source: Ballon/out/artifacts/geisa_artifact/WEB-INF/lib/mysql-connector-java-5.1.21/src/com/mysql/jdbc/RowDataCursor.java @ 848

/*
 Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
 

  The MySQL Connector/J is licensed under the terms of the GPLv2
  <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most MySQL Connectors.
  There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
  this software, see the FLOSS License Exception
  <http://www.mysql.com/about/legal/licensing/foss-exception.html>.

  This program is free software; you can redistribute it and/or modify it under the terms
  of the GNU General Public License as published by the Free Software Foundation; version 2
  of the License.

  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the GNU General Public License for more details.

  You should have received a copy of the GNU General Public License along with this
  program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
  Floor, Boston, MA 02110-1301  USA
 */

package com.mysql.jdbc;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * Model for result set data backed by a cursor. Only works for forward-only
 * result sets (but still works with updatable concurrency).
 * 
 * @version $Id: CursorRowProvider.java,v 1.1.2.1 2005/05/19 18:31:49 mmatthews
 *          Exp $
 */
public class RowDataCursor implements RowData {

        private final static int BEFORE_START_OF_ROWS = -1;

        /**
         * The cache of rows we have retrieved from the server.
         */
        private List<ResultSetRow> fetchedRows;

        /**
         * Where we are positionaly in the entire result set, used mostly to
         * facilitate easy 'isBeforeFirst()' and 'isFirst()' methods.
         */
        private int currentPositionInEntireResult = BEFORE_START_OF_ROWS;

        /**
         * Position in cache of rows, used to determine if we need to fetch more
         * rows from the server to satisfy a request for the next row.
         */
        private int currentPositionInFetchedRows = BEFORE_START_OF_ROWS;

        /**
         * The result set that we 'belong' to.
         */
        private ResultSetImpl owner;

        /**
         * Have we been told from the server that we have seen the last row?
         */
        private boolean lastRowFetched = false;

        /**
         * Field-level metadata from the server. We need this, because it is not
         * sent for each batch of rows, but we need the metadata to unpack the
         * results for each field.
         */
        private Field[] metadata;

        /**
         * Communications channel to the server
         */
        private MysqlIO mysql;

        /**
         * Identifier for the statement that created this cursor.
         */
        private long statementIdOnServer;

        /**
         * The prepared statement that created this cursor.
         */
        private ServerPreparedStatement prepStmt;

        /**
         * The server status for 'last-row-sent'...This might belong in mysqldefs,
         * but it it only ever referenced from here.
         */
        private static final int SERVER_STATUS_LAST_ROW_SENT = 128;

        /**
         * Have we attempted to fetch any rows yet?
         */
        private boolean firstFetchCompleted = false;

        private boolean wasEmpty = false;

        private boolean useBufferRowExplicit = false;
        
        /**
         * Creates a new cursor-backed row provider.
         * 
         * @param ioChannel
         *            connection to the server.
         * @param creatingStatement
         *            statement that opened the cursor.
         * @param metadata
         *            field-level metadata for the results that this cursor covers.
         */
        public RowDataCursor(MysqlIO ioChannel,
                        ServerPreparedStatement creatingStatement, Field[] metadata) {
                this.currentPositionInEntireResult = BEFORE_START_OF_ROWS;
                this.metadata = metadata;
                this.mysql = ioChannel;
                this.statementIdOnServer = creatingStatement.getServerStatementId();
                this.prepStmt = creatingStatement;
                this.useBufferRowExplicit = MysqlIO.useBufferRowExplicit(this.metadata);
                
        }

        /**
         * Returns true if we got the last element.
         * 
         * @return DOCUMENT ME!
         */
        public boolean isAfterLast() {
                return lastRowFetched
                                && this.currentPositionInFetchedRows > this.fetchedRows.size();
        }

        /**
         * Only works on non dynamic result sets.
         * 
         * @param index
         *            row number to get at
         * @return row data at index
         * @throws SQLException
         *             if a database error occurs
         */
        public ResultSetRow getAt(int ind) throws SQLException {
                notSupported();

                return null;
        }

        /**
         * Returns if iteration has not occured yet.
         * 
         * @return true if before first row
         * @throws SQLException
         *             if a database error occurs
         */
        public boolean isBeforeFirst() throws SQLException {
                return this.currentPositionInEntireResult < 0;
        }

        /**
         * Moves the current position in the result set to the given row number.
         * 
         * @param rowNumber
         *            row to move to
         * @throws SQLException
         *             if a database error occurs
         */
        public void setCurrentRow(int rowNumber) throws SQLException {
                notSupported();
        }

        /**
         * Returns the current position in the result set as a row number.
         * 
         * @return the current row number
         * @throws SQLException
         *             if a database error occurs
         */
        public int getCurrentRowNumber() throws SQLException {
                return this.currentPositionInEntireResult + 1;
        }

        /**
         * Returns true if the result set is dynamic.
         * 
         * This means that move back and move forward won't work because we do not
         * hold on to the records.
         * 
         * @return true if this result set is streaming from the server
         */
        public boolean isDynamic() {
                return true;
        }

        /**
         * Has no records.
         * 
         * @return true if no records
         * @throws SQLException
         *             if a database error occurs
         */
        public boolean isEmpty() throws SQLException {
                return this.isBeforeFirst() && this.isAfterLast();
        }

        /**
         * Are we on the first row of the result set?
         * 
         * @return true if on first row
         * @throws SQLException
         *             if a database error occurs
         */
        public boolean isFirst() throws SQLException {
                return this.currentPositionInEntireResult == 0;
        }

        /**
         * Are we on the last row of the result set?
         * 
         * @return true if on last row
         * @throws SQLException
         *             if a database error occurs
         */
        public boolean isLast() throws SQLException {
                return this.lastRowFetched
                                && this.currentPositionInFetchedRows == (this.fetchedRows
                                                .size() - 1);
        }

        /**
         * Adds a row to this row data.
         * 
         * @param row
         *            the row to add
         * @throws SQLException
         *             if a database error occurs
         */
        public void addRow(ResultSetRow row) throws SQLException {
                notSupported();
        }

        /**
         * Moves to after last.
         * 
         * @throws SQLException
         *             if a database error occurs
         */
        public void afterLast() throws SQLException {
                notSupported();
        }

        /**
         * Moves to before first.
         * 
         * @throws SQLException
         *             if a database error occurs
         */
        public void beforeFirst() throws SQLException {
                notSupported();
        }

        /**
         * Moves to before last so next el is the last el.
         * 
         * @throws SQLException
         *             if a database error occurs
         */
        public void beforeLast() throws SQLException {
                notSupported();
        }

        /**
         * We're done.
         * 
         * @throws SQLException
         *             if a database error occurs
         */
        public void close() throws SQLException {

                this.metadata = null;
                this.owner = null;
        }

        /**
         * Returns true if another row exists.
         * 
         * @return true if more rows
         * @throws SQLException
         *             if a database error occurs
         */
        public boolean hasNext() throws SQLException {

                if (this.fetchedRows != null && this.fetchedRows.size() == 0) {
                        return false;
                }

                if (this.owner != null && this.owner.owningStatement != null) {
                        int maxRows = this.owner.owningStatement.maxRows;
                        
                        if (maxRows != -1 && this.currentPositionInEntireResult + 1 > maxRows) {
                                return false;
                        }       
                }
                
                if (this.currentPositionInEntireResult != BEFORE_START_OF_ROWS) {
                        // Case, we've fetched some rows, but are not at end of fetched
                        // block
                        if (this.currentPositionInFetchedRows < (this.fetchedRows.size() - 1)) {
                                return true;
                        } else if (this.currentPositionInFetchedRows == this.fetchedRows
                                        .size()
                                        && this.lastRowFetched) {
                                return false;
                        } else {
                                // need to fetch to determine
                                fetchMoreRows();

                                return (this.fetchedRows.size() > 0);
                        }
                }

                // Okay, no rows _yet_, so fetch 'em

                fetchMoreRows();

                return this.fetchedRows.size() > 0;
        }

        /**
         * Moves the current position relative 'rows' from the current position.
         * 
         * @param rows
         *            the relative number of rows to move
         * @throws SQLException
         *             if a database error occurs
         */
        public void moveRowRelative(int rows) throws SQLException {
                notSupported();
        }

        /**
         * Returns the next row.
         * 
         * @return the next row value
         * @throws SQLException
         *             if a database error occurs
         */
        public ResultSetRow next() throws SQLException {
                if (this.fetchedRows == null && this.currentPositionInEntireResult != BEFORE_START_OF_ROWS) {
                        throw SQLError.createSQLException(
                                        Messages
                                                        .getString("ResultSet.Operation_not_allowed_after_ResultSet_closed_144"), //$NON-NLS-1$
                                        SQLError.SQL_STATE_GENERAL_ERROR, mysql.getExceptionInterceptor());
                }
                
                if (!hasNext()) {
                        return null;
                }
                
                this.currentPositionInEntireResult++;
                this.currentPositionInFetchedRows++;

                // Catch the forced scroll-passed-end
                if (this.fetchedRows != null && this.fetchedRows.size() == 0) {
                        return null;
                }

                if (this.currentPositionInFetchedRows > (this.fetchedRows.size() - 1)) {
                        fetchMoreRows();
                        this.currentPositionInFetchedRows = 0;
                }

                ResultSetRow row = this.fetchedRows
                                .get(this.currentPositionInFetchedRows);

                row.setMetadata(this.metadata);
                
                return row;
        }

        /**
         * 
         */
        private void fetchMoreRows() throws SQLException {
                if (this.lastRowFetched) {
                        this.fetchedRows = new ArrayList<ResultSetRow>(0);
                        return;
                }

                synchronized (this.owner.connection) {
                        boolean oldFirstFetchCompleted = this.firstFetchCompleted;
                        
                        if (!this.firstFetchCompleted) {
                                this.firstFetchCompleted = true;
                        }

                        int numRowsToFetch = this.owner.getFetchSize();

                        if (numRowsToFetch == 0) {
                                numRowsToFetch = this.prepStmt.getFetchSize();
                        }
                        
                        if (numRowsToFetch == Integer.MIN_VALUE) {
                                // Handle the case where the user used 'old'
                                // streaming result sets

                                numRowsToFetch = 1;
                        }

                        this.fetchedRows = this.mysql.fetchRowsViaCursor(this.fetchedRows,
                                        this.statementIdOnServer, this.metadata, numRowsToFetch, 
                                        this.useBufferRowExplicit);
                        this.currentPositionInFetchedRows = BEFORE_START_OF_ROWS;

                        if ((this.mysql.getServerStatus() & SERVER_STATUS_LAST_ROW_SENT) != 0) {
                                this.lastRowFetched = true;
                                
                                if (!oldFirstFetchCompleted && this.fetchedRows.size() == 0) {
                                        this.wasEmpty  = true;
                                }
                        }
                }
        }

        /**
         * Removes the row at the given index.
         * 
         * @param index
         *            the row to move to
         * @throws SQLException
         *             if a database error occurs
         */
        public void removeRow(int ind) throws SQLException {
                notSupported();
        }

        /**
         * Only works on non dynamic result sets.
         * 
         * @return the size of this row data
         */
        public int size() {
                return RESULT_SET_SIZE_UNKNOWN;
        }

        protected void nextRecord() throws SQLException {

        }

        private void notSupported() throws SQLException {
                throw new OperationNotSupportedException();
        }

        /*
         * (non-Javadoc)
         * 
         * @see com.mysql.jdbc.RowProvider#setOwner(com.mysql.jdbc.ResultSet)
         */
        public void setOwner(ResultSetImpl rs) {
                this.owner = rs;
        }

        /*
         * (non-Javadoc)
         * 
         * @see com.mysql.jdbc.RowProvider#getOwner()
         */
        public ResultSetInternalMethods getOwner() {
                return this.owner;
        }

        public boolean wasEmpty() {
                return this.wasEmpty;
        }
        
        public void setMetadata(Field[] metadata) {
                this.metadata = metadata;
        }

}