First, we need to define the CnC graph:

FindPrimesCncDefinition.scala
object FindPrimesCncDefinition {
  def main(args: Array[String]): Unit = {
    ApplicationName("FindPrimes")
    TargetPackage("findprimes") // default package
    TargetDirectory("findprimes")

    Comment("Item Collections")
    // The prime numbers as identified by the compute step
    ItemCollection[Point, Int]("primes")

    Comment("Tag Collections")
    // The tag values are the odd numbers in the range [3..n]
    TagCollection[Point]("oddNums")

    Comment("Step Dependences")
    // The compute step may produce a prime number (in the form of a tag instance)
    StepDependence("compute", List[String](), List("primes"))

    Comment("Step Prescriptions")
    // For each oddNums instance, there is
    Presription("oddNums", List("compute"))

    Comment("Environment Collections")
    // Input from the environment: initialize all tags
    // Output to the environment is the collection of the prime numbers
    EnvironmentDependence(
      List("oddNums"),
      List("primes")
    )
  }
}

The CnC graph states that oddNums is a Tag Collection with strings as the tags.

Next, we define the Item Collection primes which has strings as tags and integer as its values. These types are defined in the format tagType->itemType before the name of the Item Collection.

env is a keyword representing the environment and in this example we define the environment will put tags (of type Point) into the oddNums Tag Collection and read the results from the primes Item Collection.

After defining the CnC graph, we need to run this file using the CnC-Scala translator using the following command:
cnc_scala_translate FindPrimesCncDefinition

Running the command will generate some Scala files. This is how the directory should look:

FindPrimes:
  findprimes:
    FindPrimes.cnc
    FindPrimesBase.scala
    FindPrimesGraph.scala
  FindPrimesCncDefinition.scala

In short, these are what the files represent:

File Name

Function

FindPrimes.cnc

A textual form of the CnC graph understood by other CnC implementations.

FindPrimesGraph.scala

A Scala class representation the CnC graph. Users will need to instantiate instances of this graph and invoke the run() method to run their CnC program. Users should not need to edit the contents of this file.

FindPrimesBase.scala

This file includes Scala traits for the different Step instances. Users will need to implement these interfaces in their custom Steps. The file also includes default implementations of the Tag Collections. Users should not need to edit the contents of this file.

Here is how a trait for the Step looks like:

FindPrimesBase.scala
import edu.rice.cnc.api._
import edu.rice.cnc.runtime._
import util.continuations.cps

trait ComputeStep extends Step {
  def compute(
    tag: Point ,
    outPrimes: OutputCollection[Point, Int]
  ): Unit@cps[Any]
}

Below is a simple Step implementation:

UserFindPrimesStep.scala
//********************************************************************************
//
// ***** AUTO-GENERATED FILE DO NOT MODIFY!  *****//
//
//********************************************************************************

import edu.rice.cnc.api._
import util.continuations.cps

class UserComputeStep() extends ComputeStep {
  def compute(
               tag: Point,
               outPrimes: OutputCollection[Point, Int]
               ): Unit@cps[Any] = {
    val number: Int = tag(0)
    var factor: Int = 3
    while (number % factor != 0) {
      factor += 2
    }
    if (factor == number) {
      outPrimes.put(tag, number)
    }
  }
}

This step does not rely on input from an Item Collection, instead it uses the tag as the input. Please refer to the Partition String example for a step instance that retrieves inputs from Item Collections.

After providing the Step implementations and a Main class to run and launch the program, the directory should now have the following structure:

FindPrimes:
  findprimes:
    FindPrimes.cnc
    FindPrimesBase.scala
    FindPrimesGraph.scala
    FindPrimesMain.scala
    UserFindPrimesStep.scala
  FindPrimesCncDefinition.scala

Now, run the CnC-Scala compiler to compile the Scala files:
cnc_scala_compile

Once the files have been successfully compiled, the application can be run using the CnC-Scala run command:
cnc_scala_run -Dcnc.workers=4 -Dcnc.enableForkJoin=true findprimes.FindPrimesMain 100

Running this program with an input of 100 should produce the following output:

Determining primes from 1-100
Number of primes: 24
Contents of Collection'primes'
  [3]=3
  [5]=5
...
  [83]=83
  [89]=89
  [97]=97

HabaneroRuntime:
  num workers=4
  executor service=jsr166y.ForkJoinPool@39385660[Terminated, parallelism = 4, size = 0, active = 0, running = 0, steals = 49, tasks = 0, submissions = 0]
  async instances=50
  activity instances=50
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