MySQL, c3p0 and Apache Felix integration

Question

I integrate MySQL into Apache Felix. First, I use bndtools to generate MySQL bundle and c3p0 bundle. Then I add them all into my Apache Felix environment. I create a class for connection pool like below:

    public final class C3P0Manager {

        private static C3P0Manager instance;
        private DataSource pooled;

        private C3P0Manager() {
            // Of course, it is better to put all properties into a configuration file.
            // I just list them here for easy reading.

            ComboPooledDataSource cpds = new ComboPooledDataSource();
            cpds.setDriverClass("com.mysql.jdbc.Driver"));
            cpds.setJdbcUrl("jdbc:mysql://localhost/my-database?autoReconnect=true&characterSetResults=UTF-8&characterEncoding=UTF-8&useUnicode=yes");
            cpds.setUser("user");
            cpds.setPassword("password");
            cpds.setInitialPoolSize(3);
            cpds.setMaxPoolSize(15);
            cpds.setMaxIdleTime(1800);
            cpds.setAutoCommitOnClose(true);
            pooled(cpds);
        }

        public static C3P0Manager instance() throws Exception {
            if (instance == null) {
                instance = new C3P0Manager();
            }
            return instance;
        }

        public DataSource getPooled() throws SQLException {
            return pooled;
        }
    }

It works fine if I run JUnit test. But failed when running on my Apache Felix bundle with exception message. Usage in Activator class:

    Class.forName("com.mysql.jdbc.Driver");
    DataSource pooled = C3P0Manager.instance().getPooled();
    Connection con = pooled.getConnection();
    PreparedStatement stmt = null;
    ResultSet rs = null;
    int total;

    try {
        stmt = con.prepareStatement("SELECT count(*) FROM users", Statement.NO_GENERATED_KEYS);
        rs = stmt.executeQuery();
        if (rs.next()) {
            total = rs.getInt(1);
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            rs.close();
            stmt.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
    System.out.println("total = " + total);

Error messages:

    java.sql.SQLException: Connections could not be acquired from the underlying database!
        at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
        at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
    ...
    Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
        at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
        at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
        at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
    ...

MySQL works if I just use (without c3p0):

    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost/my-database?autoReconnect=true&characterSetResults=UTF-8&characterEncoding=UTF-8&useUnicode=yes","user","password");
    Statement statement = connect.createStatement();
    ResultSet resultSet = statement.executeQuery("SELECT count(*) FROM users");

So I think the problem is due to c3p0. Please help me. Thanks.

Answer 1

I am lazy to modify c3p0 source and build new c3p0 bundle version again :). So I try Apache DBCP bundle instead:

org.apache.servicemix.bundles.commons-pool-1.5.4
org.apache.servicemix.bundles.commons-dbcp-1.4.0
(dbcp needs pool to work)

It is OK to CRUD MySQL database.

If anyone want to use those bundles, here they are:

http://mvnrepository.com/artifact/org.apache.servicemix.bundles/org.apache.servicemix.bundles.commons-pool
http://mvnrepository.com/artifact/org.apache.servicemix.bundles/org.apache.servicemix.bundles.commons-dbcp

When I have time, I will take a look at bonecp if someone already builds a bundle for it. Or modify c3p0 to use it.