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The runtime library of DBFlute
/*
* Copyright 2014-2019 the original author or authors.
*
* 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.dbflute.s2dao.jdbc;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.dbflute.bhv.core.context.ResourceContext;
import org.dbflute.bhv.exception.SQLExceptionHandler;
import org.dbflute.bhv.exception.SQLExceptionResource;
import org.dbflute.cbean.paging.FetchNarrowingBean;
import org.dbflute.dbway.DBDef;
import org.dbflute.exception.FetchingOverSafetySizeException;
import org.dbflute.jdbc.FetchBean;
import org.dbflute.jdbc.PlainResultSetWrapper;
/**
* @author modified by jflute (originated in S2Dao)
*/
public class TnFetchAssistResultSet extends PlainResultSetWrapper {
// ===================================================================================
// Attribute
// =========
/** The real result set. (NotNull) */
protected final ResultSet _resultSet;
/** The bean of fetch. (NotNull) */
protected final FetchBean _fetchBean;
/** The max size of safety result. (derived from fetchBean) */
protected final int _safetyResultMaxSize;
/** Is the safety check valid? (derived from fetchBean) */
protected final boolean _safetyCheckValid;
/** The bean of fetch narrowing. (NullAllowed) */
protected final FetchNarrowingBean _fetchNarrowingBean;
/** Does it offset by cursor forcedly? */
protected final boolean _offsetByCursorForcedly;
/** Does it limit by cursor forcedly? */
protected final boolean _limitByCursorForcedly;
/** The counter of fetch. */
protected long _fetchCounter;
/** the counter of request. */
protected long _requestCounter;
/** Does it skip to cursor end? */
protected boolean _skipToCursorEnd;
/** Is the database DB2? */
protected final boolean _db2;
{
_db2 = ResourceContext.isCurrentDBDef(DBDef.DB2);
}
// ===================================================================================
// Constructor
// ===========
/**
* Constructor.
* @param resultSet Original result set. (NotNull)
* @param fetchBean The fetch-bean. (NotNull)
* @param offsetByCursorForcedly Offset by cursor forcedly.
* @param limitByCursorForcedly Limit by cursor forcedly.
*/
public TnFetchAssistResultSet(ResultSet resultSet, FetchBean fetchBean, boolean offsetByCursorForcedly, boolean limitByCursorForcedly) {
super(resultSet);
_resultSet = resultSet;
_fetchBean = fetchBean;
// derived before fetching for performance
_safetyResultMaxSize = fetchBean.getSafetyMaxResultSize();
_safetyCheckValid = _safetyResultMaxSize > 0;
_fetchNarrowingBean = fetchBean instanceof FetchNarrowingBean ? (FetchNarrowingBean) fetchBean : null;
_offsetByCursorForcedly = offsetByCursorForcedly;
_limitByCursorForcedly = limitByCursorForcedly;
skip();
}
// ===================================================================================
// Skip
// ====
/**
* Skip to the point at start index.
*/
protected void skip() {
if (!isAvailableSkipRecord()) {
return;
}
final int skipStartIndex = getFetchNarrowingSkipStartIndex();
if (isScrollableCursor()) {
try {
if (0 == skipStartIndex) {
_resultSet.beforeFirst();
} else {
_resultSet.absolute(skipStartIndex);
}
_fetchCounter = _resultSet.getRow();
} catch (SQLException e) {
final SQLExceptionResource resource = createSQLExceptionResource();
resource.setNotice("Failed to handle the result set.");
handleSQLException(e, resource);
}
} else {
try {
while (true) {
if (_fetchCounter >= skipStartIndex) {
break;
}
if (!_resultSet.next()) {
_skipToCursorEnd = true; // [DBFLUTE-243]
break;
}
++_fetchCounter;
}
} catch (SQLException e) {
final SQLExceptionResource resource = createSQLExceptionResource();
resource.setNotice("Failed to move the cursor to next.");
handleSQLException(e, resource);
}
}
}
protected boolean isAvailableSkipRecord() {
if (!isFetchNarrowingEffective()) {
return false;
}
if (isOffsetByCursorForcedly()) {
return true;
}
if (isFetchNarrowingSkipStartIndexEffective()) {
return true;
}
return false;
}
// ===================================================================================
// Next
// ====
/**
* Move to the next record.
* @return Does the result set have next record?
* @throws SQLException When it fails to handle the SQL.
*/
@Override
public boolean next() throws SQLException {
if (_db2 && _skipToCursorEnd) {
// because DB2 closes cursor when cursor end automatically [DBFLUTE-243]
return false;
}
final boolean hasNext = super.next();
++_requestCounter;
if (!isAvailableLimitLoopCount()) {
if (_safetyCheckValid) {
checkSafetyResult(hasNext);
}
return hasNext;
}
final int skipStartIndex = getFetchNarrowingSkipStartIndex();
final int loopCount = getFetchNarrowingLoopCount();
if (hasNext && _fetchCounter < skipStartIndex + loopCount) {
++_fetchCounter;
if (_safetyCheckValid) {
checkSafetyResult(true);
}
return true;
} else {
return false;
}
}
protected boolean isAvailableLimitLoopCount() {
if (!isFetchNarrowingEffective()) {
return false;
}
if (isLimitByCursorForcedly()) {
return true;
}
if (isFetchNarrowingLoopCountEffective()) {
return true;
}
return false;
}
protected void checkSafetyResult(boolean hasNext) {
if (hasNext && _requestCounter > _safetyResultMaxSize) {
throwFetchingOverSafetySizeException();
}
}
protected void throwFetchingOverSafetySizeException() {
// here simple message because an entry method catches this
String msg = "The fetching was over the specified safety size: " + _safetyResultMaxSize;
throw new FetchingOverSafetySizeException(msg, _safetyResultMaxSize);
}
// ===================================================================================
// Fetch Narrowing Bean
// ====================
/**
* Is the fetch narrowing effective?
* @return The determination, true or false.
*/
protected boolean isFetchNarrowingEffective() {
if (_fetchNarrowingBean == null) {
return false;
}
return _fetchNarrowingBean.isFetchNarrowingEffective();
}
/**
* Is the skip start index of fetch narrowing effective?
* If isFetchNarrowingEffective() is false, this is not called by anyone.
* @return The determination, true or false.
*/
protected boolean isFetchNarrowingSkipStartIndexEffective() {
if (_fetchNarrowingBean == null) {
String msg = "This method should not be called";
msg = msg + " when isFetchNarrowingEffective() is false!";
throw new IllegalStateException(msg);
}
return _fetchNarrowingBean.isFetchNarrowingSkipStartIndexEffective();
}
/**
* Is the loop count of fetch narrowing effective?
* If isFetchNarrowingEffective() is false, this is not called by anyone.
* @return The determination, true or false.
*/
protected boolean isFetchNarrowingLoopCountEffective() {
if (_fetchNarrowingBean == null) {
String msg = "This method should not be called";
msg = msg + " when isFetchNarrowingEffective() is false!";
throw new IllegalStateException(msg);
}
return _fetchNarrowingBean.isFetchNarrowingLoopCountEffective();
}
/**
* Get the skip start index of fetch narrowing.
* If isFetchNarrowingEffective() is false, this is not called by anyone.
* @return The skip start index of fetch narrowing.
*/
protected int getFetchNarrowingSkipStartIndex() {
if (_fetchNarrowingBean == null) {
String msg = "This method should not be called";
msg = msg + " when isFetchNarrowingEffective() is false!";
throw new IllegalStateException(msg);
}
return _fetchNarrowingBean.getFetchNarrowingSkipStartIndex();
}
/**
* Get the loop count of fetch narrowing.
* If isFetchNarrowingEffective() is false, this is not called by anyone.
* @return The loop count of fetch narrowing.
*/
protected int getFetchNarrowingLoopCount() {
if (_fetchNarrowingBean == null) {
String msg = "This method should not be called";
msg = msg + " when isFetchNarrowingEffective() is false!";
throw new IllegalStateException(msg);
}
return _fetchNarrowingBean.getFetchNarrowingLoopCount();
}
// ===================================================================================
// Assist Helper
// =============
protected boolean isScrollableCursor() {
try {
return !(_resultSet.getType() == ResultSet.TYPE_FORWARD_ONLY);
} catch (SQLException e) {
final SQLExceptionResource resource = createSQLExceptionResource();
resource.setNotice("Failed to get type of the result set.");
handleSQLException(e, resource);
return false; // unreachable
}
}
protected void handleSQLException(SQLException e, SQLExceptionResource resource) {
createSQLExceptionHandler().handleSQLException(e, resource);
}
protected SQLExceptionHandler createSQLExceptionHandler() {
return ResourceContext.createSQLExceptionHandler();
}
protected SQLExceptionResource createSQLExceptionResource() {
return new SQLExceptionResource();
}
// ===================================================================================
// Accessor
// ========
public boolean isOffsetByCursorForcedly() {
return _offsetByCursorForcedly;
}
public boolean isLimitByCursorForcedly() {
return _limitByCursorForcedly;
}
public boolean isSkipToCursorEnd() {
return _skipToCursorEnd;
}
}
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