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26600
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sandro.lab
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package eu.dnetlib.enabling.database.resultset;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import java.util.concurrent.BlockingQueue;
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import java.util.concurrent.TimeUnit;
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import eu.dnetlib.enabling.database.rmi.DatabaseException;
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import eu.dnetlib.enabling.database.utils.DatabaseUtils;
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import eu.dnetlib.enabling.resultset.SizedIterable;
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50981
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claudio.at
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.dom4j.Document;
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26600
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sandro.lab
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public class IterableRowSet implements SizedIterable<String> {
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private String db;
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private String sql;
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private String sqlForCount;
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private DatabaseUtils dbUtils;
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private Integer size = null;
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private static final Log log = LogFactory.getLog(IterableRowSet.class); // NOPMD by marko on 11/24/08 5:02 PM
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public IterableRowSet(final String db, final String sql, final String sqlForCount, final DatabaseUtils dbUtils) {
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super();
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this.db = db;
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this.sql = sql;
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this.sqlForCount = sqlForCount;
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this.dbUtils = dbUtils;
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}
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@Override
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@SuppressWarnings("unchecked")
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public Iterator<String> iterator() {
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try {
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50981
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claudio.at
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final BlockingQueue<Document> queue = dbUtils.executeSql(db, sql, BlockingQueue.class);
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26600
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sandro.lab
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return new QueueIterator(queue);
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} catch (Exception e) {
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throw new RuntimeException("Error creating iterator for query: " + sql, e);
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}
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}
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@Override
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public int getNumberOfElements() {
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if (size != null) { return size; }
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String query = (sqlForCount == null) || sqlForCount.isEmpty() ? "SELECT count(*) FROM ( " + sql + " ) AS TABLELISTENER" : sqlForCount;
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try {
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log.debug("Calculating size using query: " + query);
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this.size = dbUtils.executeSql(db, query, Integer.class);
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return size;
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} catch (DatabaseException e) {
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log.error("Error in getSize, query: " + query, e);
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throw new IllegalStateException("Error in getSize, query: " + query, e);
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}
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}
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private class QueueIterator implements Iterator<String> {
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claudio.at
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private Document curr;
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private BlockingQueue<Document> queue;
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26600
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sandro.lab
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50981
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claudio.at
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public QueueIterator(final BlockingQueue<Document> queue) throws InterruptedException {
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26600
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sandro.lab
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super();
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this.queue = queue;
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this.curr = queue.poll(DatabaseUtils.BLOCKING_QUEUE_TIMEOUT, TimeUnit.SECONDS);
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}
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@Override
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public String next() {
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log.debug("Reading Next Element from queue");
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try {
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50981
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claudio.at
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if ((curr == null) || !hasContent(curr)) { throw new NoSuchElementException(
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sandro.lab
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"Value from queue is null or empty, probably the producer doesn't produce"); }
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50981
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claudio.at
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String res = curr.asXML();
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26600
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sandro.lab
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curr = queue.poll(DatabaseUtils.BLOCKING_QUEUE_TIMEOUT, TimeUnit.SECONDS);
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return res;
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} catch (Exception e) {
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throw new NoSuchElementException("Error navigating rowset for query: " + sql + "\n" + e.getMessage());
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}
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}
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50981
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claudio.at
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private boolean hasContent(final Document curr) {
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return curr != null && Integer.parseInt(curr.valueOf("count(/ROW/*)")) > 0;
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}
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sandro.lab
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@Override
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public boolean hasNext() {
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// An empty Map indicates the end of the Queue
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50981
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claudio.at
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return (curr != null) && hasContent(curr);
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26600
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sandro.lab
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}
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@Override
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public void remove() {}
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}
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}
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