SqliteCancelTest.java

package org.sqlite;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * Example of invoking Statement.cancel() on long running query. If the query is expensive and blocks for a significant 
 * time in executeQuery(), then Statement.cancel() fails to work correctly.
 */
public class SqliteCancelTest {

  static PreparedStatement stmt;
	static Connection conn;

	static class RunQuery implements Runnable {

		String sql;

		public RunQuery(String sql) {
			super();
			this.sql = sql;
		}

		public void run() {
			try {
				System.out.println("RUNNING: " + sql);
				stmt = conn.prepareStatement(sql);
				ResultSet resultSet = stmt.executeQuery();
				System.out.println("executeQuery() complete");
				while (resultSet.next()) {
					String value = resultSet.getString(1);
				}
				System.out.println("Completed");
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				if (stmt != null) {
					try {
						stmt.close();
					} catch (SQLException e) {
						System.err.println("Statement.close() failed with: "
								+ e);
					}
				}
				try {
					conn.close();
				} catch (SQLException e) {
					System.err.println("Connection.close() failed with: " + e);
				}
			}
		}
	}

	public static void main(String[] args) throws Exception {
		// arguments are <sqlite-file> <query>
		// query should be an expensive query which takes a while to compute any results
		// i typically use SELECT * FROM TABLE ORDER BY COLUMN where on a table with alot of
		// rows and where COLUMN is non-indexed
		Class.forName("org.sqlite.JDBC");
		conn = DriverManager.getConnection("jdbc:sqlite:" + args[0]);
		new Thread(new RunQuery(args[1])).start();
		// Query is running in separate thread, invoke cancel on statement
		try {
			while (stmt == null) {
				Thread.sleep(100);
			}
			System.out.println("CANCEL!");
			stmt.cancel();
		} catch (Exception e) {
			System.err.println("Statement.cancel() failed with: " + e);
		}
	}
}