Memory usage optimization when parsing mapper files

* Less object creation in GenericTokenParser.
* Optimized <include /> resolution logic.

Author: harawata

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

@@ -15,6 +15,10 @@
  */
 package org.apache.ibatis.builder.xml;
 
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
 import org.apache.ibatis.builder.BuilderException;
 import org.apache.ibatis.builder.IncompleteElementException;
 import org.apache.ibatis.builder.MapperBuilderAssistant;
@@ -24,8 +28,6 @@
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 
-import java.util.Properties;
-
 /**
  * @author Frank D. Martinez [mnesarco]
  */
@@ -45,34 +47,19 @@ public void applyIncludes(Node source) {
     if (configurationVariables != null) {
       variablesContext.putAll(configurationVariables);
     }
-    applyIncludes(source, variablesContext);
+    applyIncludes(source, variablesContext, false);
   }
 
   /**
    * Recursively apply includes through all SQL fragments.
    * @param source Include node in DOM tree
    * @param variablesContext Current context for static variables with values
    */
-  private void applyIncludes(Node source, final Properties variablesContext) {
+  private void applyIncludes(Node source, final Properties variablesContext, boolean included) {
     if (source.getNodeName().equals("include")) {
-      // new full context for included SQL - contains inherited context and new variables from current include node
-      Properties fullContext;
-
-      String refid = getStringAttribute(source, "refid");
-      // replace variables in include refid value
-      refid = PropertyParser.parse(refid, variablesContext);
-      Node toInclude = findSqlFragment(refid);
-      Properties newVariablesContext = getVariablesContext(source, variablesContext);
-      if (!newVariablesContext.isEmpty()) {
-        // merge contexts
-        fullContext = new Properties();
-        fullContext.putAll(variablesContext);
-        fullContext.putAll(newVariablesContext);
-      } else {
-        // no new context - use inherited fully
-        fullContext = variablesContext;
-      }
-      applyIncludes(toInclude, fullContext);
+      Node toInclude = findSqlFragment(getStringAttribute(source, "refid"), variablesContext);
+      Properties toIncludeContext = getVariablesContext(source, variablesContext);
+      applyIncludes(toInclude, toIncludeContext, true);
       if (toInclude.getOwnerDocument() != source.getOwnerDocument()) {
         toInclude = source.getOwnerDocument().importNode(toInclude, true);
       }
@@ -83,19 +70,18 @@ private void applyIncludes(Node source, final Properties variablesContext) {
       toInclude.getParentNode().removeChild(toInclude);
     } else if (source.getNodeType() == Node.ELEMENT_NODE) {
       NodeList children = source.getChildNodes();
-      for (int i=0; i<children.getLength(); i++) {
-        applyIncludes(children.item(i), variablesContext);
+      for (int i = 0; i < children.getLength(); i++) {
+        applyIncludes(children.item(i), variablesContext, included);
       }
-    } else if (source.getNodeType() == Node.ATTRIBUTE_NODE && !variablesContext.isEmpty()) {
-      // replace variables in all attribute values
-      source.setNodeValue(PropertyParser.parse(source.getNodeValue(), variablesContext));
-    } else if (source.getNodeType() == Node.TEXT_NODE && !variablesContext.isEmpty()) {
+    } else if (included && source.getNodeType() == Node.TEXT_NODE
+        && !variablesContext.isEmpty()) {
       // replace variables ins all text nodes
       source.setNodeValue(PropertyParser.parse(source.getNodeValue(), variablesContext));
     }
   }
 
-  private Node findSqlFragment(String refid) {
+  private Node findSqlFragment(String refid, Properties variables) {
+    refid = PropertyParser.parse(refid, variables);
     refid = builderAssistant.applyCurrentNamespace(refid, true);
     try {
       XNode nodeToInclude = configuration.getSqlFragments().get(refid);
@@ -116,23 +102,29 @@ private String getStringAttribute(Node node, String name) {
    * @return variables context from include instance (no inherited values)
    */
   private Properties getVariablesContext(Node node, Properties inheritedVariablesContext) {
-    Properties variablesContext = new Properties();
+    Map<String, String> declaredProperties = null;
     NodeList children = node.getChildNodes();
     for (int i = 0; i < children.getLength(); i++) {
       Node n = children.item(i);
       if (n.getNodeType() == Node.ELEMENT_NODE) {
         String name = getStringAttribute(n, "name");
-        String value = getStringAttribute(n, "value");
         // Replace variables inside
-        value = PropertyParser.parse(value, inheritedVariablesContext);
-        // Push new value
-        Object originalValue = variablesContext.put(name, value);
-        if (originalValue != null) {
+        String value = PropertyParser.parse(getStringAttribute(n, "value"), inheritedVariablesContext);
+        if (declaredProperties == null) {
+          declaredProperties = new HashMap<String, String>();
+        }
+        if (declaredProperties.put(name, value) != null) {
           throw new BuilderException("Variable " + name + " defined twice in the same include definition");
         }
       }
     }
-    return variablesContext;
+    if (declaredProperties == null) {
+      return inheritedVariablesContext;
+    } else {
+      Properties newProperties = new Properties();
+      newProperties.putAll(inheritedVariablesContext);
+      newProperties.putAll(declaredProperties);
+      return newProperties;
+    }
   }
-  
 }

src/main/java/org/apache/ibatis/parsing/GenericTokenParser.java

@@ -31,50 +31,58 @@ public GenericTokenParser(String openToken, String closeToken, TokenHandler hand
   }
 
   public String parse(String text) {
+    if (text == null || text.isEmpty()) {
+      return "";
+    }
+    char[] src = text.toCharArray();
+    int offset = 0;
+    // search open token
+    int start = text.indexOf(openToken, offset);
+    if (start == -1) {
+      return text;
+    }
     final StringBuilder builder = new StringBuilder();
-    final StringBuilder expression = new StringBuilder();
-    if (text != null && text.length() > 0) {
-      char[] src = text.toCharArray();
-      int offset = 0;
-      // search open token
-      int start = text.indexOf(openToken, offset);
-      while (start > -1) {
-        if (start > 0 && src[start - 1] == '\\') {
-          // this open token is escaped. remove the backslash and continue.
-          builder.append(src, offset, start - offset - 1).append(openToken);
-          offset = start + openToken.length();
+    StringBuilder expression = null;
+    while (start > -1) {
+      if (start > 0 && src[start - 1] == '\\') {
+        // this open token is escaped. remove the backslash and continue.
+        builder.append(src, offset, start - offset - 1).append(openToken);
+        offset = start + openToken.length();
+      } else {
+        // found open token. let's search close token.
+        if (expression == null) {
+          expression = new StringBuilder();
         } else {
-          // found open token. let's search close token.
           expression.setLength(0);
-          builder.append(src, offset, start - offset);
-          offset = start + openToken.length();
-          int end = text.indexOf(closeToken, offset);
-          while (end > -1) {
-            if (end > offset && src[end - 1] == '\\') {
-              // this close token is escaped. remove the backslash and continue.
-              expression.append(src, offset, end - offset - 1).append(closeToken);
-              offset = end + closeToken.length();
-              end = text.indexOf(closeToken, offset);
-            } else {
-              expression.append(src, offset, end - offset);
-              offset = end + closeToken.length();
-              break;
-            }
-          }
-          if (end == -1) {
-            // close token was not found.
-            builder.append(src, start, src.length - start);
-            offset = src.length;
+        }
+        builder.append(src, offset, start - offset);
+        offset = start + openToken.length();
+        int end = text.indexOf(closeToken, offset);
+        while (end > -1) {
+          if (end > offset && src[end - 1] == '\\') {
+            // this close token is escaped. remove the backslash and continue.
+            expression.append(src, offset, end - offset - 1).append(closeToken);
+            offset = end + closeToken.length();
+            end = text.indexOf(closeToken, offset);
           } else {
-            builder.append(handler.handleToken(expression.toString()));
+            expression.append(src, offset, end - offset);
             offset = end + closeToken.length();
+            break;
           }
         }
-        start = text.indexOf(openToken, offset);
-      }
-      if (offset < src.length) {
-        builder.append(src, offset, src.length - offset);
+        if (end == -1) {
+          // close token was not found.
+          builder.append(src, start, src.length - start);
+          offset = src.length;
+        } else {
+          builder.append(handler.handleToken(expression.toString()));
+          offset = end + closeToken.length();
+        }
       }
+      start = text.indexOf(openToken, offset);
+    }
+    if (offset < src.length) {
+      builder.append(src, offset, src.length - offset);
     }
     return builder.toString();
   }