src/Pure/General/timing.scala

try to avoid races again (cf. 8c37cb84065f and fd3a36e48b09);

/*  Title:      Pure/General/timing.scala
    Module:     PIDE
    Author:     Makarius

Basic support for time measurement.
*/

package isabelle


object Timing
{
  def timeit[A](message: String, enabled: Boolean = true)(e: => A) =
    if (enabled) {
      val start = java.lang.System.currentTimeMillis()
      val result = Exn.capture(e)
      val stop = java.lang.System.currentTimeMillis()

      val timing = Time.ms(stop - start)
      if (timing.is_relevant)
        java.lang.System.err.println(
          (if (message == null || message.isEmpty) "" else message + ": ") +
            timing.message + " elapsed time")

      Exn.release(result)
    }
    else e
}

class Timing(val elapsed: Time, val cpu: Time, val gc: Time)
{
  def is_relevant: Boolean = elapsed.is_relevant || cpu.is_relevant || gc.is_relevant

  def message: String =
    elapsed.message + " elapsed time, " + cpu.message + " cpu time, " + gc.message + " GC time"

  override def toString = message
}