Identifying Connection not closed in java code using PMD

Question

For identifying connection leaks in code, i'm using PMD. Now with PMD, it will identify all collection leaks and show the following error, if it didn't find connection.close().

C:\raghu\Harmony\branch\GlobalSKUPhase1A\source\Java\DataLoadServiceApp\src\dell\harmony\data\JdoServer.java:861:   Ensure that resources like this Connection object are closed after use

However, with our project code, we also use many customized connection close, i.e) instead of using connection.close(), we call a method and close the connection i.e) ResourceClosureUtil.closeDBConnection Now while running pmd, eventhough i've closed the connection using ResourceClosureUtil.closeDBConnection, it gives a false alarm, that connection is not closed.

So i've modified the design.xml (ruleset) as follows. changes are highlighted with **

<?xml version="1.0"?>

<ruleset name="Design"
    xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.net/ruleset_2_0_0.xsd">

  <description>
The Design ruleset contains rules that flag suboptimal code implementations. Alternate approaches
are suggested.
  </description>

  <rule name="CloseResource"
          since="1.2.2"
        message="Ensure that resources like this {0} object are closed after use"
        class="net.sourceforge.pmd.lang.java.rule.design.CloseResourceRule"
          externalInfoUrl="http://pmd.sourceforge.net/pmd-5.0.5/rules/java/design.html#CloseResource">
    <description>
Ensure that resources (like Connection, Statement, and ResultSet objects) are always closed after use.
    </description>
    <priority>3</priority>
    <properties>
    <property name="types" value="Connection,Statement,ResultSet"/>
        **<property name="closeTargets" value="ResourceClosureUtil.closeDBConnection"/>**
    </properties>
    <example>
<![CDATA[
public class Bar {
  public void foo() {
    Connection c = pool.getConnection();
    try {
      // do stuff
    } catch (SQLException ex) {
     // handle exception
    } finally {
      // oops, should close the connection using 'close'!
      // c.close();
    }
  }
}
]]>
    </example>
  </rule>

</ruleset>

Now with this change it is not giving any false alarm, when connection is closed with ResourceClosureUtil.closeDBConnection.

Now we have many customized close methods like , "ClosureUtil.closeConnection", "Resource.close", how to stop false alarm with these methods? In order to solve, i've modified closeTargets property to include all such methods. changes highlighted with **

<property name="types" value="Connection,Statement,ResultSet"/>
    **<property name="closeTargets" value="ResourceClosureUtil.closeDBConnection"/>
    <property name="closeTargets" value="ClosureUtil.closeConnection"/>
    <property name="closeTargets" value="Resource.close"/>**
</properties>

or

<property name="types" value="Connection,Statement,ResultSet"/>
    <property name="closeTargets"
        value="ResourceClosureUtil.closeDBConnection,ClosureUtil.closeConnection,Resource.close"/>
</properties>

But it is not working as expected. It is still giving false alarm. When i hve one customized closure method , it works fine by not giving false alarm, but when i have many such method, it is not working, when i include all such methods in closetargets property.

I dont want to see any false alarm with any of these customized connection closures(e.g.) ResourceClosureUtil.closeDBConnection,ClosureUtil.closeConnection,Resource.close). How to solve this issue(false alarm: multiple connection closure) with PMD? How to change to closetargets property to include multiple methods?

FYI: I'm running it from command prompt, to identify the connection leaks.

pmd -d C:\raghu\Harmony\branch\GlobalSKUPhase1A\source\Java\DataLoadServiceApp\src -f text 
-R rulesets/java/unusedcode.xml,rulesets/java/controversial.xml,rulesets/java/basic.xml,rulesets/java/strings.xml,rulesets/java/design.xml,rulesets/java/naming.xml,rulesets/java/finalizers.xml,rulesets/java/braces.xml,rulesets/java/clone.xml,rulesets/java/codesize.xml,rulesets/java/imports.xml,rulesets/java/javabeans.xml,rulesets/java/logging-jakarta-commons.xml,rulesets/java/logging-java.xml,rulesets/java/migrating.xml,rulesets/java/optimizations.xml,rulesets/java/strictexception.xml,rulesets/java/sunsecure.xml,rulesets/java/coupling.xml > allexceptions.txt

command: pmd -d codesource -f output -R Ruleset > allexception.txt

allexception.txt will have the output of connection not closed violation and other violations.

Answer 1

closeTargets property is also a HashSet<String> as types property in CloseResource implementation. So, ideally the below should work for you:

<properties>
    <property name="types" value="Connection,Statement,ResultSet"/>
    <property name="closeTargets" value="closeDBConnection, closeConnection, close"/>
</properties>

Note that I am providing the method names only in closeTargets property which are used to close resources.