/**
* Uses <code>generator</code> to generate a command, execute it, then send the appropriate
* response.
*
* <p>The following steps occur:
*
* <ul>
* <li>The command and its assigned command runner are generated by the generator
* <li>The command is scheduled to execute on the command runner
* <li>The method blocks until the command is executed, or the timeout occurs, (the timeout
* period is a servlet configuration parameter)
* <li>When execution is complete, a response is sent using {@link
* JMSCommandGenerator#sendResponse(HttpServletResponse)}
* </ul>
*
* @param generator the selected <code>JMSCommandGenerator</code>
* @param request a <code>HttpServletRequest</code>
* @param response a <code>HttpResponse</code>
* @throws ServletException if there is a problem accessing the servlets <code>HJBRoot</code>
* @throws IOException if a problem occurs while writing the response
*/
protected void handleUsingSelectedGenerator(
JMSCommandGenerator generator, HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
generator.generateCommand(request, getRoot());
JMSCommand generatedCommand = generator.getGeneratedCommand();
synchronized (generatedCommand) {
HJBApplication.CommandTimeoutTask timeIsUp = new HJBApplication.CommandTimeoutTask();
try {
// Schedule the command with the command runner, then start a
// timer to time it out
generator.getAssignedCommandRunner().schedule(generatedCommand);
getTimeoutTimer().schedule(timeIsUp, getCommandTimeout());
while (!generatedCommand.isComplete()) {
// N.B. for this to work, JMSCommand#setComplete MUST be
// synchronized (and they all are! see
// BaseJMSCommand#completed)
generatedCommand.wait(getCommandTimeout());
if (timeIsUp.barIsClosed()) {
handleCommandExecutionWasTimedOut(generator, response, generatedCommand);
return;
}
}
} catch (InterruptedException e) {
handleExecutionThreadWasInterrupted(response, generatedCommand, e);
return;
} finally {
timeIsUp.cancel();
}
}
generator.sendResponse(response);
}
protected void handleCommandExecutionWasTimedOut(
JMSCommandGenerator generator, HttpServletResponse response, JMSCommand generatedCommand)
throws IOException {
// Instruct the command runner to ignore the command
// The command runner **will** log the instruction
// If the command has not run yet (i.e, the
// timeout occurred while the command was waiting to be
// run), the command runner will discard the ignored
// command
// Otherwise, at least both HJB and the HTTP user agent
// will have a message showing that something went
// wrong...
generator.getAssignedCommandRunner().ignore(generatedCommand);
String message =
strings()
.getString(
HJBStrings.COMMAND_EXECUTION_TIMED_OUT,
generatedCommand.getDescription(),
new Long(getCommandTimeout()));
LOG.error(message);
HJBException fault = new HJBException(message);
fault.fillInStackTrace();
new RuntimeExceptionHandler().sendHJBFault(response, fault);
}