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/*
Copyright (c) 2002, 2016, Oracle and/or its affiliates. All rights reserved.
The MySQL Connector/J is licensed under the terms of the GPLv2
, 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 FOSS License Exception
.
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).
*/
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 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.
*/
public boolean isAfterLast() {
return this.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"),
SQLError.SQL_STATE_GENERAL_ERROR, this.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.fetchedRows == null) || (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(0);
return;
}
synchronized (this.owner.connection.getConnectionMutex()) {
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;
}
}
