net.sf.basedb.core
Class QueryExecutor

java.lang.Object
  net.sf.basedb.core.QueryExecutor

public class QueryExecutor
extends Object

Utility class for executing SQL and Hibernate queries. If enabled, this class will use a thread pool to execute a query in separate threads. The benefits are:

• It is possible to limit the number of concurrent queries.
• It is possible to abort a running query by calling Thread.interrupt() on the thread that called one of the methods in this class.

Version:

2.6

Author:

Nicklas

Last modified

$Date: 2007-08-17 09:18:29 +0200 (fr, 17 aug 2007) $

Nested Class Summary

(package private) static interface	QueryExecutor.Cancelable Interface to be implemented by classes that knows how to cancel a query.
(package private) static class	QueryExecutor.CancelableSession Cancels the query running in a Hibernate session.
(package private) static class	QueryExecutor.CancelableStatelessSession Cancels a query running in a stateless Hibernate session.
(package private) static class	QueryExecutor.CancelableStatement Cancels a statement by calling Statement.cancel().
(package private) static class	QueryExecutor.FutureItem<T>
(package private) static class	QueryExecutor.FutureResultSet A callable implementation the calls PreparedStatement.executeQuery()
(package private) static class	QueryExecutor.FutureScrollIterator<T> Calls Query.scroll(ScrollMode) and returns the result as a ScrollIterator.
(package private) static class	QueryExecutor.FutureUpdate A callable implementation the calls PreparedStatement.executeUpdate()

Field Summary

private static ExecutorService

service

Constructor Summary

QueryExecutor()

Method Summary

static ResultSet	executeQuery(PreparedStatement ps, SessionControl sc) Execute a query by calling PreparedStatement.executeQuery().
static int	executeUpdate(PreparedStatement ps, SessionControl sc) Execute a query by calling PreparedStatement.executeUpdate().
private static <T> T	getFutureResult(Callable<T> callable, QueryExecutor.Cancelable cancelable, SessionControl sc) Run the callable and wait for the result.
(package private) static void	init() This will create a new thread for each query.
static <T> T	loadData(Class<T> clazz, Query query, StatelessSession session, SessionControl sc) Executes a Hibernate query on a stateless session.
static <T> ScrollIterator<T>	loadIterator(Class<T> clazz, Query query, StatelessSession session, SessionControl sc) Executes a Hibernate query that returns an iterator on a stateless session.
(package private) static void	unload()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

service

private static ExecutorService service

Constructor Detail

QueryExecutor

public QueryExecutor()

Method Detail

init

static void init()

This will create a new thread for each query. There is no limit on the number of threads.

unload

static void unload()

executeQuery

public static ResultSet executeQuery(PreparedStatement ps,
                                     SessionControl sc)
                              throws InterruptedException,
                                     SQLException

Execute a query by calling PreparedStatement.executeQuery().

Parameters:

ps - The prepared statement to execute

sc - A session control object that should be kept alive while the query is executing, or null

Returns:

The result from PreparedStatement.executeQuery()

Throws:

InterruptedException - If this thread was interrupted

SQLException - If there was an error executing the SQL statement

executeUpdate

public static int executeUpdate(PreparedStatement ps,
                                SessionControl sc)
                         throws InterruptedException,
                                SQLException

Execute a query by calling PreparedStatement.executeUpdate().

Parameters:

ps - The prepared statement to execute

sc - A session control object that should be kept alive while the query is executing, or null

Returns:

The result from PreparedStatement.executeUpdate()

Throws:

InterruptedException - If this thread was interrupted

SQLException

loadIterator

public static <T> ScrollIterator<T> loadIterator(Class<T> clazz,
                                                 Query query,
                                                 StatelessSession session,
                                                 SessionControl sc)
                                      throws InterruptedException

Executes a Hibernate query that returns an iterator on a stateless session.

Parameters:

clazz - The class of items returned by the iterator

query - The query to execute

session - The stateless session, this must be the same session that was used to create the query

sc - A session control object that should be kept alive while the query is executing, or null

Throws:

InterruptedException

Since:

2.7

loadData

public static <T> T loadData(Class<T> clazz,
                             Query query,
                             StatelessSession session,
                             SessionControl sc)
                  throws InterruptedException

Executes a Hibernate query on a stateless session. If the query returns more than one item, only the first one is returned.

Parameters:

clazz - The class of items returned by the iterator

query - The query to execute

session - The stateless session, this must be the same session that was used to create the query

sc - A session control object that should be kept alive while the query is executing, or null

Throws:

InterruptedException

Since:

2.7

getFutureResult

private static <T> T getFutureResult(Callable<T> callable,
                                     QueryExecutor.Cancelable cancelable,
                                     SessionControl sc)
                          throws InterruptedException,
                                 SQLException

Run the callable and wait for the result. Call Thread.interrupt() on this thread to abort the query.

Type Parameters:

T - The type of result that is returned by the callable

Parameters:

callable - The procedure to call

cancelable - An object that know how to cancel the running query if this thread is interrupted

sc - A session control object that should be kept alive while the query is executing, or null

Returns:

The result from the call

Throws:

InterruptedException - If this thread was interrupted during the query

SQLException