(fixes http://code.google.com/p/mybatis/issues/detail?id=760 ) GenericTokenParaser#parse() could cause memory/performance issue on Java 7u6+ when the parsed string contains many variables to replace.

Author: harawata

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

@@ -29,39 +29,33 @@ public GenericTokenParser(String openToken, String closeToken, TokenHandler hand
 
   public String parse(String text) {
     StringBuilder builder = new StringBuilder();
-    if (text != null) {
-      String after = text;
-      int start = after.indexOf(openToken);
-      int end = after.indexOf(closeToken);
+    if (text != null && text.length() > 0) {
+      char[] src = text.toCharArray();
+      int offset = 0;
+      int start = text.indexOf(openToken, offset);
       while (start > -1) {
-        if (end > start) {
-          String before = after.substring(0, start);
-          String content = after.substring(start + openToken.length(), end);
-          String substitution;
-
-          // check if variable has to be skipped
-          if (start > 0 && text.charAt(start - 1) == '\\') {
-            before = before.substring(0, before.length() - 1);
-            substitution = new StringBuilder(openToken).append(content).append(closeToken).toString();
+        if (start > 0 && src[start - 1] == '\\') {
+          // the variable is escaped. remove the backslash.
+          builder.append(src, offset, start - 1).append(openToken);
+          offset = start + openToken.length();
+        } else {
+          int end = text.indexOf(closeToken, start);
+          if (end == -1) {
+            builder.append(src, offset, src.length - offset);
+            offset = src.length;
           } else {
-            substitution = handler.handleToken(content);
+            builder.append(src, offset, start - offset);
+            offset = start + openToken.length();
+            String content = new String(src, offset, end - offset);
+            builder.append(handler.handleToken(content));
+            offset = end + closeToken.length();
           }
-
-          builder.append(before);
-          builder.append(substitution);
-          after = after.substring(end + closeToken.length());
-        } else if (end > -1) {
-          String before = after.substring(0, end);
-          builder.append(before);
-          builder.append(closeToken);
-          after = after.substring(end + closeToken.length());
-        } else {
-          break;
         }
-        start = after.indexOf(openToken);
-        end = after.indexOf(closeToken);
+        start = text.indexOf(openToken, offset);
+      }
+      if (offset < src.length) {
+        builder.append(src, offset, src.length - offset);
       }
-      builder.append(after);
     }
     return builder.toString();
   }

src/test/java/org/apache/ibatis/parsing/GenericTokenParserTest.java

@@ -75,4 +75,27 @@ public void shallNotInterpolateSkippedVaiables() {
     assertEquals("This is a ${skipped} variable", parser.parse("This is a \\${skipped} variable"));
   }
 
+  @Test(timeout = 1000)
+  public void shouldParseFastOnJdk7u6() {
+    // issue #760
+    GenericTokenParser parser = new GenericTokenParser("${", "}", new VariableTokenHandler(new HashMap<String, String>() {
+      {
+        put("first_name", "James");
+        put("initial", "T");
+        put("last_name", "Kirk");
+        put("", "");
+      }
+    }));
+
+    StringBuilder input = new StringBuilder();
+    for (int i = 0; i < 10000; i++) {
+      input.append("${first_name} ${initial} ${last_name} reporting. ");
+    }
+    StringBuilder expected = new StringBuilder();
+    for (int i = 0; i < 10000; i++) {
+      expected.append("James T Kirk reporting. ");
+    }
+    assertEquals(expected.toString(), parser.parse(input.toString()));
+  }
+
 }