Cursor list implementation

src/main/java/org/apache/ibatis/annotations/Options.java

@@ -20,6 +20,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.apache.ibatis.mapping.FetchType;
 import org.apache.ibatis.mapping.ResultSetType;
 import org.apache.ibatis.mapping.StatementType;
 
@@ -43,4 +44,6 @@
   String keyProperty() default "id";
 
   String keyColumn() default "";
+
+  FetchType fetchType() default FetchType.DEFAULT;
 }

src/main/java/org/apache/ibatis/builder/MapperBuilderAssistant.java

@@ -32,6 +32,7 @@
 import org.apache.ibatis.executor.keygen.KeyGenerator;
 import org.apache.ibatis.mapping.CacheBuilder;
 import org.apache.ibatis.mapping.Discriminator;
+import org.apache.ibatis.mapping.FetchType;
 import org.apache.ibatis.mapping.MappedStatement;
 import org.apache.ibatis.mapping.ParameterMap;
 import org.apache.ibatis.mapping.ParameterMapping;
@@ -287,8 +288,9 @@ public MappedStatement addMappedStatement(
       String keyColumn,
       String databaseId,
       LanguageDriver lang,
-      String resultSets) {
-
+      String resultSets,
+      FetchType fetchType) {
+
     if (unresolvedCacheRef) throw new IncompleteElementException("Cache-ref not yet resolved");
 
     id = applyCurrentNamespace(id, false);
@@ -305,6 +307,7 @@ public MappedStatement addMappedStatement(
     statementBuilder.lang(lang);
     statementBuilder.resultOrdered(resultOrdered);
     statementBuilder.resulSets(resultSets);
+    statementBuilder.fetchType(fetchType);
     setStatementTimeout(timeout, statementBuilder);
 
     setStatementParameterMap(parameterMap, parameterType, statementBuilder);

src/main/java/org/apache/ibatis/builder/annotation/MapperAnnotationBuilder.java

@@ -66,6 +66,7 @@
 import org.apache.ibatis.executor.keygen.SelectKeyGenerator;
 import org.apache.ibatis.io.Resources;
 import org.apache.ibatis.mapping.Discriminator;
+import org.apache.ibatis.mapping.FetchType;
 import org.apache.ibatis.mapping.MappedStatement;
 import org.apache.ibatis.mapping.ResultFlag;
 import org.apache.ibatis.mapping.ResultMapping;
@@ -249,6 +250,7 @@ void parseStatement(Method method) {
       ResultSetType resultSetType = ResultSetType.FORWARD_ONLY;
       SqlCommandType sqlCommandType = getSqlCommandType(method);
       boolean isSelect = sqlCommandType == SqlCommandType.SELECT;
+      FetchType fetchType = FetchType.DEFAULT;
       boolean flushCache = !isSelect;
       boolean useCache = isSelect;
 
@@ -281,6 +283,7 @@ void parseStatement(Method method) {
         timeout = options.timeout() > -1 ? options.timeout() : null;
         statementType = options.statementType();
         resultSetType = options.resultSetType();
+        fetchType = options.fetchType();
       }
 
       String resultMapId = null;
@@ -317,7 +320,8 @@ void parseStatement(Method method) {
           keyColumn,
           null,
           languageDriver,
-          null);
+          null,
+          fetchType);
     }
   }
 
@@ -553,7 +557,7 @@ private KeyGenerator handleSelectKeyAnnotation(SelectKey selectKeyAnnotation, St
 
     assistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType, fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass, resultSetTypeEnum,
         flushCache, useCache, false,
-        keyGenerator, keyProperty, null, null, languageDriver, null);
+        keyGenerator, keyProperty, null, null, languageDriver, null, FetchType.DEFAULT);
 
     id = assistant.applyCurrentNamespace(id, false);
 

src/main/java/org/apache/ibatis/builder/xml/XMLStatementBuilder.java

@@ -24,6 +24,7 @@
 import org.apache.ibatis.executor.keygen.KeyGenerator;
 import org.apache.ibatis.executor.keygen.NoKeyGenerator;
 import org.apache.ibatis.executor.keygen.SelectKeyGenerator;
+import org.apache.ibatis.mapping.FetchType;
 import org.apache.ibatis.mapping.MappedStatement;
 import org.apache.ibatis.mapping.ResultSetType;
 import org.apache.ibatis.mapping.SqlCommandType;
@@ -77,6 +78,7 @@ public void parseStatementNode() {
     boolean flushCache = context.getBooleanAttribute("flushCache", !isSelect);
     boolean useCache = context.getBooleanAttribute("useCache", isSelect);
     boolean resultOrdered = context.getBooleanAttribute("resultOrdered", false);
+    FetchType fetchType = FetchType.valueOf(context.getStringAttribute("fetchType", FetchType.DEFAULT.toString()));
 
     // Include Fragments before parsing
     XMLIncludeTransformer includeParser = new XMLIncludeTransformer(configuration, builderAssistant);
@@ -109,7 +111,7 @@ public void parseStatementNode() {
     builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType,
         fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass,
         resultSetTypeEnum, flushCache, useCache, resultOrdered, 
-        keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets);
+        keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets, fetchType);
   }
 
   public void parseSelectKeyNodes(String parentId, List<XNode> list, Class<?> parameterTypeClass, LanguageDriver langDriver, String skRequiredDatabaseId) {
@@ -146,7 +148,7 @@ public void parseSelectKeyNode(String id, XNode nodeToHandle, Class<?> parameter
     builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType,
         fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass,
         resultSetTypeEnum, flushCache, useCache, resultOrdered,
-        keyGenerator, keyProperty, null, databaseId, langDriver, null);
+        keyGenerator, keyProperty, null, databaseId, langDriver, null, FetchType.DEFAULT);
 
     id = builderAssistant.applyCurrentNamespace(id, false);
 

src/main/java/org/apache/ibatis/builder/xml/mybatis-3-mapper.dtd

@@ -169,6 +169,7 @@ resultMap CDATA #IMPLIED
 resultType CDATA #IMPLIED
 resultSetType (FORWARD_ONLY | SCROLL_INSENSITIVE | SCROLL_SENSITIVE) #IMPLIED
 statementType (STATEMENT|PREPARED|CALLABLE) #IMPLIED
+fetchType (DEFAULT|CURSOR|LAZY) #IMPLIED
 fetchSize CDATA #IMPLIED
 timeout CDATA #IMPLIED
 flushCache (true|false) #IMPLIED

src/main/java/org/apache/ibatis/executor/BatchExecutor.java

@@ -27,6 +27,7 @@
 import org.apache.ibatis.executor.keygen.KeyGenerator;
 import org.apache.ibatis.executor.statement.StatementHandler;
 import org.apache.ibatis.mapping.BoundSql;
+import org.apache.ibatis.mapping.FetchType;
 import org.apache.ibatis.mapping.MappedStatement;
 import org.apache.ibatis.session.Configuration;
 import org.apache.ibatis.session.ResultHandler;
@@ -82,7 +83,9 @@ public <E> List<E> doQuery(MappedStatement ms, Object parameterObject, RowBounds
       handler.parameterize(stmt);
       return handler.<E>query(stmt, resultHandler);
     } finally {
-      closeStatement(stmt);
+      if (ms.getFetchType() == FetchType.DEFAULT) {
+        closeStatement(stmt);
+      }
     }
   }
 

src/main/java/org/apache/ibatis/executor/SimpleExecutor.java

@@ -24,6 +24,7 @@
 import org.apache.ibatis.executor.statement.StatementHandler;
 import org.apache.ibatis.logging.Log;
 import org.apache.ibatis.mapping.BoundSql;
+import org.apache.ibatis.mapping.FetchType;
 import org.apache.ibatis.mapping.MappedStatement;
 import org.apache.ibatis.session.Configuration;
 import org.apache.ibatis.session.ResultHandler;
@@ -56,7 +57,9 @@ public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBo
       stmt = prepareStatement(handler, ms.getStatementLog());
       return handler.<E>query(stmt, resultHandler);
     } finally {
-      closeStatement(stmt);
+      if (ms.getFetchType() == FetchType.DEFAULT) {
+        closeStatement(stmt);
+      }
     }
   }
 

src/main/java/org/apache/ibatis/executor/resultset/CursorList.java

@@ -0,0 +1,182 @@
+/*
+ *    Copyright 2009-2013 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.apache.ibatis.executor.resultset;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.AbstractList;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+import org.apache.ibatis.mapping.ResultMap;
+import org.apache.ibatis.mapping.ResultMapping;
+import org.apache.ibatis.session.ResultContext;
+import org.apache.ibatis.session.ResultHandler;
+import org.apache.ibatis.session.RowBounds;
+
+/**
+ * @author Guillaume Darmont / guillaume@dropinocean.com
+ */
+public class CursorList<E> extends AbstractList<E> {
+
+  // ResultSetHandler stuff
+  private final DefaultResultSetHandler resultSetHandler;
+  private final ResultMap resultMap;
+  private final ResultSetWrapper rsw;
+  private final ResultMapping parentMapping;
+  private final ObjectWrapperResultHandler<E> objectWrapperResultHandler = new ObjectWrapperResultHandler<E>();
+
+  private boolean iteratorAlreadyOpened = false;
+
+  private boolean fetchStarted = false;
+
+  private boolean resultSetExhausted = false;
+
+  public CursorList(CursorResultSetHandler resultSetHandler, ResultSetWrapper rsw, ResultMap resultMap, ResultMapping parentMapping) {
+    this.resultSetHandler = resultSetHandler;
+    this.rsw = rsw;
+    this.resultMap = resultMap;
+    this.parentMapping = parentMapping;
+  }
+
+  @Override
+  public E get(int index) {
+    throw new UnsupportedOperationException("Cannot retrieve object at a specific index in CursorList. "
+            + "Consider using Iterator to browse the list.");
+  }
+
+  @Override
+  public int size() {
+    throw new UnsupportedOperationException("Cannot retrieve size of a CursorList. "
+            + "Consider using Iterator to browse the list.");
+  }
+
+  public boolean isResultSetExhausted() {
+    return resultSetExhausted;
+  }
+
+  public boolean isFetchStarted() {
+    return fetchStarted;
+  }
+
+  @Override
+  public Iterator<E> iterator() {
+    return new CursorIterator();
+  }
+
+  protected E fetchNextObjectFromDatabase() {
+    if (resultSetExhausted) return null;
+
+    try {
+      fetchStarted = true;
+      resultSetHandler.handleRowValues(rsw, resultMap, objectWrapperResultHandler, RowBounds.DEFAULT, parentMapping);
+    } catch (SQLException e) {
+      throw new RuntimeException(e);
+    }
+
+    E next = objectWrapperResultHandler.result;
+    if (next == null) {
+      closeResultSetAndStatement();
+      resultSetExhausted = true;
+    }
+    objectWrapperResultHandler.result = null;
+
+    return next;
+  }
+
+  public void closeResultSetAndStatement() {
+    ResultSet rs = rsw.getResultSet();
+    try {
+      if (rs != null) {
+        Statement statement = rs.getStatement();
+
+        rs.close();
+        if (statement != null) {
+          statement.close();
+        }
+      }
+    } catch (SQLException e) {
+      // ignore
+    }
+  }
+
+  /**
+   * This toString returns Object's toString default implementation since we don't want AbstractCollection#toString()
+   * to iterate on collection.
+   *
+   * @return a string representation of the object.
+   */
+  @Override
+  public String toString() {
+    return getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(this));
+  }
+
+  private static class ObjectWrapperResultHandler<E> implements ResultHandler {
+
+    private E result;
+
+    @Override
+    public void handleResult(ResultContext context) {
+      this.result = (E) context.getResultObject();
+    }
+  }
+
+  private class CursorIterator implements Iterator<E> {
+
+    /**
+     * Holder for the next objet to be returned
+     */
+    E object;
+
+    public CursorIterator() {
+      if (iteratorAlreadyOpened) {
+        throw new IllegalStateException("Cannot open more than one iterator on a CursorList. "
+                + "Use LazyList if you want to iterate more than one time.");
+      }
+      iteratorAlreadyOpened = true;
+    }
+
+    @Override
+    public boolean hasNext() {
+      if (object == null) {
+        object = fetchNextObjectFromDatabase();
+      }
+      return object != null;
+    }
+
+    @Override
+    public E next() {
+      // Fill next with object fetched from hasNext()
+      E next = object;
+
+      if (next == null) {
+        next = fetchNextObjectFromDatabase();
+      }
+
+      if (next != null) {
+        object = null;
+        return next;
+      }
+      throw new NoSuchElementException();
+    }
+
+    @Override
+    public void remove() {
+      throw new UnsupportedOperationException("Cannot remove element from CursorList");
+    }
+  }
+}