b2iforwardscan.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.impl.store.access.btree.index.B2IForwardScan

   Copyright 1999, 2004 The Apache Software Foundation or its licensors, as applicable.

   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

      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.impl.store.access.btree.index;

import org.apache.derby.iapi.services.sanity.SanityManager;

import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.store.access.conglomerate.Conglomerate;
import org.apache.derby.iapi.store.access.conglomerate.TransactionManager;
import org.apache.derby.iapi.store.access.ConglomerateController;
import org.apache.derby.iapi.store.access.DynamicCompiledOpenConglomInfo;
import org.apache.derby.iapi.store.access.GenericScanController;
import org.apache.derby.iapi.store.access.Qualifier;
import org.apache.derby.iapi.store.access.ScanController;
import org.apache.derby.iapi.store.access.StaticCompiledOpenConglomInfo;
import org.apache.derby.iapi.store.access.TransactionController;

import org.apache.derby.iapi.store.raw.ContainerHandle;
import org.apache.derby.iapi.store.raw.LockingPolicy;
import org.apache.derby.iapi.store.raw.Transaction;

import org.apache.derby.iapi.types.DataValueDescriptor;

import org.apache.derby.iapi.types.RowLocation;

import org.apache.derby.iapi.services.io.FormatableBitSet;

import org.apache.derby.impl.store.access.btree.BTreeController;
import org.apache.derby.impl.store.access.btree.BTreeLockingPolicy;
import org.apache.derby.impl.store.access.btree.BTreeForwardScan;

import org.apache.derby.impl.store.access.conglomerate.ConglomerateUtil;

/**

The btree secondary index implementation of ScanManager which provides reading 
and deleting of entries in the btree secondary index.  

This supports setting up and
iterating through a set of rows while providing a start key, stop key,
and a set of AND and OR qualifiers to skip unwanted rows.  Currently
derby only supports forward scans (but individual columns can have
descending order).  This interface is also used to delete rows from
the conglomerate.  Note that update is not supported, it must be
implemented as a delete, followed by an insert.

Note most work of this class is inherited from the generic btree implementation.
This class initializes the top level object and deals with locking information
specific to a secondary index implementation of a btree.

**/

public class B2IForwardScan extends BTreeForwardScan
{

	/*
	** Fields of B2IForwardScan.
	*/
    private ConglomerateController  base_cc_for_locking;
    private int                     init_isolation_level;

	/*
	** Methods of B2IForwardScan.
	*/

	B2IForwardScan()
	{
		// Perform the generic b-tree scan construction.
		super();
	}

    /**
    Close the scan.
	@see GenericScanController#newRowLocationTemplate
    **/
    public void close()
        throws StandardException
	{
		super.close();

        if (base_cc_for_locking != null)
        {
            base_cc_for_locking.close();
            base_cc_for_locking = null;
        }
	}


    /**
    Close the scan, a commit or abort is about to happen.
    **/
    public boolean closeForEndTransaction(boolean closeHeldScan)
        throws StandardException
	{
		boolean ret_val = super.closeForEndTransaction(closeHeldScan);

        if (base_cc_for_locking != null)
        {
            base_cc_for_locking.close();
            base_cc_for_locking = null;
        }

        return(ret_val);
	}

    /**
     * Open the container after it has been closed previously.
     * <p>
     * Open the container, obtaining necessary locks.  Most work is actually
     * done by RawStore.openContainer().  Will only reopen() if the container
     * is not already open.
     *
	 * @exception  StandardException  Standard exception policy.
     **/
    public ContainerHandle reopen()
        throws StandardException
    {

        ContainerHandle container = super.reopen();
        B2I             b2i       = (B2I) getConglomerate();

        // open and lock the base table.

        int base_open_mode = 
            getOpenMode() | TransactionController.OPENMODE_FOR_LOCK_ONLY;


        // TODO - figure out what to do with static_info stuff


        // open the base conglomerate - just to get lock
        /*
        if (static_info != null)
        {
            base_cc_for_locking = 
                xact_manager.openCompiledConglomerate(
                    false,
                    base_open_mode, lock_level, isolation_level,
                    static_info.base_table_static_info,
                    ((Conglomerate) static_info.getConglom()).
                        getDynamicCompiledConglomInfo(
                            b2i.baseConglomerateId));
        }
        else
        */
        {
            base_cc_for_locking = 
                getXactMgr().openConglomerate(
                    b2i.baseConglomerateId, 
                    false,
                    base_open_mode, init_lock_level,
                    init_isolation_level);

            setLockingPolicy(
                b2i.getBtreeLockingPolicy(
                    getXactMgr().getRawStoreXact(), 
                    getLockLevel(), 
                    getOpenMode(), 
                    init_isolation_level, 
                    base_cc_for_locking, this));
        }
        
        return(container);
    }


	/**
	Initialize the scan for use.
	<p>
	Any changes to this method may have to be reflected in close as well.
    <p>
    The btree init opens the container (super.init), and stores away the
    state of the qualifiers.  The actual searching for the first position
    is delayed until the first next() call.

	@exception  StandardException  Standard exception policy.
	**/
	public void init(
    TransactionManager              xact_manager,
    Transaction                     rawtran,
    boolean                         hold,
    int                             open_mode,
    int                             lock_level,
    LockingPolicy                   locking_policy,
    int                             isolation_level,
    boolean                         open_for_locking,
    FormatableBitSet                         scanColumnList,
    DataValueDescriptor[]	        startKeyValue,
    int                             startSearchOperator,
    Qualifier                       qualifier[][],
    DataValueDescriptor[]	        stopKeyValue,
    int                             stopSearchOperator,
    B2I                             conglomerate,
    B2IUndo                         undo,
    B2IStaticCompiledInfo           static_info,
    DynamicCompiledOpenConglomInfo  dynamic_info)
        throws StandardException
	{
        // open and lock the base table.

        int base_open_mode = 
            open_mode | TransactionController.OPENMODE_FOR_LOCK_ONLY;

        // open the base conglomerate - just to get lock
        if (static_info != null)
        {
            base_cc_for_locking = 
                xact_manager.openCompiledConglomerate(
                    false,
                    base_open_mode, lock_level, isolation_level,
                    static_info.base_table_static_info,
                    /* TODO - maintain a dynamic info for this */
                    ((Conglomerate) static_info.getConglom()).
                        getDynamicCompiledConglomInfo(
                            conglomerate.baseConglomerateId));
        }
        else
        {
            base_cc_for_locking = 
                xact_manager.openConglomerate(
                    conglomerate.baseConglomerateId, false, base_open_mode, lock_level,
                    isolation_level);
        }
        
        BTreeLockingPolicy b2i_locking_policy = 
            conglomerate.getBtreeLockingPolicy(
                rawtran, lock_level, open_mode, isolation_level, 
                base_cc_for_locking, this);

		super.init(
            xact_manager,
            rawtran,
            hold,
            open_mode,
            lock_level,
            b2i_locking_policy,
            scanColumnList,
            startKeyValue,
            startSearchOperator,
            qualifier,
            stopKeyValue,
            stopSearchOperator,
            conglomerate,
            undo,
            static_info,
            dynamic_info);


        // todo - should just save the isolation level in OpenBtree but
        // save it here for now.
        init_isolation_level = isolation_level;
	}
}