WaitAsynchronous (Daemon function)

Wait for daemon to complete actions.

WaitAsynchronous is a member of the Daemon class

This callable method waits for the completion of the commands issued on a daemon thread by the RunAsynchronously (Daemon function), and it retrieves various outputs from those commands.

WaitAsynchronous Syntax

[%strL =] %daem:WaitAsynchronous( [%outputObj] -
                                  [, Info=%infoObj] )

Syntax Terms

%strL

If specified, a Stringlist object that contains the terminal output from the command or commands run on the daemon thread.

%daem

A previously defined Daemon object.

%outputObj

The object returned from the daemon method object by the ReturnObject(Daemon function) invoked on the daemon thread. This optional argument is passed by deep copy and not by reference, so %outputObj must be deep copyable, as described in Copying objects. The object set to %outputObj is the object passed by the daemon thread using the ReturnObject(Daemon function). Because %outputObj is an output variable, it cannot itself be contained inside an object: that is, it must be a local or a common %variable.

Info=%infoObj

An optional, name required parameter that indicates a second output object returned from the daemon method object by the ReturnInfoObject(Daemon function) invoked on the daemon thread. The object set to %infoObj is the object passed by the daemon thread using the ReturnInfoObject method. This optional argument is passed by deep copy and not by reference, so %infoObj must be deep copyable, as described in Copying objects. Because %infoObj is an output variable, it cannot itself be contained inside an object: that is, it must be a local or a common %variable.

Exceptions

This subroutine can throw the following exceptions:

DaemonLost

If the daemon object is lost (probably restarted), a DaemonLost exception is thrown. This exception will only be thrown in Sirius Mods.

Usage Notes

• WaitAsynchronous was introduced in Sirius Mods Version 7.0.
• If WaitAsynchronous is issued against a daemon object that is not currently running asynchronously (RunAsynchronously was issued against it), the request is canceled. Note that this does not mean that the daemon must actually still be running -- if the daemon thread has run all the commands in the RunAsynchronously call, not only is WaitAsynchronous allowed, it is required before anything else can be done with the daemon. And, in any case, it's the only way of retrieving the outputs from the asynchronous request.
• This is an example WaitAsynchronous call:

  %daem:runAsynchronously(%commands)
  ...
  %strlist = %daem:waitAsynchronous(%list2)
  

• The output Stringlist and parameters from WaitAsynchronous are identical to the output Stringlist and parameters for the Run method, so see Daemon class. for more information on and examples of output Stringlists and objects.
• The inputs and outputs from the combination of RunAsynchronously and WaitAsynchronous are identical to the inputs and outputs from the Run method. As such, it should be a relatively simple task to split a Run into a RunAsynchronously and WaitAsynchronous, allowing the daemon processing to be performed in parallel with parent thread processing or the processing on another daemon thread. For example, if a request has the following statements:

  %out1 = %daem1:run(%cmds1, %inobj1, %outobj1)
  %out2 = %daem2:run(%cmds2, %inobj2, %outobj2)
  

  The statements can be easily split up into the following, and the processing on the two daemons would be performed in parallel with each other:

  %daem1:runAsynchronously(%cmds1, %inobj1)
  %daem2:runAsynchronously(%cmds2, %inobj2)
  %out1 = %daem1:waitAsynchronous(%outobj1)
  %out2 = %daem2:waitAsynchronous(%outobj2)
  

  Note that this will buy nothing if the requests are CPU-intensive and the request is not running with AMPSUBS>0 (requires MP/204). Note also that if the daemons hold or require record locks that might conflict with each other, such a split will not work. Finally, since RunAsynchronously is not allowed for a transactional daemon, such a split is not feasible for transactional daemons.