Defensive API: Killing Processes and Future/ Watchdog Implementation.

[hsyed]

I'm writing a Java OSGi wrapper via sPDF and i'd like to guard against denial of server and bugs in wkhtmltopdf. I think the there should be some defensive elements to the API.

The PDF Class could do with a run method that returns a handle to the Process object to enable a watchdog to kill the process.

Additionally Future and watchdog implementations would be handy.

[hsyed]

Having a method that constructs the ProcessBuilder without executing it should be a simple enough change.

  /**
   * Runs the conversion tool to convert sourceDocument HTML into
   * destinationDocument PDF.
   */
  def run[A, B](sourceDocument: A, destinationDocument: B)(implicit sourceDocumentLike: SourceDocumentLike[A], destinationDocumentLike: DestinationDocumentLike[B]): Int = {
    processBuilder(sourceDocument, destinationDocument).!
  }

  /**
   * constructs a processBuilder geared for different execution scenarios. 
   */
  def processBuilder[A, B](sourceDocument: A, destinationDocument: B)(implicit sourceDocumentLike: SourceDocumentLike[A], destinationDocumentLike: DestinationDocumentLike[B]): scala.sys.process.ProcessBuilder = {
    val commandLine = toCommandLine(sourceDocument, destinationDocument)
    println(commandLine.mkString(" "))
    val process = Process(commandLine)
    def source = sourceDocumentLike.sourceFrom(sourceDocument) _
    def sink = destinationDocumentLike.sinkTo(destinationDocument) _

    (sink compose source)(process)
  }