
            // X-lock the table to exclude writers on the same table
            acquireLock(txnId, localTableName, renderedTableName, 2);
        }
    }

    // implement FarragoSessionTxnMgr
    public void endTxn(FarragoSessionTxnId txnId, FarragoSessionTxnEnd endType) {
        super.endTxn(txnId, endType);
        tracer.fine("Transaction " + txnId + " releasing all table and database locks");
        lockMgr.releaseAll(txnId);
    }

    private void acquireLock(FarragoSessionTxnId txnId, Object resourceId, String renderedName, int lockLevel) {
        tracer.fine("Transaction " + txnId + " attempting to acquire " + ((lockLevel == 1) ? "shared" : "exclusive")
                + " lock on " + renderedName);
        if (lockMgr.tryLock(txnId, resourceId, lockLevel, true)) {
            tracer.fine("Transaction " + txnId + " acquired lock successfully");
            return;
        }
        throw FarragoResource.instance().LockDenied.ex(renderedName);
    }
}

// End LucidDbTxnMgr.java