Fetch info about the memory of you machine with Scala

memInfo.scala

import scala.language.postfixOps
import scala.util.{Success, Failure}
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.duration._
import scala.concurrent._
import scala.util.Try

import sys.process._
import concurrent.Future
import concurrent.Promise

/**
 * I am trying to use this to fetch info about memory in a mac os
 * since it does not seem to hae a /proc/memInfo file I went for the 
 * approach of running top command in batch. This information is for
 * educational purpose. Feel free to send me a better/correct approach
 * to find out the ammount of total RAM of a machine and the available
 * memory it has.
 */

trait MemInfoCommand {
	private lazy val memLineValues = getMemLineValues()

	def totalMemory = memLineValues._1 / (1024 * 1024)
	def usedMemory = memLineValues._2 / (1024 * 1024)
	def freeMemory = memLineValues._3 / (1024 * 1024)
	def availableMemory = 0 //TODO

	def getMemLineValues(): (Double, Double, Double) = {
		val memFuture = Await.result(readMemLine, 5.second)
		// KiB Mem:   8060048 total,  7586092 used,   473956 free,   672268 buffers
		val res = memFuture.split(":")(1).split(",").map(x => x.trim.split(" ")(0).toDouble)
		val (total, used, free) = (res(0), res(1), res(2))
		(total, used, free)
	}

	def readMemLine(): Future[String] = {
		val memLinePromise = Promise[String]()
		Future {
		  	//-b1 is for Linux and -l1 is for MacOS
			val memLine = Try(("top -b1" #| "head -n 10" #| "grep Mem" !!).split("\n")(0))
			//val memLine = Try(("top -l1" #| "head -n 10" #| "grep Mem" !!).split("\n")(0))
			
			memLine match {
				case Success(line) => memLinePromise.success(line)
				case Failure(ex) => memLinePromise.failure(ex)
			}
		}
		memLinePromise.future
	}

	override def toString = {
		var str = f"Total Memory [$totalMemory%2.2f GB]\n"
		str += f"Used Memory [$usedMemory%2.2f GB]\n"
		str += f"Free Memory [$freeMemory%2.2f GB]\n"
		str += f"Available Memory [$availableMemory%2.2f GB]\n"
		str
	}
}

object SystemInfo extends MemInfoCommand {
	override def toString = {
		super[MemInfoCommand].toString
	}

}

println(SystemInfo)

output.md

#Problem faced

I am new to Scala and rusty in Java.

When running the top command it throws an exception that I am not capturing properly and I dont see where the error seems to be or how could I correct it. As you can see in the output, the results are given properly, but the exception is always thrown. Ideas?

I/O error Pipe closed for process: [top, -b1]
java.io.IOException: Pipe closed
	at java.io.PipedInputStream.checkStateForReceive(PipedInputStream.java:260)
	at java.io.PipedInputStream.awaitSpace(PipedInputStream.java:268)
	at java.io.PipedInputStream.receive(PipedInputStream.java:231)
	at java.io.PipedOutputStream.write(PipedOutputStream.java:149)
	at scala.sys.process.BasicIO$.loop$1(BasicIO.scala:236)
	at scala.sys.process.BasicIO$.transferFullyImpl(BasicIO.scala:242)
	at scala.sys.process.BasicIO$.transferFully(BasicIO.scala:223)
	at scala.sys.process.ProcessImpl$PipeThread.runloop(ProcessImpl.scala:159)
	at scala.sys.process.ProcessImpl$PipeSource.run(ProcessImpl.scala:179)
Total Memory [7,69 GB]
Used Memory [7,45 GB]
Free Memory [0,24 GB]
Available Memory [0,00 GB]

I haven't tried so far but, have you tried invoking .lines instead of .!! ? Since top command output is not finite, maybe using a Stream[String] would be a good idea...

The use of .lines/ .lineStrem was solving the issue, thank you but it seems the main problem was a bad use of the top command parameters. When using the wrong top command but capturing the Stream[String], the execution was taking long time due to the nature of the top command in batches.

This solves it. Setting topas returning one and only batch
https://github.com/miguelsaddress/SystemInfoParser/blob/cf805e8eaa147ff84d4390c6bc06457fcd38dfac/src/main/scala/com/mamoreno/systemInfo/os/MacOsInfo.scala#L26
Thanks for your help ^_^