newSignal

newSignal* { ( description : string ) } : 4D.Signal

Parameter	Type		Description
description	string	→	Description for the signal
Result	4D.Signal	←	Native object encapsulating the signal

Description

The newSignal command creates a 4D.Signal object.

A signal is a shared object which can be passed as parameter from a worker process to another worker process, so that:

• the called worker can update the signal object after specific processing has completed
• the calling worker can stop its execution and wait until the signal is updated, without consuming any CPU resources.

Optionally, in the description parameter you can pass a custom text describing the signal. This text can also be defined after signal creation.

Since the signal object is a shared object, it can also be used to maintain user properties, including the .description property, by calling the use...end structure.

Returned value

A new 4D.Signal object.

Example

Here is a typical example of a worker that sets a signal:

 var signal : 4D.Signal
 var info : string
 signal = newSignal("This is my first signal")

 callWorker("myworker","doSomething",signal)
 signaled = signal.wait(1) //wait for 1 second max

 if(signaled)
    info = "myworker finished the work. Result: "+signal.myresult
 else
    info = "myworker has not finished in less than 1s"
 end

The doSomething method could be like:

 declare (signal : 4D.Signal)
  //any processing
  //...
 use(signal)
    signal.myresult = processingResult  //return the result
 end
 signal.trigger() // The work is finished