Package pl.morgwai.base.servlet.guiced.jpa

Class SimpleAsyncJpaServlet

java.lang.Object

jakarta.servlet.GenericServlet

jakarta.servlet.http.HttpServlet

pl.morgwai.base.servlet.guiced.jpa.JpaServlet

pl.morgwai.base.servlet.guiced.jpa.SimpleAsyncJpaServlet

All Implemented Interfaces:

Servlet, ServletConfig, Serializable

public abstract class SimpleAsyncJpaServlet
extends JpaServlet

Dispatches request handling to the executor associated with the configured persistence unit. This prevents requests awaiting for an available JDBC connection from blocking server threads. This way the total number of server's threads can remain constant and small regardless of the number of concurrent requests, while the JDBC connection pool will be optimally utilized.

Base class for servlets that do not perform synchronous time consuming operations other than JPA related calls.

See Also:

Serialized Form

Field Summary

Fields inherited from class pl.morgwai.base.servlet.guiced.jpa.JpaServlet

containerCallContextTracker, entityManagerProvider, jpaExecutor

Constructor Summary

Constructors

Constructor	Description
SimpleAsyncJpaServlet()

Method Summary

Modifier and Type	Method	Description
protected long	getAsyncContextTimeout()	Returns timeout for AsyncContext.setTimeout(long); Negative number indicates that AsyncContext.setTimeout(long) should not be called in which case container default will take effect.
protected void	service(HttpServletRequest request, HttpServletResponse response)	Dispatches request handling to JpaServlet.jpaExecutor.
protected boolean	shouldCallAsyncContextComplete(HttpServletRequest request)	Whether AsyncContext.complete() should be called automatically at the end of request processing.
protected AsyncContext	startAsync(HttpServletRequest request, HttpServletResponse response)	Starts AsyncContext.

Methods inherited from class pl.morgwai.base.servlet.guiced.jpa.JpaServlet

executeWithinTx, executeWithinTx, getPersistenceUnitBindingName, init, removeEntityManagerFromRequestScope

Methods inherited from class jakarta.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service

Methods inherited from class jakarta.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleAsyncJpaServlet

public SimpleAsyncJpaServlet()

Method Detail

service

protected void service(HttpServletRequest request,
                       HttpServletResponse response)
                throws ServletException,
                       IOException

Dispatches request handling to JpaServlet.jpaExecutor. Closes the obtained EntityManager at the end. By default also calls AsyncContext.complete(): if a subclass wants to dispatch processing back to the container via AsyncContext.dispatch(String) or to another executor, then shouldCallAsyncContextComplete(HttpServletRequest) should be overridden to return false.

If the invoked doXXX method throws an exception, then, unless it's an IOException (indicating broken connection), it's logged at level ERROR and an attempt to send HttpServletResponse.SC_INTERNAL_SERVER_ERROR is made.
IOExceptions are logged at level DEBUG.
Errors are additionally re-thrown after being logged.

Overrides:

service in class HttpServlet

Throws:

ServletException

IOException

getAsyncContextTimeout

protected long getAsyncContextTimeout()

Returns timeout for AsyncContext.setTimeout(long); Negative number indicates that AsyncContext.setTimeout(long) should not be called in which case container default will take effect. By default 0 (meaning no timeout).

NOTE: combining non-container threads with AsyncContext timeout mechanism requires proper synchronization between main request processing code (running on JpaServlet.jpaExecutor thread and AsyncListener.onTimeout(AsyncEvent) (running on container thread) and may result in the main processing code throwing harmless exceptions in case of timeouts even if the processing was discontinued (for example as of Jetty 10.0.x, if response output was obtained, an interceptor at the end of a given doXXX() method will throw an exception when trying to close it for the 2nd time).

shouldCallAsyncContextComplete

protected boolean shouldCallAsyncContextComplete(HttpServletRequest request)

Whether AsyncContext.complete() should be called automatically at the end of request processing. By default true. Should be overridden if processing is dispatched back to the container via AsyncContext.dispatch(String) or to another executor,

startAsync

protected AsyncContext startAsync(HttpServletRequest request,
                                  HttpServletResponse response)

Starts AsyncContext. By default calls ServletRequest.startAsync(). Can be overridden if ServletRequest.startAsync(jakarta.servlet.ServletRequest, jakarta.servlet.ServletResponse) needs to be used.