Pushing values

In this section of the guide we will push some values from the parameter server. Make sure your sbt console is still open and the matrix from the previous pull section is still available

Now let's push some values to the matrix

val result = matrix.push(Array(0L, 1L, 2L), Array(100, 200, 300), Array(0.1, 3.1415, 9.999))

This will push the following values:

• Add 0.1 to the current value of row 0, column 100
• Add 3.1415 to the current value of row 1, column 200
• Add 9.999 to the current value row 2, column 300

This method is asynchronous and it returns a Future[Boolean] immediately. Attach a callback to verify that the process completed

result.onSuccess {
    case true => println("Push successfull")
}

Now let's check whether these new values are indeed on the parameter server by pulling the values:

matrix.pull(Array(0L, 1L, 2L), Array(100, 200, 300)).onSuccess {
    case values => println(values.mkString(", "))
}

This should indeed print out the values:

0.1, 3.1415, 9.999

Now we will show the additive nature of updates of the parameter server. Let's add 0.1 to row 0, column 100 to turn the current value of 0.1 into 0.2. Let's wait for that update to complete by using Scala's Await concurrency method to block execution:

import scala.concurrent.Await
Await.result(matrix.push(Array(0L), Array(100), Array(0.1)), 30 seconds)

Now verify the result on the parameter server:

matrix.pull(Array(0L), Array(100)).onSuccess {
    case values => println(values.mkString(", "))
}

And we should observe the expected result:

0.2

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