/**
* Add a PID to the queue
*
* @param pid
*/
public void add(Pid pid) throws Exception {
Connection connection = DatabaseHelper.getConnection();
PreparedStatement stmt =
connection.prepareStatement(DatabaseHelper.ADD_QUEUE_ELEMENT_STATEMENT);
stmt.setString(1, pid.getIdentifier());
stmt.setString(2, pid.getUrl());
stmt.setString(3, DatabaseHelper.getTimeStamp());
stmt.executeUpdate();
stmt.close();
connection.close();
}
/**
* Remove a PID from the queue
*
* @param pid
*/
public void remove(Pid pid) throws Exception {
Connection connection = DatabaseHelper.getConnection();
PreparedStatement stmt =
connection.prepareStatement(DatabaseHelper.REMOVE_QUEUE_ELEMENT_STATEMENT);
stmt.setString(1, pid.getIdentifier());
stmt.executeUpdate();
stmt.close();
connection.close();
}
/**
* Current Size of the queue
*
* @return
* @throws Exception
*/
public int size() throws Exception {
Connection connection = DatabaseHelper.getConnection();
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery(DatabaseHelper.QUEUE_SIZE_STATEMENT);
int size = 0;
if (resultSet.next()) {
size = resultSet.getInt("size");
}
connection.close();
statement.close();
return size;
}
public Pid getFirst() throws Exception {
Pid pid = new Pid();
Connection connection = DatabaseHelper.getConnection();
Statement statement = connection.createStatement();
statement.setMaxRows(1);
ResultSet resultSet = statement.executeQuery(DatabaseHelper.GET_QUEUE_FIRST_ELEMENT_STATEMENT);
if (resultSet.next()) {
pid.setIdentifier(resultSet.getString("identifier"));
pid.setUrl(resultSet.getString("url"));
connection.close();
} else {
connection.close();
return null;
}
statement.close();
return pid;
}
/**
* Retrieve a PID from the queue.
*
* @param id
* @return
* @throws Exception
*/
public Pid retrieve(String id) throws Exception {
Pid pid = null;
Connection connection = DatabaseHelper.getConnection();
PreparedStatement stmt =
connection.prepareStatement(DatabaseHelper.RETRIEVE_QUEUE_ELEMENT_STATEMENT);
stmt.setString(1, id);
ResultSet resultSet = stmt.executeQuery();
if (resultSet.next()) {
pid = new Pid(resultSet.getString("identifier"), resultSet.getString("url"));
stmt.close();
connection.close();
}
stmt.close();
connection.close();
return pid;
}
public List<Pid> getFirstBlock(int size) throws Exception {
List<Pid> pids = new ArrayList<Pid>();
Connection connection = DatabaseHelper.getConnection();
Statement statement = connection.createStatement();
statement.setMaxRows(size);
ResultSet resultSet = statement.executeQuery(DatabaseHelper.GET_QUEUE_FIRST_ELEMENT_STATEMENT);
while (resultSet.next()) {
Pid pid = new Pid();
pid.setIdentifier(resultSet.getString("identifier"));
pid.setUrl(resultSet.getString("url"));
pids.add(pid);
}
statement.close();
connection.close();
logger.debug("getFirstBlock of queue returning " + pids.size() + " pids");
return pids;
}
/**
* Search a PID from his URL in the {@link Queue}: - return the PID if found - return null if not
* found
*
* @param url
* @return
* @throws Exception
*/
public Pid search(String url) throws Exception {
Pid pid = null;
Connection connection = DatabaseHelper.getConnection();
PreparedStatement stmt =
connection.prepareStatement(DatabaseHelper.GET_QUEUE_ELEMENT_URL_STATEMENT);
stmt.setString(1, url);
ResultSet resultSet = stmt.executeQuery();
if (resultSet.getFetchSize() > 1) {
throw new RuntimeException("Duplicate detected for URI: " + url);
}
if (resultSet.next()) {
pid = new Pid(resultSet.getString("identifier"), resultSet.getString("url"));
stmt.close();
connection.close();
}
stmt.close();
connection.close();
return pid;
}