Application logging throws vfrtshadow ConnectionWrapper cannot be cast to DB Connection error

This issue occurs in the following circumstances:

  1. The vFunction Sudo or Sudoless Controller Installation TGZ is installed in a Linux environment
  2. An Application Server is used to run the JVM
  3. After adding the vFunction Agent Startup Parameters into the JVM, the Application is rebooted and the following error occurs

Sample Error #1

java.io.IOException: java.lang.ClassCastException: class vfrtshadow.com.p6spy.engine.wrapper.ConnectionWrapper cannot be cast to class org.postgresql.PGConnection 
(vfrtshadow.com.p6spy.engine.wrapper.ConnectionWrapper and org.postgresql.PGConnection are in unnamed module of loader 'app')
	at simple.io.ParallelOutputStream.executeAll(ParallelOutputStream.java:158) ~[bin/:?]
	at simple.io.ParallelOutputStream.flush(ParallelOutputStream.java:124) ~[bin/:?]
	at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:143) ~[?:?]
	at java.util.zip.DeflaterOutputStream.flush(DeflaterOutputStream.java:291) ~[?:?]
	at java.io.FilterOutputStream.flush(FilterOutputStream.java:153) ~[?:?]
	at simple.io.resource.SingleStashResource$ResourceOutputStream.flush(SingleStashResource.java:52) ~[bin/:?]
	at simple.io.resource.ReplicatedStashResource$2.flush(ReplicatedStashResource.java:66) ~[bin/:?]
	...
Caused by: java.lang.ClassCastException: class vfrtshadow.com.p6spy.engine.wrapper.ConnectionWrapper cannot be cast to class org.postgresql.PGConnection 
(vfrtshadow.com.p6spy.engine.wrapper.ConnectionWrapper and org.postgresql.PGConnection are in unnamed module of loader 'app')
	at simple.io.resource.AbstractDbResourceFolder.writeFileContent(AbstractDbResourceFolder.java:364) ~[bin/:?]
	at simple.io.resource.AbstractDbResourceFolder$DbStashImpl.updateFileContent(AbstractDbResourceFolder.java:252) ~[bin/:?]
	...

Sample Error #2

java.lang.ClassCastException: class vfrtshadow.com.p6spy.engine.wrapper.ConnectionWrapper cannot be cast to class oracle.jdbc.OracleConnection 
 (vfrtshadow.com.p6spy.engine.wrapper.ConnectionWrapper is in unnamed module of loader 'app'; oracle.jdbc.OracleConnection is in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader @100eeedc)
	at com.relevant.namespace.data.NamespaceDataSource.getConnectionInternal(NamespaceDataSource.java:581)
	at com.relevant.namespace.data.NamespaceDataSource.getConnection(NamespaceDataSource.java:518)
	at com.relevant.namespace.data.internal.NamespaceConnection.createConnection(NamespaceConnection.java:201)
	at com.relevant.namespace.data.internal.NamespaceConnection.<init>(NamespaceConnection.java:78)

This issue can be resolved by taking the following steps:

  1. Modify the code for the Database Connection to unwrap rather than Cast the connection. See the samples below.
  2. Deploy the code change.
  3. Restart the Application to confirm this change resolved the problem.

Sample Resolution #1

## Before
try{
  conn = (OracleConnection) mUcpDataSource.getConnection();
  applyConnectionOverrides(conn);
}

## After
try{
  final var newConnection :Connection = mUcpDataSource.getConnection();
  if (newConnection instanceof OracleConnection) {
      conn = (OracleConnection) newConnection;
  } else {
      conn = newConnection.unwrap(OracleConnection.class);
  }
  applyConnectionOverrides(conn);

Sample Resolution #2

## Before
protected void writeFileContent(DbStashImpl stash, byte[] bytes, int byteOffset, int length, long contentOffset) throws IOException {
		if(contentOffset > Integer.MAX_VALUE)
			throw new IOException("File size is too big. Maximum is " + Integer.MAX_VALUE);
		try {
			Connection conn = dataLayer.getConnection(stash.dataSourceName, false);
			try {
				PGConnection pgConn = (PGConnection)DBUnwrap.getRealConnection(conn);
				LargeObjectManager lom = pgConn.getLargeObjectAPI();
				LargeObject lo = lom.open(stash.loid, LargeObjectManager.WRITE);

## After
protected void writeFileContent(DbStashImpl stash, byte[] bytes, int byteOffset, int length, long contentOffset) throws IOException {
		if(contentOffset > Integer.MAX_VALUE)
			throw new IOException("File size is too big. Maximum is " + Integer.MAX_VALUE);
		try {
 			Connection conn = dataLayer.getConnection(stash.dataSourceName, false);
 			try {
				PGConnection pgConn = (PGConnection)DBUnwrap.getRealConnection(conn);
				PGConnection pgConn = null;
                Connection realConn = DBUnwrap.getRealConnection(conn);
                if(realConn instanceof PGConnection) {
                    pgConn = (PGConnection)realConn;
                } else {
                    pgConn = realConn.unwrap(PGConnection.class);
                }
				LargeObjectManager lom = pgConn.getLargeObjectAPI();
 				LargeObject lo = lom.open(stash.loid, LargeObjectManager.WRITE);

Additional Documentation

Updated on 01 Dec 2023