org.lsst.ccs.gconsole.agent.command

Class CommandTask

java.lang.Object

org.lsst.ccs.gconsole.agent.command.CommandTask

public class CommandTask
extends Object

A CommandTask sends a command to a target subsystem and handles the responses. Methods are provided to check if the command processing is complete, to wait for its completion, and to retrieve the result.

Author:

onoprien

Constructor Summary

Constructors

Constructor and Description
CommandTask(CommandSender sender, CommandHandle handle, Duration timeout, String command, Object... args) Creates a CommandTask.

Method Summary

Modifier and Type	Method and Description
boolean	cancel() Cancels this command task.
Object	get() Waits if necessary for the command execution to complete, and then returns its result.
Object[]	getArguments() Returns the command arguments.
String	getCommand() Returns the command as a string in subsystem/path/method format.
Object	getResult() Waits if necessary for the command execution to complete, and then returns its result or exception.
boolean	isCancelled() Returns true if this command task was canceled before it completed normally.
boolean	isDone() Returns true if this command task has completed.
void	send() Triggers sending the command to the target subsystem.

Methods inherited from class java.lang.Object

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

Constructor Detail

CommandTask

public CommandTask(CommandSender sender,
                   CommandHandle handle,
                   Duration timeout,
                   String command,
                   Object... args)

Creates a CommandTask.

Parameters:

sender - CommandSender that created this task.

handle - Object to be notified of responses to the command.

timeout - Timeout. Zero means the command will never time out. Negative timeout means its absolute value will be used and the custom timeout suggested by the target subsystem through an ACK will be ignored.

command - Command in subsystem/path/method format.

args - Command arguments.

Method Detail

send

public void send()

Triggers sending the command to the target subsystem.

get

public Object get()
           throws IllegalStateException,
                  InterruptedException,
                  org.lsst.ccs.messaging.CommandRejectedException,
                  CancellationException,
                  TimeoutException,
                  ExecutionException

Waits if necessary for the command execution to complete, and then returns its result.

Returns:

The command result.

Throws:

IllegalStateException - If the command cannot be sent.

InterruptedException - If the current thread was interrupted while waiting.

org.lsst.ccs.messaging.CommandRejectedException - If the command was rejected by the target subsystem.

CancellationException - If the command was canceled.

TimeoutException - If the command timed out.

ExecutionException - If an exception was thrown by the target subsystem while executing the command, or the result of the execution is an instance of Throwable.

getResult

public Object getResult()
                 throws InterruptedException

Waits if necessary for the command execution to complete, and then returns its result or exception. Unlike the get() method, this method does not throw command-related exceptions. Instead, the outcome of this command task is reported through the return value.

Returns:

The command result, or the exception that would be thrown by the get() method.

Throws:

InterruptedException - If the current thread was interrupted while waiting.

cancel

public boolean cancel()

Cancels this command task. Once the command is canceled, CommandHandle methods will not be called, and the get() method will throw CancellationException. The target subsystem will not be notified of cancellation.

Returns:

False if the command task could not be canceled, typically because it has already completed normally; true otherwise.

isCancelled

public boolean isCancelled()

Returns true if this command task was canceled before it completed normally.

Returns:

True if the command was canceled.

isDone

public boolean isDone()

Returns true if this command task has completed. Completion may be due to normal completion, an exception, or cancellation.

Returns:

True if this task completed.

getCommand

public String getCommand()

Returns the command as a string in subsystem/path/method format.

Returns:

Command.

getArguments

public Object[] getArguments()

Returns the command arguments.

Returns:

Command arguments.